JPS5943620A - Piezoelectric ceramic element - Google Patents

Abstract

PURPOSE:To obtain a piezoelectric ceramic element having good dielectric constant, high mechanical Q and using the thickness slip vibration basic wave, by adhering a metallic material for mass load to at least one of a pair of counter electrodes opposing with a piezoelectric ceramic. CONSTITUTION:A pair of counter electrodes 12, 13 are formed by clipping a lead titanate piezoelectric ceramic 11. The direction of polarized axis (shown in arrow P) of the piezoelectric ceramic 11 is made perpendicular to the opposing direction of the counter electrodes 12, 13. That is, the piezoelectric ceramic element 10 utilizes the thickness slip energy confinement vibration mode. Further, lead layers 14, 15 as the mass load metallic material are formed on the upper surface of the counter electrodes 12, 13. The piezoelectric ceramic element 10 manufactured in this way has low dielectric constant, high mechanical Q and is excellent in the stability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piezoelectric ceramic element, and more particularly to a lead titanate-based piezoelectric ceramic element that utilizes a thickness-shear one-energy confined vibration mode.

Conventionally, PZT-based piezoelectric ceramic elements constituting filters, oscillators, etc., namely Pb (Zr, J
i> os ceramic materials have been used. PZl
- type ceramic elements utilize a thickness longitudinal vibration mode and a thickness shear vibration L-mode. FIG. 1 is a side view schematically showing a ZT-based piezoelectric ceramic element that utilizes the thickness group]-energy confined vibration mode among the thickness longitudinal vibration modes.

As is clear from FIG. 1, in the piezoelectric ceramic element 1 that utilizes the thickness longitudinal energy confinement vibration mode, the pair of opposing electrodes 2.3 are formed so that their opposing direction is the same as the polarization axis direction P. ing.

On the other hand, FIG. 2 is a side view showing a conventionally used PZT-based L1 electroceramic element 5 that utilizes the thickness shear energy trapped vibration mode among the thickness shear vibration modes. In the piezoelectric ceramic element 5 that utilizes the thickness shear energy trapping vibration mode, the pair of opposing electrodes 2 and 3 are formed such that the opposing direction of the pair of opposing electrodes 2 and 3 is perpendicular to the polarization axis direction P. There is. By the way, when piezoelectric ceramic elements are used in filters, etc., they are required to have a small dielectric constant ε for impedance matching, and a large QI to ensure stability. P7-type piezoelectric ceramic elements have not been able to meet these requirements.

On the other hand, in recent years, lead butanate ceramics (1-
Lead titanate ceramics (T-based ceramics) have been developed and have attracted attention because of their small dielectric constant ε and high mechanical Q. can eliminate the drawbacks of

However, at present, piezoelectric ceramic elements using lead titanate-based ceramics have three types of thickness-shear vibration.
Those using harmonics (T'E, rd) are well known, but it is possible to obtain larger vibrations using the warp longitudinal vibration fundamental wave (TEISt> and the thickness shear vibration fundamental wave (T
SISt), it is difficult to confine vibration energy, and the use of these vibration modes has not yet been implemented. Theoretically, it is possible to use lead titanate-based piezoelectric ceramics to construct a piezoelectric ceramic element that utilizes thickness vibration as shown in Figure 2, and to trap energy, but in reality it is not possible. In the piezoelectric ceramic element constructed in this way, waveform division occurred as shown in FIG. 3, and it was not possible to use the piezoelectric ceramic element at the bottom of the piezoelectric element.

Therefore, an object of the present invention is to eliminate the drawbacks of the conventional piezoelectric ceramic materials made of P/[ type ceramics by using titanium rn@1 type ceramics, which have a low dielectric constant and a high mechanical Q. It is an object of the present invention to provide a piezoelectric ceramic element that utilizes the fundamental wave of oscillation of j9 and j9 oscillations.

In summary, the present invention is a piezoelectric ceramic element that utilizes a thickness-dependent energy trapping vibration mode, which comprises a piezoelectric ceramic made of lead titanate ceramic, and a pair of opposing electrodes that face each other with the piezoelectric ceramic sandwiched between them. This is a piezoelectric ceramic element in which a mass-loading metal material (-1) is attached to at least one of a pair of opposing electrodes. The quality lies in that a load metal material is deposited on at least one of the pair of opposing electrodes.

Quality (6) Loading metal materials include l”b, Hf, and a
.

Various gold W such as W, pt, 13i! It is possible to use 4 shrines. Preferably, Pb is used.

The counter electrode is protected by the oxide film formed on the Pb surface,
Reliability is improved because the terminals are covered and the terminals are not connected to the electrodes.
This is because the solder i = J in one prefecture that covers the surface increases, and the workability improves. "Quality Lifting Load Metal Month 11"
For deposition, various known methods such as vacuum evaporation, sputtering, and incubation can be used.

