Dielectric Properties of Low Concentration Barium Doped K_0.5Na_0.5NbO₃ Lead Free Ceramics Prepared via Solid State Reaction Method

Abstract

In this work, the effect of low concentration of Barium (Ba) on the density, crystal structure, microstructure and dielectric properties of K0.5Na0.5NbO3 (KNN) lead-free piezoelectric ceramic samples have been systematically studied. The samples were calcined at 850 °C for 6 hours and pressed using a hydraulic hand press to produce a green body disc. In this way, the green body disc of KNN was doped with 0.00 to 0.10 mol % of Ba concentration and was placed in an alumina crucible before conventional sintering at 1120 °C for 2h in air atmosphere. The increasing amount of Ba shifting all the diffraction peaks to a higher angle was measured using X-Ray Diffraction. Doping the Ba also improved the density of the KNN body. The most densified body was identified for x= 0.05 mol% of Ba which is 4.21355 g/cm3. The microstructure of the surface becomes finer and smaller after Ba doping. This shifting diffraction peaks and densified body is responsible for the enhancement of dielectric properties with the optimum value obtained from the sample doped with x= 0.05 mol%. The results show that relative permittivity (ɛr) was improved by the increment of Ba2+ concentration for 0.05 mol% which is 183.9856 for 1 kHz.