Preparation And Optical Properties Of Yb Doped Lu₂O₃ Transparent Ceramics

In order to solve the issues of traditional co-precipitation method,such as low efficiency and serious agglomeration,a new type of parallel-based co-precipitation method based on micro-reaction is used to prepare Yb:Lu₂O₃ nanopowder.The effects of aging time,spray speeds,amount of dispersing agents and doping concentrations of Yb on the chemical composition and microstructure of the nanopowder are analyzed.At the same time,this paper employs the method of gel-casting molding to increase the density of the green body.In addition,the two-step sintering method of vacuum sintering followed by hot isostatic pressing sintering is applied,by which highly transparent ceramics can be prepared by eliminating the defects of pores and oxygen vacancies.No sintering aid is added during the sintering process to prevent deterioration of the laser performance.At last,the effect of Yb doping amount on the microstructure and in-line transmittance of Yb:Lu₂O₃ transparent ceramics is studied.The results show that the Yb:Lu₂O₃ nanopowder with high dispersity and sintering activity can be efficiently prepared by controlling the reaction conditions of this novel parallel-based co-precipitation method based on micro-reaction.The aging time has a great influence on the microscopic morphology of powder.As the aging time increases,the dispersity of the powders first strengthens then weakens.When the aging time is 24 h,the powders show higher uniformity.The composition and dispersity of precursor powders change with the spray speed.When the spray speed is low,more crystalline water is generated,and the main composition is basic carbonate[Lu（OH）CO₃]_n.With the increase of spray speed,the amount of crystalline water decreases,and the precursor is mainly carbonate[Lu₂（CO₃）₃·n H₂O（n=2～3）].Moreover,the dispersity of precursor and calcined powder is also different,which will eventually affect the sintering activity of powders.When the spray speed reaches 40 m L·min^-1,the particles are spherical and show higher dispersity.Appropriate addition of ammonium sulfate has a positive effect on the dispersity of the powder and the control of grain size.When the molar ratio of dispersing agent is 30%,particles also show higher dispersity,but as the amount reaches too high,the agglomeration is regenerated.The amount of Yb doping has little effect on the chemical composition and microstructure of the nanopowder.The effects of Yb doping concentrations on the microstructure,optical performance and the thermal conductivity of Yb:Lu₂O₃ transparent ceramics are investigated.The grain size of Yb:Lu₂O₃ ceramics first decrease with Yb doping concentration increasing and then keep nearly unchanged at high Yb doping concentrations.Under HIP sintering,the in-line transmittance of the 10 at%Yb:Lu₂O₃ceramics exceeds 80.90%at 1100 nm.