Combustion synthesis of Sr0.5Ba0.5Nb2O6 and effect of fuel on its microstructure and dielectric properties

Nano-sized Sr0.5Ba0.5Nb2O6 (SBN50) powder has been synthesized, at very short reaction time, for the first time by a novel combustion method. Ba(NO3)2 and Sr(NO3)2 were used as source of Sr and Ba, respectively, while Nb-oxalate was used as the source of niobium. Urea, hexamethyltetramine (HMT) and glycine were used as fuel. The crystallite sizes in the powder ranged between 14–125 nm. X-ray diffraction analysis showed complete SBN50 phase formation at 700 °C, when urea/HMT was used as fuel, and at 800 °C when glycine was used as fuel. Ferroelectric–paraelectric phase transition temperature (Tc) close to 40 °C was observed when urea and HMT were used and the Tc was −49 °C when glycine was used. When urea was used as fuel highest dielectric constant was observed for the pellets sintered at 1250 °C for 4 h. Low dielectric loss was observed when HMT was used as fuel. Larger grain sizes in the sintered pellets were observed when glycine was used as fuel.