University of Utah Research Foundation

Mark L Miller

Anil Vasudeo Virkar

Ivan B Cutler

Ronald S Gordon

Methods of preparing a dense and strong polycrystalline .beta.'-alumina-containing ceramic body exhibiting an electrical resistivity for sodium ion conduction at 300.degree. C of 9 ohm-cm or lower obtained directly after sintering and having a controlled fine microstructure exhibiting a uniform grain size under 50 micrometers. The invention more particularly relates to methods of uniformly distributing selected metal ions having a valence not greater than 2, e.g. lithium or magnesium, uniformly throughout the beta-type alumina composition prior to sintering to form .beta.'-alumina. This uniform distribution allows more complete conversion of .beta.-alumina to .beta.'-alumina during sintering. As a result, the polycrystalline .beta.'-alumina containing ceramic bodies obtained by methods of this invention exhibit high density, low porosity, high strength, fine grain size (i.e. no grains over 25-50 micrometers with an average size under 5-10 micrometers), low electrical resistivity and a high resistance to degradation by water vapor in an ambient atmosphere.

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Salt Lake City, UT, United States of America

Mark L Miller