JPH08321641A - Nonlinear device - Google Patents

Abstract

PURPOSE: To provide a nonlinear device having a large nonlinear constant. CONSTITUTION: A nonlinear device 10 is formed into a structure, wherein the device 10 comprises a substrate 12, which is formed of a Pb(Tix , Zr1-x )O3 piezoelectric porcelain material, and the ratio of components of a PbTiO3 and a PbZrO3 in the substrate 12 is compounded in the ratio of components existing in the vicinity of a phase boundary (an MPB), where a phase transition between a PbTiO3 tetragonal crystal and a PbZrO3 rhombohedral crystal appears. In this case, the ratio of components of Ti/Zr, which satisfies the condition of 40<=x<=60 (mol %), is desirable, the ratio of components of Ti/Zr, which satisfies the condition of 45<=x<=55 (mol %), is more desirable and the ratio of components of Ti/Zr, which satisfies the condition of x=50 (mol %), is most desirable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-linear device, and more particularly to a non-linear device applied to, for example, an elastic convolver, a parametric oscillator, an ultrasonic microscope, a scanning tunneling microscope and a phase conjugate wave transducer.

[0002]

2. Description of the Related Art Conventionally, as a device using a non-linear phenomenon that accompanies the propagation of a surface acoustic wave, for example, an elastic convolver, a scanning ultrasonic imaging apparatus using a phase conjugate wave, and the like have been attracting attention. As a material of the substrate used for such non-linear devices, for example quartz, single crystal such as LiNbO _3, LiTaO _3, or, for example PbTiO ₃ -PbZrO ₃ -Pb (Mn
_1/3 Nb _2/3 ) O ₃ system, PbTiO ₃ —PbZrO ₃ −
Pb (Sn _1/2 , Sb _1/2 ) O ₃ system, PbTiO ₃ -P
_{bZrO 3 -Pb (Nb 2/3 Ni 1/3} ) O 3 system, PBT
_{iO 3 -PbZrO 3 -Pb (Nb 2/3} Mg 1/3) O 3
System, PbTiO ₃ —PbZrO ₃ —In (Li _3/5 W
_2/5 ) Piezoelectric ceramics such as O ₃ system are used.

[0003]

However, with the material of the substrate used for such a conventional non-linear device, a non-linear device having a large desired non-linear effect, that is, a large non-linear constant cannot be obtained.

Therefore, a main object of the present invention is to provide a nonlinear device having a large nonlinear constant.

[0005]

The invention according to claim 1 includes a substrate formed of a Pb (Ti, Zr) O ₃ -based piezoelectric ceramic material, wherein PbTiO ₃ and PbZ in the substrate are included.
The component ratios of rO ₃ are PbTiO ₃ tetragonal and PbZrO
It is a non-linear device that is compounded by the component ratio existing near the phase boundary where the phase transition with the rhombohedral crystal of ₃ appears.

According to a second aspect of the invention, the substrate is Pb (T
i _x , Zr _1-x ) O ₃ -based piezoelectric ceramic material
The non-linear device according to claim 1, wherein the composition ratio of Zr and Zr satisfies 40 mol% ≤ x ≤ 60 mol%.

In the invention according to claim 3, the substrate is Pb (T
i _x , Zr _1-x ) O ₃ -based piezoelectric ceramic material
The non-linear device according to claim 1, wherein the component ratio of Zr and Zr satisfies 45 mol% ≤ x ≤ 55 mol%.

According to a fourth aspect of the invention, the substrate is Pb (T
i _x , Zr _1-x ) O ₃ -based piezoelectric ceramic material
The non-linear device according to claim 1, wherein the component ratio of Zr and Zr satisfies x = 50 mol%.

In a fifth aspect of the invention, the substrate is Pb (S
n _1/2 , Sb _1/2 ) _0.05 (Ti _x Zr _1-x ) _0.95 O ₃ -based piezoelectric ceramic material, and the composition ratio of Ti and Zr is 4
The nonlinear device according to claim 1, wherein 0 mol% ≦ x ≦ 60 mol% is satisfied.

In a sixth aspect of the invention, the substrate is Pb (S
n _1/2 , Sb _1/2 ) _0.05 (Ti _x Zr _1-x ) _0.95 O ₃ -based piezoelectric ceramic material, and the composition ratio of Ti and Zr is 4
The nonlinear device according to claim 1, wherein 5 mol% ≦ x ≦ 55 mol% is satisfied.

According to a seventh aspect of the invention, the substrate is Pb (S
n _1/2 , Sb _1/2 ) _0.05 (Ti _x Zr _1-x ) _0.95 O ₃ -based piezoelectric ceramic material, and the composition ratio of Ti and Zr is x
The non-linear device according to claim 1, which satisfies 50 mol%.

