| 摘要 |
PURPOSE:To obtain a high density product having a high critical current density by using Cu in excess of Ca when an oxide consisting of Bi, Pb, Sr, Ca, Cu and O is melted and beat-treated to produce an oxide superconductor. CONSTITUTION:An oxide consisting of Bi, Pb, Sr, Ca, Cu and O is heated to melt at least part of the oxide and the heated oxide is held at a temp. at which a superconducting phase is formed for a certain time to obtain an oxide superconductor. In this method, the atomic ratio of Cu to Ca in the starting material before melting is regulated to 2 to 10. Since the segregation of Ca is prevented and the amt. of Ca melted is increased, 110K phase can easily be formed by cooling and heat-treating the heated oxide at 800 to 860 deg.C below the m.p. If the atomic ratio of Cu to Ca is >10, the amt. of impurities is increased and the critical current density of the superconductor is reduced. |
