A crack-free GdTaO₄ single crystal as a promising high-density scintillator is grown successfully by the Czochralski method. High crystalline quality of the as-grown crystal has been demonstrated by its X-ray rocking curve. Its density is 8.94 g cm⁻³, which is the highest among current inorganic single-crystal scintillators. The absolute light yield of GTO is about three times as that of PbWO₄ and the scintillation decay consists of a fast component of 72.6 ns and a slow component of 1236.2 ns. Additionally, the photoluminescence measurements of GTO indicate a complicated mechanism. Its fundamental physical properties including hardness, density, and thermal properties are determined for the first time, which are very important for crystal growth and its applications.

A new laser crystal Nd:Gd_0.69Y_0.3TaO₄ (Nd:GYTO) with high quality was grown by Czochralski method. The physical properties, including temperature dependent density, specific heat, thermal expansion coefficient, and thermal conductivity, were systematically characterized. The maximum absorption cross section at 809 nm and the stimulated emission cross section at 1066.6 nm are 6.886 × 10⁻²⁰ cm² and 22 × 10⁻²⁰ cm², respectively. The fluorescence lifetime is measured to be 182.4 μs. Up to 2.37 W of continuous wave (CW) laser operating at 1066.5 nm has been successfully realized, corresponding to an optical conversion efficiency of 36.5% and a slope efficiency of 38%. Compared with Nd:GdTaO₄, Nd:GYTO shows an enhancement of the laser performance. These results demonstrate that Nd:Gd_0.69Y_0.3TaO₄ is a novel laser crystal with low symmetry and has great potential as low to moderate power lasers.

Rare-earth tantalates, with high density and monoclinic structure, and niobates with monoclinic structure have been paid great attention as potential optical materials. In the last decade, we focused on the crystal growth technology of rare-earth tantalates and niobates and studied their luminescence and physical properties. A series of rare-earth tantalates and niobates crystals have been grown by the Czochralski method successfully. In this work, we summarize the research results on the crystal growth, scintillation, and laser properties of them, including the absorption and emission spectra, spectral parameters, energy levels structure, and so on. Most of the tantalates and niobates exhibit excellent luminescent properties, rich physical properties, and good chemical stability, indicating that they are potential outstanding scintillators and laser materials.