Abstract: A method is disclosed for preparing a dense, B"-alumina-containing ceramic body exhibiting an electrical resistivity for sodium ion conduction at 300.degree. C. between about 3 and about 20 ohm-cm, by sintering a green ceramic body formed from a composition comprising at least about 90 weight percent of aluminum oxide, about 8.7 to 9.4 weight percent of sodium oxide, about 0.7-0.9 weight percent of lithium oxide, and from 0.0 to about 4.0 weight percent of magnesium oxide at a temperature between about 1400.degree. C. and about 1600.degree. C., for between about three (3) minutes and about 180 minutes to obtain a body containing both B and B"-alumina crystalline forms. The sintered body exhibits a density greater than 90% of theoretical for polycrystalline B"-alumina and a uniform grain size between about 20 and 100 micrometers. All of these compositions were prepared by using either a binary liquid forming mixture between sodium aluminate (NaAlO.sub.2) and lithium aluminate (LiAlO.sub.

Abstract: 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.

Abstract: A method for preparing shaped, green ceramic compacts suitable for firing to form high density .beta."-alumina containing ceramic bodies comprising: (1) mixing between about 2.5 parts by weight and about 4.5 parts by weight of a ceramic composition comprising at least about 80 weight percent of aluminum oxide and from about 5 to about 15 weight percent of sodium oxide with 1 part by weight of a binder composition consisting essentially of between about 20 weight percent and about 35 weight percent of polyvinyl pyrrolidone having a number average molecular weight (M.sub.n) between about 20,000 and about 160,000 and between about 80 weight percent and about 65 weight percent of ethylene glycol; (2) extruding the mixture so formed through a die of desired configuration; and (3) heating the extrudate at temperatures and for periods of time necessary to evaporate the ethylene glycol solvent and burn off the polyvinyl pyrrolidone.

Abstract: A method for preparing a dense and strong polycrystalline .beta."-alumina-containing ceramic body exhibiting an elecrical resistivity at 300.degree. C of 5 ohm-cm or lower, and a controlled and uniform grain size under 50 micrometers, comprising:A. preparing fully converted .beta."-alumina seeds;B. mechanically mixing in the above-mentioned .beta."-alumina seeds with a matrix powder of a composition consistent with the formation of .beta."-alumina upon sintering; andC. sintering at about 1600.degree. C for less than 10 minutes in an open-air atmosphere or under noble metal encapsulation, a green ceramic body formed from the powder mixture of which one ingredient is the .beta."-alumina seeds and the other ingredient is the matrix powder of a composition consistent with the formation of .beta."-alumina.The polycrystalline .beta."-alumina-containing ceramic bodies obtained by the method of this invention exhibit high density, low porosity, high strength, fine grain size, and low electrical resistivity.