Synthesis and Characterization of Some Ferroelectric Ceramics for Device Applications

Abstract

In present work, the following samples are synthesised comprising of two series. 1. K0.5Bi0.5TiO3-NaNbO3 i.e., KBT-NN as parent and x(KBT)-1-x(NN) with x= 0.025, 0.05, 0.075, 0.1, 0.15 and 0.2. 2. K0.5Bi0.5TiO3-NaVO3 i.e., KBT-NV as parent and x(KBT)-1-x(NV) with x=0.025,0.05, 0.075,0.1,0.15and0.2. Structural, dielectric, ferroelectric, optical and electrical properties are investigated. The crystal formation are confirmed from X-ray diffraction (XRD) analysis using POWD software, reflecting an orthorhombic crystal structure. The field emission scanning electron micrographs are taken at different magnifications to have grains, grain boundaries and pores existed in the materials. From EDS spectra, no foreign element is detected confirming the purity of the sample. The characteristic peak of BO6 octahedra in FTIR spectrum is appeared confirming the formation of perovskite phase. Molecular vibrations of the investigated samples have been verified using both RAMAN and FTIR spectroscopy. It is observed both bending and stretching vibration are dominated due to presence of octahedral NbO6, VO6 and C=C, C=O, Bi-O, Nb-O, V-O etc. The optical properties of the materials are studied by using UV-Vis as well as photo luminescence spectroscopy analysis. The band gap calculated from the above study shows that the materials are useful for photo catalytic as well as blue LED devices. The electrical characterization of the samples has done over a wide temperature range (25-5000C) and frequency 100Hz 1MHz. All the compounds show dielectric anomaly well above room temperature. The smooth transfer of and#949;r from ferroelectric (low symmetry) phase to paraelectric phase (higher symmetry) implies the diffusing nature. The falling trend in remnant polarization and area of the hysteresis loop with increasing concentration in all the samples once again strengthen the signature of ferroelectricity in the material. Ac conductivity of the samples was studied by complex impe