Rietveld refinement and optical properties of SrWO4：Eu^3＋ powders prepared by the non-hydrolytic sol-gel method
We investigated the effect of annealing time on the structure and optical properties of Sr WO4：Eu^3＋ powders prepared by the non-hydrolytic sol-gel method and heat treated at 800 ℃ for 2,4,8 and 16 h.Thermogravimetric and differential thermal analyses revealed that Sr WO4：Eu^3＋ powders were obtained...
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| Published in: | 中国稀土学报：英文版 Vol. 33; no. 2; pp. 113 - 128 |
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| Main Author: | |
| Format: | Journal Article |
| Language: | English |
| Published: |
2015
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | We investigated the effect of annealing time on the structure and optical properties of Sr WO4：Eu^3＋ powders prepared by the non-hydrolytic sol-gel method and heat treated at 800 ℃ for 2,4,8 and 16 h.Thermogravimetric and differential thermal analyses revealed that Sr WO4：Eu^3＋ powders were obtained at about 800 ℃.X-ray diffraction patterns and Rietveld refinement data confirmed that all powders had a scheelite-type tetragonal structure.Micro-Raman and Fourier transform infrared spectra indicated structural order at short range and anti-symmetric stretching vibrations of O-W-O bonds associated with tetrahedral[WO4]clusters.Optical properties were investigated by ultraviolet-visible（UV-vis）diffuse reflectance,and photoluminescence（PL）data which provided the evolution of quantum efficiency（η）and lifetime（τ）.UV-vis spectroscopy evidenced intermediate energy levels within the band gap of Sr WO4：Eu^3＋ powders.PL properties validated that the Eu^3＋ electric-dipole（^5D0→^7F2）transition in PL emission spectra was dominant which proved that Eu^3＋ ions were positioned in a site without an inversion center.[（^5D0→^7F2）/（^5D0→^7F1）]band ratios showed that Eu^3＋ ions were located in a low symmetry environment.The PL emission,ηandτproved the dependence on the annealing time in the behavior of Sr WO4：Eu3＋powders with a higher relative emission PL intensity as well as higherηandτvalues related to other samples when heat treated at 800℃ for 8 h. |
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| Bibliography: | 11-2788/TF SrWO4; Rietveld refinement; optical band gap; Eu^3＋-rare earth; luminescence We investigated the effect of annealing time on the structure and optical properties of Sr WO4：Eu^3＋ powders prepared by the non-hydrolytic sol-gel method and heat treated at 800 ℃ for 2,4,8 and 16 h.Thermogravimetric and differential thermal analyses revealed that Sr WO4：Eu^3＋ powders were obtained at about 800 ℃.X-ray diffraction patterns and Rietveld refinement data confirmed that all powders had a scheelite-type tetragonal structure.Micro-Raman and Fourier transform infrared spectra indicated structural order at short range and anti-symmetric stretching vibrations of O-W-O bonds associated with tetrahedral[WO4]clusters.Optical properties were investigated by ultraviolet-visible（UV-vis）diffuse reflectance,and photoluminescence（PL）data which provided the evolution of quantum efficiency（η）and lifetime（τ）.UV-vis spectroscopy evidenced intermediate energy levels within the band gap of Sr WO4：Eu^3＋ powders.PL properties validated that the Eu^3＋ electric-dipole（^5D0→^7F2）transition in PL emission spectra was dominant which proved that Eu^3＋ ions were positioned in a site without an inversion center.[（^5D0→^7F2）/（^5D0→^7F1）]band ratios showed that Eu^3＋ ions were located in a low symmetry environment.The PL emission,ηandτproved the dependence on the annealing time in the behavior of Sr WO4：Eu3＋powders with a higher relative emission PL intensity as well as higherηandτvalues related to other samples when heat treated at 800℃ for 8 h. |
| ISSN: | 1002-0721 2509-4963 |