Growth And Magneto-optical Properties Of TbPO₄ And Sr₂Dy₈（SiO₄）₆O₂ Crystals

In this thesis,some investigations of TbPO4 crystal and Sr2Dy8(SiO4)6O2 crystal,which refer to materials synthesis,crystal growth,structure,parts of physical parameters,spectrum and magnetic properties have been conducted in detail.The TbPO4 polycrystalline materials were synthesized by the state-phase reaction method or the liquid-phase reaction method.The sintering method was decided by DSC-TGA curve.XRD.infrared spectrum and EDS were used to analyze the compositions of polycrystalline materials.The temperature dependence of the magnetic susceptibility indicated that there is an existence of antiferromagnetic phase transition at low temperature for TbPO45 and Neel temperature is 2.28 K.TbPO4 polycrystalline materials were paramagnetic when the temperature is above 2.28 K.A systematic research of flux about TbPO4 crystal growth by molten salt method was discussed in the thesis.And the single crystal was grown by top seeded solvent growth(TSSG)method.The growth techniques were investigated according to the growth behavior of crystal.Ultimately,single crystal with high optical quality was obtained and fluorescence,Raman and transmission spectra were measured at room temperature.Growth habit and morphology is calculated.Faraday rotations of crystal was measured using laser sources at 532 nm,635 nm and 1064 nm wavelengths.The Verdet constants were obtained by fitting and calculating the data of Faraday rotations in different intensities of magnetic field.The results illuminated that TbPO4 crystal shows high transparency and good magneto optical properties in 500-1500 nm wavelength range with its Verdet constants larger that of terbium gallium garnet(TGG).The Sr2Dy8(SiO4)6O2 polycrystalline materials were synthesized by the state-phase reaction method and XRD,infrared spectrum were used to analyze the compositions of polycrystalline materials.The single crystal had been successfully grown by Czochralski method.The growth techniques were investigated by regulating the gradient of temperature field,rotation rate,pulling speed,annealing period.The single crystal with large size and high optical quality was obtained.Powder XRD,Rietveld refinement,element distribution,thermal expansion coefficient,density,Vickers hardness and magnetic susceptibility were measured for detecting the structure and the physics properties of as-grown crystal.The transmission spectra at 400 nm-1500 nm wavelength range were measured at room temperature.Faraday rotation was measured using laser sources at 532 nm,635 nm wavelengths.The Verdet constants were obtained by fitting and calculating the date of Faraday rotations in different intensities of magnetic field.The test results illuminated that Sr2Dy8(SiO4)6O2 crystal in 500 nm-700 nm wavelength range shows high transparency and good magneto optical properties with its Verdet constants larger than TGG.The results show that TbPO4 crystal in 500-1500 nm and Sr2Dyg(SiO4)6O2 crystal in 500-700 nm wavelength can be potential magneto-optical materials.