JPH02221155A - Piezoelectric material - Google Patents

Abstract

PURPOSE:To obtain large vibration in the case of utilizing the piezoelectric material for an ultrasonic wave motor and to prevent generation of a crack, etc., by constituting the piezoelectric material of quaternary-system fundamental composition consisting of oxide. CONSTITUTION:This piezoelectric material is shown in a general formula: aPb(Mg1/3Nb2/3)O3-bPb(Ni1/3Nb2/3)O3-cPbTiO3-dPbZrO3MnO2 and Sb2O3 are added respectively at 0.1-5mol% for 100mol% porcelain composition wherein the above mentioned (a), (b), (c) and (d) satisfy the relations of (1)-(3) described hereunder. (1) 5<=a+b<=40, (2) 35<=c<=50, (3) 10<=d<=60, wherein (a), (b), (c) and (d) show mol%, (a) and (b) are not zero and a+b+c+d=100. In the above constitution, <=10atm% of Pb may be replaced by one or more kinds selected from among Sr, Ca and Ba in accordance with necessity. Piezoelectric constant is made large by this replacement.

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention has a high mechanical quality factor and mechanical strength, and can be used as a material for piezoelectric actuators, ultrasonic motors, ultrasonic vibrators, etc. that utilize resonance displacement. Concerning suitable piezoelectric materials.

(Prior art) Piezoelectric materials include lead zirconate titanate, Pb (Zr
Ti)Os porcelain compositions are well known. This compound is difficult to manufacture because it evaporates during firing because it contains lead, but it has great piezoelectricity, can be used at a high temperature, and can be replaced or added with a third component. This has the advantage that porcelain with a high degree of modification can be obtained. In particular, PbTiO3PbZrOs Pb(Mg+7sNby
x) Os's three-component piezoelectric ceramic is easy to fire with little lead evaporation, and it is possible to give it various piezoelectric properties by adding various additives to the main component, so it is used as a piezoelectric buzzer. , frequency filter, piezoelectric ignition element,
It has been used as a material for things such as ultrasonic transducers.

In recent years, with the development of mechatronics, responsiveness has improved,
The need for displacement elements that can be precisely controlled has increased, and attempts have been made to use displacement driving elements that utilize piezoelectric strain. For example, ultrasonic motors are an example of this. Ultrasonic motors are used to drive robot arms,
It is attracting attention as an alternative to conventional electromagnetic motors for driving lenses in autofocus cameras. This ultrasonic motor uses the vibration of the piezoelectric ceramic as the driving force for rotation, and in order to obtain better motor characteristics, it is necessary that the amplitude of the vibration of the piezoelectric ceramic be large. Furthermore, in order to obtain such large vibrations, it is also required that the 411vi quality factor and piezoelectric constant be large. Furthermore, in an ultrasonic motor, the piezoelectric ceramic vibrates while being bonded to an elastic body (usually a metal material), so the vibration of the ceramic is restrained by the elastic body, and stress is applied to the ceramic. Therefore, piezoelectric ceramics for ultrasonic motors must also have mechanical strength that can withstand this stress.

The above explanation has mainly been made using piezoelectric ceramics for ultrasonic motors as an example, but there are many uses for piezoelectric ceramics that require similar characteristics.However, among the conventional materials, for example, Pb (known from the publication No.
Mg+zJbzzs)03PbTiOz PbZr0
* MIIO! Although the mechanical quality factor is large, the piezoelectric constant and mechanical strength are extremely small.

In addition, Pb (
Mg l/3Nbxzs)Ox-Pb(Ni+zsNb
z/5) Os PbTiO3PbZrOs has a large piezoelectric constant but a very low mechanical quality factor and mechanical strength.

(Problems to be Solved by the Invention) As mentioned above, the piezoelectric materials known so far have insufficient mechanical quality factor, piezoelectric constant, or mechanical strength, and are not suitable for use in ultrasonic motors, for example. Problems remain, such as not being able to produce large vibrations when used, making it impossible to expect improvements in motor characteristics, or being susceptible to breakage due to insufficient strength.

