Re:YPO₄(Re=Yb,Eu,Gd) Crystal Growth And Phosphor Preparation And Properties

In this paper,the growth and characterization of YPO4 doped Yb3+ laser crystal.The synthesis,morphology and spectral properties of YPO4 phosphorsdoped with Eu3+ and Gd3+ were also discussed.The rare earth Orthophosphate is incongruent melting compound and has a high melting point,So the crystals can only be grown in the flux method.The apparatus and technological process of crystal growth were introduced.The rodlike and platelike crystals of 5at% Yb:YPO4 were grown successfully by spontaneously nucleated flux method using lead pyrophosphate(Pb2P2O7+KDP)as the solvent.The ledgewise growth mechanism was analyzed.Moreover,the factors included the properties of flux,the cooling rate,the temperature filed and impurities,that existed in the growth experimental process were discussed.The infrared spectroscopy of 5at% Yb:YPO4 mixed crystal was measured at room temperature using Nicolet5700 type infrared spectrometer.The results indicate the flux does not enter into the crystal.The structures of the crystals were analyzed and the lattice parameters were calculated at room temperature by D8 Advance X-ray powder diffraction.The results showed that 5at%Yb:YPO4 was tetragonal xenotime structure.The cell parameters of 5at%Yb:YPO4 were also calculated.The π-polarized and σ-polarized absorption spectra of 5at%Yb:YPO4 were measured by UV-VIS-NIR(Cary500)spectrophotometer,and the absorption cross-section and bandwidth of the crystal were calculated respectively.Compared with some other Yb-doped crystals,the rare earth orthophosphate crystals were found to be more suitable for diode-laser-pumped.The preparation method and the equipment of the phosphor are introduced.The Re:YPO4(Re=Eu,Gd)phosphors were successfully synthesized by chemical coprecipitation method.Four different sintering temperatures of 600 oC,800 oC,1000oC and 1200 oC were tried.The structures of the phosphors were analyzed and the lattice parameters were calculated at room temperature by D8 Advance X-ray powder diffraction.The results showed that Re:YPO4(Re=Eu,Gd)phosphors was tetragonal xenotime structure.The synthesized phosphor was observed by scanning electron microscopy(SEM).It was found that the crystallinity of the phosphor was improved with the increase of temperature,but there was a reunion phenomenon.The fluorescence spectra of the phosphors were measured by UV-VIS-NIR(Cary500)spectrophotometer.It found the best doping concentration was 7at%.It also found that the incorporation of Gd3+ ions was helpful to the increaseof fluorescence intensity.