Crystal structure, energy transfer mechanism and tunable luminescence in Ce³⁺/Dy³⁺ co-activated Ca₂₀Mg₃Al₂₆Si₃O₆₈ nanophosphors

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• 作者：Ashwini Kumar^a ; ^b ; ^{ashwinikumar.vnit@gmail.com" class="auth_mail" title="E-mail the corresponding author} ; S.J. Dhoble^c ; D.R. Peshwe^b ; Jatin Bhatt^b ; J.J. Terblans^a ; H.C. Swart^a ; ^{swarthc@ufs.ac.za" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Rietveld analysis ; Ca20Mg3Al26Si3O68 ; Energy transfer ; Tunable luminescence ; Ce3+/Dy3+ co-doped
• 刊名：Ceramics International
• 出版年：2016
• 出版时间：July 2016
• 年：2016
• 卷：42
• 期：9
• 页码：10854-10865
• 全文大小：3919 K

文摘

Ce³⁺, Dy³⁺ and Ce³⁺/Dy³⁺ co-doped Ca₂₀Mg₃Al₂₆Si₃O₆₈ (CMAS) nanophosphors were synthesized via modified solution-combustion method. Sharp X-ray diffraction patterns confirmed the formation of pure crystalline phase of Ca₂₀Al₂₆Mg₃Si₃O₆₈ as an orthorhombic crystal system having space group Pmmn. The phase purity of as synthesized material has allowed reliable structural parameters to be obtained from the Rietveld analysis of its powder diffraction pattern. The Ce³⁺, Dy³⁺ and Ce³⁺/Dy³⁺ emission at different lattice sites in CMAS host has been identified and discussed. Under ultra-violet (UV) excitation, optical properties and the energy transfer mechanism from Ce³⁺ to Dy³⁺ in CMAS: Ce³⁺/Dy³⁺ nanophosphors have been elaborated by photoluminescence spectroscopy. Also, the effects of doping and sintering temperature on the structure of prepared CMAS host samples have been investigated in detail. The Ce³⁺/Dy³⁺ concentration quenching mechanism due to multipole–multipole interaction has been studied and the critical energy-transfer distance was calculated to be 7.8 Å. The band gap of the synthesized phosphors was calculated from diffuse reflectance spectra using the Kubelka–Munk function. A uniform layered structure network has been revealed in scanning electron microscopy images of the CMAS phosphor. Transmission electron microscopy results indicate nanocrystalline nature of synthesized phosphors. CMAS: 1 m% Ce³⁺ and CMAS: 0.5 m% Dy³⁺ nano-luminescent powders are promising candidate as a blue and blue–yellow emitting UV convertible phosphor for application in white light emitting diodes. By utilizing the energy transfer mechanism in present CMAS: Ce³⁺/Dy³⁺ nanophosphors, with an appropriate tuning of the activator content, these phosphors can exhibit great potential for white light emission, as single-emitting component phosphors in solid state lighting technology.