ELECTRICAL PROPERTIES OF MULTI-VALENT ALTERNATE ABO3 PEROVSKITE (KNN) MULTI-FUNCTIONALFERROELECTRIC CERAMICS

Abstract

Ecological-friendly and unhazardous materials are being prepared by the scientific community in search of novel lead-free ferroelectric materials. K_0.5Na_0.5NbO₃belonging to the ABO₃ perovskite was found to be promising ferroelectric lead-free material. A new set of compound, namely, double dopant LKNZN compound was prepared by solid state route. Here, Lithium is partially replaced with Sodium, at A-site, and Zirconium substituted with Niobium, at B-site. The compositional formula of the present investigations is: [((K_0.5Na_0.5)_(1-x)Li_x) (Zr_0.025Nb_0.98)O₃]_, where x=0, and 0.025 9 (labelled as KNN1 and KNN2). In addition we have prepared (K_0.5(Na_0.475L_i0.025)) (Zr_0.025N_b0.98)O₃ (labelled as KNN3). XRD patterns obtained at room temperaturehave shown maximum intensity peak of (111), confirms the formation of a single-phase. SEM pictures of KNN1 and KNN2 have shown cubical grain with bimodal grain distribution, whereas KNN3 consist of circular bimodal grain distribution. Delectric measurements were studied on the said above samples. It is observed
a hump around 200°Cand dielectric transition at 4520°C for all the samples. From this it is evident that: (i) the samples are transforming from orthorhombic phase to tetragonal phase near 200°C (ii) around 420°C, samples transform from tetragonal phase to cubic phase. Theresults were corroborated to the tolerance factor and lattice distortions.