With recent development of solid-state lasers, especially high-power fiber lasers in intelligent manufacturing, scientific research and the other fields are increasingly widespread. Eliminating the reflected light to protect the optical path system and stabilize the laser output becomes a critical issue. Magneto-optical materials with a high Verdet constant and a large size are an essential optical element for developing high-performance optical isolators, which can significantly shorten the length of magneto-optical medium, thus enabling the development of integrated and miniaturized optical isolators. Terbium (Ⅲ) oxide has no absorption peak in the range 500-1 500 nm and its Verdet constant is 3.5 times greater than that of commercial terbium gallium garnet single crystals. Magneto-optical transparent ceramics are a new inorganic transparent optical functional material, and its optical transparency comparable to that of single crystals and glasses, and it has the advantages of adjustable composition and structure of polycrystalline ceramics.

Tb₂O₃ is considered as a promising candidate medium for magneto-optical isolators due to its superior magneto-optical properties. However, challenges in the preparation are the oxidation of trivalent terbium oxide powder in air, and the reversible phase transition at 1 600 ℃, 2 167 ℃ and 2 370 ℃. To address the problems above, Tb₂O₃ crystals were grown via low-temperature flux growth, the optical floating zone method and the supercritical solvothermal method. However, Tb³⁺ ions are easily oxidized, undergoing multistage phase transitions at 1 550-2400 ℃ (i.e., the melting point, which makes it difficult to grow Tb₂O₃ single crystal from the melt. As a representative of ceramic process routes, rare-earth ions stabilized Tb₂O₃, TAG and TGG transparent ceramics are prepared via vacuum sintering, hot pressed sintering or NC-PLSH technology. This review represented the development, technologic process and key difficulties of Tb₂O₃ crystals and ceramics. Tb₂O₃ single crystals can be grown by flux and floating zone methods, but it is difficult to improve the crystal size, optical quality, and production efficiency to the application level. Tb₂O₃ crystal was prepared by a flux method, but its crystal size was only 5 mm×5 mm×2 mm. Compared with the crystal growth, a transparent ceramic technology has advantages in preparing large size and optical grade bulk materials. In order to stabilize the phase structure of terbium oxide, yttria-stabilized Tb₂O₃ ceramics was prepared by a self-propagating high-temperature method and vacuum sintering. Zirconia is used as a sintering aid to reduce the sintering temperature and accelerate the mass transport process in the ceramic sintering. Preparation schemes of transparent ceramics bring a prospect for Tb₂O₃ bulk materials.