Ferroelectrics of Ultrafine Particle Size: I, Synthesis of Titanate Powders of Ultrafine Particle Size

Two methods used to synthesize high-purity ferroelectric titanate powders in controlled, narrow size distributions, with average particle diameters <1000 A, were: (1) isothermal pyrolysis of barium titanyl oxalate or mixed calcium-barium titanyl oxalates as low as 550° and 825°C, respectively, average particle sizes depending strongly on the pyrolysis temperature; and (2) hydrolysis of titanate esters in barium hydroxide. Using solvent media of controlled polarity, high-purity stoichiometric BaTiO3 was obtained with average sizes as small as 100 A. Factors affecting stoichiometry and particle size are discussed in terms of assumed reaction mechanisms.