Effect of hydrostatic pressure on the elastic moduli of As2S3 and As2Se3 glasses at 195 and 296 K

Abstract Velocities of 30 MHz longitudinal and shear ultrasonic waves have been measured in As 2 S 3 and As 2 Se 3 glasses as a function of hydrostatic pressure up to 1.5 kbar at 195 K and 3 kbar at 296 K. The elastic stiffness moduli are found to have relatively large, positive, pressure dependences which are about the same at both temperatures for both glasses. This behavior is attributed to the weakness of bonding between layers comprised of AsS 3 and AsS 3 pyramids. Inspection of data for a variety of glasses reveals a correlation between the value of C L /3 C T and whether the elastic moduli are increased or decreased by pressure. ( C L is the longitudinal modulus and C T the shear modulus.) Using the pressure dependences of the elastic moduli obtained in the present work, it is found that volume change is responsible for most of the temperature dependences of the moduli. In addition elastic gammas are obtained which are consistent with thermal Gruneisen gammas at 12 K. The pressure dependence of the volume of As 2 S 3 glass at 296 K is calculated using the present results in the Murnagham equation. Agreement with volumetric data of Weir is obtained.