ULTRASONIC ATTENUATION AND OCCURENCE OF THE MARTENSITIC TRANSFORMATION IN THE HIGH Tc A15 COMPOUND V3Si

The [I001 shear modulus C44 i s known to be nearly temperature independent in the case of V3Si, an extensively studied compound for wich many authors t r ied to associate the l a t t i c e ins t ab i l i t y and the high superconducting transit ion temperature. We report new sound velocity and attenuation measurements of th i s [loo] shear mode. The temperature change of the sound velocity displays a 6 % re la t ive decrease while a large increase in the attenuation of th i s mode occurs for T decreasing from 80 K to Tc = 17 K. This new observation gives a strong support for a very recently proposed approach to the occurence of the structural transformation in V3Si.