高温X射线衍射研究 YBa_2Cu_3O_(7-δ)超导体的正交—四方相变

High Temperature X-ray Diffraction Study on the Orthorhombic-Tetragonal Transition of YBa_2Cu_3O_(7-δ) Superconductor

本文采用高温 X 射线衍射技术研究了 YBa_2Cu_3O_(7-δ)超导样品在升温及降温过程中的正交—四方相变。发现随着温度的升高或降低,晶体结构存在着 O(i)—O(ii)—T 的变化过程。点阵参数及其相互关系随温度的变化是(013)、(103)、(110)和(116)、(123)、(213)衍射线条分裂合并及强度比逆转的根本原因。在空气中,正交—四方相变发生在620℃附近。

High temperature X-ray diffraction method was used to investigate the orthor-hombic-tetragonal transition of YBa_2Cu_3O_(7-δ) superconducting sample during tempera-ture increasing and decreasing.There are O(i)-O(ii)-T transition in crystal structure,when the temperature is raised and lowered.The variation of lattice parameters andtheir interrelation with temperature will result in the splitting and overlapping andintensity ratio reversing of (013) (103) (110) and (116) (123) (213) diffractionlines.In the air,orthorhombic-tetragonal phase transition occurs at around 620℃.