THERMAL-EXPANSION AND SPECIFIC-HEAT OF NONRANDOM YBCO AG COMPOSITES/

We report on low-temperature thermal expansion and specific heat measu rements in a series of non-random composites YBCO/Ag x wt% (x = 0, 6, 11 and 23). A reference YBCO polycrystalline sample is also investigat ed. At the lowest temperatures, the expansivities and specific heat ar e analysed as sums of a extrinsic T-linear term and a T-3-Debye contri bution. The Gruneisen parameters are determined and shown to be almost constant for T greater than or equal to 60 K. The values of the Grune isen parameters increase with the silver content in the composites.