Polymeric Precursor Synthesis of Ceramic Materials

Abstract

ABSTRACTFor the past twenty years we have successfully synthesized a wide range of ceramic materials by using organic precursors. The organic precursors are formulated into a glass before pyrolysis. Synthesized compounds include, for example, titanates, zirconates, silicates, chromites, niobates, tantalates, ferrites and molybdates.This preparation technique is based upon having individual cations complexed in separate weak organic acid solutions. The individual solutions are gravimetrically analyzed for the respective cation concentration to a precision of 10–100 ppm. In this way it is possible to precisely control all of the cation concentrations, and to mix the ions on an atomic scale in the liquid state. There is no precipitation in the mixed solution as it is evaporated to the rigid polymeric statein the form of a uniformly colored transparent glass. The glass retains homogeneity on the atomic scale, and may be calcined at a relatively low temperature of only a few hundred degrees Celsius to the homogeneous single phase of precise cationic stoichiometry and particle size of a few hundred Å.The advantage of having such well characterized, thermodynamically defined compounds is illustrated by the resulting understanding of the solid state chemistry of multicomponent compounds that has occurred.