PRECISE MEASUREMENTS OF THE AB-PLANE RESISTANCE OF YBA2CU3O7-Y SINGLE-CRYSTALS UNDER HYDROSTATIC-PRESSURE

The temperature dependence of the ab-plane electrical resistance (R(ab )(T)) of YBa2Cu3O7-y single crystals has been studied under hydrostati c pressure up to 8 kbar using helium as the pressure transmitting medi um. The partial derivative ln(partial derivative R(ab)/partial derivat ive T)/partial derivative ln V value obtained by us is approximately f our times greater than that calculated from the data of S.W. Tozer et al. [Phys. Rev. B 47 (1993) 8089] for the pressure range 3.6-130 kbar. The lattice Gruneisen constant (gamma) estimated from our data in ter ms of the Bloch-Gruneisen model is unusually large, gamma=6.8.