Synthesis of β"-alumina polymer precursor and ultrafine β"-alumina composition powders

beta "-Alumina, an important high-temperature solid electrolyte, was synthesized from inexpensive starting materials via a polymeric, metalloorganic precursor. The precursor, made by reacting NaOH, LiOH, Al(OH)(3), and triethanolamine (TEA) in ethylene glycol (EG) while distilling off product water, is a glassy thermoplastic at room temperature, and dissolves in polar solvents, e.g. ethanol. Spheroidal, particles of <100 nm diameter were formed by flame-spray pyrolysis of ethanolic solutions of the precursor. X-ray powder diffraction showed the as-formed powders to be an intermediate phase, possibly m-alumina, which transforms to beta "-alumina on heating above 1200 degrees C.