Temperature Dependence of the Elastic, Piezoelectric, and Dielectric Constants of Lithium Tantalate and Lithium Niobate

TLDR

The elastic, piezoelectric, and dielectric constants of LiTaO₃ and LiNbO₃ were obtained by combining ultrasonic phase‑velocity measurements, resonant and anti‑resonant frequencies of a single‑length extensional bar resonator, and low‑frequency capacitances of thin flat‑plate specimens. Temperature derivatives of the elastic constants ranged from –0.4 to –6.7 × 10⁻⁴ /°C for LiTaO₃ and ≈ –2 × 10⁻⁴ /°C for LiNbO₃, while piezoelectric stress constants varied from –1.3 to +1.5 × 10⁻⁴ /°C in LiTaO₃ and 0.8–8.9 × 10⁻⁴ /°C in LiNbO₃, with dielectric permittivity derivatives positive for both materials.

Abstract

The elastic, piezoelectric, and dielectric constants, and their temperature dependence within the range 0°–110°C, have been determined for single crystals of lithium tantalate and lithium niobate. For each material, the constants were extracted from a combination of many ultrasonic phase-velocity measurements, the measured resonant and antiresonant frequencies of a single length-extensional bar resonator, and the measured low-frequency capacitances of two thin flat-plate specimens. For lithium tantalate, the normalized first temperature derivatives of the elastic constants range from −0.4 to −6.7×10−4/°C, while the derivatives for the piezoelectric stress constants range from −1.3 to +1.5×10−4/°C. In the case of lithium niobate, the elastic constant temperature derivatives are all on the order of −2×10−4/°C, while the piezoelectric temperature derivatives are all positive in the range 0.8–8.9×10−4/°C. The dielectric or permittivity temperature derivatives are positive for both materials.