PEROVSKITE OXIDE, PROCESS FOR PRODUCING THE PEROVSKITE OXIDE, AND PIEZOELECTRIC DEVICE

• US 20090230211A1
• Filed: 03/12/2009
• Published: 09/17/2009
• Est. Priority Date: 03/12/2008
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Sakashita, Yukio, Kobayashi, Hiroyuki
• Granted Patent: US 8,177,995 B2
• Time in Patent Office: Days
• US Class Current: 239/102.200
• CPC Class Codes: B41J 2/161 of film type, deformed by bending and disposed on a diaphragm
• CPC Class Codes: B41J 2/1642 thin film formation by CVD [chemical vapor deposition]
• CPC Class Codes: B41J 2/1646 thin film formation by sputtering
• CPC Class Codes: B41J 2202/03 Specific materials used
• CPC Class Codes: B41J 2202/21 Line printing
• CPC Class Codes: H10N 30/076 by vapour phase deposition
• CPC Class Codes: H10N 30/079 using intermediate layers, e.g. for growth control
• CPC Class Codes: H10N 30/2047 Membrane type
• CPC Class Codes: H10N 30/8536 Alkaline earth metal based oxides, e.g. barium titanates
• CPC Class Codes: H10N 30/8561 Bismuth based oxides

Abstract

A process for producing a piezoelectric oxide having a composition (Ba, Bi, A)(Ti, Fe, M)O₃, where each of A and M represents one or more metal elements. The composition is determined so as to satisfy the conditions (1) and (2),

0.98≦TF(P)≦1.02,  (1)

TF(BiFeO₃)<TF(AMO₃)<TF(BaTiO₃),  (2)

where TF(P) is the tolerance factor of the perovskite oxide, and TF(BaTiO₃), TF(BiFeO₃), and TF(AMO₃) are respectively the tolerance factors of the oxides BaTiO₃, BiFeO₃, and AMO₃.

Claims

1. A process for producing a piezoelectric oxide having a composition expressed by a compositional formula,

(Ba,Bi,A)(Ti,Fe,M)O₃,

where each of A and M represents one or more metal elements other than Pb;

Ba, Bi, and A are A-site elements, Ti, Fe, and M are B-site elements, Ba, Bi, Ti, Fe and O respectively represent barium, bismuth, titanium, iron, and oxygen, the one or more B-site elements represented by M are elements other than Ti and Fe when the one or more A-site elements represented by A are Ba and/or Bi, the one or more A-site elements represented by A are elements other than Ba and Bi when the one or more B-site elements represented by M are Ti and/or Fe, and the ratio of each of the total molar amount of the A-site elements and the total molar amount of the B-site elements to the molar amount of oxygen may deviate from 1;

3 within a range in which the composition expressed by the compositional formula (Ba, Bi, A)(Ti, Fe, M)O₃ can form a perovskite structure;

the composition of the compound (Ba, Bi, A)(Ti, Fe, M)O₃ is determined so as to satisfy the conditions (1) and (2),

0.98≦

TF(P)≦

1.02,and 

 

(1)

TF(BiFeO₃)<

TF(AMO₃)<

TF(BaTiO₃), 

 

(2)

where TF(P) is a tolerance factor of the piezoelectric oxide expressed by the compositional formula (Ba, Bi, A)(Ti, Fe, M)O₃, TF(BaTiO₃) is a tolerance factor of a compound expressed by a compositional formula BaTiO₃, TF(BiFeO₃) is a tolerance factor of a compound expressed by a compositional formula BiFeO₃, and TF(AMO₃) is a tolerance factor of a compound expressed by a compositional formula AMO₃.

2. A process according to claim 1, wherein said composition of the perovskite oxide is determined so as to further satisfy the condition (3),

0.98≦

TF(AMO₃)≦

1.02. 

 

(3)

3. A process according to claim 1, wherein said one or more A-site elements represented by A include Sr.

4. A piezoelectric oxide having a composition expressed by a compositional formula,

(Ba,Bi,A)(Ti,Fe,M)O₃,

where each of A and M represents one or more metal elements other than Pb;

Ba, Bi, and A are A-site elements, Ti, Fe, and M are B-site elements, Ba, Bi, Ti, Fe and O respectively represent barium, bismuth, titanium, iron, and oxygen, the one or more B-site elements represented by M are elements other than Ti and Fe when the one or more A-site elements represented by A are Ba and/or Bi, the one or more A-site elements represented by A are elements other than Ba and Bi when the one or more B-site elements represented by M are Ti and/or Fe, and the ratio of each of the total molar amount of the A-site elements and the total molar amount of the B-site elements to the molar amount of oxygen may deviate from 1;

3 within a range in which the composition expressed by the compositional formula (Ba, Bi, A)(Ti, Fe, M)O₃ can form a perovskite structure;

the composition of the compound (Ba, Bi, A)(Ti, Fe, M)O₃ is determined so as to satisfy the conditions (1) and (2),

0.98≦

TF(P)≦

1.02,and 

 

(1)

TF(BiFeO₃)<

TF(AMO₃)<

TF(BaTiO₃), 

 

(2)

where TF(P) is a tolerance factor of the piezoelectric oxide expressed by the compositional formula (Ba, Bi, A)(Ti, Fe, M)O₃, TF(BaTiO₃) is a tolerance factor of a compound expressed by a compositional formula BaTiO₃, TF(BiFeO₃) is a tolerance factor of a compound expressed by a compositional formula BiFeO₃, and TF (AMO₃) is a tolerance factor of a compound expressed by a compositional formula AMO₃.

