Near stoichiometric lithium niobate crystal with dramatically enhanced piezoelectric performance for high-temperature acceleration sensing†

Abstract

Lithium niobate (LN) is a multifunctional crystal with excellent piezoelectric properties, making it a potential candidate for piezoelectric sensing applications. In this study, the mechanism of the discrepancies of piezoelectric properties between near stoichiometric lithium niobate (NSLN) and congruent lithium niobate (CLN) were probed using Raman spectrum, first principles calculations and single crystal X-ray diffraction (XRD), where the V⁻_Li defect demonstrated a significant impact on the distortion of the NbO₆ octahedron, which in turn affected the piezoelectric properties of the LN crystal. The NSLN crystal exhibited a strong performance, with high piezoelectric coefficients d₁₅ and d₂₂ on the orders of 77.6 pC N⁻¹ and 22.8 pC N⁻¹, respectively, showing increases of 17.4% and 18.1% over the CLN crystal, and highlighting its enhanced piezoelectric characteristics. Finally, temperature-dependent behaviours of the electro-elastic constants for the NSLN and CLN crystals were discussed. The high-temperature piezoelectric performance of NSLN crystal was evaluated utilizing a prototype of shear-mode acceleration sensor, demonstrating remarkable sensing performance up to 650 °C with good temperature stability (sensitivity variation <5%).