RELATIONSHIPS OF OXYGEN INDEX AND X-RAY DIFFRACTION LINE PROFILES IN THE PHASE TRANSFORMATION OF YBa_2Cu_3O_(7-x)
YBa_2Cu_3O_(7-x)结构转变中氧含量与X射线衍射轮廓的关系

The phase transformation of orthorhombic to tetragonal phase ofY-Ba-Cu-O has been investigated in details by X-ray diffraction.This transformation isof the second order or close to second order has been observed and strongly deponds on theoxygen index which changes with annealing temperature.From some X-ray diffractionline-profile measurements have been presented and shown to be useful for identification ofY-Ba-Cu-O and estimation of oxygen index x in details.The effects of oxygen deficiencyand its ordering on the superconductivity also have been investigated.