Canadian Patents & Development Ltd.

Her Majesty the Queen in Right of Canada, As Represented by the Minister

Kimihiro Yamashita

Patrick S Nicholson

Michael Sayer

Michael F Bell

A method of converting a feed solid polycrystalline of .beta. alumina into a hydronium conductor requires the preselection of an appropriate feed ceramic preferably with a chemical formula;

Method of converting a precursor ceramic solid into a solid ceramic

The spray-drying of a feed liquid mixture containing dissolved feed elements is used to produce precursor powders of Na.sup.+ -super conducting sodium gadolinium silicate (Na.sub.5 GdSi.sub.4 O.sub.12), (NGS), and sodium yttrium silicate (Na.sub.5 YSi.sub.4 O.sub.12), NYS. Using these powders, very dense (&gt;97% theoretical) solids are obtained on sintering. The resistivities of the NGS and NYS polycrystalline ceramics are 5 and 7 (.OMEGA. cm) respectively at 300.degree. C. and are dependent on the f(NGS) or f(NYS) values. In the case of NYS, the resistivity/f(NYS) relationship takes the form ##EQU1## indicative of resistive and conductive phases mixed more in parallel than in series.

Silicate superionic conductors and method of making same

An hydronium polycrystalline superionic conductor, having the formula (H.sub.3 O.sup.+,Na.sup.+).sub.5 (Re)Si.sub.4 O.sub.12, where Re=Y or Gd, is produced from precursor material being Na.sub.5 YSi.sub.4 O.sub.12 or Na.sub.5 GdSi.sub.4 O.sub.12. In order to accomplish the aforesaid a range of intermediate ceramics may be produced replacing part of the precursor ceramic sodium by ions of elements in 1A group of the Periodic Table that have an atomic weight above 32 and preferably ions of potassium, cesium, or mixtures of potassium and cesium. To produce the superionic hydronium polycrystalline ceramic conductor and the intermediate ceramic from the feed ceramics aforesaid, the feed ceramic is placed in a chloride melt wherein part of the sodium in the feed ceramic lattice is replaced by an appropriate cation from the melt such as potassium and cesium. Subsequently, a field assisted ionic exchange takes place to now replace the interceded potassium and cesium ions with the hydronium (H.sub.3 O.sup.+) ion, whereby the aforesaid hydronium, superionic, solid polycrystalline ceramic conductor is achieved.

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Hamilton, Canada

Kimihiro Yamashita