Nd-F species in NdF3-LiF melts were studied using cryoscopic method.Liquidus temperatures of melts of various compositions were determined by differential thermal analysis(DTA).Based on the different model calculation...Nd-F species in NdF3-LiF melts were studied using cryoscopic method.Liquidus temperatures of melts of various compositions were determined by differential thermal analysis(DTA).Based on the different model calculations,NdF4- was identified as the most likely Nd-F entity in the melts in which the mole fraction of NdF3 was lower than 20%,considering only one single Nd species in the melt,and which was formed in accordance with Temkin model or Flood model.Then,activities of different components in the melts were researched.The results show that activity of LiF decreases,and that of NdF3 increases with increasing the mole fraction of NdF3.The value of activity coefficient of NdF3 is higher than 1,and that of LiF is lower than 1.展开更多
Europium(Ⅲ)-doped YFis prepared by a hydrothermal process at 200℃.X-ray diffraction(XRD) pattern identifies the formation of YFphase without detectable impurity.Environment scanning electron microscopy(ESEM) image s...Europium(Ⅲ)-doped YFis prepared by a hydrothermal process at 200℃.X-ray diffraction(XRD) pattern identifies the formation of YFphase without detectable impurity.Environment scanning electron microscopy(ESEM) image shows the even size distribution of the samples with cubic morphology.The excitation and emission spectra of the rare earth ions doped YFare investigated by fluorescence spectrophotometer.The excitation spectrum for 591 nm emission has several excitation bands at 320, 365,386,397 and 467 nm,and the main peak value was 397 nm.Typical Euemission peaks at 591 nm(~5D→~7F) and 612 nm (~5D→~7F) are observed when excited by 397 nm,and the strongest emission is 591 nm,demonstrating that the rare earth ions occupy the centrosymmetrical sites in YF.展开更多
基金Project(51004034)supported by the National Natural Science Foundation of ChinaProject(N090302009)supported by the Fundamental Research Funds for the Central Universities,China
文摘Nd-F species in NdF3-LiF melts were studied using cryoscopic method.Liquidus temperatures of melts of various compositions were determined by differential thermal analysis(DTA).Based on the different model calculations,NdF4- was identified as the most likely Nd-F entity in the melts in which the mole fraction of NdF3 was lower than 20%,considering only one single Nd species in the melt,and which was formed in accordance with Temkin model or Flood model.Then,activities of different components in the melts were researched.The results show that activity of LiF decreases,and that of NdF3 increases with increasing the mole fraction of NdF3.The value of activity coefficient of NdF3 is higher than 1,and that of LiF is lower than 1.
基金supported by the National Natural Science Foundation of China(No.50702057)the Natural Science Foundation of Zhanjiang Normal University(No.L0604)
文摘Europium(Ⅲ)-doped YFis prepared by a hydrothermal process at 200℃.X-ray diffraction(XRD) pattern identifies the formation of YFphase without detectable impurity.Environment scanning electron microscopy(ESEM) image shows the even size distribution of the samples with cubic morphology.The excitation and emission spectra of the rare earth ions doped YFare investigated by fluorescence spectrophotometer.The excitation spectrum for 591 nm emission has several excitation bands at 320, 365,386,397 and 467 nm,and the main peak value was 397 nm.Typical Euemission peaks at 591 nm(~5D→~7F) and 612 nm (~5D→~7F) are observed when excited by 397 nm,and the strongest emission is 591 nm,demonstrating that the rare earth ions occupy the centrosymmetrical sites in YF.
