Preparation And Properties Of Yttrium Oxide Powder

Yttria(Y2O3)transparent ceramics is a excellent high temperature infrared material,electronic material and fire-proof material because of its several favorable properties,such as stability,optical clarity over a broad spectral region and high thermal conductivity.Among them,cerium oxide ceramics have attracted great attention because of their excellent performance in the fields of light,electrophysical chemistry and the like.However,due to the high melting point of cerium oxide,it is difficult to prepare a highly dense cerium oxide ceramic material under low temperature and low cost conditions,which limits its widespread use.In this paper,yttrium-doped Y2O3 spherical powders were prepared by urea uniform precipitation process and fluorine-doped Y2O3:Eu3+powders were prepared by ion exchange.The main research results are as follows:(1)Spherical Y2O3:Bi3+precursors with a size of 250-350 nm were successfully prepared by uniform precipitation of urea.The spherical particle size was affected by the doping concentration of cerium ions.With the increase of cerium doping amount,the spherical particles increased first and then decrease,maximum(350 nm)at X(Bi3+)=0.8 at.%;The fluorescence intensity of the Y2O3:Bi3+spherical powder after calcination at 800?increases first and then decreases with the doping amount,and concentration quenching occurs at X(Bi3+)=1.4 at.%;After the calcined Y2O3:Bi3+powder is subjected to dry pressing and isostatic pressing,the ceramic sheet having a density of up to 96%or more is sintered only in 1300?,O2 atmosphere,which greatly improves the sintering activity of the cerium oxide powder.It is also studied that the mechanism of Bi3+is mainly to promote sintering by liquid phase sintering,but excessive doping of Bi3+ will cause segregation at the grain boundary to form a second phase,which has an adverse effect on pore elimination.(2)A 15 nm thick rare-earth layered compound(LY/EuH)was prepared by a low temperature precipitation process using ammonia as a precipitant to achieve LY/EuHFx exchange between fluoride ion and interlayer(?),and the interlayer distance is reduced from 0.888 nm of LY/EuH to 0.842 nm of LY/EuHF0.8;The incorporation of fluoride ions promotes the growth of the calcined Y2O3:Eu3+particles and enhances the fluorescence intensity of the calcined Y2O3:Eu3+powder;The above-mentioned 1100 ? calcined Y2O3:Eu3+powder was successfully molded by vacuum molding at 1750?.Transparent ceramics with a transmittance of 35%in the 780 nm and a transmittance of 46%in 1600 nm region were successfully prepared under vacuum conditions of 1750?.