Different morphologies of potassium niobates were prepared via a novel two-step solvothermal process. Firstly, a precursor polyion solution of [Nb₆O₁₉]⁸⁻ was prepared. Secondly, the different morphologies of potassium niobates were prepared by solvothermal treatment of the polyion solution in different water–organic solvents and adjusting the composition of the solvents. A meaningful KNbO₃ (KN) mesocrystal with octahedral morphology was generated for the first time using propylamine as the solvent. The as-obtained KN mesocrystal was a polycrystal constructed from uniform [110]-crystal-axis-oriented KN nanocube crystals, which show a set of single-crystal-like electron diffraction spots. The KN mesocrystal was formed via a self-assembly-topotactic conversion mechanism including the self-assembly of plate-like particles, topotactic conversion to the KN structure and mesocrystalline crystal growth of KN nanocrystals. Such mesocrystal displays a higher piezoelectric response than common individual perovskite crystals. The success in developing the KN mesocrystal can be easily applied to the preparation of a series of piezoelectric K_1−xNa_xNbO₃ continuous solid solution mesocrystals.

中文翻译：

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八面体的KNbO的结构和形态演变₃非晶经由自组装-局部规整转换处理†

通过新颖的两步溶剂热法制备了不同形态的铌酸钾。首先，制备[Nb ₆ O ₁₉ ] ^8-的前体聚离子溶液。其次，通过在不同的水-有机溶剂中对聚离子溶液进行溶剂热处理并调节溶剂的组成来制备不同形态的铌酸钾。有意义的KNbO ₃使用丙胺作为溶剂，首次生成具有八面体形态的（KN）介晶。所获得的KN中间晶体是由均匀的[110]晶轴取向的KN纳米立方体晶体构成的多晶体，其显示出一组单晶状的电子衍射点。KN介晶是通过包括板状颗粒的自组装，向KN结构的介电转化和KN纳米晶体的介晶晶体生长的自组装-阳离子转化机制形成的。与普通的单个钙钛矿晶体相比，这种中观晶体显示出更高的压电响应。KN介晶的成功开发可以轻松地应用于一系列压电K _{1- x} Na _x的制备NbO ₃连续固溶介晶。