Effect of green body annealing on microstructure and optical properties of Y2O3:Yb3+ ceramics

Influence of annealing temperature in the Т = 600–1200°С range on a mesostructure of Y2O3:Yb3+ green bodies and properties of obtained ceramics were studied. It was shown that annealing of green bodies should be carried out at the maximum possible temperatures when sintering occurs without approaching of particle centers. It was established that green bodies annealed at T = 800°C are characterized by optimal mesostructure in terms of densification efficiency during subsequent vacuum sintering. Y2O3:Yb3+ ceramics prepared from green bodies which were previously annealed at 800°C possess the highest optical quality and in-line optical transmittance of 72% at λ = 1100 nm wavelength. Annealing at lower temperatures does not remove all the defects introduced by ball-milling of powder mixture, that hinders formation of pore-free ceramics. Green bodies annealing above T = 800°C leads to partial compact densification that is accompanied with a decrease in sinterability during vacuum sintering.