Chromium(III) phosphate

Chromium(III) phosphate describes inorganic compounds with the chemical formula CrPO4.(H2O)n, where n = 0, 4, or 6. All are deeply colored solids. Anhydrous CrPO4 is green. The hexahydrate CrPO4•6H2O is violet.
Synthesis.
Chromium phosphate is prepared by treating a phosphoric acid solution of chromium(VI) oxide with hydrazine.
Hexahydrated chromium(III) phosphate.
Hexahydrate chromium phosphate, CrPO4•6H2O, is prepared by reducing chromium trioxide, CrO3, with ethanol in the presence of orthophosphoric acid, H3PO4, at temperatures ranging from −24 °C to +80 °C.
Mesoporous phase.
Gel-like chromium(III) phosphate is prepared through the reduction of ammonium dichromate, (NH4)2Cr2O7, using ethanol, CH3COOH, and nitric acid, HNO3. This process is done in the presence of ammonium dihydrogen phosphate and urea at an elevated temperature where tetradecyltrimethylammonium bromide (TTBr) is used as structure directing agent.
Films.
Preparation of textured chromium phosphate is carried out by mixing equimolar solutions of aqueous chromium nitrate and diammonium phosphate in a dish placed in a sealed chamber with the low temperature ammonia vapor catalyst diffusing into the solution at a constant rate. After 24h, the resulting purple film grows out from the liquid through the hydrolysis and polycondensation occurring in the reaction environment at the air/liquid and film/liquid boundary. Surface tension makes the film compact making it easy to insert a microscope slide and lift the film from underneath the solution surface. Once obtained the solution is washed with deionized water and ethanol, then dried in a vacuum.
Amorphous phase.
The preparation of anhydrous chromium(III) phosphate begins by grinding a mixture of 75 mol% of chromium(III) oxide, Cr2O3, and 25 mol% of pure ammonium hydrogen phosphate, (NH4)2HPO4. This mixture is pressed into pellets and heated under air pressure at 400 °C for 24h in order to remove ammonia and water. After this, a heating sequence of 450 °C (24 h), 700 °C (3⋅24 h), 800 °C (24 h) and 850 °C (2⋅24 h) occurs. The pellet mixture is gradually cooled thereafter.
Physical Properties.
Crystal Structure.
Chromium(III) phosphate can exist as two isomorphs. Its β-isoform is orthorhombic with the "Cmcm" space group (a = 0.5165, b = 0.7750, c = 0.6131 nm). The structure consists of infinite chains of trans edge-sharing CrO6 octahedra, which run parallel to the c-axis, and are linked by PO4 tetrahedra. Above 1175 °C, β-CrPO4 converts to α-CrPO4. α-CrPO4 is orthorhombic as well, with the "Imma" space group (a = 1.0380, b = 1.2845, c = 0.6278 nm). The structure consists of an infinite network of linked polyhedra with a CrO6 octahedron and a PO4 tetrahedron sharing a common edge. The Cr3+ site form edge-sharing Cr(2)/Cr(2') pairs and share two corners with the four Cr(1) octahedra.
Magnetic Properties.
The magnetic properties of the β-CrPO4 are a result of the cation-cation distances along the octahedral chains which give rise to strong direct-exchange interactions and even metal-metal bonding. Neutron diffraction studies reveal that the spiral moments in β-CrPO4 are collinear and anti-ferromagnetically coupled along the chains in the 001 planes, at low temperature (5K, µeff = 2.55µB).
Observations from a diffraction study has shown that at low temperature(2K), the α-CrPO4 octahedra CrO6 units build up an infinite, three-dimensional network expected to provide strong Cr-O-Cr magnetic superexchange linkages with exchange pathway through the phosphate group. These linkages give the structure its anti-ferromagnetic characteristic (Ɵ = -35.1 K, µeff = 3.50µB) which results in the anti-parallel magnetic spins in the plane that is perpendicular to the chains of the octahedral CrO6.
Chemical Properties.
Ion exchange.
At a high temperature and pH ranging from 283-383K and pH 4-7 respectively, equilibrated KOH/HCl solution, insoluble CrPO4 solid and aqueous cation solution yield a sorption reaction. Studies reveal that CrPO4 catalyzes the adsorption of divalent cations onto its amorphous surface through the cation exchange mechanism. The mechanism suggests that the H+ ions are liberated from the solid to aqueous phase as the cations become hydrolyzed and adsorb onto the catalyst surface. Thus, a decrease in the pH of the reaction is used as a direct indicator of the rate of adsorption in the reaction:
nP-OH + Mz+ ⇔ (P-O) n Mz-n + nH+ where P-O = solid
A plot of the Kurbatov equation is used to relate the release of H+ ion to the equilibrium constant of the reaction:
Log Kd = log Kex + npHeq
where Kd (l g-1) represents the distribution coefficient, and n is the slope of the straight line giving an indication of the H+/Mz+ stoichiometry of the exchange reaction. Under similar conditions, the selectivity of CrPO4 for dative cations follows the sequence: Pb2+ > Cu2+ > Ni2+ ≅ Cd2+. Increases in temperature and pH enhances the ion exchange reaction.
Chromium(III) phosphate is also used to catalyze cation exchange in sorption reactions. This catalysis is widely used in the reduction of metal toxicity during environmental clean-ups. This has been applied in decreasing the concentration of lead in aquatic habitat and drinking water.
Application.
Anti-corrosive Coating.
Paints containing chromium(III) phosphate have been used as corrosion resistant coating for metals. The paints consist of aqueous acidic chromium (III) phosphate solution which convert to a consistent film when applied onto metals heavily used in manufacturing and utility such as zinc, zinc alloy, aluminum and aluminum alloy substrates. Application methods include electroplating, immersing or spraying the solution on the surface of the substrate.
Catalyst.
Chromium (III) phosphate has various applications in the polymer industry. Combined chromium(III) aluminum phosphate is widely used as a catalyst in the alkylation of aromatic hydrocarbons using alcohols such as the methylation of toluene using methanol. The alcohol is dehydrated into ether while the alkyl substituted product could be used as an intermediate in the manufacture of synthetic fibers such as poly(ethylene terephthalate).
Polymer.
Pretreatment with chromium (III) phosphate-silicate is also used as a laminated structure to dampen vibration and noise in a motor.
Toxicity.
Although chromium(III) phosphate is hardly soluble in water, overexposure to the compound from the environment, industrial location and abrasions from metal on metal implants could have harmful effects. The toxicity of chromium(III) phosphate depends on the duration of exposure, chromium(III) phosphate concentration, entry routes across a membrane barrier and release of trivalent chromium ion from the chromium(III) phosphate. Macrophage cells in the body exposed to chromium(III) phosphate engulf or phagocytize the compound into its endosomal and lysosomal environment which is acidic. This catalyzes a proteolytic reaction yielding a dose-dependent increase in chromium(III) ion release in the affected cells. The Cr3+ ions has toxic effects on the proteins of the cytosol and mitochondria by oxidatively modifying their chemical properties thus disenabling from performing their functions. Proteins with high metal affinity such as enolase, catalase enzymes and hemoglobin, ferritin molecular transporters are affected. This may ultimately lead to nephrotoxicity, reproductive and developmental toxicity due to tissue damage, necrosis and inflammation.


Germanium nitride

Germanium(IV) nitride is an inorganic compound with the chemical formula Ge3N4. It can be produced through the reaction of germanium and ammonia:
Structure.
In its pure state, germanium(IV) nitride is a colorless, inert solid that crystallizes in many polymorphs, of which the most stable is the trigonal β-form (space group "P"31"c"). In this structure, the germanium atoms are tetrahedrally coordinated while the nitrogen atoms are trigonal planar. The γ-form, which forms under high pressure, has a spinel structure.


Deuterated DMF

Deuterated dimethylformamide ((CD3)2NCOD), also known as deuterated DMF, is an isotopologue of DMF ((CH3)2NCOH) in which the hydrogen atom ("H") is replaced with a deuterium isotope ("D"). Deuterated DMF is a relatively uncommon solvent used in NMR spectroscopy.


