Photoluminescence and ESR identification of γ-ray irradiation induced defects responsible for thermoluminescence in Tb³⁺ activated hibonite (CaAl₁₂O₁₉) powder material

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• 作者：Vijay Singh ; S. Watanabe ; T. K. Gundu Rao ; N. Singh&#8230
• 关键词：Tb3+ ; Hibonite ; Defect centers ; Luminescence ; electron spin resonance
• 刊名：Journal of Electroceramics
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：37
• 期：1-4
• 页码：58-65
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Optical and Electronic Materials; Ceramics, Glass, Composites, Natural Materials; Characterization and Evaluation of Materials; Electrochemistry; Crystallography and Scattering Methods;
• 出版者：Springer US
• ISSN：1573-8663
• 卷排序：37

文摘

CaAl₁₂O₁₉ powder activated with Tb ions has been prepared by the urea combustion route. Phase evolution of the powder is determined by X-ray diffraction techniques. Photoluminescence emission of CaAl₁₂O₁₉:Tb consists of a dominant peak at 544 nm when excited with UV radiations. Thermoluminescence (TL) peaks at approximately 140 °C, 245 °C and 458 °C are observed in the CaAl₁₂O₁₉:Tb phosphor. Investigations using the technique of electron spin resonance (ESR) were carried out to study the defect centers induced in the phosphor by γ-ray irradiation. ESR study reveals the presence of several distinct centers. One of the centers (center I) with an isotropic g factor 2.0110 is tentatively assigned to an intrinsic O− type center and this center relates with the TL peak at 140 °C. Center II with an axially symmetric g-tensor with principal values g_∥ = 2.0324 and g_⊥ = 2.0060 is attributable to an O₂− ion and also appears to correlate with the 140 °C TL peak. Several F+-centers have been identified and their correlation with the observed TL peaks will be discussed.