Synchrotron radiation investigations of the Sr_2MgSi_2O_7:Eu~(2+),R~(3+) persistent luminescence mat

• 作 者: Tuomas Aitasalo Jukka Hassinen Jorma Hls Taneli Laamanen Mika Lastusaari Marja Malkamki Janne Niittykoski Pavel Novák
• 机 构: Department of Chemistry, University of Turku FI-20014 Turku, Finland,Turku University Centre for Mat
• 出 处: Journal of Rare Earths
• 发表日期: 2009年04期
• 关键词: luminescence persistent practically remaining contributions agreed excitation sy

The electronic and defect energy level structure of polycrystalline Sr2MgSi2O7:Eu2+,R3+ persistent luminescence materials were studied with thermoluminescence and different synchrotron radiation spectroscopies (UV-VUV emission and excitation, X-ray absorption near-edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS)). Special attention was paid on the effect of the R3+ co-dopants on the persistent luminescence properties of the materials. Theoretical calculations using the density functional theory (DFT) were carried out simultaneously with the experimental work. The experimental band gap energy (Eg) value of ca. 7.1 eV agreed very well with the DFT value of 6.7 eV. The variation of the Eg value was attempted to relate with the trap structure as well as with the different properties of the R3+ co-dopants. The trap level energy distribution depended strongly on the R3+ co-dopant except for the shallowest trap energy above the room temperature remaining practically the same, however. The different processes in the mechanism of persistent luminescence from Sr2MgSi2O7:Eu2+,R3+ were assembled and their contributions discussed.

The electronic and defect energy level structure of polycrystalline Sr2MgSi2O7: Eu2 +, R3 + persistent luminescence materials were studied with thermoluminescence and different synchrotron radiation spectroscopies (UV-VUV emission and excitation, X-ray absorption near-edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS)). Special attention was paid on the effect of the R3 + co-dopants on the persistent luminescence properties of the materials. Theoretical calculations using the density functional theory (DFT) were carried out simultaneously with the experimental work. The variation of the Eg value was attempted to relate with the trap structure as well as with the different properties of the R3 + co- dopants. The trap level energy distribution depended strongly on the R3 + co-dopant except for the shallowest trap energy above the room temperature remaining practica lly the same, however. The different processes in the mechanism of persistent luminescence from Sr2MgSi2O7: Eu2 +, R3 + were assembled and their contributions discussed.