Lead zirconate titanate (PZT) based piezo-ceramics have been widely used in the manufacture of actuators, sensors, transducers and in other electromechanical devices because of their excellent piezoelectric properties [1]. However, Lead and its compounds are highly toxic. There is therefore a need to replace lead in the field of piezoelectric ceramics and limit the environmental pollution. Lead-free ferroelectric ceramics based on alkali niobates is one of the most promising material classes and is a subject of growing interest.

In the present work, lead-free eco-friendly Na0.5Bi0.5TiO3 (NBT) ceramic is chosen due to their high electromechanical coupling, high Curie temperature and excellent mechanical properties [3]. A chemical substitution of K+ ions at Na+ sites is adopted to tune the piezoelectric behavior of new Na0.4K0.1Bi0.5TiO3 (NKBT) ceramic synthesized by conventional solid state sintering route. Thermal techniques, TG-DTA and Dilatometry, are used to determine the calcination (800 ℃) and sintering (1150 ℃) temperatures, respectively. Structural analysis using X-ray diffraction and Raman spectroscopy confirmed an average pseudo-cubic structure with locally distorted nano regions. Rhombohedral and tetragonal symmetry with 65 and 35 volume percent fitting was observed in Rietveld refinement of XRD pattern after electric poling. Density is found to be around 96-98% of the theoretical value which is complimented with dense, compact, minimal pore SEM images of grain size 1.2 μm. The EDS spectra and elemental mapping were recorded and confirmed the formation of a stoichiometric compound. The atomic constituents of NKBT along with their chemical state and binding energy were recorded by High resolution X-ray Photoelectron Spectroscopy (XPS). The measured electrical properties at room temperature showed good agreement with the previous work. Relative permittivity (ɛr) = 1370 at 1 kHz frequency. Remnant polarization (Pr) = 39 µC/cm2, Coercive field (EC) = 28 kV/cm, converse piezoelectric coefficient (d*33) = 326 pm/V. Temperature dependent dielectric, ferroelectric and piezoelectric properties were studied in a systematic manner. The dielectric study revealed the critical slowing down of polar domain dynamic below a diffuse phase transition.