新块材超导体Pr_(1-x)Ca_xBa_2Cu_3O_(7-δ)(0.4≤x≤0.6)的高压合成与超导电性

HIGH PRESSURE SYNTHESIS AND SUPERCONDUCTIVITY OF NEW BULK Pr_[1-x]Ca_xBa_2Cu_3O_[7-δ]SUPERCONDUCTORS

采用高温高压合成方法，合成出了Ｐｒ１－ｘＣａｘＢａ２Ｃｕ３Ｏ７－δ（０４≤ｘ≤０６）系列块材超导体，在缺氧的Ｐｒ０．５Ｃａ０．５Ｂａ２Ｃｕ３Ｏ７－δ四方１２３结构样品中得到了Ｔｃ为９８Ｋ．实验结果表明Ｐｒ在１２３结构中的价态为大于３＋的混合价态，因而空穴填充和杂化导致的载流子局域化是Ｐｒ抑制１２３相超导电性的关键因素．

AbstractThe new bulk superconductors of Pr_[1-x]Ca_xBa_2Cu_3O_[1-δ] (0.4≤x≤0.6) have been synthesized under high pressure for the first time to our knowledge. The highest Tc of 98K was observed for Oxygen deficient tetragonal Pr_0.5Ca_0.5Ba_2Cu_3O_[7-δ] sample. Our results demonstrate the valence state of Pr in 123 structure is a mixed sate greater than 3+, hole filling and hybridization are the primary cause of the suppression of superconductivity by Pr in 123 structure.