Fabrication of lanthanum doped yttria transparent ceramics

Yttria nanocrystalline powder doped with 9% lanthanum was synthesized by co-precipitation method using ammonia for pH adjusting. After calcinations, finer particles with narrow distribution and large surface area were obtained. After dry pressing, samples were sintered at 1500–1700° for 4 h in vacuum to produce transparent polycrystalline ceramics with uniform grains. Samples with 9 mol% lanthanum were transparent in visible light after being sintered at 1500° for 4 h. The grain sizes increased with lanthanum doping compared with those of pure yttria transparent ceramic sintered at the same conditions. Relative density of the transparent ceramic was 99.7%. The in-line transmittance was 73% at 580 nm wavelength after milling and polishing. Supported by the Shanghai Science and Technology Committee (Grant No. 07DJ14001) and State Key Laboratory of High Performance Ceramics and Superfine Microstructures