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

作　　者：Yue Zhang Wenhao Liu Jin Si Xiyu Zhu Chengping He Haonan Zhao Hai-Hu 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)》2018年第9期82-85,共4页中国科学：物理学、力学、天文学（英文版）

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.Superconductivity is observed in a new nontoxic cuprate system Ga-Ba-Ca-Cu-O,with Tc=82 K for Ga Ba2Ca5Cu6O（14＋δ）（Ga-1256）and Tc=116 K probably for Ga Ba2Ca3Cu4O（10＋δ）（Ga-1234）or Ga Ba2Ca2Cu3O（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 Tcof 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 O2with 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 Tcof 116 K,which may be a promising prospective for the synthesis of Ga-1234 or Ga-1223 phase.

关 键 词：CUPRATES high pressure and high temperature SUPERCONDUCTIVITY 

分 类 号：TM26[一般工业技术—材料科学与工程]