High-purity ceramic samples of the modulation-free Bi2-xPbxSr2Ca1-yYyCu2Oz with a wide range of composition (x=(l+y)/2±0.2, 0.25≤y≤0.8) have been prepared by the polymerized complex method. The method is based on the formation of a polymer complex which is obtained through polyesterfication between metal citrate complexes and ethylene glycol. This method yielded almost homogeneous x=0.8 materials with Y compositions of y=0.2, 0.6 and 0.8 through relatively short sintering periods of 32 hours. The corresponding X-ray diffraction and Raman scattering analyses have shown that the materials are virtually of single phase with only minor traces of Sr2.5Bi0.5Pb3Ca2CuOz (< 1 %). The lattice parameters a and b increase, while the c-axis value decreases with increasing Y content, y. Complex magnetic susceptibility measurements have confirmed the presence of a single bulk Bi2212 phase. For Bi1.2Pb0.8Sr2Ca0.8Y0.2Cu2Oz, the onset temperature of superconducting transition Tc was 89.5 K and the transition width (10-90 %) of full diamagnetism was 6.4 K for the measuring field of 100 mOe. The variation of Tc with Y content in the modulation-free Bi2212 phase was similar with that observed in the modulated Bi2Sr2Ca1-yYyCu2Oz.
|ジャーナル||journal of the japan society of powder and powder metallurgy|
|出版ステータス||Published - 1995|
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