Temperature-dependent characterization of piezoelectric, dielectric, and elastic properties in K0.61Na0.39NbO3 single crystals

Abstract

Accurate and self-consistent measurement of the dielectric, piezoelectric, and elastic parameters of potassium-sodium niobate (K1−xNaxNbO3, KNN) single crystals is essential for both theoretical studies and the development of KNN-based device applications. In this study, K0.61Na0.39NbO3 single crystals demonstrate a markedly higher shear-mode piezoelectric coefficient d15 (210.34 pC/N) compared to the longitudinal coefficient d33 (60.36pC/N) and thus classified as “rotator” ferroelectric crystals. The crystals exhibit exceptional thermal stability in the orthorhombic phase, with d33 increasing by only ∼1% over a wide temperature range from −100 to 150 °C. Additionally, calculations of piezoelectric coefficients along the [001] direction show that ferroelectric domain contributions account for over 40% of the total piezoelectric response at room temperature. At the same time, ferroelectric domains also exhibit significant temperature sensitivity. This dual behavior offers key insights for domain engineering of KNN-based materials aimed at enhancing electromechanical performance.