The crystal structure of Bi and of solid solutions of Pb, Sn, Sb and Te in Bi

Abstract

Lattice constants, atomic positional parameters and Debye-Waller temperature factors were measured for Bi and Bi-rich binary solid solutions containing atomic percentages 0 to 30 Sb, 0.39 Pb, 0.125 Sn, 0.15 Te, and 0.22 Te at 4.2, 78, and 298 °K.The alloys were made by zone levelling and were based on very pure, zone refined Bi.The lattice constants of the Bi-Sb alloys vary linearly in the composition range x --0 to 30 atomic percent Sb.The variation can be described by the equations: a --4.at 298 ± 3 °K.;[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] at 78 °K.;.10-4x at 4.2 °K.(a,c in /~); the average error is estimated to be 1 part in 2000.The atomic positional parameter z in the Bi-Sb alloys remains approximately constant up to about 12% Sb, and then rises from 0.23407 to 0.23420 at 4.2 °K., 0.23400 to 0.23413 at 78 °K., as the Sb content increases from 0 to 30 atomic percent Sb; the standard deviations of the z's are estimated as 25 × l0 -6.At room temperature z =0.23389.At 78 °K. the z for the other alloys is not significantly different from the value for pure Bi.The temperature factors B, for vibrations parallel to the c axis, are approximately 0.10, 0.32 and 1.14 at 4.2, 78 and 298 °K., respectively, for pure Bi, and increase slightly with increasing Sb content in the Bi-Sb alloys.