Discovery of a new nontoxic cuprate superconducting system Ga-Ba-Ca-Cu-O

查看全文 作　　者：Yue [1]Zhang;Wenhao [1]Liu;Jin [1]Si;Xiyu [1]Zhu;Chengping [1]He;Haonan [1]Zhao;Hai-Hu [1]Wen 机构地区：[1]Center for Superconducting Physics and Materials, National Laboratory of Solid State Microstructures and Department of Physics,National Collaborative Innovation Center of Advanced Microstructures, Nanjing University 出　　处：《Science China(Physics,Mechanics & Astronomy)》索引2018年第61卷第9期,共4页 基　　金：supported by the National Key Research and Development Program of China(Grant Nos.2016YFA0300401,and 2016YFA0401704);the National Natural Science Foundation of China(Grant Nos.A0402/11534005,and A0402/11674164) 摘　　要：Superconductivity is observed in a new nontoxic cuprate system Ga-Ba-Ca-Cu-O,with T_c=82 K for Ga Ba_2Ca_5Cu_6O_(14+δ)(Ga-1256)and T_c=116 K probably for Ga Ba_2Ca_3Cu_4O_(10+δ)(Ga-1234)or Ga Ba_2Ca_2Cu_3O_(8+δ)(Ga-1223),respectively.All compounds are fabricated by solid state reaction method under high pressure and high temperature.Samples are characterized by resistivity,magnetization and X-ray diffraction(XRD)measurements.The temperature dependence of magnetization measured in both zero-field-cooled and field-cooled processes on one sample(S1)shows two superconducting transitions at about 82 K and113 K.The estimated shielding fraction for the phase with T_cof 82 K is about 67%,while the fraction for another phase with T_(c )of 113 K is quite small.The XRD Rietveld refinement for S1 indicates two main phases existing in the sample,Ga-1256 with fraction of about 58%and non-superconducting Ca_(0.85)Cu O_2with fraction of about 42%respectively.Thus,we can conclude the superconducting phase with transition temperature of 82 K is due to Ga-1256.The resistivity measurement also confirms the superconductivity for S1,and the resistivity reaches zero at about 82 K.The temperature dependence of magnetization for another sample(S2)shows much higher superconducting shielding fraction for the phase with T_cof 116 K,which may be a promising prospective for the synthesis of Ga-1234 or Ga-1223 phase. 关 键 词：超导性 无毒 系统 温度依赖 X光检查 GA 高压力 混合物