NANOCRYSTALLINE BATIO3 FROM FREEZE-DRIED NITRATE SOLUTIONS

An aqueous, all nitrate, solution-based preparation of BaTiO3 is repor ted here. Rapid freezing of a barium and titanyl nitrate solution, fol lowed by low temperature sublimitation of the solvent, yielded a freez e-dried nitrate precursor which was thermally processed to produce BaT iO3. XRD revealed that 10 min at temperatures greater than or equal to 600 degrees C resulted in the formation of phase pure nanocrystalline BaTiO3. TEM revealed that the material was uniform and nanocrystallin e (10-15 nm). The high surface to volume ratio inherent in these small particles stabilized the cubic phase of BaTiO3 at room temperature. I t was also found that the average particle size of the BaTiO3 produced was highly dependent upon calcination temperature and only slightly d ependent upon annealing time. This result suggests a means of selectio n of particle size of the product through judicious choice of calcinat ion temperature. The experimental details of the freeze-dried precurso r preparation, thermal processing of the precursor, product formation, and product morphology are discussed.