Temperature dependence of elastic properties and piezoelectric applications of BaTeMo2o9 single crystal [Correspondence]

BaTeMo₂O₉ (BTM) single crystal, as a lead-free piezoelectric material, belongs to the monoclinic system, space group P2₁. We report the temperature dependence of the elastic constants by the transmission method over the range -50°C to 150°C. The first-order temperature coefficients of the elastic constant s₄₄ is about 180 × 10^-6/°C. Piezoelectric resonators based on BTM crystal using the thickness-stretching vibration and the shear vibration modes were designed and evaluated, which eliminated or minimized the influence of the off-principal axis coefficients. The Q_m of one of the resonators is about 600. Our results show that the elastic constants have good temperature stability, and the resonators have already met the requirements for some piezoelectric applications. This study on the BTM crystal has revealed the application for the low-symmetry crystal.