压力及高压增氧对La_(2-x)Sm_xCuO_4结构及输运性质的影响  

Structure Evolution and Transport Properties of La_(2-x)Sm_xCuO_4 at High Pressure

作　　者：吴云龙[1] 宋春梅[1] 熊玉峰 李来风[1] 

机构地区：[1]中国科学院理化技术研究所 [2]国家纳米科学研究中心,北京100080

出　　处：《高压物理学报》2006年第4期415-420,共6页Chinese Journal of High Pressure Physics

摘　　要：对常压、高压、高压增氧条件下合成的La2-xSmxCuO4(0≤x≤2.0)结构进行了研究。常压合成样品清晰地反应出样品由T→T+T′→T′相的变化,其中,T相:0<x<0.2;T+T′相:0.2<x<1.0;T′相:1.0<x<2.0。随着x的增加,晶胞参数呈现下降趋势。高压样品没有明显出现T+T′相的过渡阶段,而高压增氧样品更表现为稳定的T相。并且高压、高压增氧样品比常压合成样品含有较多的缺陷。SEM照片显示高压和高压增氧样品比常压合成样品具有更高的质密度,而高氧压的过程也使晶粒变得粗糙和易碎。只有T相高氧压合成样品呈现金属性电阻行为,在x≤0.5时,低温下出现超导电性,并且与交流磁化率结果相吻合。The structure evolution and transport properties of La2-xSmxCuO4 synthesized both at atmosphere pressure and high pressure have been studied. The crystal structure changed from T phase to the T′ phase. Following treatment in high pressure of 6 GPa in 850℃ ,a slight modification in the lattice constants was observed. The results also showed that oxygen pressure tended to stabilize the T structure. The pressure caused the sample density increasing. The high oxygen pressure treatment for the T structure resulted in a drastic decrease of the resistivity at low temperature,indicatlng a superconductivity with Sm concentration≤0.5.

关 键 词：T相 T′相 高压 高温超导 R2CuO4 

分 类 号：O521[理学—高压高温物理]