Structures and Polymorph-Sensitive Luminescence Properties of BiPO4/Eu Grown in Hydrothermal Conditions

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• 作者：Minglei Zhao ; Guangshe Li ; Liping Li ; Liusai Yang ; Jing Zheng
• 刊名：Crystal Growth & Design
• 出版年：2012
• 出版时间：August 1, 2012
• 年：2012
• 卷：12
• 期：8
• 页码：3983-3991
• 全文大小：498K
• 年卷期：v.12,no.8(August 1, 2012)
• ISSN：1528-7505

文摘

In this work, BiPO₄/Eu of different polymorphs was prepared using a simple hydrothermal method. It is found that a hexagonal phase (HP) was formed at 100 掳C, which transformed to a low-temperature monoclinic phase (LTMP) when hydrothermal temperature was increased to 160 掳C. This LTMP transformed reversely to HP when the temperature increased beyond 180 掳C. This phase evolution is quite distinct from those when using high-temperature calcinations ( CrystEngComm, 2011, 13, 6251鈥?257). Accompanying this phase evolution, sample morphology varied from homogeneous rodlike shape to prismlike shape, while the lattice strain features changed from tensile to compressive, and then to tensile, as followed by a decrease in symmetry of tetragonal PO₄ groups from pseudo-T_d to C₁. These variations were closely related to the reaction mechanism in solution chemistry, in which two interfacial processes were indicated, differing from the ionic diffusion process during calcination. As a consequence, luminescence properties become sensitive to polymorphs. All Judd鈥揙felt parameters (惟_位, 位 = 2, 4, 6) were calculated to evaluate the asymmetric nature for the polymorph-sensitive luminescence. It is found that the 惟₂ value for HP was 1.66 脳 10^鈥?0 cm², which increased to 2.10 脳 10^鈥?0 cm² for LTMP; meanwhile, the quantum efficiency increased from 9.33% for HP to 36.09% for LTMP. These results demonstrated that BiPO₄ of different polymorphs can be obtained through the hydrothermal method, which may enrich the significance of solution chemistry in preparing advanced materials of tailored functionalities.