摘要
Single crystals of cuprate oxychloride superconductor Ca2鈭?/sub>xNaxCuO2Cl2 (Na-CCOC) with a systematic variant Tc as a function of Na content are synthesized under high pressure and high temperature. The pressure effect on the superconducting transition temperature in Na-CCOC single crystal is investigated by electrical resistance measurements up to 6.5 GPa. It is found that the Tc decreases almost linearly with increasing pressure, exhibiting a negative pressure shift, which is totally different pressure behavior from that of isostructural (La,Sr)2CuO4 and other cuprate superconductors.