Contorted aromatics

Contorted aromatics or more precisely contorted polycyclic aromatic hydrocarbons are polycyclic aromatic hydrocarbons (PAHs) in which the fused aromatic molecules deviate from the usual planarity.
Introduction.
The comparison of structures of graphene and fullerene can help comprehend the origin of curved pi surfaces and contortion in PAHs. Both graphene and fullerene bear resemblance in having sp2 hybridized carbons however, exhibit different geometries (allotropes of carbon). The fact that fullerenes have five membered rings incorporated among six membered rings, makes them spherical whereas graphene remains planar due to the presence of exclusively all six membered rings in it. In general, the ideal C-C bond length and angle for C-C-C or C-C-H is about 1.42 Å and 2π/3 respectively whereas in corannulene structure, a five membered ring is surrounded by six membered rings contributing to non-planarity in the molecule. This leads to change in bond angles and bond lengths rendering non-planarity in the structure. Such type of contortions in the structure of PAHs are known as ‘arching distortions’. The hydrogen and carbon atoms of the PAH molecule which are either closest to one another due to non-planar structure or suffer from angle strain are known as the "saturated" ones and may serve as a source of ‘splitting distortions’ Figure 2.
The region of a contorted molecule having saturated hydrogens and carbons is known as bay region (having white spheres or saturated hydrogens) Figure 4.
Another reason for making the PAHs molecules contorted may be the size of these molecules. Theoretical vibrational frequency studies of C6n2 H6n (n=2-12) on coronenes using quantum chemical calculation (Hartree-Fock and DFT) show accelerated loss of planarity on increasing size of PAH molecules in-spite of having a stable structure due to conjugation, delocalization and aromatization. A gas phase coronene can be expected to switch to non-planar geometry around n=9-12. The combined strain of arching and splitting distortion is thought to force the PAH molecules out of the plane and generate contortions. A switch to umbrella geometry may occur at n=12 Figure 3.
Figure 4 illustrates the strain energies carried by three different PAH molecules. The white spheres represent saturated hydrogens and the grey spheres as the leading carbons contributing to strain energy due to non-planar distortions.
Table1 shows the energy values for non-planarity (strain) of PAHs in k cal/mole for five membered and six membered ring molecules with common helicene and coronene units with reference to fullerenes C60=483.91 k cal/mol and C70=492.58 kcal/mol. The shaded parts indicate the bay regions in PAH molecules bearing the most strain. The strain energy is expressed in units of 10-2 kcal/mol.
The Enp non-planar strain (contortion) energies indicate how much a PAH molecule deviate from the standard planar structure in terms of bond angles and bond lengths. The standard for PAHs is usually graphite. An Enp is introduced in the molecular structure whenever it deviates from the standard structural geometries to get the strain relief. The Enp values represented for a variety of PAHs in Table 1 are shown. Two types of contortions or Enp can be observed based on the data in Table 1. The PAH molecules shown in table 1 are based on two kinds of motifs. The ones based on helicenes and the others on corannulenes. The small Enp values (ranging from 0.25-8 k cal/mol) represented by the helicene based molecules and are because of weak contortions in their structures. The contributing factor seems to be the presence of only splitting distortions in the bay region of these PAHs. However, the other group based on corannulenes show higher Enp values (ranging from 1.86-116 k cal/mol). The higher Enp values suggest stronger contortions which may have originated due to the higher number of fused rings and a five membered ring core in PAH molecules along with the bay region contortions.
Based on the above discussion it can be cautiously inferred that the combined effects of non-planar strain caused by arching and splitting distortions as well as the size of PAH molecules give birth to contortions in PAHs structures.
These unparalleled contorted molecules exhibit wide absorption spectrum and enhanced charge transport properties which make them potential candidates for electronic and optoelectronic applications. The curvature in these molecules cause slight shifting of the frontier orbitals from ideal parallel symmetry. The departure from parallel overlap induces modification in HOMO and LUMO eventually giving birth to changed optical properties. Inversion of these molecules in solution may allow changes in orbital geometry, thereby, broadening the absorption and emission spectra which is useful for light emitting diode applications. Some derivatives of corannulenes act as blue emitters. The efficient charge transport in contorted aromatic molecules is related with self-assembly and crystal packing. The discotic contorted molecules in crystals tilt relative to the columnar axis because of the interaction of protons with the electronic cloud of neighboring PAHs molecules. This tilt forbids the latitudinal stacking of molecules and allows only the longitudinal stacking Fig 6. This property enhances the linear overlap of orbitals and promote the charge carrier mobility. All these properties make the contorted PAHs excellent candidates for semiconductor, organic field effect transistors (OFETs), and organic photovoltaic (OPV) devices applications.
Discs and ribbons Fig:1 constitute the major classes of contorted aromatic structures. The discs possess a concave π molecular surface and upon substitution with a hydrocarbon side chain can be self- assembled to turn into columns figure5. These columns can express the desired properties of nanoscale phase separation, charge separation and charge transport in films. The concave discs can behave as molecular sensors for electron deficient aromatic molecules. Once in contact with electron acceptors like fullerenes they show typical characteristics of a p-n junction in shape of a ball and socket joint model Figure 7.
The ribbons, on the other hand, can be envisioned as pieces of graphene being spun into ribbons owing to contortions. They are good materials for OFETs as electron transporting materials. With the incorporation of donor polymers they behave as potential alternative for non-fullerene based organic solar cells. The focus on developing the non-fullerene organic semiconductor is because of some potential
downsides of fullerene-based materials for n-type organic molecules. Fullerenes fail to fulfil the basic criterion of good organic semiconductors by not having good absorption in UV-Vis region and poor tunability upon substitution with various groups. These demands have fuelled research towards finding new materials including contorted aromatic molecule which possess fundamental qualities of wide absorption range and better charge transportation. These molecules also provide controlled π-π stacking in small domains and excellent charge percolation pathways.
History.
The Nobel Prize of 1953 won by Hermann Staudinger for characterizing macromolecules as polymers opened the gateway for a new field of materials. Ever since that time the polymers have been replacing conventional materials like wood, metals and now are widely used as conductors and semiconductors in commercialized products. The age of plastic based society really began in the wake of 1953’s Nobel prize. It was later revealed in 1970 that some polymers can exhibit appropriate electrical conductivity. The thought would have been consolidated by the fact that graphite a purely carbon-based material was capable of electric conduction due to its expansive π conjugation
system. The organic conductors are however, not as good as metal-based conductors. By late 1970s efforts were made for fabricating polymer-based power transmission lines, light weight motors and novel approaches for achieving superconductivity. Currently massive worldwide efforts for achieving higher power conversion efficiencies in OPVs, better hole carrier mobilities in OFETs in π-conjugated polymer domain are underway. The discovery of iodine doped polyacetylene and its electrical properties in 1977 fuelled the research work towards finding better and more efficient conjugated organic polymers. The ‘2000’ Nobel Prize in chemistry by Alan J. Heeger, Alan G. Macdiarmid, and Hideki Shirakawa in recognition of their contribution towards unravelling the polyacetylene figure electronics set another milestone in the journey of finding conducting polymers. Over the past two decades developments have been made in synthesizing new polymers like polythiophenes, polyphenylenes and polyphenylene sulphides and small organic molecules. The contorted aromatic molecules due to their properties of making ladder polymers, self-assembly and innate charge percolation pathways because of small domains and π stacking other than providing conjugations throughout their structure became another focal point for their use in a variety electronic application. These contorted molecules offer a delicate balance and phase separation which can promote the power conversion efficiency (PCE) close to theoretical limit of 20%. Widespread futuristic studies on synthesizing new small contorted aromatic molecules capable of being stable over longer period and higher PCE are being carried out.
From inorganic semiconductors to Contorted Aromatic Small molecules.
One may keep getting pestered by the simple question of why we need the organic solar cells? No wonder if the commercial inorganic silicon based solar cells had been doing fine no one would have ever thought of an alternative way of getting at the same point. The answer is very simple. Inorganic solar cells have their own pros and cons. But the point of concern would be to address the issues which have limit their wide spread use so far. One of the major drags in commercializing this technology on massive scale is the cost. Highly purified silicon production needs a lot of energy which would add to the cost of this technology on one hand and hurt the green chemistry on the other. Efforts are underway to bring about new ways to aggregate as much stacks of silicon material as possible to increase the PCE which does not seem to help as far as cost reduction is concerned. The inorganic solar panels are heavy and non-flexible. These factors count towards limiting this technology for mass adaptation and may not be able to compete with other green and cheap energy sources like wind and hydro power. Multi junction silicon based solar cells however, are the best so far for providing highest PCE 44.4%.
All the above-mentioned challenges have been pushing the scientific community to seek for new opportunities. The organic solar cells seem to supersede their predecessors in many aspects but the challenge of competing with PCE remains. Unlike the inorganic solar cells, the material requirement for fabrication of OPV is much smaller. They can be printed out using printing tools which would help in low cost commercialization of these materials. Solution processable organic semiconductors can be easily fabricated into thin films. In short OPVs, OFETs and organic light emitting diodes OLEDs are light weight, flexible, easy to fabricate, inexpensive and tunable to demand as compared to the conventional inorganic materials. The downsides of organic small contorted molecules as semiconductors is their less reliable long-term usability and low PCE so far. The highest PCE for organic solar cell achieved so far is 11%.
When it comes to the reasons that limit OPVs power conversion efficiencies, we need to understand the structural and chemical limitations that existing organic small molecules offer.
The OPVs make use of a pair of electron acceptor fullerene or another non-fullerene (n-type) and electron donor molecules (p-type) creating heterojunctions within the active film. There are distinctive designs in which these molecules can be used in blends.
Mostly planar heterojunction (Fig.8) is used for fullerene based organic semiconductors in which the two molecules end up on top of each other to create a ball and socket joint model1. Bulk heterojunctions (Fig 8) have reportedly produced better PCEs when solution processed in single active layer. The use of fullerene in OPVs and semiconductors generate a variety of challenges that are detrimental for good light harvesting and power generation. Fullerenes do not give a strong absorption in visible (ε = 724 L mol−1 cm−1) and near-IR region (ε = 7500 L mol−1 cm−1) which reduces the charge generation capability for these devices. Since conduction in organic semiconductors is thermally activated phenomenon of hopping electrons through sp2 hybridized p-orbitals, therefore electron acceptors with better absorption in visible-near IR regions are superior performers. The fullerenes offer less tunability and poor electronic communication between the cage (C60 or C70) and its substituent.
Another challenge is high probability of exciton recombination in fullerenes-based electron acceptors. Contrary to the inorganic semiconductors, the excitons formed in organic materials possess a higher binding energy (0.3-1.0 eV). This issue is resolved at the acceptor donor interface by matching HOMO (donor) and LUMO (acceptor) energy gaps. Planar heterojunction (PHJ) is the commonly used OPV architecture in which donor and acceptors molecules are joined with one another. The contorted PAHs owing to their non-polar and non-planar topology and shape are expected to offer a balance between miscibility and self-aggregation for optimal charge transport to electrodes. These contorted conjugated aromatic molecules support the charge transport due to resonance of electrons and hinder the possibility of electron hole pair recombination for having suitable HOMO and LUMO offsets at donor and acceptor interphase while allowing the antagonistic charge percolation pathways.
Self-Assembled Materials.
These contorted molecules show the remarkable phenomenon of self-assembly. Based upon the data collected from OFET and OPVs, these molecules show efficient charge transport. The c-HBC, c-OCBC and c-DBTTC act as electron donors and c-PDIs as electron acceptors. The contorted non-planar structure allows these molecules to express sufficient charge transport in self-assembled layers. The self-assembly characteristics change in case of alkyl chain derivatives of c-HBC into orthorhombic crystalline cables which act as p-type semiconductors. The contorted peripheral edges of these molecules serve to provide unique intermolecular contacts which make these molecules efficient in charge transport. The tetra-dodecaloxy side chains in c-HBC promotes the self-assembly. These materials are deposited in the form of columnar hexagonal liquid crystals. The main aromatic core transport the charges and side chains act as insulators. In thin film, the columns arrange themselves parallel to the surface and allow lateral charge transport.
Designing and Synthesis of Contorted PAHs.
Influenced by fullerenes themselves, the following structural features are incorporated into the non-fullerene-based electron acceptors. Figure 9
Cyclopentafused Contorted PAHs.
More recently a Pd-catalyzed cyclopentannulation followed by Scholl cyclodehydrogenation devised by Kyle Plunkett's research group has been found valuable for synthesizing the five-membered ring core poly aromatic contorted molecules. Based on the hypothesis that the five membered cyclopentaaceanthralene core is a part of the fullerene itself and can help assist conjugation in the molecule in its substituted form.
The resonance structures Figure 10 show that the five-membered aromatic ring core can accept a pair of electrons in one of its (anti aromatic) resonance structures to afford cyclopentadienyl anion (aromatic) rings and thus can behave as a good electron acceptor molecule. The tendency to achieve low energy aromatic structure makes it a good electron acceptor core. This methodology helps in relatively easy extension of conjugated aromatic core of the molecule which serves as a conduit for charge transfer. These contorted aromatic molecules provide better solubility and solution processability besides exhibiting the π stacking in solid state. The contortions thus enhance the π-stacking ability through a lock and key like model by giving reasonable phase separation favorable for isotropic charge transport.
The synthetic scheme-I shows the use of above mentioned cyclopentadienyl anion scaffold in synthesizing contorted aromatic molecules. The reaction of dibromoanthracene with 3,3 dialkoxy 1,1 diphenyl acetylene (R=CH3, C12H25) in the presence of Pd2(dba)3 P("o"-tol)3, KOAc, LiCl, and DMF gives 1,2,6,7-tetra(3-alkoxyphenyl)cyclopenta["hi"]aceanthrylene which after Scholl cyclodehydrogenation affords 2,7,13,18-Tetraalkoxytetrabenzo["f,h,r,t"]-rubicene.
The crystal structure figure 11 of above shown compound 2, 7, 13, 18-Tetraalkoxytetrabenzo [f,h,r,t]-rubicene in scheme 1 shows the non-planar contorted structure. The splay angles of bay regions manifest the contorted structure. So the synthesis of cyclopentafused contorted PAHs can be done by this method. The contortion enhances the solubility of these molecules compared to their planar counterparts.
Device Fabrication And Testing.
These contorted PAH molecules are used in the fabrication of OFET devices in form of a thin film to test their semiconducting properties (Figure 12). The contorted PAHs are usually used as solution on an insulator dielectric layer of SiO2/Si substrate. Three electrodes source (S) drain (D) and gate (G) are affixed for providing potential and charge measurement. A significantly higher than the threshold value of voltage is applied between gate and source VGS which generates positive (p-type) channel at the semiconductor and dielectric interface. On applying a negative voltage from source to drain VSD, the hole flows from source to drain which is also equivalent to flow of electron in opposite direction. By increasing the VGS the flow of current from drain/source IDS increases. The process continues until the maximum value of current “pinch off” reaches at which point the positive channel gets saturated on one side. Data at different VGS values is collected and plotted in the form of an output plot for c-HBC with tetra-dodecyloxy side chains as shown in Figure 5. The p-type semiconductors exhibit negative VSD & VGS values and vice versa for n-type semiconductors.
Plotting with the (ID-S)1/2 Vs VG (transfer plot) gives the slope for calculation of mobility.
μ(mobility)=2L/WCi (formula_1
Where,
L' is the Channel length
W’ …….. Channel width
Ci’ ……. Capacitance in F/cm2
dVG‘ …….. Slope of the transfer plot
The units of mobility are cm2/ V.s
The c-HBC, c-OCBC and c-DBTTC and their many derivatives act as p-type and c-PDI and its oligomers as electron acceptors. Experiments indicate that the photon conversion efficiency of contorted c-HBC is better than the planar HBC in OPVs1. The contorted shape enhances the electronics properties of the molecules by building intimate structural interfaces between donor and acceptors. The c-PDI dimers on the other hand show better electron mobility (~10−2 cm2 V−1 s−1), electron acceptability and almost similar LUMO levels as fullerenes.
Applications.
The generalized applications of contorted PAHs and organic semiconductors are given as follows.
Organic Light Emitting Diodes.
The organic semiconductors are being used as OLEDs in various electronic display applications. Philips launched Sensotech Philishave in 2002 featuring first OLED based display panel. Kodak has also introduced LS633 digital camera with award winning OLED display technology. Sony also produced a 27” OLED prototype TV88
Organic Photovoltaic Cells.
Another extensively researched area toward the applications of organic semiconductors is light harvesting. The current photon conversion efficiency may be an obstacle in commercialization of this technology but there are many attractive features like low cost, flexibility and miniaturization attached.
Organic Field Effect Transistors.
OFETs being another exciting application of organic semiconductors. This technology with the right pre-requisites hold enough potential to revolutionise the existing technologies in use.
Smart Textiles.
The flexibility and light weight feature of organic semiconductors offer futuristic applications like smart fabric for health care, military, sporting and space exploration ventures. This will allow the real time observation of the person's health wearing these fabrics.
Healthcare.
Organic light emitting diodes can also be used in photodynamic therapy for skin cancer and cosmetic industry for antiaging treatment.
Flexible Screen and Displays Units.
Flexibility gives another edge to organic semiconductors being better than inorganic semiconductors. This technology may allow us to have screens capable of rolling into small devices. Philips has made a black and white prototype
Lab on a Chip.
The organic semiconducting technology is replacing silicon and may one day achieve the goal of having a lab on a chip.
The contorted aromatic molecules offer a wide variety of tuning and suitability options. Both electron acceptor (n-type) and electron donor (p-type) contorted molecules can be manufactured. The non-planar structure offers self-assembly characteristics leading to simultaneously optimized miscibility and phase separation. The charge mobility of contorted aromatic molecules being higher in two orders of magnitude than the planar structures points towards them having well-tuned charge percolation pathways. There is still a long way to go from 11% of PCE to theoretical maximum of 20%. If the researchers are able to strike the right balance between miscibility and phase separation of these materials and tune the orbitals correctly they may be able to find the best organic semiconductors.


