Is BiPO4 a Better Luminescent Host? Case Study on Doping and Annealing Effects

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• 作者：Minglei Zhao ; Liping Li ; Jing Zheng ; Liusai Yang ; Guangshe Li
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：January 18, 2013
• 年：2013
• 卷：52
• 期：2
• 页码：807-815
• 全文大小：556K
• 年卷期：v.52,no.2(January 18, 2013)
• ISSN：1520-510X

文摘

Metal phosphates have been popularly regarded as excellent luminescence hosts of lanthanide ions, while such an issue is challenged by the ignorance about the structural stability that may originate from the different chemical nature between the framework and the dopant lanthanide ions. Here, we choose BiPO₄ as a model compound to study. A detailed investigation of the effects of Eu doping and annealing on the structures and related luminescence properties of Bi_1鈥?i>xPO₄:Eu_x (x = 0鈥?.199) has been carried out. A monoclinic phase (denoted as LTMP) was obtained for the undoped sample, which gradually transformed to a hexagonal phase (HP) with increasing doping level of Eu³⁺ to x = 0.068. Further, it is also found that annealing had an obvious impact on the structures of the resulted samples. With increasing the annealing temperature up to 400 掳C a phase transformation from HP to LTMP happens, which is opposite to that with doping. The above phase transformation behaviors were further confirmed by performing structural studies of doping with Dy³⁺ ions and annealing undoped BiPO₄. The structural evolution had a great influence on the luminescent properties. Initially a significant decrease in Eu³⁺ luminescence intensity and quantum efficiency was observed when LTMP transformed to HP. Afterward, a converse situation, increasingly enhanced luminescence performance, appeared when HP transformed to LTMP. Therefore, whether metal phosphates could be taken as better luminescence hosts must take into account their structural changes caused by the different chemical natures between framework and dopant ions, which may provide an important reference for designing new luminescent materials.