Dense ceramics of NaNbO3 produced from powders prepared by a new chemical route

A sodium niobate precursor was prepared by evaporating a solution of an oxalato-niobium complex, sodium nitrate, oxalic acid and ammonium hydroxide. The thermal evolution of the precursor powder, to the point of formation of the NaNbO3 phase, was followed by thermal analysis and powder X-ray diffraction. Calcination of the precursor above 500°C for 5 h in air yielded a pure single phase NaNbO3. The non-isothermal densification behaviour was followed by dilatometric measurements. Highly sinterable powders were prepared by this new chemical route. Densities higher than 95% of the theoretical one were reached after sintering at 1250°C for 2 h in air.