Growth And Magneto-optical Properties Of Sr₂Tb_xGd_8-x（SiO₄）₆O₂ Crystal With Apatite Structure

In this thesis, some investingations of Sr2TbxGdg-x(SiO4)O2 crystals, which refer to materials synthesis, crystal growth, structure, parts of physical parameters, spectrum and magnetic properties have been conducted in detail.The Sr2Gdg(SiO4)O2、Sr2Tb8(SiO4)O2 polycrystalline materials were synthesized by the state-phase reaction method. TG-DSC curve was gained by Thermal analysis machine, and the sinter technics can be decided. XRD, infrared spectrum and DRS were used to measured polycrystalline materials.All the Sr2TbxGd8-x(SiO4)O2 crystals were grown by the Czochralski technique. Combining with the growth habits of crystals, the growth processes were optimized gradually. By adjusting the temperature gradient, the choice of seed, rotation rate, pulling rate and annealing time, the good crystals were obtained successfully.Combining the XRD data with Jade software, the cell parameters of Sr2TbxGd8-x(SiO4)O2 were acquired. The apatite hexagonal system of crystals were assured. By means of ICP-AES, percentage compositions for the elements in the crystals were measured. Then respective distribution coefficients were calculated. The content of each element in the crystals were measured by energy spectrum analysis. The components of crystals were confirmed combing with atomic percentage content of each element.Scanning electron microscopy and energy spectrum analysis preliminary study the existence of the crystal defects such as inclusion. The Vichers hardness, thermal expansion coefficient, the thermal conductivity were measured for researching crystals’ physical-chemical properties.After direction-making, cut and polishing, the transmission spectrum and absorption spectrum of Sr2TbxGd8-x(SiO4)O2 crystals in 400 to 1500nm were measured. It shows a high transparency from the absorption edge in the violet at 400 nm until the near IR cutoff at 1500 nm, and presents a characteristic absorption of Tb3+ caused by the energy level transition 7F6�'5D4 at 485 nm. The variable-temperature magnetic susceptibility of Sr2Tbg(SiO4)O2 crystal was measured and analyzed. The Faraday rotation angle of the Sr2TbxGd8-x(Si04)O2 crystals in the direction of the c optical axis were measured by the extinction method with the man-made Faraday rotation mersurement system at three wavelengths 532,633, and 1064 nm at room temperature. The Verdet constants of Sr2Tbg(SiO4)O2 crystal was as 1.65 to 1.75 times as the TGG reported. Sr2Tbg(SiO4)O2 crystal may be an applicable magneto-optical material in the visible and near-infrared areas.