Elastic constants of the layered compounds Gas, GaSe, InSe, and their pressure dependence I. Experimental part

The elastic constants of the lamellar compounds Gas, GaSe, InSe are measured on several samples using an ultrasonic method, and the results are compared with previous publications. The variations of C 33 , C 11 , and C 66 with an hydrostatic pressure are measured up to 3 kbars. In the range of pressure studied, the variations of these constants are perfectly linear. The results on the three compounds are very similar, and typical of the lamellar structure: an important variation of C 33 caused by the weakness of the interlayer bond; on the other hand, C 66 is very few affected by pressure.