Isotopes of mercury

There are seven stable isotopes of mercury (80Hg) with 202Hg being the most abundant (29.86%). The longest-lived radioisotopes are 194Hg with a half-life of 444 years, and 203Hg with a half-life of 46.612 days. Most of the remaining 40 radioisotopes have half-lives that are less than a day. 199Hg and 201Hg are the most often studied NMR-active nuclei, having spin quantum numbers of 1/2 and 3/2 respectively.
180Hg, producible from 180Tl, was found in 2010 to be capable of an unusual form of spontaneous fission. The fission products are 80Kr and 100Ru.


Oxybismuthides

Oxybismuthides or bismuthide oxides are chemical compounds formally containing the group BiO, with one bismuth and one oxygen atom. The bismuth and oxygen are not bound together as in bismuthates, instead they make a separate presence bound to the cations (metals), and could be considered as a mixed bismuthide-oxide compound. So a compound with OmBin requires cations to balance a negative charge of 2m+3n. The cations will have charges of +2 or +3. The trications are often rare earth elements or actinides. They are in the category of oxypnictide compounds.
Many of the bismuthide oxides have bismuth in an unusual -2 oxidation state. The ones with Ln2BiO2 have the anti-ThCr2Si2 structure. They include alternating layers of LnO (anti-fluorite-type) and LnBiO. The Eu4Bi2O has an anti-K2NiF4 structure, the same as for Na2Ti2As2O. Some other compounds contain calcium and a rare earth CaRE3BiO4, and Ca2RE8Bi3O10.
Some of these compounds are superconductors at very low temperatures and many are semiconductors at standard conditions.


