Fabrication and Luminescent Properties of Nd~(3+)-Doped Lu_2O_3 Transparent Ceramics by Pressureless Sintering

摘要

The fabrication of transparent Nd~(3+) ion-doped Lu_2O_3 ceramics is investigated by pressureless sintering under a flowing H_2 atmosphere. The starting Nd-doped Lu_2O_3 nanocrystalline powder is synthesized by a modified coprecipitant processing using a NH_4OH+NH_4HCO_3 mixed solution as the precipitant. The thermal decomposition behavior of the precipitate precursor is studied by thermogravimetric analysis and differential thermal analysis. After calcination at 1000℃ for 2 h, monodispersed Nd~(3+):Lu_2O_3 powder is obtained with a primary particle size of about 40 nm and a specific surface area of 13.7 m~2/g. Green compacts, free of additives, are formed from the as-synthesized powder by dry pressing followed by cold isostatic pressing. Highly transparent Nd :Lu_2O_3 ceramics are obtained after being sintered under a dry H_2 atmosphere at 1880 ℃ for 8 h. The linear optical transmittance of the polished transparent samples with a 1.4 mm thickness reaches 75.5% at the wavelength of 1080 nm. High-resolution transmission electron microscopy observations demonstrate a "clear" grain boundary between adjacent grains. The luminescent spectra showed that the absorption coefficient of the 3 at.% Nd-doped Lu_2O_3 ceramic at 807 nm reached 14 cm~(-1), while the emission cross section at 1079 nm was 6.5 × 10~(-20) cm~2.