Piezoelectric Multilayer Component and Method for Producing a Piezoelectric Multilayer Component

Abstract

In an embodiment a piezoelectric multilayer component includes a ceramic main body comprising a ceramic material, wherein a main component of the ceramic material has the general empirical formula (K.sub.XNa.sub.1-X)NbO.sub.3, where 0≤x≤1, wherein the ceramic material comprises at least two additives selected from a number of compounds respectively comprising at least one metal, wherein a metal of a first additive comprises at least K, Nb, Cu, Mn or Ta, and wherein a metal of a second additive comprises K, Nb or Ta.

Claims

1.-15. (canceled)

16. A piezoelectric multilayer component comprising: a ceramic main body comprising a ceramic material, wherein a main component of the ceramic material has the general empirical formula (K.sub.XNa.sub.1-X)NbO.sub.3, where 0x1, wherein the ceramic material comprises at least two additives selected from a number of compounds respectively comprising at least one metal, wherein a metal of a first additive comprises at least K, Nb, Cu, Mn or Ta, and wherein a metal of a second additive comprises K, Nb or Ta.

17. The piezoelectric multilayer component according to claim 16, wherein the ceramic main body has a large number of internal electrodes.

18. The piezoelectric multilayer component according to claim 17, wherein the internal electrodes comprise at least Ag, Pd, Pt, Cu or Ni, or an alloy comprising at least two of the metals mentioned.

19. An atmospheric pressure plasma generator comprising: the piezoelectric multilayer component according to claim 16, wherein the pressure plasma generator is configured to generate a cold plasma.

20. A method for producing a piezoelectric multilayer component comprising a ceramic main body that comprises a ceramic material, the method comprising: performing a first calcination step; and performing a second calcination step.

21. The method according to claim 20, wherein the second calcination step is performed at a maximal temperature which differs from a maximal temperature at which the first calcination step is performed.

22. The method according to claim 21, wherein the first calcination step is performed at the maximal temperature selected from a range of 700° C. to 800° C., and wherein the second calcination step is performed at the maximal temperature selected from a range of 800° C. to 900° C.

23. The method according to claim 20, wherein a retention time of the second calcination step is equal to a retention time of the first calcination step.

24. The method according to claim 23, wherein the first and second calcination steps respectively are performed with a retention time selected from a range of two hours to six hours.

25. The method according to claim 20, further comprising performing a sinter step for which a maximal temperature selected is between 1000° C. and 1080° C. and a retention time selected is between 30 minutes and 120 minutes.

26. The method according to claim 25, wherein the sinter step is performed in an inert atmosphere.

27. The method according to claim 25, further comprising performing a tempering step after performing the sinter step.

28. The method according to claim 27, wherein the tempering step is performed at a maximal temperature selected between 800° C. and 900° C. and a retention time selected between one and two hours.

29. The method according to claim 27, wherein air or an atmosphere with an oxygen partial pressure of 2×10.sup.−1 to 2×10.sup.−6 is selected as atmosphere during performance of the tempering step.

30. A method for producing of a piezoelectric multilayer component comprising a ceramic main body that comprises a ceramic material, the method comprising: processing starting materials for producing the ceramic material in water.

31. The method according to claim 30, further comprising performing sintering with a maximal temperature selected between 1000° C. and 1080° C. and with a retention time selected between 30 minutes and 120 minutes.

32. The method according to claim 31, wherein sintering is performed in an inert atmosphere.

33. The method according to claim 31, further comprising performing tempering after performing sintering.

34. The method according to claim 33, wherein tempering is performed with a maximal temperature selected between 800° C. and 900° C. and with a retention time selected between one and two hours.

35. The method according to claim 33, wherein air or an atmosphere with an oxygen partial pressure of 2×10.sup.−1 to 2×10.sup.−6 is selected as atmosphere while performing tempering.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] A ceramic main body, a ceramic green film and a piezoelectric multilayer component are described below with reference to diagrammatic drawings.

[0033] FIG. 1 shows a ceramic main body;

[0034] FIG. 2 shows a plan view of a ceramic green film;

[0035] FIG. 3a shows a longitudinal section of a piezoelectric multilayer component; and

[0036] FIG. 3b shows a cross section of a piezoelectric multilayer component.

[0037] Elements that are identical or similar, or that are visually identical, have identical reference signs in the figures. The figures, and the size relationships therein, are not to scale.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0038] FIG. 1 shows a ceramic main body 1 of a piezoelectric multilayer component. The ceramic main body 1 has a longitudinal side x, which is longer than a first perpendicular side y and a second perpendicular side z. The first perpendicular side y is moreover longer than the second perpendicular side z. The ceramic main body 1 comprises a ceramic material that comprises a main component with the general empirical formula (Na.sub.0.5K.sub.0.5)NbO.sub.3. K.sub.5.4Cu.sub.1.3Ta.sub.10Nb.sub.29 and MnCO.sub.3 were additionally added as additives to the main component.

