The paper is published in Sov. Phys. Solid State 30, N 2, 303 (1988).

X-ray diffraction investigations of phase transitions in narrow-gap semiconductors

V. F. Kozlovskii and A. I. Lebedev
M.V. Lomonosov State University, Moscow

An X-ray diffraction investigation was made of the distortions of the fcc lattice in a series of solid solutions of IV-VI semiconductors in which low-temperature phase transitions were expected. Samples of Pb0.8Sn0.2Te and PbTe0.95S0.05 showed no lattice distortions at temperatures T>100 K. Introduction of In and S impurities into Pb1-xGexTe solid solutions reduced the temperature Tc of the ferroelectric phase transition Oh->C3v. A study was made of the influence of the Te->Se substitution on the phase transition in Pb1-xGexTe: it was found that in the case of Pb0.92Ge0.08Te1-ySey the temperature Tc and the temperature coefficient of the rhombohedral distortion angle d(alpha)/dT varied nonmonotonically with y. These effects were explained by the influence of random deformation and quasielectric fields on the ordering of the dipole moments of the noncentral Ge atoms.

Keywords: semiconductor solid solutions, lead tin telluride, lead telluride sulfide, lead germanium telluride, lead germanium telluride selenide, indium, sulfur, Curie temperature


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