Sodium ion conductor, solid electrolyte strengthened with zirconia
AssigneeRockwell International Corporation
InventorFrederick F. Lange
Life of this patent
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Abstract
Fracture toughness and strength of .beta.-Al.sub.2 O.sub.3, .beta."-Al.sub.2 O.sub.3, and Na.sub.1+x Zr.sub.2 Si.sub.x P.sub.3-x O.sub.12 solid electrolytes are increased by incorporating metastable grains of tetragonal ZrO.sub.2 in the structure. The ZrO.sub.2 occupies from 5 to 40% of the volume of the ceramic. To enable retention of the metastable tetragonal structure at room temperature, the ZrO.sub.2 has a grain size less than about 2 .mu.m and has dissolved in it a rare earth oxide such as Y.sub.2 O.sub.3, CeO.sub.2, La.sub.2 O.sub.3 and/or Er.sub.2 O.sub.3.
Claims11
A ceramic comprising:
- 5 to 40 v/o ZrO.sub.2 in the form of crystalline grains having a diameter less than about 2 .mu.m and having a substantially tetragonal structure;
- a rare earth oxide selected from the group consisting of Y.sub.2 O.sub.3, CeO.sub.2, Er.sub.2 O.sub.3, and La.sub.2 O.sub.3, there being at least enough of said rare earth oxide to increase the amount of ZrO.sub.2 having a tetragonal crystal structure, but not enough of said rare earth oxide to form substantial amounts of said ZrO.sub.2 having a cubic crystal structure;
- and
- the remainder of said ceramic being substantially a sodium ion conductor solid electrolyte selected from the group consisting of .beta.--Al.sub.2 O.sub.3, .beta."--Al.sub.2 O.sub.3, and Na.sub.1+x Zr.sub.2 Si.sub.x P.sub.3-x O.sub.12.
A ceramic comprising:
- 5 to 40 v/o ZrO.sub.2 in the form of crystalline grains having a diameter less than about 2 .mu.m and having a substantially tetragonal structure;
- about 2.5 m/o Y.sub.2 O.sub.3 ;
- and
- the remainder of said ceramic being substantially .beta.--Al.sub.2 O.sub.3.
A ceramic comprising:
- 5 to 40 v/o ZrO.sub.2 in the form of crystalline grains having a diameter less than about 2 .mu.m and having a substantially tetragonal structure;
- about 2.5 m/o Y.sub.2 O.sub.3 ;
- and
- the remainder of said ceramic being substantially .beta."--Al.sub.2 O.sub.3.
A ceramic comprising:
- 5 to 40 v/o ZrO.sub.2 in the form of crystalline grains having a diameter less than about 2 .mu.m and having a substantially tetragonal structure;
- about 2.5 m/o Y.sub.2 O.sub.3 ;
- and
- the remainder of said ceramic being substantially Na.sub.1+x Zr.sub.2 Si.sub.x P.sub.3-x O.sub.12.
A ceramic comprising:
- 5 to 40 v/o ZrO.sub.2 in the form of crystalline grains having a substantially tetragonal structure and having a diameter less than about 2 .mu.m;
- 2 to 5.5 m/o Y.sub.2 O.sub.3 ;
- and
- the remainder of said ceramic being substantially a sodium ion conductor solid electrolyte selected from the group consisting of .beta.--Al.sub.2 O.sub.3, .beta."--Al.sub.2 O.sub.3, and Na.sub.1+x Zr.sub.2 Si.sub.x P.sub.3-x O.sub.12.
A two phase ceramic comprising:
- a first phase occupying 5 to 40 o/o of the volume of said ceramic, said first phase comprising ZrO.sub.2 grains having a diameter less than about 2 .mu.m with a rare earth oxide dissolved therein, said ZrO.sub.2 having a tetragonal structure, said rare earth oxide being selected from the group consisting of Y.sub.2 O.sub.3, CeO.sub.2, La.sub.2 O.sub.3, and Er.sub.2 O.sub.3 ;
- and
- a second phase comprising a sodium ion conductor solid electrolyte selected from the group consisting of .beta.--Al.sub.2 O.sub.3, .beta."--Al.sub.2 O.sub.3, and Na.sub.1+x Zr.sub.2 Si.sub.x P.sub.3-x O.sub.12, said second phase occupying substantially all remaining volume of said ceramic.
Dependencies are inferred from the claim text.