Self-Diffusion in Tin Crystals

Abstract

The rate of self-diffusion in single crystals of white tin of various orientations has been measured using the radio-active isotope Sn¹¹³. The ratio of the diffusion coefficients parallel and perpendicular to the tetragonal (c) axis is approximately 2 at 180 °C. and approximately 3 at 223 °C. The diffusion coefficients in both directions at various temperatures are given by the Arrhenius expressions D_c= 1.2 x 10^-5e^-10,1500/RT cm.²sec.^-1 and D_a=3.7 X 10^-8e^-5,900/RT cm.²sec.^-l. The anisotropy is discussed in terms of the vacancy mechanism of diffusion.