Methods of identifying and preparing a ceramic material exhibiting an electric field induced strain

Patent metadata

Field	Value
Publication number	US-11124456-B2
Application number	US-201816483604-A
Country	US
Kind code	B2
Filing date	Feb 2, 2018
Priority date	Feb 3, 2017
Publication date	Sep 21, 2021
Grant date	Sep 21, 2021

Abstract

The present invention relates to a method for identifying a solid solution ceramic material of a plurality of perovskite compounds which exhibits an electric field induced strain derived from a reversible phase transition, as well as a method for making such ceramic materials and ceramic materials obtainable therefrom. In particular, the present invention is directed to a method of identifying a solid solution ceramic material of at least three perovskite compounds which exhibits an electric field induced strain derived from a reversible phase transition; said method comprising the steps of: i) determining a molar ratio of at least one tetragonal perovskite compound to at least one non-tetragonal perovskite compound which, when combined to form a solid solution, provides a ceramic material comprising a major portion of a tetragonal phase having an axial ratio c/a of greater than 1.005 to 1.04; and ii) determining a molar ratio of at least one additional non-tetragonal perovskite compound to the combination of perovskite compounds from step i) at the determined molar ratio which, when combined to form a solid solution, provides a ceramic material comprising a major portion of a pseudo-cubic phase having an axial ratio c/a of from 0.995 to 1.005 and/or a rhombohedral angle of 90±0.5 degrees.

First claim

The invention claimed is:

1. A method of identifying a solid solution ceramic material of at least two perovskite compounds which exhibits a reversible phase transition induced by an electric field and a strain derived from the reversible phase transition; the method comprising steps of:
1) selecting at least a tetragonal perovskite compound suitable for forming a ceramic material comprising a major portion of a tetragonal phase having an axial ratio c/a of between 1.005 and 1.04; and
2) determining a molar ratio of the ceramic material from step 1) to at least one additional non-tetragonal perovskite compound which, when combined to form a solid solution, provides a ceramic material comprising a major portion of a pseudo-cubic phase having at least one of an axial ratio c/a from 0.995 to 1.005 or a rhombohedral angle of 90±0.5 degrees.

2. A method according to claim 1 , wherein step 1) comprises selecting at least one tetragonal perovskite compound and at least one non-tetragonal perovskite compound and determining a molar ratio of at least one tetragonal perovskite compound to at least one non-tetragonal perovskite compound which, when combined to form a solid solution, provides a ceramic material comprising a major portion of a tetragonal phase having an axial ratio c/a of greater than 1.005 to 1.04.

3. A method according to claim 2 , wherein step 1) comprises sub-steps of:
1-a) preparing at least one solid solution ceramic material of at least one tetragonal perovskite compound and at least one non-tetragonal perovskite in a particular molar ratio; and
1-b) determining whether the axial ratio c/a for the major phase of the solid solution ceramic material prepared in step 1-a) corresponds to a tetragonal phase having an axial ratio c/a of greater than 1.005 to 1.04.

4. A method according to claim 3 , wherein step 1) further comprises a sub-step of:
1-c) repeating sub-steps 1-a) and 1-b) using a different molar ratio of the at least one tetragonal perovskite compound and at least one non-tetragonal perovskite until the axial ratio c/a for the major phase of the solid solution ceramic material prepared corresponds to a tetragonal phase having an axial ratio c/a of greater than 1.005 to 1.04.

5. A method according to claim 3 , wherein the at least one solid solution ceramic material prepared in sub-step 1-a) includes the at least one tetragonal perovskite and the at least one non-tetragonal perovskite at a molar ratio of 3:1 to 1:3.

6. A method according to claim 1 , wherein step 2) comprises the following sub-steps:
2-a) preparing at least one solid solution ceramic material comprising the ceramic material from step 1) and the at least one additional non-tetragonal perovskite compound at a particular molar ratio; and
2-b) determining whether at least one of the axial ratio c/a or the rhombohedral angle of the major phase of the at least one solid solution ceramic material prepared in step 2-a) corresponds to a pseudo-cubic phase having at least one of an axial ratio c/a from 0.995 to 1.005 or a rhombohedral angle of 90±0.5 degrees.

