Effect of fuel composition and concentration on dielectric properties of bismuth titanate (Bi4Ti3O12) synthesized by microwave-induced combustion method

In this work, ferroelectric bismuth titanate was prepared by a microwave-assisted auto-combustion method using different fuel agents (glycine, acetylacetone, and urea). X-ray diffraction patterns show that bismuth titanate with perovskite structure has been formed successfully in all cases. Although bismuth oxide as a major impurity is also identified, its quantitative amount has been minimized when glycine used as fuel in the combustion reaction. The effects of glycine concentration (fuel-deficient, stoichiometric, and fuel-rich) on the properties also have been evaluated. The results show that the degree of crystallinity increases when the fuel-rich reaction was used. Dielectric properties were measured as a function of frequency by means of an LCR meter. It is found that both parts of permittivity decrease with increasing frequency; conversely, AC conductivity rises with frequency. Furthermore, one semicircle is detected in the impedance spectra, demonstrating a significant contribution of the grain boundary. It is also observed that the higher the molar value of glycine, the greater the value of dielectric constant and the lower level of impurity.