Hydrothermal Synthesis of Open-Framework Borophosphates with Tunable Micropore Sizes, Crystal Morphologies, and Thermal Stabilities

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• 作者：Wei Sun ; Ya-Xi Huang ; Sergiy Nokhrin ; Yuanming Pan ; Jin-Xiao Mi
• 刊名：Crystal Growth & Design
• 出版年：2015
• 出版时间：August 5, 2015
• 年：2015
• 卷：15
• 期：8
• 页码：3594-3601
• 全文大小：622K
• ISSN：1528-7505

文摘

Thermal stabilities of zeolitic frameworks are important parameters for many applications. Two decades of research have produced only a very small number of zeolitic borophosphates such as Na₂[VO(B₂O)(PO₄)₂(HBO₃)]路xH₂O (x 鈮? 2.92) (denoted as B₃P₂), which shows the onset dehydration and a complete decomposition at 200 and 400 掳C, respectively. In order to enhance thermal stabilities of borophosphate frameworks, a water-deficient hydrothermal route with phosphoric acid as the sole solvent has been developed and led to controlled syntheses of B₃P₂ and a new vanadium borophosphate, K_1.33Na_0.67[VO(B₂O)(PO₄)₂(HPO₄)]路xH₂O (x 鈮? 1.63) (denoted as B₂P₃). The latter is the first-ever borophosphate possessing the zeolite RHO-type net and is characterized by superlarge spherical cages, including 16-ring and 8-ring channels along the axes and 12-ring channels along the diagonals of the cubic cell. The new compound B₂P₃ has larger structural cages and higher thermal stability than B₃P₂, where the enhanced thermal stability is attributable to different bonding arising from the substitution of [BO₂(OH)] by [PO₃(OH)] in the framework. This is the first demonstration that the micropore size, crystal morphology, and thermal stability of zeolitic borophosphates can be tuned by changing the fundamental building units of their frameworks via adjusting the B/P ratios in the starting materials.