正交和四方YBa2Cu3O7-x的热膨胀系数

用电容法测量了正交和四方YBa₂Cu₃O_7-x的热膨胀系数与温度的关系。结果表明,正交样品在205K附近,四方样品在92—130K之间热膨胀系数有异常。估计前者可能与晶格的不稳定性有关,说明具有较强的电-声子相互作用,后者可能与结构转变有关,因此破坏了高温超导电性。同时也发现正交样品在92K热膨胀系数有微小跳跃。由此估计了压力效应 关键词：

THERMAL EXPANSION COEFFICIENT OF YBa2Cu3O7-x WITHORTHORHOMBIC AND TETRAGONAL PHASES

Thermal expansion coefficient of YBa₂Cu₃O_7-x with the tetragonal and orthorhombic structural phases were measured by the method of differential parallel-plate capacitance. There exist anomalies near 205 K for orthorhombic phase and between 92 K-130 K for tetragonal phase respectively. We suggest that the former may be related to the lattice instability, indicating that there is a strong electronphonon interaction; the latter may result from the structure phase transition which destroys the high T_c superconductivity. A small jump of the thermal expansion coefficient at T_c was observed in the orthorhombic phase and from this the pressure effect was estimated.