Conductive ceramic composition and method of preparation
AssigneeThe United States of America as represented by the United States Department of Energy
InventorsJames L. Smith, Eugenia H. Kucera
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Abstract
A ceramic anode composition is formed of a multivalent metal oxide or oxygenate such as an alkali metal, transition metal oxygenate. The anode is prepared as a non-stoichiometric crystalline structure by reaction and conditioning in a hydrogen gas cover containing minor proportions of carbon dioxide and water vapor. The structure exhibits a single phase and substantially enhanced electrical conductivity over that of the corresponding stoichiometric structure. Unexpectedly, such oxides and oxygenates are found to be stable in the reducing anode fuel gas of a molten carbonate fuel cell.
Claims16
A ceramic composition comprising a multivalent metal oxide, said metal oxide including an alkali metal-transition metal oxygenate, with the ratio of oxygen to multivalent metal in non-stoichiometric relation, deficient in oxygen and wherein the composition exhibits an electrical conductivity substantially greater than the electrical conductivity of a corresponding stoichiometric composition with balanced oxygen.
A ceramic composition comprising a multivalent metal oxide with the ratio of oxygen to multivalent metal in non-stoichiometric relation, deficient in oxygen and wherein the composition exhibits an electrical conductivity substantially greater than the electrical conductivity of a corresponding stoichiometric composition with balanced oxygen, wherein the composition is selected from the group of non-stoichiometric, oxygen deficient variants of the nominally stoichiometric ceramics consisting of LiFeO.sub.2, Li.sub.3 VO.sub.4, LiTaO.sub.4, LiNbO.sub.4, Li.sub.2 TiO.sub.3, Li.sub.2 ZrO.sub.3, MnO, and CeO.sub.2.
A ceramic anode composition comprising:
- A.sub.x T.sub.y O.sub.z
- where:
- A is an alkali metal
- T is a transition metal and
- O is oxygen.
- and x, y, and z are in non-stoichiometric relation deficient in oxygen,
- the composition exhibiting substantially greater electrical conductivity than that of a corresponding stoichiometric composition.
A method of preparing an electrically conductive, non-stoichiometric ceramic composition comprising:
- providing a transition metal oxide of near stoichiometric proportions;
- exposing said oxide to a reducing gas modified with carbon dioxide to convert a portion of the transition metal species to a lower valence state than that required in the corresponding stoichiometric composition.
Dependencies are inferred from the claim text.