The full matrix of electro-elastic constants of sillenite-type crystals Bi₁₂TiO₂₀ (BTO) and Bi₁₂SiO₂₀ (BSO) were determined by the resonance method, with d₁₄ and k₁₄ being on the order of 40–48 pC/N and 31%–36%, respectively. In addition, double-rotated orientation dependence of d₃₃ was investigated, with the maximum values of 25–28 pC/N being achieved in ZXtl45°/54°-cut samples. The electrical resistivity of BSO was found to be two orders higher than that of BTO, being on the order of 7 × 10⁵ Ω cm at 500 °C. The temperature dependence of dielectric and piezoelectric properties were investigated. BSO exhibited a high thermal stability in the temperature range of 25–500 °C, while BTO showed a variation of ~3% in the range of 25–350 °C. The high values of d₁₄ and k₁₄, together with the good thermal stability, make BTO and BSO crystals potential candidates for electromechanical applications in medium temperature range.

A 10 at% Pr³⁺ doped BaGd₂ (MoO₄)₄ single crystal for the first time was grown by the Czochralski method. Details on the preparation and growth procedures were discussed. The crystal has a perfect (010) cleavage plane, and the cleavage character makes the crystal suitable as a gain medium for microchip lasers. The effective segregation coefficients of Pr³⁺, Ba²⁺, Gd³⁺, and Mo⁶⁺ in the as-grown crystal are determined to be 0.5991, 1.0106, 1.0948 and 0.9935, respectively. The absorption spectrum in the visible and near-infrared (NIR) regions was measured at room temperature. There are several strong absorption peaks in the range from 400 to 2500 nm. The fluorescence spectrum excited by a Xenon lamp was also measured. A strong emission peak located at 651 nm was observed. Using the measured spectra, the optical parameters were calculated using the J–O theory.