Lead-free Sb-modified potassium sodium niobate ceramics for enhanced energy harvesting and superior performance in piezoelectric transducers for ultrasonic inspection

Abstract

In this work, the properties of lead-free piezoelectric K_0.5Na_0.5NbO₃ (KNN) were enhanced by antimony (Sb) doping on the B-site using a solid-state reaction method. XRD and Raman analysis confirmed phase purity, showing an orthorhombic structure. X-ray diffraction patterns were fitted using FullProf to determine lattice parameters, revealing reduced bond angles and lengths in Sb-doped KNN (KNNS). The dielectric properties showed a phase transition in pure KNN at 185 °C (orthorhombic to tetragonal) and 380 °C (tetragonal to cubic), while KNNS exhibited relaxer ferroelectric behaviour. KNNS displayed enhanced ferroelectricity (2P_s = 26.2 μC/cm²) and low leakage current (4.17 nA-cm⁻²). KNNS also demonstrated superior energy harvesting, producing 25.2 V and a power density of 7.71 mW-cm⁻² under finger tapping, a 280% improvement over pure KNN. The study highlights the benefits of Sb doping in improving the electrical properties and Curie temperature of KNN, as well as its successful application in energy harvesting and ultrasonic testing of aluminium alloy specimens.