Hydrogen Energy California

Hydrogen Energy California (HECA) was an alternative energy, hydrogen power project in development with support from the U.S. Department of Energy in Kern County, California.
The facility proposed to convert coal and refinery waste into an impure hydrogen fuel that would be used to generate electricity and fertilizer. HECA was supposed to capture ninety percent of its carbon dioxide (CO2) emissions to theoretically minimize greenhouse gas (GHG) emissions and inject it, for enhanced oil recovery.
If it had become fully operational, HECA would have generated nearly 300MW of clean electricity and will produce one million tons of locally manufactured, low-carbon fertilizer. But, most of the electricity produced by HECA would have been consumed by the different processes at the plant.
On March 4, 2016, the California Energy Commission ordered the HECA application to be terminated.
HECA would have produced over 500 tons of criteria air pollutants. This air pollution would have been added to an area that already has the worst air pollution in the entire United States.
The facility was to be located on of prime farmland in western Kern County, about west of Bakersfield and northwest of the unincorporated community of Tupman. The site is near the Elk Hills Oil Field where the captured CO2 was to be used for enhanced oil recovery by Occidental of Elk Hills, Inc. HECA would have employed an expected 2,000 union workers to construct the facility and would have created approximately 200 permanent jobs.
HECA was a project of SCS Energy LLC, an independent developer of clean power. HECA was cofunded by the U.S. Department of Energy’s Office of Fossil Energy and administered by the National Energy Technology Laboratory. The HECA project was awarded a $408 million grant by the U.S. Department of Energy under Clean Coal Power Initiative Round 3.
Process.
The HECA project will be an Integrated Gasification Combined Cycle (IGCC) facility using Mitsubishi Heavy Industries, Ltd.’s oxygen–blown gasifier technology. IGCC technology allows for highly efficient power generation with minimal emissions. IGGC facilities, including HECA, are different from conventional fossil fueled power generation plants in that there is no combustion of the actual fossil fuels. Instead, HECA converts, through gasification, a blend of recycled petroleum coke, a low value by-product that comes from oil refining, and coal to manufacture hydrogen fuel.
The clean burning hydrogen fuel will be used for two purposes: to generate low-carbon electricity; and to produce approximately one million tons of low-carbon fertilizer per year.
A Rectisol acid gas removal system will separate and capture more than ninety percent of the carbon dioxide (CO2) produced during the hydrogen manufacturing process. Most of the captured CO2 will be used for enhanced oil recovery at the nearby Elk Hills Oil Field, enabling the production of millions of additional barrels of domestic oil, a 10-20% increase in the amount of oil recovered. Some of the CO2 will be used in the manufacturing of fertilizer. The project will use brackish groundwater for its process water needs and will have a Zero Liquid Discharge (ZLD) system in order to protect and conserve local freshwater sources.
Schedule.
The project was currently progressing through the regulatory approval process, and was expected to be completed and operating by 2017. But, the project has now been terminated by the California Energy Commission for lack of progress.


Bismuth-209

Bismuth-209 (209Bi) is the isotope of bismuth with the longest known half-life of any radioisotope that undergoes α-decay (alpha decay). It has 83 protons and a magic number of 126 neutrons, and an atomic mass of 208.9803987 amu (atomic mass units). Primordial bismuth consists entirely of this isotope.
Decay properties.
Bismuth-209 was long thought to have the heaviest stable nucleus of any element, but in 2003, a research team at the Institut d’Astrophysique Spatiale in Orsay, France, discovered that 209Bi undergoes alpha decay with a half-life of approximately 19 exayears (1.9×1019, approximately 19 quintillion years), over a billion times longer than the current estimated age of the universe. The heaviest nucleus considered to be stable is now lead-208 and the heaviest stable mononuclidic element is gold as the 197Au isotope.
Theory had previously predicted a half-life of 4.6 years. The decay event produces a 3.14 MeV alpha particle and converts the atom to thallium-205.
Bismuth-209 will eventually form 205Tl if unperturbed:
If perturbed, it would join in lead-bismuth neutron capture cycle from lead-206/207/208 to bismuth-209, despite low capture cross sections. Even in thallium-205 case above, once fully ionized, again reverts to lead.
Due to its extraordinarily long half-life, for nearly all applications 209Bi can still be treated as if it were non-radioactive. Its radioactivity is much slighter than that of human flesh, so it poses no meaningful hazard from radiation. Although 209Bi holds the half-life record for alpha decay, bismuth does not have the longest half-life of any radionuclide to be found experimentally—this distinction belongs to tellurium-128 (128Te) with a half-life estimated at 7.7 × 1024 years by double β-decay (double beta decay).
The half-life value of bismuth-209 was confirmed in 2012 by an Italian team in Gran Sasso who reported years, and an even longer half-life, for bismuth-209 alpha decay to the first excited state of thalium-205 at 204 keV, was estimated to be 1.66 years. Even though this value is shorter than the measured half-life of tellurium-128, both alpha decays of bismuth-209 hold the record of the thinnest natural line widths of any measurable physical excitation, estimated respectively at ΔΕ~5.5×10−43 eV and ΔΕ~1.3×10−44 eV in application of the uncertainty principle of Heisenberg (double beta decay would produce energy lines only in neutrinoless transitions, which has not been observed yet).
Uses.
210Po can be manufactured by bombarding 209Bi with neutrons in a nuclear reactor. Only some 100 grams of 210Po are produced each year. Astatine can also be produced by bombarding 209Bi with alpha particles.
Formation.
In the red giant stars of the asymptotic giant branch, the s-process (slow process) is ongoing to produce bismuth-209 and polonium-210 by neutron capture as the heaviest elements to be formed, and the latter quickly decays. All elements heavier than it are formed in the r-process, or rapid process, which occurs during the first fifteen minutes of supernovas.


Selenate

The selenate ion is .
Selenates are analogous to sulfates and have similar chemistry. They are highly soluble in aqueous solutions at ambient temperatures.
Unlike sulfate, selenate is a somewhat good oxidizer; it can be reduced to selenite or selenium.
In strongly acidic conditions, the hydrogen selenate ion, , is formed. It corresponds to the selenic acid, H2SeO4, which is a strong acid and can in its concentrated form dissolve gold.
The element selenium exhibits several valence states. Selenate is the least reduced, followed by selenite, and elemental selenium; selenide is even more reduced than elemental selenium. The valence state is an important factor to the toxicity of selenium. Selenate is the form required by organisms that need selenium as a micronutrient. These organisms have the ability to acquire, metabolize and excrete selenium. The level at which selenium becomes toxic varies from species to species and is related to other environmental factors like pH and alkalinity that influence the concentration of selenite over selenate.
Selenate and other forms of selenium are highest in areas where ancient seas have evaporated. These areas are enriched in selenium and over millennia, biologic adaptation has occurred.


5-Chloromethylfurfural

5-Chloromethylfurfural is an organic compound with the formula C4H2O(CH2Cl)CHO. It consists of a furan substituted at the 2- and 5-positions with formyl (CHO) and chloromethyl (CH2Cl) groups. CMF, as it is called, is obtained by dehydration of fructose and other cellulose derivatives using hydrochloric acid. It is a colourless liquid. It can be reduced to give 5-methylfurfural, and can be hydrolyzed to give hydroxymethylfurfural.


Carbonado

Carbonado, commonly known as black diamond, is one of the toughest forms of natural diamond. It is an impure, high-density, micro-porous form of polycrystalline diamond consisting of diamond, graphite, and amorphous carbon, with minor crystalline precipitates filling pores and occasional reduced metal inclusions. It is found primarily in alluvial deposits where it is most prominent in mid-elevation equatorial regions such as Central African Republic and in Brazil, where the vast majority of carbonado diamondites have been found. Its natural colour is black or dark grey, and it is more porous than other diamonds.
Unusual properties.
Carbonado diamonds are typically pea-sized or larger porous aggregates of many tiny black crystals. The most characteristic carbonados are mined in the Central African Republic and in Brazil, in neither place associated with kimberlite, the source of typical gem diamonds. Lead isotope analyses have been interpreted as documenting crystallization of carbonados about 3 billion years ago; yet carbonado is found in younger sedimentary rocks.
Mineral grains included within diamonds have been studied extensively for clues to diamond origin. Some typical diamonds contain inclusions of common mantle minerals such as pyrope and forsterite, but such mantle minerals have not been observed in carbonado. In contrast, some carbonados contain authigenic inclusions of minerals characteristic of the Earth's crust; the inclusions do not necessarily establish formation of the diamonds in the crust, but because while the obvious crystal inclusions occur in the pores that are common in carbonados, they may have been introduced after carbonado formation. Inclusions of other minerals, rare or nearly absent in the Earth's crust, are found at least partly incorporated in diamond, not just in pores: among such other minerals are those with compositions of Si, SiC, and Fe‑Ni. No distinctive high-pressure minerals, including the hexagonal carbon polymorph, lonsdaleite, have been found as inclusions in carbonados although such inclusions might be expected if carbonados formed by meteorite impact.
Isotope studies have yielded further clues to carbonado origin. The carbon isotope value is very low (little carbon‑13 compared to carbon‑12, relative to typical diamonds).
Carbonado exhibits strong luminescence (photoluminescence and cathodoluminescence) induced by nitrogen and by vacancies existing in the crystal lattice. Luminescence halos are present around radioactive inclusions, and it is suggested that the radiation damage occurred after formation of the carbonados, an observation perhaps pertinent to the radiation hypothesis listed below.
Hypotheses for origin.
The origin of carbonado is controversial, and some proposed hypotheses are as follows:
None of these hypotheses for carbonado formation had come into wide acceptance in the scientific literature by 2008. 13C/12C ratios in carbonado are identical to local sediments.
Extraterrestrial origin hypothesis.
Supporters of an extraterrestrial origin of carbonados propose that their material source was a supernova which occurred at least 3.8 billion years ago. After coalescing and drifting through outer space for about one and a half billion years, a large mass fell to earth as a meteorite approximately 2.3 billion years ago. It possibly fragmented during entry into the Earth's atmosphere and impacted in a region which would much later split into Brazil and the Central African Republic, assumed to be the only two known locations of carbonado deposits (which is not an accurate representation of the true distribution of carbonado diamondite).


