Thermal properties of high-Tcsuperconductors

Abstract
Data are reported for the linear thermal expansivity, alpha , of one sample of La1.85Sr0.15CuO4 and four samples of YBa2Cu3O7 in the temperature range 2 to 1000 K. Values are calculated for the Gruneisen parameter, gamma approximately=0.7, using ultrasonic data for the elastic moduli. Published compressibility measurements give much higher values of the bulk modulus and of gamma .