JPH03148885A - Large-displacement electrostrictive element - Google Patents

Abstract

PURPOSE:To enlarge the application field of an electrostrictive element through an electrostrictive material having large displacement and small hysteresis by adding a specific metal to a PBZT group composition which has not been researched approximately as a porcelain composition having small displacement. CONSTITUTION:An electrostrictive element is prepared of (PhyBa1-y)a Meb(ZrxTi1-x)cOd. In formula, (x), (y), (a) and (b) are specified respectively as follows. That is, y<(4/3)x holds, and the conditions of 0.60<=y<=0.80, 0.45<=x<=0.60, 0.85<=a<=1.15, 0.001<=b<=0.02 and 0.85<=c<=1.15 are satisfied. (d) represents a numeric value determined by the states of oxidation of each element. At least one kind of an element selected from a group consisting of La, Ce and Pb is used as Me. Such a composition is mixed sufficiently by a ball mill, calcined at 860-900 deg.C, pulverized by the ball mill again, dried and formed in a discoid shape by applying pressure of two ton/cm<2>, and the discoid fine particles are sintered at 1200-1350 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a ceramic composition suitable for manufacturing a large displacement electrostrictive element and a large displacement electrostrictive element obtained by sintering the ceramic composition.

Conventional technology Traditionally, typical actuators include motors that operate using electromagnetic force, those that convert the rotation of this electromagnetic motor into linear motion using a combination of gears, and voice coils that combine an electromagnetic coil and a spring. It is something. These actuators are used for high-speed continuous rotation, positioning, etc.
Widely used in all types of machinery. In recent years, the need for new displacement elements has been increasing rapidly, mainly in the fields of optical precision instruments, semiconductor devices, etc. For example, requirements for processing accuracy of optical equipment such as lasers and cameras, positioning accuracy for semiconductor manufacturing equipment, and requirements for optical path length of 511 in optics and astronomy have already reached the level of 1 micron or less, and these requirements will continue to increase in the future. It is clear that positioning using electromagnetic motors has become increasingly complex in terms of structure and control, and voice coils have different strengths in terms of generated force and response speed. There's a problem.

Recently, electromagnetic arechiators have been attracting a lot of attention as new actuators that do not use electromagnetic force, and there are great expectations for their future potential as they expand into new genres in the electronics ceramics market.

The general conditions required for such a displacement element are as follows.

(1) The amount of displacement (the amount of displacement in the 31 large field) is large.

The history (value obtained by dividing the displacement difference at half of the maximum electric field by the maximum displacement) is small.

(3) Fast response speed.

(4) Good temperature characteristics.

(5) Can be driven with low energy.

10 Generated stress is large.

ω Small size and weight.

(8) No deterioration during use.

The amount of displacement of the solid-state displacement element material must be controllable by external commands, and the external command factors include temperature,
Possible fields are magnetic fields and electric fields. Displacement elements that utilize temperature changes require a large amount of energy and have the drawbacks of slow response speed. Magnetostrictive materials that utilize a magnetic field have the disadvantage that the amount of displacement is small and that an operating coil is required, leading to an increase in the size of the device. There are piezoelectric materials and electrostrictive materials as materials that obtain displacement using an electric field, but these have the disadvantage that their maximum displacement is small. Many studies have been conducted to overcome this drawback, but they have not yet reached a sufficient level.

Electrostrictive materials have advantages over piezoelectric materials, such as (1) less ff history, (2) no need for electric field polarization treatment, and (0) resistance to deterioration under harsh usage conditions.

P b (MgtzsNbxzs) O as electrostrictive material
s(PMN) is known, and (Pb, Ba)(Zr
, Ti)03 (hereinafter abbreviated as PBZT)-based ceramics. This system has already been developed by Honeywell (HAN).
EW 11! LL) IMJ, LHllNG et al. (Ferroelectric,
t9ao.

vol 27. pp41-43), KJ, LIE
llNG et al. found that the composition was (P b *, t3B a s
-xt) @, lI? B ie, ezZ r s-t
The paper reports on the results of the research on ceramics in sTi・, 3.03, but the amount of displacement of the ceramics is small, 0.0 for a voltage of l OkV/c+m.
Furthermore, when ceramics having the above composition formula are sintered, the weight Nti decreases significantly by 10% during sintering.
%. This weight loss is presumed to be due to the volatilization of Pb, and such volatilization of Pb becomes an important problem when producing electrostrictive materials industrially. Further, when an element was prepared using the ceramic having the above composition formula under the conditions described in Examples below and its performance was evaluated, the dielectric constant was 5000 to 6000. The dielectric constant is related to electricity consumption when incorporated into an actual device, and a smaller dielectric constant is better because it saves energy.