[0012]

According to the invention described in claims 1 to 7, since the composition ratio of Ti / Zr of the material of the substrate is formed by the composition ratio of the composition near the phase boundary, a substrate having a large nonlinear constant can be obtained. Therefore, the nonlinear device using this substrate has a large nonlinear constant and a large nonlinear effect. in this case,
The Ti / Zr component ratio is preferably 40-60 / 60-40 (mol%), more preferably 45-55 / 55-45 (mol%), and even more preferably 50/50 (mol%). Most preferred.

[0013]

According to the invention described in claims 1 to 7, it is possible to obtain a nonlinear device having a large nonlinear constant.
That is, a highly efficient nonlinear device having a large nonlinear effect can be obtained.

The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

[0015]

1 is an illustrative view showing one embodiment of the present invention. In this embodiment, for example, an elastic convolver will be described as an example of a non-linear device. The elastic convolver 10 includes a piezoelectric substrate 12 having a rectangular plate shape, for example. The piezoelectric substrate 12 is made of, for example, a lead zirconate titanate (PZT) -based piezoelectric ceramic material. In this embodiment, for example, Pb (Sb _1/2 ,
_{Sn 1/2) 0.05 (Ti x Zr} 1-x) 0.95 O piezoelectric substrate 12 in three-component PZT piezoelectric ceramic material ₃ system is formed.

Further, in the elastic convolver 10 of this embodiment, in the composition of the PZT-based piezoelectric ceramic material forming the piezoelectric substrate 12, the component ratio of Ti and Zr is P.
The components are mixed in such a proportion that they exist near the phase boundary where the phase transition between the tetragonal crystal of bTiO ₃ and the rhombohedral crystal of PbZrO ₃ appears.

In this case, the Ti / Zr component ratio is 40 to 6
It is preferably 0/60 to 40 (mol%), and T
i / Zr compounding ratio is 45-55 / 55-45 (mol%)
Those having a Ti / Zr compounding ratio of 50/50 (mol%) are most preferable. In this embodiment, in particular, for example, the Ti / Zr compounding ratio is 50/5.
A piezoelectric substrate formed of 0 (mol%) is used.

At the center of the surface of the piezoelectric substrate 12, a central electrode 14 made of, for example, a substantially plate-shaped metal is formed.
Further, on the surface of the piezoelectric substrate 12, two input interdigital transducers 16 and 18 are formed at intervals in the longitudinal direction.

One of the interdigital transducers 16 for input is formed on one side of the piezoelectric substrate 12 in the longitudinal direction, and the other of the interdigital electrodes 18 is formed on the other side of the piezoelectric substrate 12 in the longitudinal direction. In this case, the interdigital electrodes 16 and 18 are
The central electrode 14 is sandwiched between the central electrode 14 and the central electrode 14. Further, a ground electrode 20 is formed on the back surface of the piezoelectric substrate 12 so as to face the central electrode 14 with the piezoelectric substrate 12 interposed therebetween.

In this elastic convolver 10,
When an input signal is applied to each of the two interdigital electrodes 16 and 18, two surface acoustic waves propagating in opposite directions are excited from both of the interdigital electrodes 16 and 18,
The center electrodes 14 are crossed. Then, the convolution signals of the two surface acoustic waves are extracted from the central electrode 14 through the nonlinearity of the medium.

That is, surface acoustic waves having angular frequencies ω ₀ , wave numbers k and -k, which are generated at the interdigital electrodes 16 and 18 on both sides of the piezoelectric substrate 12 in the longitudinal direction, are mutually central electrodes of the piezoelectric substrate 12. 14 is propagated to 14, interacts between the two interdigital electrodes 16 and 18, and due to the non-linear action of the piezoelectric substrate 12, which is a propagation medium,
A relatively weak electric field with a wave number of 0 and an angular frequency of 2ω ₀ , a so-called convolution signal, is generated and taken out from the central electrode 14 as an output.

Elastic convolver 1 of this embodiment
In 0, in the composition of the PZT-based piezoelectric ceramic material forming the piezoelectric substrate 12, PbTiO ₃ and the component ratio of PbZrO ₃ is near the phase boundary appearing phase transition between the rhombohedral tetragonal and PbZrO ₃ of PbTiO ₃ Since it is mixed with the component ratio existing in, a piezoelectric substrate having a large nonlinear constant can be obtained. Elastic convolver 10 of this embodiment
In particular, for example, when the Ti / Zr component ratio is 50/50,
Since the piezoelectric substrate formed of (mol%) is used, the elastic convolver 10 having a particularly large non-linear effect and extremely high efficiency can be obtained.

