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A novel co-precipitation process was adopted for the preparation of highly sinterable europium-doped lutetia powders using ammonium hydroxide (NH 3 . H 2 O) and ammonium hydrogen carbonate (NH 4 HCO 3 ) as the mixed precipitant. The resultant powders calcined at 10001C for 2 h showed good dispersity and excellent sinterability. Highly transparent polycrystalline lutetia ceramics with a relative density of B99.9% were fabricated by pressureless sintering in flowing H 2 atmosphere at 18501C for 6 h without any additives. The average grain sizes of the transparent material were estimated to be 50-60 lm. Optical in-line transmittance in the visible wavelength region for Lu 2 O 3 ceramics (1 mm in thickness) reached 80%. The luminescence and decay behavior of the obtained transparent plate and the corresponding nanophosphors were also investigated. J ournal

Transparent lutetium titanate (Lu2Ti2O7) was fabricated by reactive spark plasma sintering. Effects of sintering and annealing temperature on the microstructure, optical and mechanical properties of Lu2Ti2O7 bodies were investigated. Pyrochlore Lu2Ti2O7 was obtained at above 1273 K and a full dense specimen was obtained above 1373 K. The average grain size increased from 0.22 to 10.85 μm up to 1773 K and abnormal grain growth occurred at 1823 K. The Lu2Ti2O7 body obtained at 1723 K for 2.7 ks for sintering and 1023 K for 21.6 ks for annealing shows the maximum transmittance with a thickness of 1 mm of 74% at a wavelength of 2000 nm. The hardness was dependent on the relative density and the grain size, while the fracture toughness slightly decreased with increasing annealing and sintering temperatures.

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