Effect of Mn doping on Structural, Dielectric and Ferroelectric Properties of (K0.5Na0.5)NbO3 Lead Free Ceramics

Abstract

Lead free ferroelectric ceramics of (K0.5Na0.5)(Nb1-xMnx)O3 (x = 0, 0.01) were prepared by solid state reaction technique and the effect of Mn doping on their crystal structure, dielectric and ferroelectric properties was investigated. Rietveld refinement on the XRD data was carried out using an orthorhombic crystal structure having Amm2 space group, suggesting the formation of single phase compounds. The temperature dependent dielectric properties for both the compounds show two phase transitions, one corresponding to orthorhombic to tetragonal (TO-T) phase transition and the other to the tetragonal to cubic phase transition (TC). An improved dielectric constant of 345 (at RT) and 5175 (at TC) in Mn doped KNN is observed compared to pure KNN (285 at RT and 4610 at TC). Ferroelectric properties measurement at room temperature indicates a significant enhancement of remnant polarization (2Pr) in Mn doped KNN (25.26 μC/cm2) ceramics with respect to pure KNN (16.38 μC/cm2).