Terbium (III) Oxide (Tb2O3) Transparent Ceramics by Two-Step Sintering from Precipitated Powder

As a result of preliminary air calcination and subsequent reduction in a flowing NH3 atmosphere of the precursor from the liquid precipitation method for the first time, pure-phase Tb2O3 powder with an average particle size of 135 nm was prepared. The Tb2O3 magneto-optical transparent ceramics with the average grain size of 1.3 μm were successfully fabricated by vacuum pre-sintering and hot isostatic pressing post-treatment from the as-synthesized Tb2O3 powder. In-line transmittance values of Tb2O3 ceramics reach 70.3% at 633 nm, 78.1% at 1064 nm, and 79.4% at 1400 nm, respectively. Thanks to the high intrinsic concentration of Tb3+, Tb2O3 ceramics present high Verdet constants of −427.3 and −123.7 rad·T−1·m−1 at 633 and 1064 nm, which are about 3.1 and 3.4 times higher than those of commercial Tb3Ga5O12 crystals, respectively. Due to the excellent magneto-optical properties, Tb2O3 ceramics are promising candidates for the development of Faraday isolator toward compaction used in visible and near-infrared bands.