Solid Solutions Based on Laminated Chalcogenides of Bismuth and Lead in Ternary Reciprocal Pb, Bi||Se, Te System

摘要

X-ray diffraction and metallographic studies of solid solution alloys are carried out in the PbSe-Bi_2Se_3 and PbTe-Bi_2Te_3 quasi-binary systems. Also, the alloys in the PbTe-Bi_2Se_3 and PbSe-Bi_2Te_3 diagonal cross sections of the reciprocal ternary system Pb, Bi||Se, Te are studied in the range of compositions near the solid solution PbTe_(1-x)Se_x (δ). The PbSe-Bi_2Se_3 phase diagram is refined and it is shown that the phases with orthorhombic lattices existing in the PbS-Bi_2S_3 system do not form in the PbSe-Bi_2Se_3 system. In the Pb, Bi||Se, Te ternary reciprocal system, the presence of extended ranges of quadruple solid solutions of trigonal symmetry based on seven compounds is detected: Pb_2Bi_2Te_5, Pb_3Bi_4Te_9, PbBi_2Te_4, Pb_2Bi_6Te_(11), PbBi_4Te_7, PbBi_6Te_(10), and PbBi_8Te_(13) from the homologous series [PbTe]_m[Bi_2Te_3]_n. The extent of the 8 range of the solid solution with NaCl cubic structure is established at the PbTe-PbSe side. It is found that the extent of the δ-solid solution region decreases as the PbTe content increases. The phase diagram of the PbSe-PbTe-Bi_2Te_3-Bi_2Se_3 reciprocal system illustrates the phase composition of the alloys after homogenizing at 770 K.