Ceramic

Patent metadata

Field	Value
Publication number	US-11873253-B2
Application number	US-201816612903-A
Country	US
Kind code	B2
Filing date	May 10, 2018
Priority date	May 12, 2017
Publication date	Jan 16, 2024
Grant date	Jan 16, 2024

Abstract

There is disclosed a piezoelectric ceramic having the composition: a[PbTiO 3 ]-b[SrTiO 3 ]-c[BiFeO 3 ]-d[(K x Bi 1-x )TiO 3 ]; wherein 0.4<x<0.6; 0.1<a<0.4; 0.01<b≤0.2; c≥0.05; d≥0.01; and a+b+c+d=1 optionally comprising an A- or B-site metal dopant in an amount of up to 2 at. %.

First claim

The invention claimed is:

1. A piezoelectric ceramic comprising:
a first portion poled in a first direction; and
a second portion poled in a second direction opposite to the first direction, the first and second portions being in contact with each other,
wherein the first portion and the second portion comprise:
a Berlincourt d 33 value ≥250 pm/V;
a Curie temperature, T c , of ≥300° C.; and
a fracture toughness, K 1c (×10 6 ), of ≥3 MPa×m 1/2 .

2. A piezoelectric ceramic according to claim 1 wherein the first portion and the second portion further comprise at least one of:
a coercive field, Ec, of ≥|1.75| kV/mm;
a Vickers hardness, H v , (×10 9 )≥3.5 kgf/mm 2 ; or
a flexural strength, σ, ≥100 MPa.

3. A piezoelectric ceramic having a composition of:
a[PbTiO 3 ]-b[SrTiO 3 ]-c[BiFeO 3 ]-d[(K x Bi 1-x )TiO 3 ],
wherein:
0.4≤×≤0.6, 0.1≤a≤0.4, 0.01≤b≤0.2, c≥0.05, d 0.01, and a+b+c+d=1
the piezoelectric ceramic comprises:
a first portion poled in a first direction;
a second portion poled in a second direction opposite to the first direction:
at least one of an A- metal site dopant or a B- metal site dopant in an amount up to 2 at. % per respective metal site;
a Berlincourt d 33 value ≤ 250 pm/V;
a Curie temperature, T c , of ≥ 300° C.; and
a fracture toughness, K 1c (×10 6 ), of ≥3 MPa×m 1/2 .

4. The piezoelectric ceramic of claim 3 wherein the piezoelectric ceramic deforms in a chevron configuration in response to a drive waveform.

5. A piezoelectric ceramic according to claim 3 , wherein:
0.3≤c≤0.7; and
0.05≤d≤0.25.

6. A piezoelectric ceramic according to claim 3 , wherein 0.2≤a≤0.3.

7. A piezoelectric ceramic according to claim 3 , wherein 0.02≤b≤0.15.

8. A piezoelectric ceramic according to claim 3 , wherein:
0.23≤a≤0.27; and
0.025≤b≤0.10.

9. A piezoelectric ceramic according to claim 3 , wherein:
0.4≤c≤0.6; and
0.1≤d≤0.2.

10. A piezoelectric ceramic according to claim 3 , wherein x is 0.5.

11. A piezoelectric ceramic according to claim 3 , wherein the at least one of an A- metal site dopant or a B- metal site dopant comprises at least one of Ti, Zr, W, Nb, V, Ta, Mo, or Mn.

12. A piezoelectric ceramic according to claim 11 , wherein the at least one of an A- metal site dopant or a B- metal site dopant comprises at least one of Mn or Nb and is present in an amount of from 0.25 at. % to 2 at. % per respective metal site.

13. A piezoelectric ceramic according to claim 1 , wherein the piezo electric ceramic is a solid solution substantially free of non-perovskite phases comprising PbTiO 3 , SrTiO 3 , BiFeO 3 and (K x Bi 1-x )TiO 3 wherein 0.4≤×≤0.6.

14. The piezoelectric ceramic of claim 1 , wherein:
the first direction and the second direction are substantially parallel to a height direction of a pair of parallel electrodes in contact with the first portion and the second portion.

15. The piezoelectric ceramic of claim 1 , wherein:
the first portion and the second portion are each in contact with a pair of electrodes configured to apply an electric field to the piezoelectric ceramic; and
the first direction and the second direction are substantially perpendicular to the applied electric field.

16. The piezoelectric ceramic of claim 15 , wherein a distance between the pair of electrodes is less than 60 micrometers.

17. The piezoelectric ceramic of claim 1 , wherein:
the first portion and the second portion deform in shear mode in opposite senses in response to a voltage.

18. A piezoelectric ceramic having a composition of:
a[PbTiO 3 ]-b[SrTiO 3 ]-c[BiFeO 3 ]-d[(K x Bi 1-x )TiO 3 ],
wherein:
0.4≤×0.6, 0.2≤a≤0.3; 0.025≤b≤0.125; 0.4≤c≤0.6; 0.05≤d≤0.25, and a+b+c+d=1;
b is selected so the piezoelectric material has a Berlincourt d 33 value greater than 250 pm/V;
c is selected so the piezoelectric material has a Curie temperature greater than 300° C.; and
the piezoelectric ceramic comprises a first portion poled in a first direction and a second portion poled in a second direction opposite to the first direction.

19. The piezoelectric ceramic of claim 18 , wherein:
0.24≤a≤0.26; 0.05≤b≤0.10; 0.46≤c≤0.58; 0.08≤d≤0.21.

Assignees

• Xaar Technology Ltd
• Ionix Advanced Tech Ltd

Inventors

• Watson Michael
• Condie Angus
• Comyn Timothy Paul
• Bell Andrew

Classifications

• C04B35/475 Primary

  based on bismuth titanates · CPC title

• B41J2/14209

  of finger type, chamber walls consisting integrally of piezoelectric material · CPC title

• C04B35/6262

  of calcined, sintered clinker or ceramics · CPC title

• C04B35/62645

  Thermal treatment of powders or mixtures thereof other than sintering · CPC title

• C04B35/6455

  Hot isostatic pressing · CPC title