Melting and Polymorphism of Indium Antimonide at High Pressures

Abstract

THE change of electrical resistivity with pressure of indium antimonide has been studied by Keyes¹ up to 12,000 atmospheres and recently by Gebbie et al.², who extended measurements to 70,000 atmospheres. The resistivity measured at room temperature, according to them, shows an initial increase with pressure and drops several orders of magnitude at 30,000 atmospheres. This sharp drop in resistance was attributed by Gebbie et al. to melting, with the indium antimonide changing from a state of semi-conduction in the crystal to metallic conduction in the liquid phase. A melting curve, based on the pressures giving a drop in resistivity at temperatures of 150°–800° K., was presented by them. The plotted points exhibit a wide scatter and the authors mention that the latent heat of melting calculated from the melting curve slope, namely 27 cal./gm., compares unfavourably with the experimentally determined value of 47.2 cal./gm. Hence it appeared to us that the melting curve of indium antimonide should be investigated again.