Abstract
We synthesized metastable phases of Sb2Te3 and Bi0.4Sb1.6Te3 by quenching after high-pressure (4 GPa) and high-temperature (873 K) treatment and specify them as m-Sb2Te3 and m-Bi0.4Sb1.6Te3. The metastable phases of both alloys crystallize in the same structure type. The crystal structure of metastable phases, determined by the powder X-ray and electron diffraction methods, is monoclinic (C2/m). The cell dimensions of m-Sb2Te3 are: a = 15.644(80) Å, b = 4.282(8) Å, c = 9.382(20) Å, β = 89.70(5)°, the cell dimensions of m-Bi0.4Sb1.6Te3 diverge by a hundredth of angstrom units and monoclinic angle – by tenths of a degree. We revealed that the structure of β-Sb2Te3-phase, observed in situ under high pressure, may be represented as a structure of m-Sb2Te3-type and thus it can be retained at ambient conditions. We investigated the temperature dependencies of the electrical resistivity and the Hall coefficient of recovered samples in the range of T = 1.8–450 K. The structure of metastable phases possesses metallic type bonding and m-Sb2Te3 phase is superconductive at T < 2 K. The ab initio study verified metallic character of the quenched phases. After annealing at 673 K during 2.5 h the structures of the recovered samples Sb2Te3 and Bi0.4Sb1.6Te3 returned to initial rhombohedral symmetry.
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