The object of the present invention is to provide a piezoelectric material that can be used in ultrasonic motors, etc., to obtain large vibrations, and that does not cause cracks or the like.
That is, the object of the present invention is to provide a piezoelectric material whose mechanical integrity coefficient, piezoelectric constant, and mechanical strength are all above a certain level.

(Means for solving problems) The gist of the present invention lies in the following piezoelectric material.

■aPb(Mg+7sNbzz3)03bPb(Ni+
7Jbzzs) OsCPbTiOs d PbZrO
s, and the above aSb, c and d are the following (1) to
A piezoelectric material in which 0.1 to 5 mol% of Mn01 and 5bs03 are each added to 100 mol% of a ceramic composition that satisfies the formula (3).

5≦a+b≦40...■ 35≦c≦50 ......■ 10≦d≦60 ......■ However, a, b, c, and d are mol%, and a and b is not 0, but a+bfc+d=100.

Furthermore, the gist of the present invention is as follows: ■ The above a Pb(Mg+/5Nbxzs)Oz b
Pb(Ni1/3Nb!/3)03 CPbTiO
P of the 6f vessel composition represented by s d PbZrOs
Similar to ■, Mn is substituted with 141 or more of Sr, Ca, and Ba in which 10 at% or less of b atoms are substituted.
O.

and a piezoelectric material to which sb and o are added.

(Function) The piezoelectric material of the present invention has Pb(Mg+zJbxzi)Oz
Pb(Ni+7Jbzz)Ox PbTiOs
After appropriately selecting the ratio of the oxides constituting the basic composition of the quaternary system of PbZr0*, that is, the above-mentioned values of a, b, c≦d, some of the pb atoms may be replaced with Sr, Sr, Ca
, Ba, and further substituted with Mn0t and Zr.
It is characterized by the addition of Ox.

The reason why the ratios of oxides in the basic composition, that is, the values of a, b, c, and d, are determined as above is because the piezoelectric constant becomes small outside this range. Mn0i, sb, and o3, which will be described later, may be added to the porcelain composition having this basic composition, but
IO atomic% or less of pb in the basic composition is S'', Ca and [
The basic composition is one or more of Ia replaced with W, and Mn
O□ and 5bt03 may be added.

The piezoelectric constant can be increased by this substitution with Sr, Ca, and Ba. However, this amount of substitution is p
When b exceeds 10 atomic %, the piezoelectric constant becomes smaller on the contrary.

With respect to 100 mol% of the above porcelain composition, Mn0
1 and 5b103 are added in an amount of 0.1 to 5 mol %, respectively.

The reason why 0.1 to 5 mol% of MnOx is added is to improve the mechanical quality factor of the piezoelectric material. This effect is
It appears from 0.1 mol%, and when it exceeds 5 mol%, both the mechanical quality factor and the piezoelectric constant decrease.

5b103 refines the crystal grains of the piezoelectric material and increases its mechanical strength. If it is less than 0.1 mol%, the effect will be small, and if it exceeds 5 mol%, the piezoelectric constant will decrease.

The piezoelectric material of the present invention has the above composition, and the manufacturing method thereof is the same as that for conventional ceramic compositions of this type. That is, 2. It can be manufactured by blending oxides, carbonates, hydroxides, etc. of each element to have the above-mentioned composition, molding, and then sintering.

(Example) The basic composition is a Pb(Mg+zsNbxzs)Os b Pb
(Old wsNb*ys>0s-c PbTjOs -d
PbZr0s (however, a+b+c+d=100) is expressed as PbO, Zr01. TlGg, MgO, Nip,
Nb1Os.

CaC0! + 5rCOs+ BaC0,, Mn0g+
Each raw material of Sb*Os was weighed so as to have the composition shown in Table 1, and thoroughly mixed using a ball mill. The obtained mixed powder was calcined at 800 to 1000° C. for about 2 hours, and the calcined product was thoroughly ground and mixed again in a ball mill, and then an organic binder was mixed and granulated. Approximately 1) of this granulated powder, /
It is formed into a diameter of 20 m and a thickness of 2 fins using a pressure of d.
It was baked at a temperature of 00 to 1300°C for about 2 hours.

