Claims
- 1. A method for providing a perovskite having a dielectric constant of at least 20 and a structure which is stable at pressures above 1 GPa, said method comprising:
identifying a composition having at least a 50 percent probability of forming a stable structure, wherein said identification comprises estimating the dielectric constant of said composition and predictive modeling the structure of said stable structure with the computer program called “Program Originated To Analyze Tilted Octrahedral” to determine the stability of said stable structure; and subjecting said composition to a pressure of at least about 5.0 GPa and a temperature of at least about 700° C. to form said stable structure; wherein said stable structure has a dielectric constant of at least 20 and is stable in the high pressure phase above 1 GPa.
- 2. The method according to claim 1, wherein said stable structure comprises a three-dimensional framework of corner-linked MX6 octahedra.
- 3. The method according to claim 2, wherein said predictive modeling uses the metal-oxygen bond distance of said stable structure to select the bond valence of the metal cation so that bond valence of the metal cation in relation to the bond valences of said stable structure's constituent ions will provide a stable structure.
- 4. The method according to claim 1, wherein identifying said composition further comprises estimating the molecular polarizability of said composition by summing the atomic polarizabilities of said composition's constituent ions, determining said composition's molar volume based on the atomic radii of said composition's constituent ions and calculating said composition's relative dielectric constant using the Clausius-Mossotti equation.
- 5. The method according to claim 1, further comprising reducing the pressure to about one atmosphere pressure, wherein said synthesized structure remains stable.
- 6. The method according to claim 1, wherein said stable structure is an A-cationed ordered perovskite.
- 7. The method according to claim 2, wherein said synthesizing comprises distorting said structure.
- 8. The method according to claim 1, wherein said composition comprises oxygen ions and cations.
- 9. The method according to claim 8, wherein said synthesizing comprises shifting said oxygen ions closer to said cations.
- 10. The method according to claim 1, wherein said synthesis of said composition comprises a phase transition.
- 11. The method according to claim 1, wherein the probability of forming a stable structure from said composition is at least two out of three.
- 12. The method according to claim 1, wherein said synthesis of said composition comprises a structural transition to a denser phase.
- 13. The method according to claim 1, wherein said synthesis is carried out at temperatures of at least 1000° C. and pressures of at least 5GPa.
- 14. The method according to claim 1, wherein said composition is a metal oxide compound.
- 15. The method according to claim 1, wherein said identifying further comprises selecting combinations of ions having complimentary ionic radii and bonding preferences.
- 16. The method according to claim 2, wherein said estimating comprises calculating the dielectric characteristics of said stable structure based on the size of the octahedra, the octahedra tilt system and the magnitude of the tilt angles.
- 17. A method for providing a perovskite structure having a dielectric constant of at least 20 and a structure which is stable at pressures above 1 GPa, said method comprising:
identifying an ilmenite composition having at least a 50 percent probability of forming a stable perovskite structure, wherein said identification comprises estimating the dielectric constant of said composition and predictive modeling the structure of said stable perovskite structure with the computer program called “Program Originated To Analyze Tilted Octrahedral” to determine the stability of said stable perovskite structure; and subjecting said ilmenite composition to a pressure of at least about 5.0 GPa and a temperature of at least about 700° C. to form said stable perovskite structure; wherein said stable perovskite structure has a dielectric constant of at least 20 and is stable in the high pressure phase above 1 GPa.
- 18. The method according to claim 17, wherein said stable perovskite structure comprises a three-dimensional framework of corner-linked MX6 octahedra.
- 19. The method according to claim 18, wherein said predictive modeling uses the metal-oxygen bond distance of said stable structure to select the bond valence of the metal cation so that bond valence of the metal cation in relation to the bond valences of said table structure's constituent ions will provide a stable structure.
- 20. The method according to claim 17, wherein said predictive modeling further comprises estimating the molecular polarizability of said composition by summing the atomic polarizabilities of said composition's constituent ions, determining said composition's molar volume based on the atomic radii of said composition's constituent ions and calculating said composition's relative dielectric constant using the Clausius-Mossotti equation.
- 21. The method according to claim 17, further comprising reducing the pressure to about one atmosphere pressure, wherein said synthesized perovskite structure remains stable.
- 22. The method according to claim 17, wherein said stable perovskite structure is an A-cationed ordered perovskite.
- 23. The method according to claim 17, wherein said synthesizing comprises distorting said structure.
- 24. The method according to claim 17, wherein said composition comprises oxygen ions and cations.
- 25. The method according to claim 24, wherein said synthesizing comprises shifting said oxygen ions closer to said cations.
- 26. The method according to claim 17, wherein said synthesis of said composition comprises a phase transition.
- 27. The method according to claim 17, wherein the probability of forming a stable perovskite structure from said composition is at least two out of three.
- 28. The method according to claim 17, wherein said synthesis of said composition comprises a structural transition to a denser phase.
- 29. The method according to claim 17, wherein said synthesis is carried out at temperatures of at least 1000° C. and pressures of at least 5GPa.
- 30. The method according to claim 17, wherein said composition is a metal oxide compound.
- 31. The method according to claim 17 wherein said identifying further comprises selecting combinations of ions having complimentary ionic radii and bonding preferences.
- 32. The method according to claim 17, wherein said estimating comprises calculating the dielectric characteristics of said stable perovskite structure based on the size of the octahedra, the octahedra tilt system and the magnitude of the tilt angles.
- 33. A method for providing a perovskite structure having a dielectric constant of at least 20 and a structure which is stable at pressures above 1 GPa, said method comprising:
identifying a composition having at least a 50 percent probability of forming a stable perovskite structure comprising a three-dimensional framework of corner-linked MX6 octahedra, wherein said identification comprises estimating the dielectric constant of said composition and predictive modeling the structure of said stable structure with the computer program called “Program Originated To Analyze Tilted Octrahedral” to determine the stability of said stable structure, wherein said predictive modeling comprises:
using the metal-oxygen bond distance of said stable structure to select the bond valence of the metal cation so that bond valence of the metal cation in relation to the bond valences of said stable structure's constituent ions will provide a stable structure; estimating the molecular polarizability of said composition by summing the atomic polarizabilities of said composition's constituent ions, determining said composition's molar volume based on the atomic radii of said composition's constituent ions and calculating said composition's relative dielectric constant using the Clausius-Mossotti equation; and selecting combinations of ions having complimentary ionic radii and bonding preferences; and subjecting said composition to a pressure of at least about 5.0 GPa and a temperature of at least about 700° C. to form said stable perovskite structure, wherein said synthesis comprises:
distorting said structure; and inducing a structural transition of said composition to a denser phase, wherein said stable perovskite structure has a dielectric constant of at least 20 and is stable in the high pressure phase above 1 GPa.
- 34. The method according to claim 33, wherein said composition is an ilmenite composition.
- 35. The method according to claim 33, wherein said stable perovskite structure is an A-cationed ordered perovskite.
Parent Case Info
[0001] This application is a continuation-in-part of U.S. patent application Ser. No. 09/300,869, filed on Apr. 28, 1999.
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
09300869 |
Apr 1999 |
US |
Child |
10185432 |
Jun 2002 |
US |