The Growth And Magneto-optical Properties Of Tb₃NbO₇, Ca_{2（1-x）}Tb_3xNb_{（2-x）}O₇ And Ba₃Tb（PO₄）₃ Crystals

In this thesis, the meterials systhesis, fluxes selection by molten salt method about Tb3NbO7 were discussed. And crystal growth by Czochralski method, defect analysis, basic physicochemical properties and magneto optical performance about its doped crystal Ca2(1-x)Tb3xNb(2-x)O7have been systematic discussed. In the end crystal growth by melt cooling method, single-crystal structure,spectrum and magneto optical performance about Ba3Tb(PO4)3 were discussed.The cubic Tb3NbO7 polycrystalline were synthesized by high-temperature solid-state method, solid flux method and liquid co-precipitation method separately during the study.Characterization of XRD, FTIR and EDS were used to analyse the obtained powers. The temperature dependence of the magnetic susceptibility and specific heat at low temperature indicated that Tb3NbO7 polycrystalline power is paramagnetic substance. An existence of antiferromagnetic phase transition at low temperature was studied, Neel temperature is 3.16 K. Tb3NbO7 also shares lager magnetic susceptibility than TGG.A preliminary study of fiuxes systems about TbsNbO7 crystal growth by molten salt method was discussed in the thesis. Then a series of cubic fluorite structure magneto-optical crystal Ca2(1-x)Tb3xNb(2-x)O7(CTN) were grown by Czochralski method. The composition of crystals were illustrated by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). The structure of CTN-1# crystal was calculated out by Rietveld refinement method to disscuss the influence of Ca2+ and Nb5+in the change of structure. Characterization of XPS illustrates the various valency of Tb and Nb element. In combination with SEM-EDS, the mechanism of generation of defects were analysised.Cubic Ba3Tb(PO4)3 crystal with good optical quality and a certain dimension was grown by melt cooling method. Single crystal structure analysis shows that Ba3Tb(PO4)3 crystal structure fits the structure of eulytite compouds.The thermal and mechanical properties of Ca2(1-X)Tb3xNb(2-X)O7 and Ba3Tb(PO4)3 were measured, such as density, vichers hardness and thermal expansion coefficient. The analysis of the light-absorption of crystal under 400-1600 nm wave band was conducted by the UV/VIS/IR spectrograph. Make use of the self-assembly magneto-optical Faraday rotation Angle measurement system, which apply to test Faraday rotation angle of magneto-optical crystals at 532 nm and 633 nm wavelength. And then works out the Verdet constants of the crystals in order to discusses the magneto-optic performance of these crystals. The result illuminated that the crystals above have a certain transmittance in 400-1500 nm wave band, but there is a absorption peak near by 485 nm wavelength which is caused by the 7F6â†'5D4 transition. In the 400-650 nm wave band, Ba3Tb(PO4)3 crystal shows a higher visible transparency than TGG obviously. Ca2(1-X)Tb3xNb(2-x)O7 crystals shows a good magneto-optic performance. The Verdet constant is 1.51 times larger than TGG when x=2/3. Ca2(1-x)Tb3xNb(2-x)O7 is therefore a very promising magneto-optical material in the visible-near IR wavelength region.