Further, IT electrodes were baked on both surfaces of the obtained disc-shaped 0 sintered body, and polarization treatment was performed by applying a DC voltage of 3 kv/m in silicone oil at 100°C.

The piezoelectric properties of the porcelain thus obtained are shown in Table 1. In the table, d31 is a piezoelectric constant, 0 is a mechanical quality factor, and σ is a bending strength.

Sample Na1-14 is Pb(Mg+z3Nb*zi)O
s, Pb(Ni l/3Nbxzz)Os, PbTi0
t, the ratio of PbZrO3, i.e. a, b.

This shows changes in characteristics due to differences in c and d.

Here, the position tAffi of the pb atom is kept constant at 5 at % due to Sr, and the amounts of Mn01 and 5bxOs added are also kept constant at 2 mol % and 1 mol %, respectively.

Looking at the characteristics of N11l to N14 in Table 1, the values of a, b%C and d are outside the range defined by the present invention (comparative example)
It can be seen that d□ is extremely small.

Samples 15 to 19 are examples in which the amounts of MnOt and Sb*Os added were changed without substitution with Cas, Sr, and Ba.

If MnOx or 5bxOs is not added, Qs, σ
It is clear that the value decreases (81117.18).

Samples Nos. 20 to 25 are examples in which the amount of 5b103 added was varied while the amount of pb replaced by Sr was kept constant. Added amount is 0
．． If it is less than 1 mol%, the effect of improving σ is small (Na
20, 21) On the other hand, when the amount added exceeds 5 mol %, not only σ but also d, 1 and OW deteriorate as shown in 25.

Samples 26 to 31 are examples in which the amount of Mn0t added was changed while the amount of pb replaced by Sr was kept constant. Mn
Sample N [126,2
7 had no effect of improving Qm, and conversely, in sample N1131 to which more than 5 mol% was added, Qm decreased and (
h+ has also become smaller.

Samples Nn32 to 36 have p due to Ca, Sr, and Ba.
This is an example in which the amount of substitution of b is changed. When the amount of substitution reaches 10 atomic%, d21 and 0 are small (
Become.

Whether Ca or 5rSBa is a negative element or a combination of three or more elements, the effect is recognized as long as the total amount is 10 atomic % or less.

(Hereinafter, blank spaces) (Effects of the invention) As shown in the examples, the piezoelectric material of the present invention has a high piezoelectric constant, mechanical quality factor, and mechanical strength, so it can obtain large vibrations and It can be widely used as a material for sonic motors, ultrasonic vibrators, etc.

Claims (2)

[Claims] (1) aPb(Mg_1_/_3Nb_2_/_3)O
_3-bPb(Ni_1_/_3Nb_2_/_3)O
_3-cPbTiO_3-dPbZrO_3,
A piezoelectric material in which 0.1 to 5 mol% of MnO_2 and Sb_2O_3 are added to 100 mol% of a ceramic composition in which the above a, b, c, and d satisfy the following formulas (1) to (3). . 5≦a+b≦40 (1) 35≦c≦50 (2) 10≦d≦60 (3) However, a, b, c, d are moles %, a and b are not 0, and a+b+c+d=100. (2) aPb(Mg_1_/_3Nb_2_/_3)O
_3-bPb(Ni_1_/_3Nb_2_/_3)O
_3-cPbTiO_3-dPbZrO_3,
The above a, b, c and d satisfy the following formulas (1) to (3), and 10 atomic% or less of Pb atoms are Sr, Ca,
Porcelain composition 100 substituted with one or more types of Ba
A piezoelectric material in which MnO_2 and Sb_2O_3 are added in an amount of 0.1 to 5 mol%, respectively. 5≦a+b≦40 (1) 35≦c≦50 (2) 10≦d≦60 (3) However, a, b, c, d are moles %, a and b are not 0, and a+b+c+d=100.