The study of the elastic constants of white tin by diffuse X-ray reflexion

Abstract

Tin crystals were grown by lowering a tube containing the melt through a vertical furnace, at a rate of 5 mm.hr.-L Crystals obtained were spherical or cylindrical of diameter about 2 em. Faces parallel to (100), (110) and (103) were cut with a chisel or microtome. The surface imperfections were removed by electrolytic polishing. The diffuse reflexions from regions of reciprocal space surrounding the reciprocal points 400, 440 and 103 were investigated using a Geiger-counter spectrometer. The results were: c n ----8.6, caa = 13.3, c44 = 4.9, c66 ---5.3, c12----3-5, c13----30×10 n dyne. era.-, the estimated accuracy being 7 %. The values for caz, c44, c6~ and c~2 differ considerably from previous values given by Bridgman. A noteworthy feature of the diffuse reflexion was the backgrotmd intensity. Although this did not interfere with the measurement of the elastic constants, it indicates the presence of diffuse refle.vion due to some other cause than that which is associated with the long acoustic waves.