Nickel succinate

Nickel succinate is a transition metal carboxylic acid salt. It crystallises in several forms. Nickel coordinates in a far more diverse way than other transition elements enabling a variety of structures for the same constituents. Succinate is dibasic, so its two ends can connect onto two different nickel atoms. Succininate is flexible, so that it can be bent to different angles and lengths. This allows formation of metal organic framework solids.
In a water solution one Ni2+ ion can be connected to both ends of a succinate ion to yield a neutral complex.
The neutral nickel succinate NiC4H2O4·4H2O, can be made from succinic acid and nickel carbonate. It dehydrates between 114 and 200°, Andydrous nickel succinate breaks down at 380° and over 450°C only nickel oxide is left. The gaseous decomposition products mainly consist of water, methane, ethylene, propane and carbon dioxide. Minor output included butene and pentane.The salt has two strong infrared absorption bands. One at 3220-2950 cm−1 due to OH and another at 1550 due to carboxylate -COO−.
Basic salts.
One structure called MIL-73, with formula [Ni7(C4H2O4)4(OH)6·3H2O]·7H2O, crystallises in the monoclinic system with a=7.8597 b=18.8154 c=23.4377 β=92.029° unit cell volume V=3463.9 Å3. The structure consists of alternating layers of nickel hydroxide chains running in the b direction stacked side by side in the a direction, and succinate aligned in the c direction. Thermal decomposition resulted in stages of water loss at 45°, 60°, 110° (reversibly losing the .7H2O. More water is lost at 225° and total decomposition occurs at 280°C.
Under 20K MIL-73 is ferrimagnetic.
Another structure has formula [Ni7(C4H2O4)6(OH)2·2H2O]·2H2O. It has a three dimensional honey comb structure with pores running through it. [Ni7(C4H2O4)6(OH)2·2H2O]·2H2O is made by dissolving succinic acid in cyclohexanol and a nickel salt in water and then mixing. This structure has high stability. It loses water at 200 to 240°, but keeps its structure up till 380°C.


Deuterated dichloromethane

Deuterated dichloromethane (CD2Cl2) is a form (called an isotopologue) of dichloromethane (DCM, CH2Cl2) in which the hydrogen atoms ("H") are replaced with deuterium (heavy hydrogen) isotope ("D"). Deuterated DCM is not a common solvent used in NMR spectroscopy as it is expensive compared to deuterated chloroform.


Ytterbium(III) oxide

Ytterbium(III) oxide is the chemical compound with the formula Yb2O3. It is one of the more commonly encountered compounds of ytterbium. It has the "rare-earth C-type sesquioxide" structure which is related to the fluorite structure with one quarter of the anions removed, leading to ytterbium atoms in two different six coordinate (non-octahedral) environments.


Sodium ferric gluconate complex

Sodium ferric gluconate complex, sold under the brand name Ferrlecit, is an intravenously administered iron medication for the treatment of iron deficiency anemia in adults and in children aged six years and older with chronic kidney disease receiving hemodialysis who are receiving supplemental epoetin therapy. The macromolecule has an apparent molecular weight of 289,000 – 440,000 Dalton.
The most common side effects in adults are nausea, vomiting and/or diarrhea, injection site reaction, hypotension, cramps, hypertension, dizziness, dyspnea, chest pain, leg cramps, and pain. In children the most common side effects are hypotension, headache, hypertension, tachycardia and vomiting.


Inner transition element


Monopotassium phosphite

Monopotassium phosphite is an inorganic compound with the formula KH2PO3. A compositionally related compound has the formula H3PO3.2(KH2PO3). Both are white solids that consist of salts of the phosphite anion H2PO3−, the conjugate base of phosphorous acid. These materials have been used in some fertilizers.


Lithium aluminate

Lithium aluminate (), also called lithium aluminium oxide, is an inorganic chemical compound, an aluminate of lithium. In microelectronics, lithium aluminate is considered as a lattice matching substrate for gallium nitride. In nuclear technology, lithium aluminate is of interest as a solid tritium breeder material, for preparing tritium fuel for nuclear fusion.
Lithium aluminate is a layered double hydroxide (LDH) with a crystal structure resembling that of hydrotalcite. Lithium aluminate solubility at high pH (12.5 – 13.5) is much lower than that of aluminium oxides. In the conditioning of low- and intermediate level radioactive waste (LILW), lithium nitrate is sometimes used as additive to cement to minimise aluminium corrosion at high pH and subsequent hydrogen production. Indeed, upon addition of lithium nitrate to cement, a passive layer of · 5 is formed onto the surface of metallic aluminium waste immobilised in mortar. The lithium aluminate layer is insoluble in cement pore water and protects the underlying aluminium oxide covering the metallic aluminium from dissolution at high pH. It is also a pore filler. This hinders the aluminium oxidation by the protons of water and reduces the hydrogen evolution rate by a factor of 10.
Lithium aluminate also finds its use as an inert electrolyte support material in molten carbonate fuel cells, where the electrolyte may be a mixture of lithium carbonate, potassium carbonate, and sodium carbonate.
History.
In 1906 Weyberg described his newly synthesized compound, lithium hydrogen aluminate. This was the first known synthesis of this unique compound. He asserted that this new compound had the corresponding chemical formula:

In 1915 Allen and Rogers asserted that an insoluble aluminate of lithium is formed when aluminum is dissolved in a solution of lithium hydroxide. This air-dried substance had an atomic ratio of 2Li:5Al and the chemical formula:
In 1929 Prociv recreated Allen and Rogers experiment and through a series of conductometric measurements on the saturated solution of the substance concluded that lithium and aluminum were present in the ratio of 0.8Li:2Al, which, he says, is an atomic ratio of approximately 1Li:2Al. According to him lithium aluminate may also be precipitated by the addition of a solution of lithium hydroxide to a solution of aluminum salt or by adding a solution of lithium salt to a solution of an alkali aluminate. Thus there was disagreement between Allen/Rogers and Prociv as to the composition of lithium aluminate. This may have been attributed to variations between their precipitation conditions.
In 1932 Dobbins and Sanders described the formation of lithium aluminate by the addition of dilute ammonia to a solution containing lithium and aluminum salt, in the presence of phelphtalein as an indicator. In their preparation of acid lithium aluminate they dissolved strips of amalgamated aluminum in normal and tenth normal solutions of lithium hydroxide. The lithium aluminate was precipitated by the addition of a solution of lithium hydroxide to a solution of aluminum salts, or by adding a solution of lithium salt to a solution of alkaline aluminate. In all cases the composition of the compound of lithium aluminate was expressed by the formula:
They claimed that the formed compound contained lithium and aluminum in the atomic ratio of 2Li:5Al. Their chemical formula was simplified into the modern formulation for lithium aluminate:
Fields of interest.
The fundamental compound of lithium aluminate has found attention in two different fields: nuclear physics and solid-state chemistry. At least five different phases of lithium aluminate have been found. The lithium aluminate crystal structure may be found in either α, β, or γ phases.
Nuclear physicists are interested in the modification of lithium aluminate, because of its good performance under high neutron and electron radiation. This modification also exhibits the essential chemical, thermo physical and mechanical stability at high temperature along with the required irradiation behavior. This phase appears to be a promising lithium ceramic, suitable as an in site tritium breeding material in future fusion reactors.
Solid-state chemists investigating preparational routes to lithium aluminate discovered its interesting acid-base chemistry. The modification (but neither or ) reacts with molten benzoic acid leading to nearly total proton exchange thus forming There is a lot of interest in the chemical reactivity among the three modifications of . The reasons for the modification being highly reactive and the or modifications being totally unreactive is currently a mystery.
Formation.
Early methods.
Lithium aluminate powder preparation was based on the solid-state reactions between and lithium-containing compounds like , LiOH, , LiAc, and reactions occurred at temperatures between 400Deg C to 1000 Deg C. Due to the evaporation of lithium at high temperatures and contamination from grinding operations, pure lithium aluminate with controlled particle size has been difficult to synthesize.
Current methods.
Synthesis of lithium aluminate has been essentially performed by several methods: in the solid state, by wet chemical, sol-gel, with the use of templates, various precursors, and combustion processes. The main product in a solid state reaction is the phase; in a wet chemical reaction, the main product is a solid solution of and phases. The α-LiAlO2 modification (low temperature phase), with a hexagonal structure, undergoes transformation to the γ-modification (High temperature phase), with a tetragonal structure, at about 900 °C. The metastable β-modification, with a monoclinic structure, is assumed to transform to the γ-modification at about 900 °C.
Natural occurrence.
The compound is unknown in the natural environment. However, a related compound, LiAl5O8, is known as the very recently discovered (as of 2020) and very rare mineral chukochenite.