PBZT+Pb-B in JP-A-60-144984
Although an a-Bt-W based electrostrictive ceramic composition is disclosed,
As shown in the comparative example below, these devices have a very long history of device performance (therefore, not only do the devices generate a lot of heat, but also make precise position control very difficult), so they are not recommended as actuator devices. It's inappropriate.

Furthermore, numerous patent applications have been filed for porcelain compositions in which various metals are added to PZT, and there are also a number of patent applications filed for porcelain compositions in which Pb is replaced with alkali metals and alkaline earth metals (although a few patent applications have been filed). None of them are characterized by a large amount of displacement.As mentioned above, the reality is that there is still no piezoelectric material or electrostrictive material that can precisely control a large amount of displacement and a displacement on the micron order.

Problems to be Solved by the Invention An object of the present invention is to provide an electrostrictive material that has a large amount of displacement and a small history.

Means for Solving the Problem The inventors of the present invention conducted intensive studies to achieve the above-mentioned object. As a result, the composition of the PBZT system, which had been little studied in the past because it is a porcelain composition with a small amount of displacement (Pb
We discovered that by adding a specific metal to xBa+-x)+sMet (ZrvTi+-v), it was possible to obtain an electrostrictive element whose history was almost the same as that of a commercially available product, but whose displacement was about twice as large. , we have completed the present invention.

That is, the present invention provides a composition formula (% formula %) (where x, y, a, b, and C are each y< (4
/3) x, 0160≦y≦0.80. 0845≦X≦0.60°0685≦a≦1.15. This value satisfies the following conditions: 0.001<boo, 02 and 0.85≦C≦1.15.

d is a numerical value determined by the oxidation state of each element. Me is at least one element selected from the group consisting of La%Ce and Pr.

Further, the present invention is a large displacement electrostrictive element formed by sintering the above-described ceramic composition.

Regarding the electrostrictive element of the present invention, "M history" means the value (%) obtained by dividing the displacement difference when an electric field of 5 kV/cs+ is applied by the displacement amount when an electric field of 10 kV/cm is applied. The displacement t'' means the value (%) obtained by dividing the elongation of the sample by the thickness when an electric field of 10 kV/cm is applied.

The porcelain composition of the present invention uses Pb, Ba, Me as starting materials.
(La, Ce, Pr), Zr, and Ti can be produced using any compound selected from their oxides, nitrides, hybrids, carbonates, and the like.

In the ceramic composition of the present invention, the amount of Me metal added is 0.
．． Optimal is 1m01% or more and 2m01% or less. If the added amount is less than 0.1m01%, the history exceeds 25%, and if the added amount exceeds 2m01%, the maximum displacement is 0.
．． It will be less than 10%.

In the above composition formula, y≧4/3x or y is 0.60
or when a and b are each less than 0.85 or more than 1.15, the large displacement characteristic of the present invention is not achieved, and when y exceeds 0.80 or X is less than 0.45 If this is the case, an electrostrictive element with a small history cannot be obtained.The electrostrictive porcelain composite of the present invention has little volatilization of PB during sintering, and the weight reduction is 1% or less.

Further, the electrostrictive element of the present invention has a displacement amount of 0.1 θ% or more. The largest displacement in the range shown in the example is 0.
．． The dielectric constant is as high as 18%, the history is less than 25%, and the dielectric constant is 3000 to 4000.

Although the electrostrictive element of the present invention has almost no change in history compared to conventional piezoelectric materials, the amount of displacement increases by about twice or more.

Example 1 Example 1 pbo, B a COs, ZrO*, T as starting materials
Using tO* and Me metal oxides, the mixture was weighed and mixed in a ball mill for 710 hours so that the values of x, y, a%b and C became the values shown in the table below. The resulting mixture was heated to 800
It was calcined at ~900°C for 2 hours. Thereafter, it was finely ground again using a ball mill, dried, and then molded into a disk at a pressure of 2 tons/d. This was sintered at 1200-1350°C for 3 hours.

The sintered disk was cut into 0.5 mm thick pieces, and a silver electrode was baked onto its surface. Regarding the sample obtained from this birch,
An electric field was applied to both ends, and the displacement amount and history at 10 kV/cm were measured. The amount of displacement and history were measured using a potency turf meter. The measurement results are shown in the table below. In the table, sample No. 1.4.7.9 is an electrostrictive element within the scope of the present invention.

