Synthesis of Rare Earth Polyborates Using Molten Boric Acid as a Flux

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• 作者：Linyan Li ; Peichao Lu ; Yaoyang Wang ; Xianglin Jin ; Guobao Li ; Yingxia Wang ; Liping You ; and Jianhua Lin
• 刊名：Chemistry of Materials
• 出版年：2002
• 出版时间：December 2002
• 年：2002
• 卷：14
• 期：12
• 页码：4963 - 4968
• 全文大小：128K
• 年卷期：v.14,no.12(December 2002)
• ISSN：1520-5002

文摘

Hydrated rare earth hexaborates H₃LnB₆O₁₂ (Ln = Sm-Lu) have been synthesized byusing molten boric acid as the reaction medium. H₃LnB₆O₁₂ decomposes at certaintemperatures to form anhydrous pentaborates LnB₅O₉ (Ln = Sm-Er) or orthoborates LnBO₃(Ln = Tm-Lu). The crystal structures of the hexaborates and pentaborates have beendetermined by single-crystal and powder diffraction techniques. The hydrated hexaboratesH₃LnB₆O₁₂ crystallize in a trigonal structure in the space group R3c, which contain a six-membered ring B₆O₁₅ as a fundamental fragment. Anhydrous pentaborates LnB₅O₉ crystallizein a tetragonal structure that is built up with B₄O₉ and BO₃. LnB₅O₉ decomposes at highertemperature to metaborates (Ln = Sm-Tb) and orthoborates (Ln = Dy-Er). A phase diagramis presented that shows the stable range of both H₃LnB₆O₁₂ and LnB₅O₉. The luminescentproperty of the europium-doped GdB₅O₉ was studied.