YBa₂Cu₃O_7-yのTcとJcにおよぼす熱処理時の冷却速度の影響

抄録

The oxygen concentration in Y-Ba-Cu-O is one of the dominant factors to control the superconducting properties. Since oxygen concentration is controlled by the cooling rate, the cooling rate affects the superconducting properties. The lattice constant of the c-axis is related to oxygen concentration. Thus, we undertook to obtain the change of superconducting properties (Tc and Jc) and the lattice constant of the c-axis with the cooling rate in Y-Ba-Cu-O. The cooling curves were dominated Newton analysis.
Based on the relaxation theory, we showed the existence of an approximately linear relationship between the lattice constant of the c-axis and the cooling rate, between Tc and the cooling rate and between Jc at 15K and the cooling rate. we conclude that the relaxation theory can be explained by oxygen concentration change in oxygen-deficient perovskite of Y-Ba-Cu-O.
The abnormal Jc change is found from 45 to 65K for slow cooled specimen. The probable explanation is discussed by two phases. The slow cooled specimen has the ortho-I (matrix) and the ortho-II, the ortho-II can be the pinning site and then causes the abnormal Jc change.