Laser Ablation Synthesis and Characterization of Tb2O3 Nanoparticles for Magneto-Optical Ceramics

In this study, nano-sized individual Tb2O3 particles synthesized by the laser ablation method were extensively characterized and assessed as suitable precursors for the fabrication of transparent magneto-optical ceramics without requiring the introduction of grain growth inhibitors and stabilizing additives. The as-produced powder comprised 13 nm particles with a spherical shape and monoclinic crystal structure, whose full transformation into cubic phase was achieved after heating at 950 degrees C and 700 degrees C under vacuum and Ar gas, respectively. After subjecting the nanopowder compact to pre-sintering at 1350 degrees C, the microstructural features were investigated along with their correlation to the optical transmittance of Tb2O3 ceramic hot isostatically pressed (HIPed) for 2 h at 1450 degrees C under 200 MPa. The as-HIPed sample had a brownish color, with an optical transmittance of 65.3% at a wavelength of 1060 nm and an average grain size of 14 mu m. The Verdet constant measured at wavelengths of 633 nm and 1060 nm was 471 rad T-1 m(-1) and 142 rad T-1 m(-1) to confirm a very high content of magneto-active Tb3+ ions. The obtained results indicate that laser ablation synthesis of nanoparticles followed by pre-sintering and HIP is a promising approach for the manufacture of magneto-optical Tb2O3 ceramics without specific sintering aids.