Tripuhyite

Tripuhyite is an iron antimonate mineral with composition FeSbO4.
Nomenclature.
The name of the mineral comes from the locality of Tripuhy, Ouro Preto, Minas Gerais, Brazil, where it was discovered. Hussak and Prior first described the mineral tripuhyite as an oxide of iron and antimony, and assigned it the composition Fe2Sb2O7. When a mineral with composition FeSbO4 was later discovered in Squaw Creek, New Mexico (US), it was considered erroneously as a new mineral and it was given the name "squawcreekite". However, other studies had shown that the original tripuhyite was also FeSbO4. In 2002, the Commission on New Minerals and Mineral Names (CNMMN) of the International Mineralogical Association (IMA), approved the redefinition of tripuhyite as FeSbO4 and the discreditation of squawcreekite.
Crystal Structure.
FeSbO4 exhibits the rutile structure, with a tetragonal unit cell. The cations are octahedrally coordinated to oxygen anions, with the octahedra sharing edges along the c-direction. Fe(III) and Sb(V) cations are distributed in a disordered way over the octahedral sites.


Trona

Trona (trisodium hydrogendicarbonate dihydrate, also sodium sesquicarbonate dihydrate, Na2CO3•NaHCO3•2H2O) is a non-marine evaporite mineral. It is mined as the primary source of sodium carbonate in the United States, where it has replaced the Solvay process used in most of the rest of the world for sodium carbonate production.
Etymology.
The word entered English by way of either Swedish () or Spanish (), with both possible sources having the same meaning as in English. Both of these derive from the Arabic "trōn", which in turn derives from the Arabic "natron", and Hebrew ("natruna"), which comes from ancient Greek ("nitron"), derived ultimately from ancient Egyptian "ntry" (or "nitry'’).
Natural deposits.
 Trona is found at Owens Lake and Searles Lake, California; the Green River Formation of Wyoming and Utah; the Makgadikgadi Pans in Botswana and in the Nile Valley in Egypt. The trona near Green River, Wyoming, is the largest known deposit in the world and lies in layered evaporite deposits below ground, where the trona was deposited in a lake during the Paleogene Period. Trona has also been mined at Lake Magadi in the Kenyan Rift Valley for nearly 100 years. The northern part of Lake Natron is covered by a 1.5 m thick trona bed, and occurs in 'salt' pans in the Etosha National Park in Namibia. The Beypazari region in the Ankara Province of Turkey has some 33 trona beds in two fault-bound lensoid bodies in and above oil shales of the Lower Hirka Formation (16 in the lower and 17 in the upper body). The Wucheng basin trona mine, Henan Province China has some 36 trona beds (693–974 m deep), the lower 15 beds are 0.5–1.5 m thick, thickest 2.38 m; the upper 21 beds are 1–3 m thick, with a maximum of 4.56 m hosted and underlain by dolomitic oil shales of the Wulidui Formation.
Trona has also been found in magmatic environments. Research has shown that trona can be formed by autometasomatic reactions of late-magmatic fluids or melts (or supercritical fluid-melt mixtures), with earlier crystallized rocks within the same plutonic complex, or by large-scale vapor unmixing in the very final stages of magmatism.
Crystal structure.
The crystal structure of trona was first determined by Brown et al. (1949). The structure consists of units of 3 edge-sharing sodium polyhedra (a central octahedron flanked by septahedra), cross-linked by carbonate groups and hydrogen bonds. Bacon and Curry (1956) refined the structure determination using two-dimensional single-crystal neutron diffraction, and suggested that the hydrogen atom in the symmetric (HC2O6)3− anion is disordered. The environment of the disordered H atom was later investigated by Choi and Mighell (1982) at 300 K with three-dimensional single-crystal neutron diffraction: they concluded that the H atom is dynamically disordered between two equivalent sites, separated from one another by 0.211(9) Å. The dynamically disordered H atom was reinvestigated at low temperature by O'Bannon et al. 2014 and they concluded that it does not order at temperatures as low as 100K.


Minyulite

Minyulite is a rare phosphate mineral with a chemical formula of KAl2(OH,F)(PO4)2·4(H2O).
It occurs as groups of radiating fine fibrous crystals within rock cracks of phosphatic ironstone. Minyulite belongs to the orthorhombic crystal system. This indicates that it has three axes of unequal length yet all are perpendicular to each other. Its cell constants are a=9.35, b=9.74 c=5.52.
As for its optical properties, Minyulite is an anisotropic mineral which means the velocity of light differs when traveling through it depending on the cut of its cross-section which gives it more than one refractive index. The mineral is optically biaxial. Its birefringence value is 0.007. It has three refractive indices which are nα=1.531 nβ=1.534 nγ=1.538. Refractive indices are a ratio of the speed of light in a median with respect to the speed of light passing through the mineral.
Occurrence.
It was first described in 1933 for an occurrence in Western Australia and named after the type locality, Minyulo Well in Western Australia.
Minyulite is considered as a secondary phosphate since it is formed by the alteration of a primary phosphate. It occurs in association with dufrenite, apatite, fluellite, wavellite, variscite and leucophosphite.
The mineral can be found in the underlying phosphatized rock zone of ornithogenic soil. Minyulite is not found in abundance, it can be found in the seashore of the maritime Arctic.


Potassium selenocyanate

Potassium selenocyanate is the inorganic compound with the formula KSeCN. It is a hygroscopic white solid that is soluble in water, decomposing in air to red selenium and potassium cyanide. The compound has been characterized by X-ray crystallography, which confirms that it is a salt. The C-N and C-Se distances are 1.12 and 1.83, respectively, consistent with triple and single bonds.
It serves as a source of Se0, e.g., in its reaction with triphenylphosphine to give triphenylphosphine selenide.


Rhodium(III) sulfate

Rhodium(III) sulfate refers to inorganic compounds of the formula Rh2(SO4)3. It is a red crystalline solid.


Thorium(IV) carbide

Thorium(IV) carbide (ThC) is an inorganic thorium compound and a carbide.


Tungsten alloys


Sodium bromite

Sodium bromite is a sodium salt of bromous acid. Its trihydrous form has been isolated in crystal form. It is used by the textile refining industry as a desizing agent for oxidative starch removal.


Unpentoctium


Charcoal Kilns

Charcoal Kilns may refer to:


Diethyl selenide

Diethyl selenide is an organoselenium compound with the formula . First reported in 1836, it was the first organoselenium compound to be discovered. It is the selenium analogue of diethyl ether. It has a strong and unpleasant smell.
Occurrence.
Diethyl selenide has been detected in biofuel produced from plantain peel.
It is also a minor air pollutant in some areas.
Preparation.
It may be prepared by a substitution reaction similar to the Williamson ether synthesis: reaction of a metal selenide, such as sodium selenide, with two equivalents of ethyl iodide or similar reagent to supply the ethyl groups:


Low valent magnesium compounds

A number of stable low valent magnesium compounds containing a metal-metal, Mg-Mg, bond, where magnesium exhibits the formal oxidation state of +1 are known. These compounds generally have the formula L2Mg2, where L represents a bulky ligand. The first examples of these stable magnesium(I) compounds were reported in 2007. The chemistry of Mg is dominated by the +2 oxidation state and prior to 2007 only examples of crystalline compounds with short Mg-Mg distances that may indicate an Mg-Mg bond were known, such as the ternary metal hydrides Mg2RuH4, Mg3RuH3, and Mg4IrH5 and magnesium diboride, Calculations had also indicated the stability of the Mg22+ cation.
The preparation of the first compounds made involved the reduction of MgII iodine complexes with potassium metal and the bulky ligands were:
Both examples have the formula L2Mg2, where L represents the bulky anionic bidentate ligand. X-ray crystallographic studies showed an Mg-Mg bond length of 285.1 pm and 284.6 pm. Theoretical studies indicate an essentially ionic formulation Mg22+(L−)2. The Mg22+ ion is the group 2 analogue of the group 12 Hg22+ (present in e.g. mercury(I) chloride) and Cd22+ ions (present in cadmium(I) tetrachloroaluminate).
Since then a variety of stable Mg(I) compounds have been prepared, some melting over 200 °C, some colorless, others colored, but all involving very bulky ligands. Also complexes of the LMgMgL with monodentate ligands have been prepared and in these the coordination of the Mg atom increases from three to four. The magnesium(I) dimers have proved to be useful reducing agents, for example in the preparation of tin(I) compounds.


Iodine tribromide

Iodine tribromide is an interhalogen with chemical formula IBr3.
Properties.
Iodine tribromide is a dark brown liquid that is miscible in ethanol and ethers.
Uses.
Iodine tribromide can be used as a brominated flame retardant when producing semiconductors. It also can be used in dry etching.


Plutonium carbide

Plutonium carbide comes in several stoichiometries (PuC and Pu2C3).
It can be used as a nuclear fuel for nuclear reactors in conjunction with uranium carbide. The mixture is also labeled as uranium-plutonium carbide (UPuC).


Peretaite

Peretaite is a sulfate of antimony and calcium. The mineral, Ca(SbO)4(SO4)2(OH)2
(2(H2O)), was named Peretaite for its locality. It was first discovered in an antimony-bearing vein at Pereta, Tuscany, Italy.
Occurrence.
Peretaite occurs in only small quantities, as aggregates of tabular crystals. The crystals are found in the geodes of a deeply silicified limestone. It also occurs in the cavities of columnar stibnite. Other associated minerals are stibnite, quartz, calcite, pyrite, valentinite, kermesite, sulfur, and gypsum. Peretaite can often be red from the inclusion of valentinite. The mineral was formed by the action of sulfuric acid on the stibnite; peretaite is closer to the boundary of the country rock limestone, which is the source of the calcium in peretaite.
Physical properties.
The mineral peretaite has transparent crystals that are colorless. It has a vitreous luster and perfect {100} cleavage. The density of peretaite was determined by a heavy-liquid method, crystals tend to float in a Clerici solution, which has a density of 4.0 g/cm3, therefore the density is 3.8 g/cm3.
Chemical properties.
The mineral is made up of 4 oxides. Most of this mineral is made up of an Antimony oxide, Calcium, and a sulfur oxide. Some of the qualitative analyses of peretaite were done by an ORTEC X-ray microanalyzer and an ARL SEMQ electron microprobe. Later it was discovered that the crystals would disintegrate under the electron beam. Therefore, a wet chemical analysis was performed for the sulfur content, calcium was determined by atomic absorption, and antimony was determined by alternating current anodic stripping voltammetry.
Crystallography.
X-ray single-crystal study indicated peretaite had a symmetry of 2/m with a space group of C2/c or Cc and a crystal system of monoclinic.


