EFFECT OF TEMPERATURE ON THE CRYSTALLINE STRUCTURE OF K0.5Na0.5NbO3 CERAMICS POWDER OBTAINED BY COMBUSTION REACTION SYNTHESIS

Abstract

This paper discusses how temperature influences the obtention of single-phase K0.5 Na0.5 NbO3 (KNN) nanometric ceramic powders, synthesized by the combustion method. K2CO3, Na2CO3, and NH4 [NbO (C2O4) 2 (H2O)] ⋅ H2O were used as cation sources and a mixture of urea / glycine in relation 50/50 was used as fuel. The solution containing precursors and fuel was placed in a preheated muffle furnace, where the combustion took place. In this process, the effect of four different temperatures (500, 600, 700 and 800°C) was analyzed. The phases present in the ceramic powders, the microstructure and the morphology were determined by X-ray diffraction (XRD), Fourier transform infrared (FTIR) Spectroscopy, and scanning electron microscopy (SEM). Experimental results show that pure perovskite phase was formed at temperatures as low as 500°C. Furthermore, the obtained powder has monoclinic symmetry and average particle size of ~ 27 nm. We conclude that the homogeneity of the precursor solution and a low processing temperature play a key role in the formation of nano-particles of KNN.