Effect of (Tb+Y)/Al ratio on Microstructure Evolution and Densification Process of (Tb(0.6)Y(0.4))(3)Al(5)O(12) Transparent Ceramics

(Tb(0.6)Y(0.4))(3)Al(5)O(12) transparent ceramics were successfully fabricated by solid-state reactive sintering using Tb(4)O(7), Y(2)O(3), and α-Al(2)O(3) powders as raw materials. The effect of (Tb+Y)/Al ratio on microstructure evolution and densification process was investigated in detailed. The results showed that the grain growth kinetics were significantly affected by (Tb+Y)/Al ratio. Al-rich and Tb-rich phases appeared in part of the samples of different ratios. Particularly, excess aluminum increased the diffusing process, leading to a higher densification rate, while samples with excess terbium ratios displayed a smaller grain size and lower relative density. The optical quality was highly related to the amount of the secondary phase produced by different (Tb+Y)/Al ratios. Finally, (Tb(0.6)Y(0.4))(3)Al(5)O(12) transparent ceramics have been fabricated through pre-sintering in vacuum, followed by hot isostatic sintering (HIP), and the best transmittance of sample with a 4 mm thickness was approximately 78% at 1064 nm.