Sulfur oxide

Sulfur oxide refers to many types of sulfur and oxygen containing compounds such as SO, SO2, SO3, S7O2, S6O2, S2O2, etc.
Sulfur oxide (SO"x") refers to one or more of the following:


Chlorine peroxide

Chlorine peroxide (also known as dichlorine dioxide or ClO dimer) is a molecular compound with formula ClOOCl. Chemically, it is a dimer of the chlorine monoxide radical (ClO·). It is important in the formation of the ozone hole. Chlorine peroxide catalytically converts ozone into oxygen when it is irradiated by ultraviolet light.
Production.
Chlorine peroxide can be produced by laser or ultraviolet photolysis of the chlorine molecule with ozone. The lasers used to break up the chlorine molecule into atoms can be an excimer laser at 248, 308, or 352 nm wavelength. Difluorodichloromethane (CF2Cl2) can also act as a source of chlorine atoms for the formation of the peroxide. Microwave discharge can also break up chlorine molecules into atoms that react with ozone to make chlorine peroxide.
Properties.
Chlorine peroxide absorbs ultraviolet light with a maximum absorbing wavelength of 245 nm. It also absorbs longer wavelengths up to 350 nm to a lesser extent. This is important as ozone absorbs up to 300 nm.
The Cl−O bond length is 1.704 Å, and the O−O bond is 1.426 Å long. The ClOO bond angle is 110.1°, and the dihedral angle between the two Cl−O−O planes is 81°


Bisulfite

The bisulfite ion (IUPAC-recommended nomenclature: hydrogen sulfite) is the ion HSO3−. Salts containing the HSO3− ion are termed bisulfites also known as "sulfite lyes".
Structure.
The proton in bisulfite shuttles between S and O. The H-S tautomer has "C"3v symmetry. The H-O tautomer has been observed by 17O NMR spectroscopy. The "C"3v structure is supported by X-ray crystallography and, in aqueous solution, by Raman spectroscopy (ν(S–H) = 2500 cm−1).
Reactions.
Acid-base reactions.
Solutions of bisulfite are typically prepared by treatment of sulfur dioxide with aqueous base:
HSO3− is the conjugate base of sulfurous acid, (H2SO3), which does not exist in the aqueous phase. An equilibrium that is much more consistent with spectroscopic evidence is:
HSO3− is a weak acidic species with a p"K"a of 6.97. Its conjugate base is the sulfite ion, SO32−:
Dehydration/hydration equilibria.
Attempted isolation of the common salts of bisulfite results in dehydration of the anion with formation of metabisulfite (), also known as disulfite:
Because of this equilibrium, anhydrous sodium and potassium salts of bisulfite cannot be obtained. However, there are some reports of anhydrous bisulfites with large counter ions.
Redox reactions.
Bisulfite is a good reducing agent, especially for oxygen scrubbing:
Its reducing properties are exploited to precipitate gold from auric acid (gold dissolved in aqua regia) and reduce hexavalent chromium to trivalent chromium. In water chlorination, sodium bisulfite is used to reduce the residual 'chlorine' which can have a negative impact on aquatic life.
Organic synthesis.
In organic chemistry, "sodium bisulfite" is a routine reagent but its composition is imprecisely known. Sodium bisulfite is used interchangeable with sodium metabisulfite, which is Na2S2O5 as a solid but dissolves to give a solution of Na+HSO3−.
Bisulfite forms adducts with aldehyde and with certain cyclic ketones to give α-hydroxysulfonic acids. This reaction is useful for the purification of aldehydes. The bisulfite adducts precipitate as solids from solution. The reaction can be reversed in base. Examples of such procedures are described for benzaldehyde, 2-tetralone, citral, the ethyl ester of pyruvic acid and glyoxal. In the ring-expansion reaction of cyclohexanone with diazald, the bisulfite reaction is reported to allow differentiation between the primary reaction product cycloheptanone and the main contaminant cyclooctanone.
Another use of bisulfite in organic chemistry is as a mild reducing agent, e.g. to remove traces or excess amounts of chlorine, bromine, iodine, hypochlorite salts, osmate esters, chromium trioxide and potassium permanganate. Sodium bisulfite is a decoloration agent in purification procedures because it reduces strongly coloured oxidizing agents, conjugated alkenes and carbonyl compounds.
Bisulfite is also the key ingredient in the Bucherer reaction. In this reaction an aromatic hydroxyl group is converted to the corresponding amine group. This is a reversible reaction. The first step in this reaction is an addition reaction of sodium bisulfite to an aromatic double bond. The Bucherer carbazole synthesis is a related organic reaction that uses sodium bisulfite as a reagent.
Bisulfite DNA sequencing.
Sodium bisulfite is used in the analysis of the methylation status of cytosines in DNA.
In this technique, sodium bisulfite deaminates cytosine into uracil, but does not affect 5-methylcytosine, a methylated form of cytosine with a methyl group attached to carbon 5.
When the bisulfite-treated DNA is amplified via polymerase chain reaction, the uracil is amplified as thymine and the methylated cytosines are amplified as cytosine. DNA sequencing techniques are then used to read the sequence of the bisulfite-treated DNA. Those cytosines that are read as cytosines after sequencing represent methylated cytosines, while those that are read as thymines represent unmethylated cytosines in the genomic DNA.


Zinc sulfate

Zinc sulfate is an inorganic compound. It is used as a dietary supplement to treat zinc deficiency and to prevent the condition in those at high risk. Side effects of excess supplementation may include abdominal pain, vomiting, headache, and tiredness.
The most common form includes water of crystallization as the heptahydrate, with the formula ZnSO4•7H2O. It was historically known as "white vitriol". Zinc sulfate and its hydrates are colourless solids.
Uses.
Medicine.
In medicine it is used together with oral rehydration therapy (ORT) and an astringent.
Manufacturing.
The hydrates, especially the heptahydrate, are the primary forms used commercially. The main application is as a coagulant in the production of rayon. It is also a precursor to the pigment lithopone.
It is also used as an electrolyte for zinc electroplating, as a mordant in dyeing, and as a preservative for skins and leather.
Other.
Zinc sulfate is used to supply zinc in animal feeds, fertilizers, toothpaste, and agricultural sprays. Zinc sulfate, like many zinc compounds, can be used to control moss growth on roofs.
Zinc sulfate can be used to supplement zinc in the brewing process. Zinc is a necessary nutrient for optimal yeast health and performance, although it is not a necessary supplement for low-gravity beers, as the grains commonly used in brewing already provide adequate zinc. It is a more common practice when pushing yeast to their limit by increasing alcohol content beyond their comfort zone. Before modern stainless steel, brew Kettles, fermenting vessels and after wood, zinc was slowly leached by the use of copper kettles. A modern copper immersion chiller is speculated to provide trace elements of zinc; thus care must be taken when adding supplemental zinc so as not to cause excess. Side effects include "...increased acetaldehyde and fusel alcohol production due to high yeast growth when zinc concentrations exceed 5 ppm. Excess zinc can also cause soapy or goaty flavors."
Toxicity.
Zinc sulfate powder is an eye irritant. Ingestion of trace amounts is considered safe, and zinc sulfate is added to animal feed as a source of essential zinc, at rates of up to several hundred milligrams per kilogram of feed. Excess ingestion results in acute stomach distress, with nausea and vomiting appearing at 2–8 mg/Kg of body weight.
Production and reactivity.
Zinc sulfate is produced by treating virtually any zinc-containing material (metal, minerals, oxides) with sulfuric acid.
Specific reactions include the reaction of the metal with aqueous sulfuric acid:
Pharmaceutical-grade zinc sulfate is produced by treating high-purity zinc oxide with sulfuric acid:
In aqueous solution, all forms of zinc sulfate behave identically. These aqueous solutions consist of the metal aquo complex [Zn(H2O)6]2+ and SO42− ions. Barium sulfate forms when these solutions are treated with solutions of barium ions:
With a reduction potential of -0.76, zinc(II) reduces only with difficulty.
When heated above 680 °C, zinc sulfate decomposes into sulfur dioxide gas and zinc oxide fume, both of which are hazardous.
Minerals.
As a mineral, ZnSO4•7H2O is known as goslarite. Zinc sulfate occurs as several other minor minerals, such as zincmelanterite, (Zn,Cu,Fe)SO4•7H2O (structurally different from goslarite). Lower hydrates of zinc sulfate are rarely found in nature: (Zn,Fe)SO4•6H2O (bianchite), (Zn,Mg)SO4•4H2O (boyleite), and (Zn,Mn)SO4•H2O (gunningite).


