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Monoclinic structure and electrical properties of metastable Sb 2 Te 3 and Bi 0.4 Sb 1.6 Te 3 phases
Author(s) -
Serebryanaya Nadezhda,
Tatyanin Evgeny,
Buga Sergey,
Kruglov Ivan,
Lvova Natalia,
Blank Vladimir
Publication year - 2015
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201451241
Subject(s) - monoclinic crystal system , metastability , crystallography , electrical resistivity and conductivity , materials science , crystal structure , annealing (glass) , chemistry , metallurgy , physics , quantum mechanics , organic chemistry
We synthesized metastable phases of Sb 2 Te 3 and Bi 0.4 Sb 1.6 Te 3 by quenching after high‐pressure (4 GPa) and high‐temperature (873 K) treatment and specify them as m‐Sb 2 Te 3 and m‐Bi 0.4 Sb 1.6 Te 3 . 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‐Sb 2 Te 3 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‐Bi 0.4 Sb 1.6 Te 3 diverge by a hundredth of angstrom units and monoclinic angle – by tenths of a degree. We revealed that the structure of β‐Sb 2 Te 3 ‐phase, observed in situ under high pressure, may be represented as a structure of m‐Sb 2 Te 3 ‐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‐Sb 2 Te 3 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 Sb 2 Te 3 and Bi 0.4 Sb 1.6 Te 3 returned to initial rhombohedral symmetry.