Abstract
Two peaks in the resistivity of the Bi2Sr2CaCu2Oy were detected at 300 and 650°C on heating process, but no peak was detected at 300°C on cooling process in spite of holding at 300°C for 100hr. In order to elucidate the cause of the peak at 300°C, the measurments of high temperature resistivity, Tc, thermogravimetry and X-ray diffraction were carried out for the Bi2Sr2CaCu2Oy quenched for various temperatures. Tc and normal-state resistivity as a function of a quenching temperature, Tq, had a steep minimum at Tq=300°C. The high temperature resistivity was also strongly dependent on Tq, but had a peak or a slope change at about 300°C on heating. X-ray diffraction showed that no change was found before and after quenching or high temperature resistivity measurement up to 400°C. The weight decrease was detected at 350°C during heating in air, but little change during cooling process. From these results, it may be considered that the peak in the resistivi-ty at 300°C is due to the decrease in the electrical hole concentration compensating the increase in the oxygen vacancy concentration. Further detailed research is in progress.