Further, the metal material for pawn work may be formed on [at least one side]. That is, it may be formed on both sides of the opposing electrodes, or only on one side.

Since the piezoelectric ceramic element of the present invention has the above-mentioned "metal material for mass loading" attached to at least one of the pair of opposing electrodes, the piezoelectric ceramic element of the present invention can completely suppress energy confinement vibration due to the angular charge effect. It becomes possible to move. In other words, it becomes possible to effectively confine the vibration energy based on the fundamental wave of thickness shear vibration, which was conventionally impossible to confine. Furthermore, since the piezoelectric ceramic element of the present invention is made of lead titanate-based ceramics, the electromechanical coupling coefficient of the spreading vibration is negligibly smaller than the electromechanical coupling coefficient +<t in the thickness direction. It is possible to obtain a piezoelectric ceramic material with an ultra-low spurious level because it is difficult to generate unnecessary vibrations other than the vibrations of , and the thickness-shear one-energy confined vibration mode is used. Furthermore, as mentioned above, lead titanate ceramics have a small dielectric constant ε and a large mechanical Q, so it is easy to achieve high impedance of the element, and piezoelectric ceramics have excellent stability. element can be obtained.

Examples will be described below.

Example (Pho3oLac, Tsuyu) T
: 03 →-0.5wt%Mn 02 +0.3m
A sample with a composition of m% CUO was prepared, wet-mixed in a mixing mill, dehydrated and dried, roughly calcined, mixed with a binder, dried in weak water and granulated.
It was formed to a size of 12 mm x 12 mm. Next, after holding and baking at 1250℃ for 2 hours, the polarization electrode was heated to 80”C.
Thereafter, a DC electric field of 3 KV/ml was applied at 80° C. for 1 hour to perform polarization treatment, and sliced using a slicing machine. The sliced ceramics were then lapped and silver deposited to form a -C counter electrode.

Roughly, Ni
Lead as an additional material was deposited by vacuum evaporation. The piezoelectric ceramic element 10 prepared in this way was
It is shown in side view in the figure.

As is clear from Fig. 4, (P b, 2a L
aθμ ) T'i Os +0.5% by weight M002 +
Piezoelectric ceramics 11 having a composition of 0.3% by weight CuO
A pair of opposing layers tM12 and tM13 are formed between them.

The direction of the polarization axis of the piezoelectric ceramic 11 is indicated by an arrow P.

) is in the opposite direction of the counter electrode 12.13 and short toothed -C
There is. In other words, the piezoelectric ceramic element 10 of this example
utilizes a thickness-thickness one-energy confined vibration mode. Moreover, on the upper surface of each counter electrode 12.13,
Lead layers 14 and 15 are formed as mass-loading metal materials.

The attenuation a-frequency characteristics of the piezoelectric ceramic element 10 of this example manufactured as described above were measured.

The results are shown in Figure 5.1. As is clear from FIG. 11, in this embodiment, almost no waveform division occurs in the fundamental wave of the thickness-recovery J-energy confined vibration. This means that the lead titanate-based piezoelectric device, which does not have any metal material for the load, can be purchased! This will be clearly understood if you compare it with Figure 3, which was measured for Lamics.

[Brief explanation of drawings]

¥51 is a side view of an example of a conventional piezoelectric ceramic element using PZT ceramics. FIG. 2 is a side view showing another example of a conventional piezoelectric ceramic element. Third
Figure (J) is a graph showing the waveform of the thickness-shear energy trapped vibration fundamental wave of a conventional piezoelectric ceramic element using lead titanate-based ceramics. Figure 4 is a side view showing an embodiment of the present invention. Fig. 5 is a graph showing the waveform of the fundamental wave of the thickness-shear energy confined vibration of the embodiment shown in Fig. 4. In the figure, 10 is a piezoelectric ceramic element, 11 is a piezoelectric ceramic element, 12, 134, etc. A pair of opposing electrical cables, 14.1
5 indicates a mass-loading metal material fl. Current applicant Murata Seihakuzo Co., Ltd. Representative Patent attorney Hisabe Fukaji 1. ′:1′i
]"ri+4,- (2 others)"-I example L Q- thread 11) 7, 2 3 2nd (2) 7. Z

Claims (1)

[Scope of Claims] A piezoelectric ceramic element comprising a piezoelectric ceramic made of lead titanate-based ceramics and a pair of opposing electrodes sandwiching the piezoelectric ceramic, and utilizing a thickness shear energy trapping vibration mode, comprising: A piezoelectric ceramic element in which a mass-loading metal material is attached to at least one of a pair of opposing electrodes.