Bi-1212相和Bi-1222相铜氧化合物的合成和超导电性

PREPARATION AND SUPERCONDUCTIVITY OF Bi-1212 AND Bi-1222 PHASE CUPRATES

对名义组份为(Bi_(1-x),M_x)Sr_2YCu_2O_y(x=0.6—0.7)的样品,当M=Cd,Ni和Zn时合成了Bi-1212相材料,实验发现Cd占据Bi位,可以稳定单BiO层,高压氧下退火,在32K出现超导转变,而Zn和Ni进入CuO平面,占据Cu位,破坏了材料的超导电性。用Cd稳定单BiO层还能够合成Bi-1222相化合物,它的固溶范围比Bi-1212大,对这一现像进行了结构上的分析。在不同氧压退火处理下的Bi-1222相样品,电阻随氧压增大而变小,但在4.2K以上未观察到超导转变。

The Bi-1212 phase cuprates with a range of composition around (Bi,M)Sr2YCu2-O, (M=Cd,Ni, or Zn) were prepared. It was found that Cd2+ ions were present at the Bi3+ sites, and could stabilize the BiO monolayers, while Ni2+ and Zn2+ ions substituted for Cu2+ ions in the CuO sheets. After annealing in high pressure oxy-gen, (Bi0.3Cd0.7)Sr2YCu2Oy sample exhibited superconducting transition at 32K. Bi-1222 phase compound was synthesized with the BiO monolayers stabilized by Cd2+ ions, superconductivity was not observed at above 4.2K.