Vicker’s microhardness of Bi1−xSbx (x = 0.05–0.30) crystals

Abstract

The solid–liquid interface of Bi1−xSbx crystal growth is very favorable for investigations of electron–phonon phenomena. Bismuth is a semimetal with high electron and hole mobilities. When Bi is doped with Sb in the range of 7–22 atomic percentage, it undergoes semimetal–semiconductor transition. Interest in Bi–Sb materials system has recently been stimulated due to promise of a new generation of thermoelectric materials based on these alloys. The starting materials used in this study, Bi and Sb, were both of 99.999% purity. The authors have studied microhardness of these crystals with the above said composition range. The crystals were grown using Zone melting method with 0.35 cm/h growth speed and 25 zone passes. The indentation method is the most widely used method for measurement of hardness of the crystals either of metallic or nonmetallic nature. This method does not require large specimens and even on a small specimen a number of measurements can be carried out. Microhardness indentation tests were carried out on the cleavage planes (111) of the Bi1−xSbx (x = 0.5 to 0.30) crystals, using the Vickers diamond pyramidal indenter. The results of Vickers microhardness studies on Bi1−xSbx (x = 0.05, 0.10, 0.15, 0.20, 0.25, 0.30) are presented in this paper.