Spark plasma sintering of transparent Y2O3 ceramic using hydrothermal synthesized nanopowders

Y2O3 nanopowders were synthesized by the hydrothermal treatment of Y(NO3)3·6H2O and citric acid (CA) as Y+3 and the capping agent, respectively. The effect of different CA:Y+3 mol ratios, heat treatment time, and calcination temperature was investigated in order to determine their influence on the morphology, particle size and phase of Y2O3 nanopowders. The narrow size distribution of particles was obtained with CA:Y+3 mol ratio=1.6, heat treatment time of 6 h, and a calcination temperature at 900 °C for 90 min. Then, the synthesized Y2O3 nanopowder was consolidated by the spark plasma sintering technique at 1500 °C with a heating rate of 100 °C/min and held for 8 min before turning off the power. As a result, the ceramic prepared with 3 mm thickness got the highest transmission of 80% at 2.5-6 µm wavelength. The highest density and the grain size of yttria ceramic were 99.58% and 1-1.2 µm at 1500 °C, respectively.