Metalloid for carbon in steel casting. Of the non-metallic elements less often recognised as metalloids, selenium—in the form of ferroselenium (50–58% selenium)—is used to improve the machinability of stainless steels. All six of the elements commonly recognised as metalloids have toxic, dietary or medicinal properties. Arsenic and antimony compounds are especially toxic; boron, silicon, and possibly arsenic, are essential trace elements. Boron, silicon, arsenic, and antimony have medical applications, and germanium and tellurium are thought to have potential. Boron is used in insecticides and herbicides. It is an essential trace element. As boric acid, it has antiseptic, antifungal, and antiviral properties.
Germanium-tin Germanium-tin Germanium-tin is an alloy of the elements germanium and tin, both located in group 14 of the periodic table. It is only thermodynamically stable under a small composition range. Despite this limitation, it has useful properties for band gap and strain engineering of silicon integrated optoelectronic and microelectronic semiconductor devices. Germanium-tin alloys must be kinetically stabilized in order to prevent decomposition. Therefore, low temperature molecular beam epitaxy or chemical vapor deposition techniques are typically used for their synthesis. Germanium-tin alloys have higher carrier mobilities than either silicon or germanium. Therefore it has been proposed that they can be used