Synthesis of highly sinterable Tb2O3 powders by spray coprecipitation for transparent ceramics: The influence of ammonium hydrogen carbonate to metal ions molar ratio

Abstract

A modified spray coprecipitation method was used to prepare highly sinterable Tb2O3 nanopowders. The effects of R (molar ratio of ammonium hydrogen carbonate to metal ions) were studied throughout the preparation process. The characteristics of the precursors and Tb2O3 powders were determined using analytical techniques including XRD, FTIR, TG-DSC, and SEM. It was discovered that altering the R values significantly affected the chemical components, microstructure, and homogeneity of the precursors and oxide powders. Ultrafine, monodispersed, and spherical terbium (III) oxide powders were obtained when R = 4, while inhomogeneous rhombic flake-shaped particles were prepared with R ≥ 5. The powders calcined at 800 °C produced Tb2O3 ceramics with the highest optical transmittance of 64.08% at a wavelength of 1064 nm via flowing hydrogen atmosphere sintering at 1520 °C for 10 h. The Verdet constant measured at 632.8 nm for the obtained Tb2O3 sample was −466.3 rad T−1 m−1, which was approximately 3.5 times that of the Tb3Ga5O12 single crystal.