Next, Pb (T
i _x, in Zr _1-x) O ₃ based piezoelectric ceramic material, component ratio present in the vicinity of phase boundaries above, i.e., 40 mol% ≦ x
An experimental example showing that the nonlinear constant becomes large when the Ti / Zr ratio satisfies ≦ 60 mol% is shown below. [Experimental Example] First, as starting materials, PbO, TiO ₂ ,
ZrO ₂ , SnO ₂ and Sb ₂ O ₃ were used, and these powders were mixed with Pb (Sb _1/2 , Sn _1/2 ) _0.05 (Ti _x Z
r _{1 -x} ) _0.95 O ₃ [where x is in the range of 10 ≦ x ≦ 80 (mol%)], and the raw materials were prepared by weighing them. Next, the prepared raw material is processed in the same process as in the normal piezoelectric ceramics manufacturing method, that is, calcination process → grinding process → binder mixing process → granulation process → molding process → firing process → polishing cutting process → electrode application. A sample to be the piezoelectric substrate 12 was produced by a series of steps such as step → polarization step.

Then, the propagation characteristics of the bulk wave and the leaky surface acoustic wave when a voltage is applied to the prepared sample, for example, a quantitative measurement system using an ultrasonic microscope such as pulse interferometry or V (z) measurement method. (Not shown). Further, the results obtained by changing the voltage at several points are analyzed based on, for example, the FFT method, and the nonlinear constant of the sample is calculated. The calculation results are shown in FIGS. 2 (A) and 2 (B). 2A is a graph showing the relationship between the Ti / Zr ratio (Ti amount) due to the bulk wave and the nonlinear constant, and FIG. 2B is the graph showing the Ti / Zr ratio due to the leaky surface acoustic wave.
It is a graph which shows the relationship between a Zr ratio (Ti amount) and a nonlinear constant.

As is clear from the graphs shown in FIGS. 2A and 2B, the Ti / Zr component ratio / mixing ratio is 50.
It can be seen that the nonlinear constant becomes the largest when the ratio is mol% / 50 mol%. In this case, it can be seen that the bulk wave is about twice less, and the leaky surface acoustic wave (LSAW) is about four times larger.

[Brief description of drawings]

FIG. 1 is an illustrative view showing one embodiment of the present invention;

FIG. 2A is a graph showing the relationship between the Ti / Zr ratio due to bulk waves and the nonlinear constant, and FIG. 2B is a graph showing the relationship between the Ti / Zr ratio due to leaky surface acoustic waves (LSAW) and the nonlinear constant. It is a graph shown.

[Explanation of symbols]

 10 Elastic Convolver 12 Piezoelectric Substrate 14 Central Electrode 16 First Interdigital Electrode 18 Second Interdigital Electrode 20 Ground Electrode

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H03H 9/72 C04B 35/49 A H04N 5/31 H01L 41/18 101D

Claims (7)

[Claims] 1. A substrate comprising a Pb (Ti, Zr) O ₃ -based piezoelectric ceramic material, wherein PbTiO 3 in the substrate.
_The non-linear device in which the component ratios of ₃ and PbZrO ₃ are blended with the component ratio existing near the phase boundary where the phase transition between the tetragonal crystal of PbTiO ₃ and the rhombohedral crystal of PbZrO ₃ appears. 2. The substrate is Pb (Ti _x , Zr _1-x ) O.
It is formed of a _3- system piezoelectric ceramic material, and the composition ratio of Ti and Zr satisfies 40 mol% ≤ x ≤ 60 mol%.
Non-linear device described in. 3. The substrate is Pb (Ti _x , Zr _1-x ) O.
It is formed of a ₃ type piezoelectric ceramic material, and the composition ratio of Ti and Zr satisfies 45 mol% ≤ x ≤ 55 mol%.
Non-linear device described in. 4. The substrate is Pb (Ti _x , Zr _1-x ) O.
The nonlinear device according to claim 1, wherein the nonlinear device is formed of a _3- system piezoelectric ceramic material, and a component ratio of Ti and Zr satisfies x = 50 mol%. 5. The substrate is Pb (Sn _1/2 , Sb _1/2 )
_0.05 (Ti _x Zr _1-x ) _0.95 O ₃ type piezoelectric ceramic material, and the composition ratio of Ti and Zr is 40 mol% ≦ x ≦ 60.
The nonlinear device according to claim 1, which satisfies the mol%. 6. The substrate is Pb (Sn _1/2 , Sb _1/2 )
_0.05 (Ti _x Zr _1-x ) _0.95 O ₃ type piezoelectric ceramic material, and the composition ratio of Ti and Zr is 45 mol% ≦ x ≦ 55.
The nonlinear device according to claim 1, which satisfies the mol%. 7. The substrate is Pb (Sn _1/2 , Sb _1/2 )
The nonlinear device according to claim 1, wherein the nonlinear device is formed of _0.05 (Ti _x Zr _1-x ) _0.95 O ₃ -based piezoelectric ceramic material, and the component ratio of Ti and Zr satisfies x = 50 mol%.