Relationship between critical temperature, oxygen deficiency and Meissner fraction inIMG/IMGsuperconductors

摘要

The relationship between the oxygen deficiencyand the critical temperaturein the YBCO system has been studied by many authors; most workers are in agreement that the region of superconductivity in YBCO starts at. Also, they leave unanswered questions. Why isnearly equal to 0 and not exactly equal to 0? What is the definite value ofcorresponding to the end of the superconductivity region? In this work a relationship between Meissner fraction and the grain diameter of the presintered powder is presented. A new function(whereis the Meissner fraction) is introduced. This function increases linearly with. Also, it is found that the range of good superconductivity in YBCO starts atand ends at.