Rietveld refinement and optical properties of SrWO4:Eu3+ powders prepared by the non-hydrolytic sol-gel method
来源期刊：JOURNAL OF RARE EARTHS2015年第2期
论文作者：P.F.S.Pereira I.C.Nogueira E.Longo I.L.V.Rosa
文章页码：113 - 128
摘 要：We investigated the effect of annealing time on the structure and optical properties of Sr WO4:Eu3+powders prepared by the non-hydrolytic sol-gel method and heat treated at 800 oC for 2,4,8 and 16 h.Thermogravimetric and differential thermal analyses revealed that Sr WO4:Eu3+powders were obtained at about 800 oC.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:Eu3+powders.PL properties validated that the Eu3+electric-dipole（5D0→7F2）transition in PL emission spectra was dominant which proved that Eu3+ions were positioned in a site without an inversion center.[（5D0→7F2）/（5D0→7F1）]band ratios showed that Eu3+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 oC for 8 h.
P.F.S.Pereira1，I.C.Nogueira2，E.Longo1，I.L.V.Rosa2
1. Chemistry Institute, University of the State of Sao Paulo Julio de Mesquita Filho-UNESP, Francisco Degni,Araraquara-SP 14800-900, Brazil2. LIEC-Chemistry Department, Federal University of Sao Carlos, Via Washington Luis Km 235,Sao Carlos-SP 13565-905, Brazil
摘 要：We investigated the effect of annealing time on the structure and optical properties of Sr WO4:Eu3+powders prepared by the non-hydrolytic sol-gel method and heat treated at 800 oC for 2,4,8 and 16 h.Thermogravimetric and differential thermal analyses revealed that Sr WO4:Eu3+powders were obtained at about 800 oC.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:Eu3+powders.PL properties validated that the Eu3+electric-dipole（5D0→7F2）transition in PL emission spectra was dominant which proved that Eu3+ions were positioned in a site without an inversion center.[（5D0→7F2）/（5D0→7F1）]band ratios showed that Eu3+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 oC for 8 h.
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