An anomalous resistance drop was observed near 190K in the R-T measurement on a sample in Bi-Sr-Ca-Cu-O system and the transition completed at 80K.After keeping the sample at room temperature for 10h,the temperature d...An anomalous resistance drop was observed near 190K in the R-T measurement on a sample in Bi-Sr-Ca-Cu-O system and the transition completed at 80K.After keeping the sample at room temperature for 10h,the temperature dependence of the resistance changed from semiconducting to metallic behavior,while the ending of the transition remained at 80K.This might be an evidence of the existence of a metastable superconducting phase in Bi-Sr-Ca-Cu-O system with Tc as high as 190K.展开更多
Superconducting transition has been observed by electrical resistance and a.c.magnetic susceptibility measurements in Tm_(x)Ba_(1-x)CuO_(3-y) with x=0.6 and 0.7 and y>0.The highest T_(c) of the samples measured is ...Superconducting transition has been observed by electrical resistance and a.c.magnetic susceptibility measurements in Tm_(x)Ba_(1-x)CuO_(3-y) with x=0.6 and 0.7 and y>0.The highest T_(c) of the samples measured is observed in Tm_(0.6)-Ba_(0.4)CuO_(3-y) which has the T_(c)(mid)=91K with ΔT_(c)=0.5K,and T_(c)(ρ=0)=90.1K.The a.c.magnetic susceptibility measurements show a very strong diamagnetism at the temperature of resistive midpoint.展开更多
In high temperature oxide superconductors, such as Sr-La-Cu-O,Ba-Y-Cu-O, there is a phase transition from semiconductor to metal as the composition changes under the same condition of heat treatment. Recently the theo...In high temperature oxide superconductors, such as Sr-La-Cu-O,Ba-Y-Cu-O, there is a phase transition from semiconductor to metal as the composition changes under the same condition of heat treatment. Recently the theoretical explanations are proposed, hut the research is still at an initial stage. Thus study in different ways on the cause of the phase transition and its relationship with high temperature superconductivity is one of the important current subjects.展开更多
基金Project suppprted by the Naticma J.Science Foundstion of China(No.1860860)and the Chinese Superconducting Research Center.
文摘An anomalous resistance drop was observed near 190K in the R-T measurement on a sample in Bi-Sr-Ca-Cu-O system and the transition completed at 80K.After keeping the sample at room temperature for 10h,the temperature dependence of the resistance changed from semiconducting to metallic behavior,while the ending of the transition remained at 80K.This might be an evidence of the existence of a metastable superconducting phase in Bi-Sr-Ca-Cu-O system with Tc as high as 190K.
文摘Superconducting transition has been observed by electrical resistance and a.c.magnetic susceptibility measurements in Tm_(x)Ba_(1-x)CuO_(3-y) with x=0.6 and 0.7 and y>0.The highest T_(c) of the samples measured is observed in Tm_(0.6)-Ba_(0.4)CuO_(3-y) which has the T_(c)(mid)=91K with ΔT_(c)=0.5K,and T_(c)(ρ=0)=90.1K.The a.c.magnetic susceptibility measurements show a very strong diamagnetism at the temperature of resistive midpoint.
文摘In high temperature oxide superconductors, such as Sr-La-Cu-O,Ba-Y-Cu-O, there is a phase transition from semiconductor to metal as the composition changes under the same condition of heat treatment. Recently the theoretical explanations are proposed, hut the research is still at an initial stage. Thus study in different ways on the cause of the phase transition and its relationship with high temperature superconductivity is one of the important current subjects.
