【摘要】 研究了YBa₂Cu₃O_7-δ正交相和四方相中氧在Cu（1）-O基平面上跳动引起的两低频内耗峰;研究了在正交-四方相变过程中它们随氧含量的变化规律,并据此分析了YBCO中正交-四方相变的级次,认为在～200℃该相变实际上可能是一个一级相变。更多还原

【Abstract】 Two low frequency internal friction peaks, one induced by oxygen jumping in the Cu(l)-O basal planes in the orthorhombic phase and the orther in the tetragonal phase, were systematically studied. The order of orthorhombic-tetragonal phase transition was analysed based upon the internal friction data. It was inferred that the transition, generally considered as second order, may actually be first order, at least near 200℃.更多还原