Fabrication Of Terbium Aluminum Garnet(TAG) Transparent Ceramics By Hot Isostatic Pressure(HIP)

As the core component of the magneto-optic device,the magneto-optic material determines the performance of the magneto-optic device to a large extent.With the constant development of magneto-optic devices towards miniaturization,high power and low cost,the requirements for magneto-optic materials are also increasing.Now,TGG(Tb₃Ga₅O₁₂)transparent ceramics are reported and used the most widely used magneto-optic materials in visible and near infrared regions.However,with the emergence of TAG(Tb₃Al₅O₁₂)magneto-optical transparent ceramics,its excellent magneto-optical properties,thermal conductivity and lower prices make the TAG magneto-optical transparent ceramics become the most prospective magneto-optic material.Although transparent ceramics have been studied since the last century,there are not many reports on TAG transparent ceramics.In this paper,Commercial powders are used as raw materials for preparing the TAG transparent ceramics.In addition,TAG transparent ceramics were prepared by a reactive sintering method with HIP treatment,and the main research as follows:1.The effect of sintering aid MgO on the properties of TAG transparent ceramic.TAG transparent ceramic doped with MgO was successfully fabricated by a reactive sintering method with HIP treatment.The effect of MgO as the sintering aid on the densification,microstructure and transmittance of TAG transparent ceramics is systematically studied.Compared to the without MgO doped,MgO has the effect of inhibiting the grain growth and promoting the densification at 1600 ℃.Meanwhile,moderate concentration of MgO did not have the effect on the phase evolution.After HIP treatment,the sample was basically dense,and the grain size was less than 10μm,and no secondary phase was found.A few pores were found in the samples undoped with the MgO.The grain size of TAG samples doped with 0.1 wt.%MgO is most homogeneous.The transmittance of the TAG sample increased with the MgO reaching to 0.1 wt.%.When the concentration of MgO exceeded to 0.1 wt.%,the transmittance of the sample decreased.In other words,the transmittance of TAG transparent ceramics had the best optical property,when the concentration of MgO was 0.1 wt.%.2.The effect of different stoichiometric on the properties of TAG transparent ceramic.TAG transparent ceramic with different Al₂O₃ addition was successfully fabricated by a reactive sintering method with HIP treatment.The thermogravimetric curve of the Tb₄O₇ powder was studied by analyzing the Tb-O binary phase diagram.The effects of different Al₂O₃ additions on the phase and microstructure of TAG ceramics and the influence of the microstructure and transmittance after HIP treatment were also studied.The result showed that the deoxygenation reaction of Tb₄O₇ powder happened at 550℃ and 950 ℃.At pre-sintering stage,as the addition of Al₂O₃ gradually decreased from16.000g to 15.598g,TAG ceramic samples were all TAG pure phase,when the addition of Al₂O₃ was lower than 15.598g,the TbO₂ peak appeared in the XRD spectrum at about 35°.With the increasing of sintering temperature,the grain size of the same component samples increased and then stabilized.At the same sintering temperature,the overall grain size decreases firstly and then increases.When the addition amount of Al₂O₃ is 15.734g,the grain size is the smallest.After HIP treatment,in addition to 1700℃,the grain size had little change.When Al₂O₃ was changed from 15.473g to 15.000g,the grains were all abnormal,and the TbO₂ phase was not eliminated.When the pre-sintering temperature was 1675 ℃,the transmittance of samples after HIP treatment was the best,which can reach to 72%,while the addition of Al2O3 was 15.743g.