For example, Qin’s $\alpha$-T boron was designated as ${\rm B_{50}}$.[@Qin12] However, this is only because they could not measure the chemical composition accurately. Owing to the lack of reliable characterization, it is not even certain if the reported $\alpha$-T borons are all the same. In this paper, we shall refer to the reported $\alpha$-T borons by the name of the first author, for example, Ekimov’s $\alpha$-T boron. Kurakevych’s $\alpha$-T borons are actually a series of crystals containing a C coagent ranging from 0 to 5 at.%.[@Kurakevych12]

Hyodo analyzed Kirihara’s samples, reporting a slight non-stoichiometry ($\delta$=+0.2).[@HyodoTh] However, Kirihara’s $\alpha$-T boron comes from nanostructures[@Kirihara05] and therefore his analysis will not be discussed on the same ground as the results for bulk crystals. Only Ekimov [*et al*]{} clarified the chemical composition of their bulk $\alpha$-T boron, the value being 51.5 ($\delta$=-0.5).[@Ekimov11; @Ekimov11a] As shown in Table \[tbl:alpha-tetra\], Ekimov’s $\alpha$-T boron has the largest lattice parameter $a_{0}$ ever obtained. Our calculations show that the lattice parameters shrink when C or N impurities occupy the $2b$ site. This was also reported experimentally.[@Ekimov13] From this, Ekimov [*et al*]{} claimed that their crystals are pure $\alpha$-T boron. Because of their synthesis method (pyrolysis of decaborane ${\rm B_{10}H_{14}}$) 