Terbium silicide

Terbium silicide is a chemical compound of the rare earth metal terbium with silicon having chemical formula TbSi2. It is a gray solid first described in detail in the late 1950s.
The metallic resistivity and low Schottky barrier of TbSi2 (on n-type doped silicon) make it a potential candidate for applications such as infrared detectors, ohmic contacts, magnetoresistive devices, and thermoelectric devices.
It exhibits antiferromagnetism at 16K.


Kharidhunga mine

The Kharidhunga mine is one of the largest magnesium mines in Nepal and in the world. The mine is located in the east of the country in the Janakpur Zone. The mine has estimated reserves of 180 million tonnes of ore 88% magnesium.
Dolakha-Sindhupalchwok ropeway.
The Dolakha-Sindhupalchwok ropeway is an ropeway conveyor connecting the talc and magnesium mine at Kharidhunga with the processing plant at Lamosanghu in Nepal. It is one of the longest ropeways in Nepal, crossing two districts: Sindhupalchok and Dolakha. The talc plant used to be 3rd largest talc plant in South Asia.
The ropeway is long. It was operational in the 1990s, but has since been closed down. It travels through Kharidhunga, Tauthali, Tekanpur and Lamosangu.


Monofluoride

A monofluoride is a chemical compound with one fluoride per formula unit. For a binary compound, this is the formula XF.
Organofluorine compounds.
Common monofluoride are organofluorine compounds such as methyl fluoride and fluorobenzene.
Inorganic compounds.
All the alkali metals form monofluorides. All have the sodium chloride (rock salt) structure and are soluble in water and even some alcohols. Because the fluoride anion is highly basic, many alkali metal fluorides form bifluorides with the formula MHF2. Sodium and potassium bifluorides are significant to the chemical industry. Among other monofluorides, only silver(I) and thallium(I) fluorides are well-characterized. Both are very soluble, unlike the other halides of those metals.
Selected inorganic monofluorides.
Examples of the monofluorides include:


Tungsten pentoxide

Tungsten pentoxide () was reported in early literature but proved to have the stoichiometry W18O49. Sometimes called mineral blue, it is a blue solid formed by the reaction of tungsten trioxide, WO3, and tungsten metal at 700 °C.
Intermediate oxides of tungsten.
There are a number of these unusual intermediate oxides formed from reacting metal and trioxide namely, W20O58, W24O70. W18O49 contains both octahedral and pentagonal bipyramidal co-ordination of the metal atoms by oxygen.


Calciovolborthite


Isotopes of francium

Francium (87Fr) has no stable isotopes. A standard atomic weight cannot be given. Its most stable isotope is 223Fr with a half-life of 22 minutes, occurring in trace quantities as an intermediate decay product of 235U.
Of elements whose most stable isotopes have been identified with certainty, francium is the most unstable. All elements with atomic number of 106 (seaborgium) or greater have most-stable-known isotopes shorter than that of francium, but as those elements have only a relatively small number of isotopes discovered, the possibility remains that undiscovered isotopes of these elements may have longer half-lives.


Phenylmercury acetate

Phenylmercuric acetate is an organomercury compound. This compound was formerly used as a preservative in paints, and as a disinfectant. When applied to the leaves of plants, it is an antitranspirant.
Applications.
Phenylmercuric acetate (PMA) has been used against fungal activity in agriculture and in leather processing and has been known to work well. PMA has also been used as an additive in eye-drops and paint in order to preserve them, as a disinfectant, and as a catalyst in polyurethane systems. In the 1950s–1970s, PMA was used as a catalyst in the 3M Tartan brand polyurethane flexible floors that were commonly found in school gymnasiums. School officials worried that mercury vapor was being released into air above the surface of these floors. They had to be carefully removed since mercury is such a toxic heavy metal.
Findings.
The study on PMA as an anti-fungal is the most studied topic for this compound. It has been found that plants treated with PMA transpired more due to the retarded stomatal closure in the plants. Day-time reductions in transpiration by PMA greatly exceed night-time increases in water loss. PMA stunts stomatal closures as well as openings. Research has found that PMA may plausibly decrease the absorbency of guard cell membranes to solutes, thereby retarding all stomatal movements that are osmotically prompted.
Hazards.
PMA can cause Contact Urticaria Syndrome (CUS). Contact urticaria refers to a wheal-and-flare response occurring on the application of chemicals to intact skin. A wheal-and-flare response is a skin eruption that may follow injury or injection of an antigen. It is characterized by swelling and redness caused by a release of histamine. The reaction usually occurs in three stages, beginning with the appearance of an erythematous area at the site of injury, followed by development of a flare surrounding the site; finally a wheal forms at the site as fluid leaks under the skin from surrounding capillaries. CUS has been categorized as an immediate hypersensitivity reaction with IgE (a type of anti-body) playing a crucial role in its pathogenesis. Investigations dealing with CUS seem to suggest that a percentage of urticarias encompass a contact mechanism.


Zemannite

Zemannite is a very rare oxide mineral with the chemical formula Mg0.5ZnFe3+[TeO3]3·4.5H2O. It crystallizes in the hexagonal crystal system and forms small prismatic brown crystals. Because of the rarity and small crystal size, zemannite has no applications and serves as a collector's item.
History and etymology.
Zemannite was discovered in 1961 in a tellurium deposit near Moctezuma, Sonora, Mexico as an unnamed new mineral. It was not accepted then by the International Mineralogical Association (IMA) due to the uncertainty in its chemical composition.
The mineral structure was solved in 1967 by Eckhart Matzat as (Na,H)2(Zn,Fe)3+(Mn,Mg)2[TeO3]3·nH2O is specified. Two years later, the mineral was recognized by the IMA under the name zemannite, in honor of the Austrian mineralogist Josef Zemann (born 1923), who had worked extensively on tellurium minerals.
Later investigations showed that zemannite, as well as the related mineral kinichilit, often contains impurities of sodium and magnesium and thus the formula was refined to its current form, Mg0.5ZnFe3+[TeO3]3·4.5H2O.
Related minerals.
Zemannite is a secondary mineral produced by weathering of native tellurium minerals, such as sylvanite or calaverite. As a result of this process, the elemental tellurium or tellurium-anions (Te2− or Te22−) transform into the Te4+ cation bound with oxygen into the tellurate ion [TeO3]2−.
Zemannite is chemically and structurally similar to keystoneite and kinichilite; together, these minerals form the so-called "zemannite group".
In addition to Moctezuma, zemannite was also found in Vielsalm – a municipality in the Belgian province of Luxembourg and near Shimoda, Shizuoka, Japan.
Morphology and structure.
Zemannite crystallizes in the hexagonal crystal system, space group P63m with the lattice parameters "a" = 941 pm and "c" = 764 pm and two formula units per unit cell. The Te4+ bind with three oxygen atoms forming [TeO3]2− anions, where oxygens form trigonal pyramids around the tellurium ion. The Zn2+ and Fe3+ cations share the same cite with typical respective probabilities of 40% and 60%; those values can vary from crystal to crystal. The Mn2+ impurity, if present, also shares the same site. This site is surrounded by a distorted octahedron of six oxygen atoms. These tellurium-oxygen and Fe/Zn-oxygen polyhedra form a network with wide (0.83 nm diameter) channels parallel to the crystallographic "c" axis (normal to the picture). Therefore, zemannites are often attributed to zeolite materials. The channels are often occupied by sodium impurity and water.
The Mg2+ cations form octahedral Mg[(H2O)6]2+ complexes with six water molecules which are located in the channels of the crystal structure. The occupancy of the Mg sites is 50% which is reflected by the coefficient 0.5 in the chemical formula.
Zemannite forms prismatic crystals, usually smaller than 1 mm. Because zemannite is secondary mineral, its crystals usually on other rocks and retain the hexagonal shape corresponding to their crystal symmetry. The ideal pyramidal tips, as in the infobox image, are often absent.


Tungstic acid

Tungstic acid refers to hydrated forms of tungsten trioxide, WO3. Both a monohydrate (WO3·H2O) and hemihydrate (WO3·0.5H2O) are known. Molecular species akin to sulfuric acid, i.e. (HO)2WO2 are not observed.
The solid-state structure of WO3·H2O consists of layers of octahedrally coordinated WO5(H2O) units where 4 vertices are shared. The dihydrate has the same layer structure with the extra H2O molecule intercalated. The monohydrate is a yellow solid and insoluble in water. The classical name for this acid is 'acid of wolfram'. Salts of tungstic acid are tungstates.
The acid was discovered by Carl Wilhelm Scheele in 1781.
Preparation.
Tungstic acid is obtained by the action of strong acids on solutions of alkali metallic tungstates. It may also be prepared from the reaction between hydrogen carbonate and sodium tungstate. It can also be obtained from pure tungsten by reaction with hydrogen peroxide.
Uses.
It is used as a mordant and a dye in textiles.


Nuragheite

Nuragheite is a rare natural thorium molybdate, formula Th(MoO4)2·H2O, discovered in Su Seinargiu, Sarroch, Cagliari, Sardegna, Italy. This locality is also a place of discovery of the other thorium molybdate - ichnusaite, which is a trihydrate.
Occurrence and association.
Nuragheite is a part of molybdenum-bismuth mineralization. It coexists with ichnusaite, muscovite, and xenotime-(Y).
Notes on chemistry.
Nuragheite is chemically pure.
Crystal structure.
The crystal structure of nuragheite is composed of (100) layers with IXTh-centered polyhedra and Mo-centered tetrahedra. It is thus similar to that of ichnusaite.