Effect of BeO Addition on Sintering of Transparent Y2O3

The effects of BeO addition (0-2 wt%) on the pressureless sintering process and the transparency of yttria were studied. The addition of BeO (0.1-0.5 wt%) promoted the sintering of Y2O3 to decrease markedly the residual pores in sintered bodies above 2100°C. The transparency of sintered Y2O3 was independent of compacting pressure (1-10 t/cm2). BeO vaporized with the increase of sintering temperature and more than half of the initial contents of BeO decreased above 1800°C. The transmittance (thickness 1.0 mm, wavelength 300-7000 nm) of the 0.1 wt% BeO-Y2O3 sintered at 2150-2250°C for 50-300 min. in H2 was 80%. It was suggested that the liquid phase formation of Y2O3-BeO system and the vaporization of BeO contributed to the fabricating of the transparent Y2O3.