Piezoelectric and Ferroelectric Properties of Lead-free 0.9(Na0.97K0.03NbO3)- 0.1BaTiO3 Solid Solution

Abstract

Lead-free piezoelectric 0.9(Na0.97K0.03NbO3)-0.1BaTiO3 ceramic has been synthesized using conventional solid-state reaction method. The results of X-ray diffraction analysis (XRD) show that the prepared sample displays typical perovskite structure with tetragonal space group P4mm. The crystal structure of 0.9(Na0.97K0.03NbO3)-0.1BaTiO3 powder was determined by Rietveld refinement analysis. The charge density distribution of the prepared sample has been investigated by using maximum entropy method. The optical band gap of the solid solution has been investigated using UV-visible spectroscopy (UV-Vis). Scanning electron microscopic (SEM) measurements were performed to study the surface morphology. The elemental composition of the 0.9(Na0.97K0.03NbO3)-0.1BaTiO3 sample was analyzed by energy-dispersive X-ray (EDS) spectrometer. The ferroelectric nature of the sample has been determined through polarization and electric field hysteresis measurements. Introduction. Lead-based piezoelectric materials like PZT (lead zirconate titanate) are the most widely used piezoelectric materials for its superior piezoelectric properties, but these Pb-based systems are highly toxic and volatile causing serious environmental hazards [1,2]. Recently, considerable research has been intensified on lead-free based piezoelectric materials [3]. In this context, (Na, K) NbO3 based ceramic systems are emerging as promising candidates for replacement of lead-based ceramics due to their excellent piezoelectric properties, high Curie temperature and environmental friendliness. Pure NKN ceramics are difficult to synthesize using the solid state reaction method due to the evaporation of K2O and Na2O at high temperatures and degradation of resistivity and the piezoelectric properties. It is also very difficult to control the evaporation of Na2O and K2O by muffling. So, to synthesize the pure NKN samples and optimizations have been adapted by adjusting the Na/K ratio in A site of perovskite structure [4]. Several research works have been carried out by doping the extrinsic materials to increase the piezoelectric properties of NKN-based ceramic materials. Dopants such as LiTaO3 [5], CuO [6], ZnO, LiSbO3 [7], LiNbO3 [8], BaTiO3 [9], SrTiO3 [10], CaTiO3 [11], AgTaO3 [12], Fe2O3 [13], and Sb2O5 [14] have been added to NKN-based ceramics to form new NKN-based ceramic systems. In the present work, we report 0.9(Na0.97K0.03NbO3)-0.1BaTiO3 ceramic was synthesized by solid-state reaction method. The ferroelectric and piezoelectric properties of 0.9(Na0.97K0.03NbO3)-0.1BaTiO3 ceramic were analyzed through charge density studies.