煅烧碳酸盐沉淀前驱物制备YBa_2Cu_3O_(7—δ)超导体的研究

STUDY ON THE SYNTHESIS OF YBa_2Cu_3O_(7-δ) BY CALCINING CARBONATE COPRECIPITATE PRECURSOR

本文研究钇钡铜碳酸盐共沉淀前驱物的物相组成及其煅烧过程。该前驱物是由钇钡碳酸盐和碱式碳酸铜、碱式硝酸铜等组成的混合物。在温度达到700℃之前,铜和钇的化合物先后分解为氧化物,900℃之后开始生成YBa_2Cu_3O_(7-δ),BaCO_3的分解是该反应的限速步骤。为了制备单相的YBa_2Cu_3O_(7-δ)粉体,应降低原料中BaCO_3的粒度,并在流动氧气或流动空气中进行煅烧。

Phase composition and calcination process of Y-Ba-Cu carbonate precursor are studied in this paper. It is revealed that the precursor is a mixture of some 'basic salts of copper and carbonates of yttrium and barium. Compounds of copper and yttrium decompose before the temperature reaches 700℃. Formation of YBa_2Cu_3O_(7_δ) begins above 900℃ and becomes very fast as the temperature reaches 950℃. The decomposition of BaCO_3 is the ratelimiting step of the reaction. In order to prepare single phase YBa_2Cu_3O_(7-δ) powder from BaCO_3 and oxides of yttrium and copper, powder size of BaCO_3 should be reduced and the calcination should be carried out in flow oxygen or flow air.