Enhanced transmittance of Y2O3 transparent ceramics from near-UV to near-infrared through reduced atmosphere annealing

Y2O3 transparent ceramics were annealed under different atmospheric conditions. The samples annealed in H2 containing atmosphere were colorless and had high in-line transmittances from the near-UV to the mid-infrared wavelength range. This is due to the elimination of carbon contamination and preventing the formation of high concentration oxygen interstitial defects in the sintered samples. Annealing in oxygen containing atmosphere resulted in stronger optical absorption in the visible wavelength region. High temperature annealing in O2 or hot isostatic pressing under high partial pressure of O2 (O2 HIP) led to obviously declining of transparency in a broader wavelength range of 230–800 nm. The Er:Y2O3 ceramics annealed in H2 containing atmosphere had high in-line transmittance of about 80% at 400 nm as well. Room temperature laser oscillation at 2.7 µm was also obtained on the 5%H2/95%Ar atmosphere annealed Er:Y2O3 ceramics.