Preparation, structure analysis and dielectric characteristics of the novel ferroelectric ceramics (1-x)Sr3.35Ba1.65Nb10O30 (SBN) - (x) Ba4Na2Nb10O30 (BNN) with potassium tungsten - bronze structure

Abstract

The polycrystalline samples of the new ferroelectric ceramics (1-x)Sr3.35Ba1.65Nb10O30 (SBN) - (x) Ba4Na2Nb10O30 (BNN) with potassium tungsten bronze structure were prepared using a high temperature solid - state reaction technique. They are novel inorganic materials with potassium tungsten bronze structural type. The formation of the ceramics under the reported conditions has been confirmed by an X - ray diffraction technique. The ceramic microstructures were observed using scanning electron microscopy (SEM) techniques associated with energy dispersive X ray spectroscopy (EDX) analysis. The SEM micrograph exhibits grain boundary distribution. Dielectric properties of the SBN - NBN compounds as a function of temperature (300-850 K) at frequencies 1-1000 KHz were studied. Detailed studies of variation of dielectric parameters with temperature and frequency confirmed the existence of ferroelectricity in these materials. The difference between the high - frequency dielectric constants and the low - frequency dielectric constants indicates that the ferroelectric phase transition in SBN - NBN compounds is of rather diffuse nature than relaxor type. According to the experimental data, it is suggested that ferroelectrics phase transition is a first - order transition. (C) 2017 Elsevier B.V. All rights reserved.