Research On Preparation And Properties Of Rare Earth Doped Vanadate Glass Ceramics

Vanadate salts have stable physical and chemical properties and self luminescent properties with a large amount of absorption in the ultraviolet or near ultraviolet region which can effectively transfer energy to rare earth ions.In this paper,Dy³⁺doped GdVO₄glass ceramics,Eu³⁺doped GdVO₄ glass ceramics,and Dy³⁺-Eu³⁺co-doped GdVO₄glass ceramics with excellent luminescent properties were prepared by melt crystallization method.The main research contents are as follows:1.Dy³⁺doped GdVO₄ glass-ceramic was prepared.The best heat treatment conditions were studied by differential scanning calorimetry（DSC）,X-ray diffraction（XRD）and scanning electron microscopy（SEM）.Finally,the optimal heat treatment conditions for Dy³⁺doped glass ceramics samples were determined to be 700℃/2 h.The fluorescence spectrum analysis of GdVO₄ glass-ceramics without rare earth indicates that GdVO₄ glass-ceramics are self-activated blue-green luminescent materials with efficient absorption in the near ultraviolet wavelength range and strong broadband blue-green emission centered at 521 nm.The optimal concentration of Dy³⁺doped glass ceramic samples was determined to be 0.3%according to the fluorescence spectrum.VO₄^3-can transfer energy to Dy³⁺which enhancing the characteristic emission peak intensity of Dy³⁺.The chromaticity coordinate CIE of the 0.3%Dy³⁺doped glass ceramic sample was（0.3114,0.3829）,located in the yellow green light region.At 438K,the emission intensity at 574 nm of the sample remained 85.28%of that at 298 K.Its thermal quenching activation energy was 0.274 e V.Thus,the Dy³⁺doped GdVO₄glass ceramics prepared has good thermal stability.2.Eu³⁺doped GdVO₄ glass ceramics were prepared and the optimal heat treatment condition was determined to be 690℃/1.5 h,the optimal doped concentration of Eu³⁺was 0.4%.The CIE of 0.4%Eu³⁺doped glass ceramic sample was（0.612,0.3456）,located in the red light region.At 438 K,the emission intensity of ⁵D₀→⁷F₂ transition of the sample remained 87.17%of that at 298 K.Its thermal quenching activation energy was 0.307 e V,which was superior to the precursor glass（72.2%,0.269 e V）.The results showed that the thermal stability of glass ceramic is significantly better than that of precursor glass.3.Dy³⁺-Eu³⁺co-doped GdVO₄ glass ceramics were prepared and the optimal heat treatment condition was determined to be 690℃/1.5 h,the optimal doped concentration was 0.3%Dy³⁺-0.6%Eu³⁺.The energy transfer from Dy³⁺to Eu³⁺in Dy³⁺-Eu³⁺co-doped glass ceramics was determined by the change of emission peak intensity and fluorescence lifetime.Its energy transfer mechanism is dipole-dipole interaction.The CIE of the 0.3%Dy³⁺-0.6%Eu³⁺co-doped glass ceramic sample was（0.363,0.3946）,located in the white light region.The emission intensity at 617 nm of the sample at 438K remained 81.24%of that at 298 K.Its thermal quenching activation energy was 0.27e V.The results show Dy³⁺-Eu³⁺co-doped GdVO₄ glass ceramics has a broad application prospect in the field of WLED.