Synthesis of Ba2Ti9O20 materials via a dissolution-precipitation mechanism in a hydrothermal process
Synthesis of Ba2Ti9O20 materials via a dissolution-precipitation mechanism in a hydrothermal process
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DOI：
10.1016/j.actamat.2005.11.037
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发表时间：
2006-04
期刊：
影响因子：
9.4
通讯作者：
Li-Wen Chu;G. Hsiue;I. Lin
中科院分区：
文献类型：
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作者：
Li-Wen Chu;G. Hsiue;I. Lin
采用水热法成功地制备了类奥朗德Ba2Ti9O20前驱体。透射电子显微镜结合反应粉末的化学分析表明，Ti 4+物种首先溶解在溶液中，然后与Ba 2+物种反应，形成钙钛矿相的BaTiO 3在水热过程中。对于起始TiO 2（TiO2粉末）而言，过大的粒度导致溶剂中的Ti离子不足以及与Ba2+物质的不完全反应，这导致缺乏Ba2+的粉末混合物。因此，在煅烧后产生残留的TiO 2相。只有小的TiO2颗粒（40 nm）才能在溶液中产生足够的Ti4+物种，其与Ba2+物种充分反应并导致正确化学计量的TiO2/BaTiO3比率以形成Ba2Ti9O20。用此方法制备的TiO_2/BaTiO_3粉末混合物具有较高的活性，可转化为纯的Ba_2Ti_9O_（20）材料。经煅烧和烧结处理后，该材料具有较高的烧结密度（~93%TD）和良好的微波介电性能（K = 36，Q × f = 27,000）。
A hydrothermal process has been successfully utilized for the preparation of Hollandite-like Ba2Ti9O20precursors. Transmission electron microscopy in conjunction with chemical analyses of reacted powders indicate that Ti4+species are first dissolved in the solution and then react with Ba2+species to form perovskite-phased BaTiO3in the hydrothermal process. An excessively large particle size for the starting TiO2(anatase powders) results in insufficient Ti ions in the solvent and incomplete reaction with Ba2+species, which leads to a Ba2+-deficient powder mixture. A residual TiO2phase thus results after calcination. Only small TiO2particles (40nm) can result in sufficient Ti4+species in the solution, which fully react with Ba2+species and lead to a TiO2/BaTiO3ratio of the correct stoichiometry to form Ba2Ti9O20. TiO2/BaTiO3powder mixtures prepared in this way possess high activity and can be converted into pure Ba2Ti9O20materials. After calcination and sintering processes, such materials possess high sintered density (∼93% TD) and good microwave dielectric properties (K=36 and Q×f=27,000).