Preparation And Properties Of La_2-xM_xZr₂O₇?M=Pr,Er,Yb,Gd? Transparent Ceramics

Pyrochlore-type transparent ceramic is a new system emerging from the background of exploring new inorganic scintillator materials.These compound s have high hardness,density,melting point and effective atomic coefficient.It has great application prospects in laser media,scintillation ceramics,infrared transparent ceramics,high temperature window materials and so on.However,the pyrochlore type compound generally has a high melting point and it is difficult to prepare a large-sized single crystal,which limits the application of the material to a certain extent.With the development and evolution of preparation technology,it is a convenient and effective way to obtain pyrochlore-type transparent ceramics by using ceramic preparation technology.According to the method of preparing powder?solution burning method and solid phase method?,it can be divided into two parts and the first attempt to prepare non-stoichiometric samples has obtained excel ent results.A simple and rapid solution combustion method was used to synthesize a La_2-xM_xZr₂O₇?M=Pr,Er,Yb,Gd,x=0.4-2.0?nano-powder with a narrow particle size distribution and uniform dispersion.The final transparent ceramics sample were then formed by molding and sintering.The x=1.2?72.84%@1132 nm?sample in the La_2-x-x Pr_x Zr₂O₇?x=0.4-2.0?system has the highest transmittance.As the Pr content increase,the ceramic density ehances linearly?6.01-6.72 g/cm³?.The phase transition behavior of La_2-x-x Er_x Zr₂O₇?x=0.4-2.0?ceramics was studied,with the increase of Er content,the ceramics changed from pyrochlore phase to defect fluorite phase.In the two-phase region the particle size is small?2-5?m?.The grain size of the single-phase region is about 80?m.In this study,non-stoichiometric La_1.28Er_1.28Zr₂O_7.84 and La_1.28Yb_1.28Zr₂O_7.84 ceramics were prepared for the first time,the transmittance?81.34%@1100 nm and 83.01%@1100 nm,respectively?is higher than the normal stoichiometric sample.Rayleigh-Gans-Debye scattering theory can be used to explain the phenomenon of two-phase coexistence,small grain size and high transmittance.The phase change behavior of this system has great applications in the field of high-level radioactive waste.The La_2-x-x Yb_x Zr₂O₇?x=0.4-2.0?system ceramics were prepared by the same process,but the ideal experimental results were not obtained.Subsequent research is underway.La_2-xPr_xZr₂O₇ and La_2-x-x Gd_x Zr₂O₇?x=0.4-2.0?system ceramics were prepared by solid phase method combined with vacuum sintering.Among them,La_0.4Gd_1.6Zr₂O₇ has a high transmittance of 83.84%?@1100 nm?and the infrared cutoff band is about 8.3?m.Due to the wide range of high transmittance?0.4-6?m?,the La_2-xGd_x Zr₂O₇ system is an ideal window material.The sample of La_0.4Pr_1.6Zr₂O₇ has a maximum transmittance of 58.88%near 1154 nm.The larger grain size is the reason why the transmittance of the system is lower than that of the Gd-doped system.Samples prepared by the solid phase method exceed the expected results.But the ball milling time,number of times,uniformity and impurities are still issues of concern.