7. A method according to claim 6 , wherein step 2) further comprises the following sub-step:
2-c) repeating sub-steps 2-a) and 2-b) using a different molar ratio of the ceramic material from step 1) and the additional non-tetragonal perovskite compound until at least one of the axial ratio c/a or the rhombohedral angle of the major phase of the resulting solid solution ceramic material corresponds to at least one of a pseudo-cubic phase having an axial ratio c/a from 0.995 to 1.005 or a rhombohedral angle of 90±0.5 degrees.

8. A method according to claim 6 , wherein the at least one solid solution ceramic material prepared in sub-step 2-a) has the ceramic material from step 1), consisting of one tetragonal perovskite compound, present in an amount of more than 50 mol. %, and has the at least one non-tetragonal perovskite compound in sub-step 2-a) present in an amount of less than 50 mol. % of the ceramic material.

9. A method according to claim 6 , wherein the at least one solid solution ceramic material prepared in sub-step 2-a) has the ceramic material from step 1), comprising a combination of perovskites, present in an amount of more than 80 mol. % of the ceramic material and has the at least one additional non-tetragonal perovskite compound in sub-step 2-a) present in an amount of less than 20 mol. of the ceramic material.

10. A method according to claim 2 , wherein the at least one non-tetragonal perovskite compound in step 1) is at least one of a cubic, rhombohedral, orthorhombic or monoclinic perovskite compound.

11. A method according to claim 1 , wherein
the tetragonal phase of the solid state ceramic material of step 1) has an axial ratio c/a from 1.01 to 1.02; and
the at least one additional non-tetragonal perovskite compound in step 2) is a cubic perovskite compound.

12. A method according to claim 1 , wherein an effective ionic charge of a metal cation occupying at least one of an A-site or a B-site of the at least one tetragonal perovskite compound of step 1), differs from that of a corresponding metal cation occupying at least one of an A-site or B-site of the additional non-tetragonal perovskite compound in step 2).

13. A method according to claim 1 , wherein the Shannon-Prewitt effective ionic radius of a metal cation occupying at least one of an A-site or B-site of the at least one tetragonal perovskite compound of step 1), differs from that of a corresponding metal cation occupying at least one of an A-site or B-site of the additional non-tetragonal perovskite compound in step 2).

14. A method according claim 1 , wherein the Pauling electronegativity value of an element occupying at least one of an A-site or B-site of the at least one tetragonal perovskite compound of step 1), differs from that of a corresponding element occupying at least one of an A-site or B-site of the additional non-tetragonal perovskite compound in step 2).

15. A method according to claim 1 , wherein the ceramic material of step 2) has a remnant polarization of less than 5 μC/cm 2 .

16. A method according to claim 1 , wherein the ceramic material of step 2) has a maximum electromechanical strain value from 0.1% to 0.5%, when measured at 10 Hz and at standard temperature and pressure.

17. A method according to claim 1 , wherein the ceramic material of step 2) has a field induced polarization from 10 to 50 μC/cm 2 .

18. A method of preparing a ceramic material comprising at least one tetragonal perovskite compound and at least one non-tetragonal perovskite compounds, the method comprising steps of:
I) mixing precursors for the perovskite compounds of the ceramic material in predetermined molar ratios; and
II) utilizing the mixture of precursors formed in step I) in a solid-state synthesis to prepare the solid solution ceramic material;
wherein:
the ceramic material comprises a major portion of a pseudo-cubic phase having at least one of an axial ratio c/a from 0.995 to 1.005 or a rhombohedral angle of 90±0.5 degrees;
the predetermined molar ratios of the precursors are determined based on the molar ratio of the precursors for the at least one tetragonal perovskite compound, wherein the tetragonal perovskite compound is suitable for forming a ceramic material comprising a major portion of a tetragonal phase having an axial ratio c/a of between 1.005 and 1.04;
the at least one non-tetragonal perovskite compound required to form the solid solution ceramic material has a major portion of the pseudo-cubic phase; and
the at least one te

Assignees

• Cann David
• Gibbons Brady
• Mardilovich Peter
• Xaar Technology Ltd

Inventors

• Cann David
• Gibbons Brady
• Mardilovich Peter

Classifications

• C01P2002/34

  perovskite-type (ABO3) · CPC title

• C04B2235/3298

  Bismuth oxides, bismuthates or oxide forming salts thereof, e.g. zinc bismuthate · CPC title

• C04B2235/81

  Materials characterised by the absence of phases other than the main phase, i.e. single phase materials · CPC title

• C04B2235/765

  Tetragonal symmetry · CPC title

• C04B2235/3244

  Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof · CPC title