5. A piezoelectric oxide according to claim 4, wherein said composition of the perovskite oxide further satisfies the condition (3),

0.98≦

TF(AMO₃)≦

1.02. 

 

(3)

6. A piezoelectric oxide according to claim 4, wherein said one or A-site metal elements represented by A include Sr.

7. A piezoelectric oxide according to claim 4, wherein said one or more A-site elements represented by A include at least one of Bi and Ba.

8. A piezoelectric oxide according to claim 4, wherein said one or more B-site elements represented by M include at least one of Ti and Fe.

9. A piezoelectric oxide according to claim 4, containing a first component BaTiO₃, a second component BiFeO₃, and a third component AMO₃, where the ratio of each of the molar amount of an A-site element and the molar amount of a B-site element to the molar amount of oxygen atoms in each of the first component BaTiO₃, the second component BiFeO₃, and the third component AMO₃ may deviate from 1:

3 within a range in which said each of the first component BaTiO₃, the second component BiFeO₃, and the third component AMO₃ can form a perovskite structure.

10. A piezoelectric oxide according to claim 9, wherein said first component, said second component, and said third component each form a crystal structure corresponding to a different crystal system.

11. A piezoelectric oxide according to claim 10, wherein said first component forms a first crystal structure of a tetragonal system, said second component forms a second crystal structure of a rhombohedral system, and said third component forms a third crystal structure of one of cubic and pseudocubic systems.

12. A piezoelectric oxide according to claim 4, having,

a composition at or near a morphotropic phase boundary, and

a mixed-crystal structure composed of at least two first crystal phases which are ones of tetragonal, orthorhombic, and rhombohedral phases, and at least one second crystal phase which is at least one of cubic and pseudocubic phases.

13. A piezoelectric oxide according to claim 12, wherein said mixed-crystal structure is composed of the tetragonal phase, the rhombohedral phase, and one of the cubic and pseudocubic phases.

14. A piezoelectric oxide according to claim 13, having a structure which exhibits a high-resolution X-ray diffraction profile including a first diffraction peak corresponding to a tetragonal phase, a second diffraction peak corresponding to a rhombohedral phase, and a third diffraction peak corresponding to a phase different from the tetragonal phase and the rhombohedral phase.

15. A ferroelectric compound containing said perovskite oxide according to claim 4.

16. A piezoelectric body containing said perovskite oxide according to claim 4.

17. A piezoelectric body according to claim 16, having a form of a film.

18. A piezoelectric body according to claim 17, being produced by epitaxial growth.

19. A piezoelectric body according to claim 16, containing a ferroelectric phase which has crystal orientation.

20. A piezoelectric body according to claim 19, containing at least one ferroelectric phase, where each of the at least one ferroelectric phase has a spontaneous polarization axis along a first direction and crystal orientation along a second direction different from the first direction.

21. A piezoelectric body according to claim 20, wherein each of said at least one ferroelectric phase is at least one of a rhombohedral phase having crystal orientation along approximately a <

100>

direction, a rhombohedral phase having crystal orientation along approximately a <

110>

direction, a tetragonal phase having crystal orientation along approximately a <

110>

direction, a tetragonal phase having crystal orientation along approximately a <

111>

direction, an orthorhombic phase having crystal orientation along approximately a <

100>

direction, and an orthorhombic phase having crystal orientation along approximately a <

111>

direction.

22. A piezoelectric body according to claim 21, wherein at least a portion of said each of the at least one ferroelectric phase transitions to a ferroelectric phase corresponding to a crystal system different from a crystal system corresponding to said each of the at least one ferroelectric phase, when an electric field is applied to said piezoelectric body along a direction different from said first direction.

23. A piezoelectric device comprising:

said piezoelectric body according to claim 16; and

electrodes arranged to apply an electric field to the piezoelectric body.

24. A piezoelectric device comprising:

said piezoelectric body according to claim 20; and

electrodes arranged to apply an electric field to the piezoelectric body along a direction different from said first direction.

25. A liquid discharge device comprising:

said piezoelectric device according to claim 23; and

a discharge member being arranged adjacent to the piezoelectric device, and including,

a liquid-reserve chamber which reserves liquid, and

a liquid-discharge outlet arranged to externally discharge said liquid in response to application of an electric field to said piezoelectric body in the piezoelectric device.