Preparation And Luminescent Properties Of Y₂O₃-based Transparent Ceramics

Yttria transparent ceramic is excellent optical materials due to its outstanding stability,high thermal conductivity and wide optical transparency region,such as rare earth doped Y₂O₃ exhibits cubic structure with high refractive index and low phonon energy.It has wide application prospects in sea detection,aviation,aerospace defense industry and other fields.Yttria transparent ceramics have more application prospects in laser ceramics with Yb³⁺/Tm³⁺ or Yb³⁺/Tb3 co-doping in them.The nanoscale powders of Y₂O₃:Yb³⁺/Tm³⁺ and Y₂O₃:Yb³⁺/Tb³⁺ were prepared by the carbonate coprecipitation method respectively.The yttria transparent ceramics were fabricated by atmosphere sintering in hydrogen atmosphere.The properties of the powders,the microstructure,mechanical properties and optical property of the ceramics were investigated.The influence of sintering aids on microstructure and properties of yttria transparent ceramics together with luminescent properties of Yb³⁺/Tm³⁺ and Yb³⁺/ Tb³⁺ doped Y₂O₃ powders were evaluated.The results showed that Y₂O₃:Yb³⁺/Tm³⁺ and Y₂O₃:Yb³⁺/Tb³⁺ nanopowders prepared by carbonate coprecipitation were nearly spherical,uniform size?particle size of 50nm?and well dispersed.There was no serious reunion exhibited by the powders when the concentration of the salt solution was 0.2mol/L with the adding of dispersant.All the powders were single cubic yttrium oxide phase after calcined at different temperatures,and the lattice constant of the powders reached the maximum value of 10.67562 ? at 900? with perfect crystallization.With the increasing of rare earth concentration and calcined temperature,the intensity of upconversion luminescence and fluorescence luminescence of the powders were both enhanced first,reaching a maximum value at 900?,and then weakened.The green and red fluorescence emission intensity reached a maximum value when the concentrations of Yb³⁺ and Tm³⁺ ions were 4mol% and 0.4mol% respectively.However,the blue and red upconversion emission intensity reached a maximum value when the concentrations of Tm³⁺ ions was 0.5mol% and Yb³⁺ ions was still 4mol% in the Y₂O₃:Yb³⁺/Tm³⁺ doped system.While in the Y₂O₃:Yb³⁺/Tb³⁺ doped system,the intensity of green and red upconversion emission and fluorescence emission both reached the maximum value when the concentration of Yb³⁺ and Tb³⁺ ions were 4mol% and 1.5mol% respectively.The relative density of Y₂O₃:4%Yb³⁺/0.5%Tm³⁺ transparent ceramics increased with the increasing of the sintering temperatures.The hardness and fracture toughness of the transparent ceramics increased first,reaching a maximum value of 10.2GPa and 3.4MPa?m1/2 at 1570 ? respectively,and then decreased.All of the relative density,hardness,fracture toughness and transmittance of the samples were improved effectively by adding sintering aid La₂O₃.It indicated that the sintering aid could reduce the sintering temperature of yttrium oxide transparent ceramic and improve its mechanical properties and optical performance simultaneously.