Anisotropic Thermal Diffusivity and Conductivity of YBCO(123) and YBCO(211) Mixed Crystals. I

Abstract

The anisotropic thermal diffusivity α of the highly c-axis-oriented Y–Ba–Cu–O bulk superconducting crystals has been measured quasi-simultaneously with the thermal conductivity κ. The estimated values of the specific heat C by use of α and κ values parallel and perpendicular to the c-direction agreed with each other. In these crystals prepared by the modified melt texture growth (MMTG) method, fine Y₂BaCuO₅ particles are dispersed in the YBa₂Cu₃O_{7- x} superconducting matrix phase. Based on a simple model, the thermal diffusivity and the specific heat of the YBa₂Cu₃O_{7- x} matrix phase are separated using independently measured data of a Y₂BaCuO₅ polycrystal. The influence of Y₂BaCuO₅ particles on the thermal properties of the mixed crystals is discussed.