Preparation of Bi_2Sr_2CaCuO_8+x-matrix composites containing fine strontinum calcium indate inclusions via glass crystallization

摘要

The crystallization of glass with a composition of Bi_2Sr_2CaCu_2O_8+x + 0.2 Sr_0.6Ca_0.4In_2O_4 was studied in air between 400 and 800 deg. C. Below 700 deg. C, crystalline phases were formed in the following sequence: (Sr, Ca)_0.9Bi_1.0O_2.55, Cu_2O, Bi-2201, (Sr,Ca)In_2O_4,(Sr, Ca)_3Bi_2O_6, and Bi-2212. Above 700 deg. C, the predominant phases were Bi-2212 and(Sr, Ca(In_2O_4. The introduction of In into Bi-Sr-CA-Cu-O was shown to reduce the glass-forming capability of this system, without suppressing Bi-2212 formation. The Bi_2Sr_2CaCu_2O_8+x + 0.25Sr_0.6Ca_0.4In_2O_4 composites prepared by annealing the precursor glass contained 0.2-to 0.4-μm inclusions and possessed enhanced superconducting properties.