[0039] Raw materials, for example K.sub.2CO.sub.3, Na.sub.2CO.sub.3 and Nb.sub.2O.sub.5, are mixed and ground for the production of the main component. The raw materials are then calcined in a first calcination step at 750° C. and with a retention time of four hours. The first calcination step is followed by a second calcination step, which is carried out at 880° C. and with a retention time of four hours. 0.38 mol % of K.sub.5.4Cu.sub.1.3Ta.sub.10Nb.sub.29 and 0.25 mol % of MnCO.sub.3, based on 100 mol % of (Na.sub.0.5K.sub.0.5)NbO.sub.3, are then added to the main component in order to obtain the ceramic material.

[0040] For the production of the ceramic main body 1, ceramic green films are produced from the ceramic material and are printed with internal electrodes made of copper (not depicted). A large number of printed ceramic green films are then stacked on one another and pressed, in order to form a green body. The green body is used in a next step, at 1050° C. and with a retention time selected from a range of 30 min to 120 min, to carry out a sinter step, in order to obtain a ceramic main body 1. The sinter step is carried out here in an inert atmosphere, for example a nitrogen atmosphere. After the sinter step, a tempering step is carried out with the ceramic main body 1. The tempering step is carried out in air at a maximal temperature between 800° C. and 900° C. and with a retention time between one hour and two hours.

[0041] After the tempering step, external contacts (not depicted), for example made of Ag, are applied on the ceramic main body 1, in order to provide contact to the internal electrodes (not depicted).

[0042] FIG. 2 shows a plan view of a ceramic green film 1′. The ceramic green film 1′ has been to some extent printed with an internal electrode 2 made of copper. The green film 1′ depicted can be used to construct a ceramic main body, similar to that described in FIG. 1.

[0043] FIG. 3a shows a longitudinal section of a piezoelectric multilayer component. The piezoelectric multilayer component comprises a ceramic green body 1, similar to that described in FIG. 1. The longitudinal section runs in a plane through the ceramic main body 1, said plane being parallel to an area bounded by the longitudinal side x and the second perpendicular side z. The piezoelectric multilayer component has a region with internal electrodes 2 and a region without internal electrodes 2. The region having the internal electrodes 2 is termed input side A, and the region having no internal electrodes 2 is termed output side B. The piezoelectric multilayer component is configured as a piezotransformer.

[0044] FIG. 3b shows a cross section through a multilayer component similar to that described in FIG. 3a. The cross section runs through the ceramic main body 1 in a plane that is parallel to an area bounded by the first perpendicular side y and by the second perpendicular side z. The cross section runs through the input side A of the multilayer component, said side having the internal electrodes 2. The internal electrodes 2 can be divided into first internal electrodes 2a and second internal electrodes 2b. The first internal electrodes 2a have contact to a first external contact 2a′, and the second internal electrodes 2b have contact to a second external contact 2b′. The first external contact 2a′ and the second external contact 2b′ have opposite polarity.

[0045] Application of a voltage to the first external contact 2a′ and to the second external contact 2b′ induces, by means of the first internal electrodes 2a and the second internal electrodes 2b, an electromagnetic field in the input side A of the ceramic main body 1. By virtue of an inverse piezoelectric effect, this results in a length change of the input side A of the ceramic main body 1 along the induced electromagnetic field. Possible directions of length changes are depicted in FIG. 3b by the arrows.

[0046] Application of an alternating voltage to the first external contact 2a′ and to the second external contact 2b′ produces an alternating length change in the input side A of the ceramic main body 1. In other words, the input side A of the ceramic main body 1 begins to vibrate. This vibration is transferred from the input side A of the ceramic main body 1 to the output side B of the ceramic main body 1.

[0047] By virtue of a piezoelectric effect, the alternating length change of the output side B produces an alternating voltage. This alternating voltage can be extracted by means of third external contacts (not depicted) at the output side B of the ceramic main body 1. The position of the third external electrodes (not depicted) at the output side B of the ceramic main body 1 can be such that the alternating voltage extracted at the output side B is several times higher than the voltage applied at the input side A.

[0048] The voltages generated at the output side B of the ceramic main body 1 can be sufficiently large to produce spontaneous electrical discharges. The component described here is therefore particularly suitable for a use in an atmospheric pressure plasma generator.

[0049] Although the figures describe exclusively a piezoelectric transformer, the present invention is not restricted to same. Configurations as, for example, sensors or resonators are also possible.