The thermal stability and structural site-distribution of Eu³⁺ ions in the red-emitting phosphors Ca₉Eu₂W₄O₂₄ and Sr₉Eu₂W₄O₂₄

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• 作者：Chuanxiang Qin^a ; Yanlin Huang^a ; Hyo Jin Seo^b ; ^{hjseo@pknu.ac.kr}
• 关键词：Optical materials and properties ; Thermal quenching ; White LEDs ; Rare-earth compounds ; Luminescence
• 刊名：Journal of Alloys and Compounds
• 出版年：2012
• 期刊代码：45_09258388
• 类别：ms
• 出版时间：5 September, 2012
• 卷：534
• 期：Complete
• 页码：86-92
• 文件大小：1189 K

摘要

The red-emitting phosphors Ca₉Eu₂W₄O₂₄ and Sr₉Eu₂W₄O₂₄ were synthesized by the solid-state reaction method. The crystal phases were characterized by X-ray powder diffraction. The photoluminescence excitation and emission spectra were investigated. The luminescence excitation and emission spectra confirm that the phosphors are efficiently excited by near UV light. The dependence of luminescence intensities on the heating temperatures was investigated. The Ca₉Eu₂W₄O₂₄ phosphor exhibits higher thermal stability than that of Sr₉Eu₂W₄O₂₄. The crystallographic sites for Eu³⁺ ions in Ca₉Eu₂W₄O₂₄ and Sr₉Eu₂W₄O₂₄ are investigated by the site-selective excitation spectra in the ⁵D₀ 鈫?#xA0;⁷F₀ wavelength region. It is identified that the Eu³⁺ ions occupy only M sites (statistically occupied by 0.5Eu and 0.5Ca) in Ca₉Eu₂W₄O₂₄ and, however, the Eu³⁺ ions can substitute both M sites (Eu³⁺ + Sr²⁺) and Sr²⁺ sites in Sr₉Eu₂W₄O₂₄. The luminescence spectra and the thermal stability are discussed on the basis of the crystal structure, Eu³⁺ site-distributions and the energy transfer.