固相反应合成钙钛矿型氧化物Ba1.0Co0.7Fe0.2Nb0.1O3-δ的机理

Synthetical process of perovskite-type oxide Ba_(1.0)Co_(0.7)Fe_(0.2)Nb_(0.1)O_(3-δ) by solid state reaction

以BaCO3、Co3O4、Fe2O3和Nb2O5粉末为原料,通过固相反应合成了钙钛矿型复合氧化物Ba1.0Co0.7Fe0.2Nb0.1O3-δ.利用XRD、SEM和TGA-DSC同步热分析仪等研究了合成该材料的反应过程.结果发现,在固相反应法合成Ba1.0Co0.7Fe0.2-Nb0.1O3-δ的过程中,首先出现的是BaCoO3、BaFeO2.9相和Ba5Nb4O15相,在1 473 K烧结10 h能够得到立方钙钛矿相的Ba1.0-Co0.7Fe0.2Nb0.1O3-δ.通过分析,整个反应过程分为两个阶段:第一阶段为BaCO3和Co3O4、Fe2O3、Nb2O5之间的加成反应;第二阶段为加成反应生成的BaCoO3、BaFeO2.9和Ba5Nb4O15三相之间逐渐固溶生成均相Ba1.0Co0.7Fe0.2Nb0.1O3-δ,此过程伴随有氧的脱出.

A perovskite-type composite oxideBa1.0Co0.7Fe0.2Nb0.1O3-δ（BCFN） was successfully synthesized by solid state reaction with BaCO3, Co3O4, Fe2O3 and Nb2O5 powders as raw materials. The synthetical process and morphology of BCFN fine particles were studied by non-isothermal thermogravimetry and differential scanning calorimetry （DSC）, X-ray diffraction analysis, and scanning electron microscope. The results show that during the synthesis process, BaCO3、BaFeO2.9 and BasNb4O15 phases firstly appeared, and after 10 h sintering at 1473 K, a cubic perovskite-type oxide Ba1.0Co0.7Fe0.2Nb0.1O3-δ was synthesized. The overall reaction process is considered involving two stages. The first stage is addition reaction between BaCO3 and CO3O4, Fe2O3, Nb2O5 parti- cles and the second is solid solution reaction between BaCoO3 and BaFeO2.9, Ba5Nb4O15 phases formed in the first stage. Oxygen escaping was observed during the second stage.