Effects of Sintering and Annealing Temperature on Fabrication of Transparent Lu2Ti2O7 by Spark Plasma Sintering

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 Lu-2 Ti2O7 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 mu m 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.