High dielectric capacitor materials and method of their production
View Patent ↗Methods of producing polycrystalline and single crystal dielectrics are disclosed, including dielectrics comprising CaCu 3 Ti 4 O 12 or La 3 Ga 5 SiO 4 . Superior single crystals are manufactured with improved crystallinity by atomic lattice constant adjustments to the dielectric and to the substrate on which it is grown. Dielectric materials made according to the disclosed methods are useful for manufacture of energy storage devices, e.g. capacitors.
1. A lattice-matched capacitor which comprises at least a first and second layer,
a) the first layer comprising a conductive oxide electrode material having first a lattice constant which comprises (LaSr) 2 CuO 4 (LSCuO),(LaSr) 2 CoO 4 (LSCoO), or both; and
b) the second layer comprising a dielectric material having a second lattice constant which comprises (Ca,Sr)Cu 3 Ti 4 O 12 (CSCTO), CaCu 3 Ti 4 O 12 (CCTO) or both; wherein said first lattice constant, said second lattice constant, or both are engineered by ion substitution to achieve a smaller lattice constant mismatch between said first layer and said second layer and wherein at least part of the calcium ions of said dielectric material are substituted with ions selected from the group consisting of strontium ions, bismuth ions, sodium ions, lanthanum ions, an ion of a lanthanide element, and a combination of any thereof.
2. A capacitor of claim 1 wherein said lattice constant mismatch is below about 4.1%.
3. A capacitor of claim 1 wherein said lattice constant mismatch is below about 2.4%.
4. A capacitor of claim 1 wherein said lattice constant mismatch is less than 1%.
5. A capacitor of claim 1 wherein at least part of the titanium ions of said dielectric material are substituted with ions selected from the group consisting of iron ions, ruthenium ions, chromium ions, germanium ions, manganese ions, and a combination of any thereof.
6. A capacitor of claim 1 wherein calcium ions of said dielectric material are substituted with strontium ions.
7. A capacitor of claim 1 wherein 20% to about 22% of the calcium ions of said dielectric material are substituted with strontium ions.
8. A capacitor of claim 1 wherein said dielectric material comprises Ca 0.8 Sr 0.2 Cu 3 Ti 4 O 12 .
9. A capacitor of claim 1 wherein said dielectric material has been produced by liquid phase epitoxy.
10. A capacitor of claim 1 wherein said dielectric material has been produced by melt growth.
11. A capacitor of claim 1 herein said dielectric material has been produced by a flux method.
12. A capacitor of claim 1 herein said dielectric material has been produced by pulsed laser deposition.
13. A capacitor of claim 1 , which further comprises a third substrate layer adjacent to said first layer, wherein said first lattice constant is engineered by ion substitution to achieve a smaller lattice constant mismatch between said first layer and said third layer.
14. A capacitor of claim 13 wherein said third layer is about 5 nm thick.