Calcination temperature effect on dielectric, structural and morphology properties of BaTiO₃ nano-structure prepared by modified sol—gel technique

The motivation of this work was to improve the dielectric properties of nano-structure BaTiO₃ prepared in powder form, using a modified sol-gel method and calcinated in the air at different calcination temperatures between 350 and 1050 °C. For that, we choose to measure the dielectric properties over the high frequency range (10⁶–10⁸ Hz) at room temperature (RT), which makes it the candidate for high-frequency ultrasonic and energy storage applications. The dielectric properties give remarkable results obtained maybe for the first time for this compound at the mentioned frequency range. Both the dielectric permittivity and AC conductivity were found to increase with the calcination temperature due to an increase in the crystallite size. Particularly, it has been reported that sample calcinated at 1050 °C shows high permittivity values. The effect of calcination temperature on the morphology, structure, and dielectric properties of the prepared BaTiO₃ nano-powdered was investigated. Transmission electron microscope (TEM) confirmed the nano-crystalline form of prepared samples. X-ray powder diffraction (XRD) results revealed a pure tetragonal phase between 1000 °C and 1050 °C. However, more than one phase was detected at lower temperatures. Furthermore, Raman spectra showed that the tetragonal peaks at 306 and 715 cm⁻¹, increase with the increase of the calcination temperature. Fourier transformation infrared spectroscopy (FTIR) showed that the crystallinity improved, accompanied with a gradual disappearance of carbonates by increasing calcination temperature. (paper)