PIEZOELECTRIC CERAMIC COMPOSITION AND LAMINATED PIEZOELECTRIC ELEMENT

Abstract

Provided is a piezoelectric ceramic composition capable of being sintered at low temperatures and in a low-oxygen reductive atmosphere and capable of attaining a sufficient displacement even at high voltages of 1 kV/mm or more. The piezoelectric ceramic composition includes: a composite oxide, as a main constituent thereof, represented by the following composition formula; Cu and/or Ag, each as a first additive, Cu being included in a content α, in terms of Cu2O, falling within a range 0<α≦0.5% by mass and Ag being included in a content β, in terms of Ag2O, falling within a range 0<β≦0.4% by mass, in relation to the main constituent; wherein: composition formula: Pba[(Zn1/3Nb2/3)xTiyZrz]O3, where 0.96≦a≦1.03, 0.005≦x<0.05, 0.42≦y≦0.53, 0.45≦z≦0.56, and x+y+z=1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an EPMA element mapping image of a sintered body obtained by printing a Cu paste;

FIG. 2 is an EPMA element mapping image of a sintered body obtained by adding a Cu₂O powder;

FIG. 3 is a TEM image of the sintered body obtained by adding a Cu₂O powder;

FIG. 4 is a view illustrating a construction example of a laminated piezoelectric element in an embodiment of the present invention;

FIG. 5 is a flow chart showing production procedures of the laminated piezoelectric element in the embodiment of the present invention;

FIG. 6 is a table showing the conditions (first additive) and the evaluation results of the density and d33 in Example 1;

FIG. 7 is a table showing the conditions and the evaluation results in Example 2;

FIG. 8 is a table showing the conditions and the evaluation results in Example 3;

FIG. 9 is a table showing the conditions and the evaluation results in Example 4;

FIG. 10 is a table showing the conditions and the evaluation results in Example 5;

FIG. 11 is a table showing the conditions and the evaluation results in Example 6;

FIG. 12 is a table showing the conditions and the evaluation results in Example 7;

FIG. 13 is a table showing the conditions and the evaluation results in Example 8;

FIG. 14 is a table showing the conditions and the evaluation results in Example 9;

FIG. 15 is a table showing the conditions and the evaluation results in Example 10;

FIG. 16 is a table showing the conditions and the evaluation results in Example 11;

FIG. 17 is a table showing the conditions and the evaluation results in Example 12;

FIG. 18 is a table showing the conditions and the evaluation results in Example 13; and

FIG. 19 is a table showing the conditions and the evaluation results in Example 14.

Claims

1. A piezoelectric ceramic composition comprising: a composite oxide, as a main constituent thereof, represented by the following composition formula (1) or (2);one or two of Cu and Ag, each as a first additive, Cu being comprised in a content α, in terms of Cu2O, falling within a range 0<α≦0.5% by mass and Ag being comprised in a content β, in terms of Ag2O, falling within a range 0<β≦0.4% by mass, in relation to said main constituent; andat least one selected from Ta, Nb, W and Sb, as a second additive, in a content y, in terms of oxide, falling within a range 0<γ≦0.6% by mass in relation to said main constituent;wherein: Pba[(Zn1/3Nb2/3)xTiyZrz]O3,  composition formula (1)

2. The piezoelectric ceramic composition according to claim 1, wherein x in said composition formula (1) or (2) satisfies 0.01≦x≦0.047.

3. The piezoelectric ceramic composition according to claim 1, wherein x in said composition formula (1) or (2) satisfies 0.01≦x≦0.04.

4. The piezoelectric ceramic composition according to claim 1, wherein x in said composition formula (1) or (2) satisfies 0.015≦x≦0.025.

5. The piezoelectric ceramic composition according to claim 1, comprising Cu, as said first additive, in a content α, in terms of Cu2O, falling within a range 0.01 ≦α≦0.2% by mass.

6. The piezoelectric ceramic composition according to claim 1, comprising Ag, as said first additive, in a content β, in terms of Ag2O, falling within a range 0.05 ≦β≦0.4% by mass.

7. The piezoelectric ceramic composition according to claim 1, comprising both of Cu and Ag, as said first additives, Cu being comprised in a content α, in terms of Cu2O, falling within a range 0<α≦0.5% by mass and Ag being comprised in a content β, in terms of Ag2O, falling within a range 0<β≦0.4% by mass.

8. The piezoelectric ceramic composition according to claim 7, comprising Cu in a content α, in terms of Cu2O, falling within a range 0.03≦α≦0.07% by mass and Ag in a content β, in terms of Ag2O, falling within a range 0.25'β≦0.35% by mass.

9. The piezoelectric ceramic composition according to claim 8, comprising W as said second additive in a content γ, in terms of oxide, falling within a range 0.05 ≦γ≦0.4% by mass.

10. The piezoelectric ceramic composition according to claim 8, comprising W as said second additive in a content γ, in terms of oxide, falling within a range 0.1 ≦γ≦0.35% by mass.

11. A laminated piezoelectric element comprising: a plurality of piezoelectric layers each comprising a piezoelectric ceramic composition; anda plurality of internal electrodes interposed between said piezoelectric layers; wherein:said piezoelectric ceramic composition comprising:a composite oxide, as a main constituent thereof, represented by the following composition formula (1) or (2);one or two of Cu and Ag, each as a first additive, Cu being comprised in a content α, in terms of Cu2O, falling within a range 0<α≦0.5% by mass and Ag being comprised in a content β, in terms of Ag2O, falling within a range 0<β≦0.4% by mass, in relation to said main constituent; andat least one selected from Ta, Nb, W and Sb, as a second additive, in a content γ, in terms of oxide, falling within a range 0<γ≦0.6% by mass in relation to said main constituent;wherein: Pba[(Zn1/3Nb2/3)xTiyZrz]O3,  composition formula (1)

12. The laminated piezoelectric element according to claim 11, wherein a conductive material forming said internal electrodes is Cu.

13. The laminated piezoelectric element according to claim 12, wherein: said piezoelectric ceramic composition comprises Cu as said first additive; andthe Cu as said first additive is due to partial diffusion of the Cu contained in said internal electrodes into said piezoelectric layers.

14. The laminated piezoelectric element according to claim 11, wherein x in said composition formula (1) or (2) satisfies 0.01≦x≦0.047.

15. The laminated piezoelectric element according to claim 11, comprising Cu, as said first additive, in a content α, in terms of Cu2O, falling within a range 0.01 ≦α≦0.2% by mass.

16. The laminated piezoelectric element according to claim 11, comprising Ag, as said first additive, in a content β, in terms of Ag2O, falling within a range 0.05 ≦β≦0.4% by mass.

17. The laminated piezoelectric element according to claim 11, comprising both of Cu and Ag, as said first additives, Cu being comprised in a content α, in terms of Cu2O, falling within a range 0<60≦0.5% by mass and Ag being comprised in a content β, in terms of Ag2O, falling within a range 0<β≦1% by mass.

18. The laminated piezoelectric element according to claim 17, comprising Cu in a content α, in terms of Cu2O, falling within a range 0.03≦α≦0.07% by mass and Ag in a content β, in terms of Ag2O, falling within a range 0.25'β≦0.35% by mass.

19. The laminated piezoelectric element according to claim 18, comprising W as said second additive in a content γ, in terms of oxide, falling within a range 0.05 ≦γ≦0.4% by mass.