LAMINATED PIEZOELECTRIC ELEMENT AND PRODUCTION METHOD OF THE SAME

Abstract

A laminated piezoelectric element capable of being sintered at low temperatures and high in piezoelectric properties is provided. The laminated piezoelectric element comprises a plurality of piezoelectric layers each comprising a composite oxide as a main constituent thereof and a plurality of internal electrode layers formed between the piezoelectric layers and containing Ag, wherein the piezoelectric layers are each comprised of a sintered body comprising the composite oxide, as a main constituent thereof, represented by (Pba-bMb)[(Zn1/3Nb2/3)xTiyZrz]O3 with the proviso that 0.96≦a≦1.03, 0≦b≦0.1, 0.05≦x≦0.15, 0.25≦y≦0.5, 0.35≦z≦0.6, x+y+z=1, and M represents at least one selected from Sr, Ca and Ba, and Ag in a content of 1.0% by weight or less (not inclusive of 0) in terms of Ag2O in relation to the main constituent.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view illustrating a construction example of a laminated piezoelectric element in an embodiment of the present invention;

FIG. 2 is a flow chart showing production procedures of the laminated piezoelectric element in the embodiment of the present invention;

FIG. 3 is a graph showing the relation between the addition amount of Ag₂O and the electromechanical coupling coefficient k31;

FIG. 4 is a graph showing the relation between the addition amount of Ag₂O and the displacement magnitude d; and

FIG. 5 is a graph showing the relation between the addition amount of Ag₂O and the ratio of the change (d/k31)/(d_STD/k31_STD).

Claims

1. A laminated piezoelectric element comprising: a plurality of piezoelectric layers each comprising a composite oxide as a main constituent thereof; anda plurality of internal electrode layers formed between the piezoelectric layers and comprising Ag; wherein:the piezoelectric layers are each comprised of a sintered body comprising:the composite oxide, as a main constituent thereof, represented by (Pba-bMb)[(Zn1/3Nb2/3)xTiyZrz]O3 with the proviso that 0.96≦a≦1.03, 0≦b≦0.1, 0.05≦x≦0.15, 0.25≦y≦0.5, 0.35≦z≦0.6, x+y+z=1, and M represents at least one selected from Sr, Ca and Ba; andAg in a content of 1.0% by weight or less (not inclusive of 0) in terms of Ag2O in relation to the main constituent.

2. The laminated piezoelectric element according to claim 1, wherein the piezoelectric layers are each comprised of the sintered body comprising Ag in a content of 0.05 to 0.8% by weight in terms of Ag2O.

3. The laminated piezoelectric element according to claim 1, wherein the piezoelectric layers are each comprised of the sintered body comprising Ag in a content of 0.2 to 0.5% by weight in terms of Ag2O.

4. The laminated piezoelectric element according to claim 1, wherein the piezoelectric layers are each comprised of the sintered body comprising Ta in a content of 0.7% by weight or less (not inclusive of 0) in terms of Ta2O5.

5. The laminated piezoelectric element according to claim 1, wherein the piezoelectric layers are each comprised of the sintered body comprising at least one selected from Sb, Nb and W in a content of 1.0% by weight or less (not inclusive of 0) in terms of oxide.

6. The laminated piezoelectric element according to claim 1, wherein the internal electrode layers are constituted of a Ag—Pd alloy and the content of Pd in the Ag—Pd alloy is 20% by mass or less.

7. The laminated piezoelectric element according to claim 1, wherein 0.97≦a≦1.02.

8. The laminated piezoelectric element according to claim 1, wherein 0≦b≦0.06.

9. The laminated piezoelectric element according to claim 1, wherein 0.06≦x≦0.125.

10. The laminated piezoelectric element according to claim 1, wherein 0.275≦y≦0.48.

11. The laminated piezoelectric element according to claim 1, wherein 0.375≦z≦0.55.

12. The laminated piezoelectric element according to claim 1, wherein the M represents Sr.

13. A production method of a laminated piezoelectric element in which piezoelectric layers and Ag-containing internal electrode layers are laminated, the piezoelectric layers each comprising a composite oxide, as a main constituent thereof, represented by (Pba-bMb)[(Zn1/3Nb2/3)xTiyZrz]O3 with the proviso that 0.96≦a≦1.03, 0≦b≦0.1, 0.05≦x≦0.15, 0.25≦y≦0.5, 0.35≦z≦0.6, x+y+z=1, and M represents at least one selected from Sr, Ca and Ba, and Ag in a content of 0.05 to 1.0% by weight in terms of Ag2O in relation to the main constituent, the production method comprising steps of: obtaining a laminate by alternately laminating piezoelectric layer precursors comprising a raw material composition for the main constituent and internal electrode layer precursors; andsintering the laminate at a predetermined temperature.

14. The production method of a laminated piezoelectric element according to claim 13, wherein the piezoelectric layer precursors further comprise Ag.

15. The production method of a laminated piezoelectric element according to claim 13, wherein a part or the whole of the Ag contained in the piezoelectric layers is provided by the diffusion, at the time of sintering, of a part of the Ag contained in the internal electrode layer precursors.

16. The production method of a laminated piezoelectric element according to claim 13, wherein the laminate is sintered at 800 to 1000° C. in the sintering step.

17. The production method of a laminated piezoelectric element according to claim 13, wherein the piezoelectric layers contain Ag in a content of 0.05 to 0.8% by weight in terms of Ag2O.

18. The production method of a laminated piezoelectric element according to claim 13, wherein the piezoelectric layers contain Ag in a content of 0.2 to 0.5% by weight in terms of Ag2O.

19. The production method of a laminated piezoelectric element according to claim 13, wherein 0.97≦a≦1.02, 0≦b≦0.06, 0.06≦x≦0.125, 0.275≦y≦0.48, 0.375≦z≦0.55.

20. The production method of a laminated piezoelectric element according to claim 13, wherein 0.99≦a≦1.00, 0≦b≦0.04, 0.08≦x≦0.1, 0.3≦y≦0.45, 0.4z≦0.5.