酸化物超伝導体に関する研究Ⅱ

Abstract

Y-Ba-Cu-O oxide, one of the materials of superconductivity, was made and examined the electrical characteristic and the crystallization. Oxide superconductor was mixed from CuO, BaCO3 and Y2O3 with stoichiometric composition. The mixture was pre-sintered a 　900℃ for 5 hours in air. The pre-sintered product was powdered, and then sintered again at 900℃ for 5 hours. These processes were repeated several times for enough chemical reaction. Then the product pressed at an applied pressure to produce pellets of 10mm in diameter and 3mm in height. Subsequently, the pellets were sintered at 940℃ for 5 hours in air and finally cooled to room temperature in the furnace. Measurment of resistivity was done by using four-terminal method and transition temperature above 90K was obtained. And Meissner effect was certified by floating up of a magnet over the sample of the oxide at liquid nitrogen temperature. The crystallization of the sample was recognized by X-ray diffraction analysis and Electron Probe Micro Analysis (EPMA). In this paper the electrical characteristic and the crystallization are examined with relation of the times of pre-sintering processes.