A high-quality Ba₂TiSi₂O₈ (BTS) single crystal was grown using the Czochralski (Cz) pulling method. The thermal expansion and electro-elastic properties of BTS crystal were studied for high temperature sensor applications. The relative dielectric permittivities ${\epsilon }_{11}^T/{\epsilon }_0$ and ${\epsilon }_{33}^T/{\epsilon }_0$ were determined to be 16.3 and 11.8, while the piezoelectric coefficients d_15, d_31, d₃₃ were found to be 17.8, 2.9, and 4.0 pC/N, respectively. Temperature dependence of electro-elastic properties were investigated, where the variation of elastic compliance $s_{55}^E$ (= $s_{44}^E$ ) was found to be 8.5 pC/N) and linear thermal expansion coefficient (8.03 ppm/°C) achieved for BTS crystal along the (47°, φ) direction (φ is arbitrary in 0–360°), together with its good temperature stability up to 650 °C, make BTS crystal a promising candidate for high temperature piezoelectric sensors.

A new kind of borate crystalline material Sr₃(BO₃)₂ with a similar calcite type structure was designed and synthesized by solid state reaction method, moreover, the single crystal growth was attempted with traditional Czochralski pulling method. Crystal phase of Sr₃(BO₃)₂ was investigated by using X-Ray powder diffraction (XRPD) at room temperature and found similar to Ca₃(BO₃)₂ crystal with space group of R-3c. The phase stability was studied by means of thermogravimetric differential thermal analysis (TG/DTA) and high temperature XRPD up to 1350 °C, where an obvious endothermic peak was observed in DTA curve around 1250 °C, and weak splits of diffraction peaks were found at temperatures above 1250 °C, indicating the existence of structure transformation for Sr₃(BO₃)₂ crystal. Raman properties were studied experimentally and theoretically by using density functional perturbation theory, though the strongest frequency shift of Sr₃(BO₃)₂ crystal (900 cm⁻¹) was comparable to that of Ca₃(BO₃)₂ (927 cm⁻¹), the line width of the strongest Raman peak obtained for Sr₃(BO₃)₂ (5.72 cm⁻¹) was much lower than Ca₃(BO₃)₂ (7.01 cm⁻¹), indicating a larger Raman gain for Sr₃(BO₃)₂ crystal, which would be favorable for stimulated Raman scattering application.

The non-centrosymmetric bismuth-based oxyborate crystals have been extensively studied for non-linear optical, opto-electric and piezoelectric applications. In this work, single crystal growth and electro-elastic properties of α-BiB₃O₆ (α-BIBO) and Bi₂ZnB₂O₇ (BZBO) crystals are reported. Centimeter-sized α-BIBO and BZBO crystals were grown by using the Kyropoulos method. High resolution X-ray diffraction tests were performed to assess the crystal quality. The full-width at half-maximum values (FWHM) of the rocking curves were evaluated to be 35.35 arcsec and 47.85 arcsec for α-BIBO and BZBO samples, respectively. Moreover, the electro-elastic properties of α-BIBO and BZBO crystals are discussed and summarized, based on which the radial extensional and the face shear vibration modes were studied for potential acoustic device applications. The radial extensional mode electro-mechanical coupling factors k_p were evaluated and found to be 32.0% and 5.5% for α-BIBO and BZBO crystals, respectively. The optimal crystal cuts with face shear mode were designed and found to be (YZt)/−53° (or (YZt)/37° cut) for α-BIBO crystal, and (ZXt)/±45° cut for BZBO crystal, with the largest effective piezoelectric coefficients being in the order of 14.8 pC/N and 8.9 pC/N, respectively.