Lilliwyte Societe Anonyme

Peter Barrow

Arnold Van Zyl

Michael M Thackeray

Michael L Wright

James H Duncan

Graham K Duncan

Angus I Kingon

The invention provides a method of making an analogue of .beta.'-alumina, the analogue having a layered .beta.'-alumina spinel-type structure in which ate least some of the Na ions in the layers of Na ions separated by layers of Al and O ions in said .beta.'-alumina spinel-type structure are replaced by substitute metal cations. The substitute metal cations are mono-, d- and/or trivalent. The method comprises dispersing in a boehmite having a well developed and highly ordered crystal structure at least one oxide of the substitute metal cations or a precursor thereof to form a starting mixture, and heating the mixture to a conversion temperature at which it is converted to the analogue.

Method of making analogues of .beta.-alumina

The invention provides a method of making .beta.'-alumina by heating aluminium oxide in the presence of Na.sub.2 O. A metal oxide dopant in the form of Li.sub.2 O, MgO, ZnO, CoO, NiO, FeO or mixtures thereof, or a precursor of the dopant, is dispersed in a cubic-close packed aluminium oxide or a precursor thereof to form a starting mixture which is calcined by heating to 250.degree.-1100.degree. C. in an oxygen-containing atmosphere. Na.sub.2 O is then dispersed in the calcined starting mixture to form a final mixture, and the final mixture is heated in an oxygen-containing atmosphere to above 1100.degree. C. to produce .beta.'-alumina.

Method of making .beta.'-alumina

The invention provides a method of preparing a surface of a ceramic solid electrolyte conductor of alkali metal ions for wetting by said alkali metal in molten form. The method comprises doping the ceramic surface with an oxide of a transition metal. Transition metals such as Fe, Ni, Cu, Mn, Co, Cr or Mo have suitable oxides for doping beta-alumina for wetting by sodium.

Method of preparing ceramic surfaces for wetting thereof by alkali metals

A method of making beta'-alumina comprises dispersing in a precursor of aluminum oxide a member of the group comprising sodium oxide and its precursors, and dispersing in the precursor of aluminum oxide a spinel stabilizer which is a member of the group comprising spinel-forming oxides and the precursors thereof, to form a mixture. The mixture is then heated to a temperature at which at least some of the precursor of aluminum oxide is converted to beta'-alumina. The precursor of aluminum oxide is one which, when calcined in air by itself, has a calcination product which, when subjected to X-ray diffraction, displays a predetermined X-ray diffraction trace. The X-ray diffraction trace is one whose peak with the highest intensity in the 2 (theta) range of 44.degree.-48.degree. and whose peak with the highest intensity in the 2 (theta) range of 63.degree.-69.degree. respectively have maximum intensities and integrated intensities which comply with equations (I) and (II):

Growing community of inventors

Alvaston, United Kingdom

Peter Barrow