Thermal expansion of alkali halides from 70 to 570 K

Abstract

The thermal expansion of 15 alkali halides has been investigated from 70 to 570 K. The single-crystal specimens of LiF, LiCl, LiBr, NaF, NaCl, NaBr, NaI, KF, KCl, KBr, KI, RbI, CsCl, CsBr, and CsI are examined using a high-precision differential dilatometer in conjunction with an electronic micrometer. The results are compared with those available in the literature and are found to be in reasonable agreement. The Grüneisen parameter γ has been calculated using the present thermal expansion data. For a given cation group, the value of γ is very close, but increase in the cation size decreases γ slightly. The indications are that in the temperature range under investigation γ increases very slowly with temperature.