Comparative Example 1 Composition formula % Formula % (wherein, X is 0.01, A is 0.21, B
(0.53) was prepared in the same manner as in the example, and the amount of displacement and history were measured in the same manner. The amount of displacement is 0
．． 09%, and history was 40%.

[When Me=La] Sample Displacement History No., xy
abc (%) (%) 1 0.550.730.970.0051.00 0
．． 12 152 0.550.730.970.00
51, OOO, 081030, 500, 730, 970
,0051,0G OO0? 154 0.55
0.730.970.0051, OOO, 122050
゜630.73 G, 970.0051.00 0-0
8 216 0.550.730.970.0051
,OOOO0? 387 0.550.620.9
70.0051.00 0.10 1580°550
．． 580-970.0051.00 0.02 10
9 0.460.610.970.0051.00
LIO25100,550,731,OO0,0001
,OOO,0640110,550,730,970,
0251,000-0815120,550,730,
970,0051,180,0410130,550,
730,970,0050,830,0512140,
550,731,180,0051,OOO,0415
150,550,730,830,0051,OO0,
-0318 [When Me=Pr] Sample Displacement History No., xy
abc (%) (%) 1 0.550-730.970.005100 0-
．． 13 142 °0.55 0.75 G, 9
7 02oos t,oo OO0?
133 0.550-730.970.005i1
．． GO0,071740,550,730,970,0
051,0G 0.13 205 0.630,7
30.970.0-051, OO000? 216
0.550.730.970.0051,OOO,0
74170, 550J2G, 97G, O051,00
0,111? g o, sso, sao, q7o, oo
sx,oo O,031090,460,61G,9
70. O051000,1225)0 0. S50.7
31.000. OO01,OOO,0646110,5
50,130,970,0251,000,08151
2G, 550.730.970.0051.18 0.
04 1013 G, 550.730.970. (
X) 50,83 0.03 1314 0.550.
731.180.0051.00 0-04 151
5 0.550.730.830.0051.00 0
．． 04 18 [When Me=Ce 1 Sample Displacement History No., xy
abc (%) (%) 1 0.550.730.970.0051.00 0
．． 15 142 0.550.750.970.00
51.00 0.08 183 0.550.730
．． 970.0051.00 000? 154 0
．． 550.730.970.0051.00 0.14
225 0.63 0.73 0.97 G,
005 1.00 0. Cough 216 0.5
50.730.970.0051.0G OO0?
387 0.550.620°970.0051.
00 0.12 17B 0.550.580.9
70.0051, OOO, 04129G-460,61
0,97G,O051,OOO,1225100,55
0,731,000,0001,OOO,064011
0,550,730-970,0251,00G,0B
1512 0.550.730.970.005
1.18 0.04 1013 0.550.730
．． 970.0051.83 0.04 1314 0
．． 550.731.180.0051,OOO,031
5150, 550, 730, 83 (LOO51-000
, 0218 Effects of the Invention Although the electrostrictive element of the present invention has almost no change in history compared to conventional piezoelectric materials, the amount of displacement increases by about twice or more. The application fields of materials with such a large amount of displacement are very wide.

Claims (1)

[Claims] 1) Compositional formula (Pb, Ba_1_-_y)_aMe_b(Zr_xT
i_1_-_x)_cO_4 (in the formula, x, y, a, b,
and c are respectively y<(4/3)x, 0.60≦y≦0.80, 0.45≦x≦0.60, 0.85≦a≦1.15, 0.001≦b<0 This is a numerical value that satisfies the conditions of .02 and 0.85≦c≦1.15. d is a numerical value determined by the oxidation state of each element. Me is at least one element selected from the group consisting of La, Ce, and Pr. ) Porcelain composition represented by. 2) Composition formula (Pb_yBa_1_-_y)_aMe_b(Zr_x
Ti_1_-_x)_cO_4 (in the formula, x, y, A, b
N and c are respectively y<(4/3)x, 0.60≦y≦0.80, 0.45≦x≦0.60, 0.85≦a≦1.15, 0.001≦b< This value satisfies the conditions of 0.02 and 0.85≦c≦1.15. d is a numerical value determined by the oxidation state of each element. Me is at least one element selected from the group consisting of La, Ce, and Pr. ) A large displacement electrostrictive element made by sintering a ceramic composition represented by: