JPS60103079A - Piezoelectric ceramic composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a porcelain composition that is electrically activated by applying a polarizing electric field after firing a porcelain body using a normal ceramic method, and utilizes its residual piezoelectric properties. r,
Pb (Zn +/a ・Nb2/a) 03Pb
(Nit/a・N1)2/8 ) 03Pb Ti 0
3 pb zr 03t7) It relates to a porcelain composition in which the Pb content in four-component solid solution porcelain is slightly reduced from the stoichiometric value.

One of the alternative uses of piezoelectric ceramic materials is astral acoustic transducers such as speakers and sensors, and in this case, it is desired that a large displacement and stress can be output for a small input energy. This type of application is different from the conventional one, and the piezoelectric constant a (
d81, clas),'i[air-mechanical coupling ia
(Ksl, N88) and dielectric constant (E 33/E o
) There is a demand for materials with excellent piezoelectric properties.
One such material is Pb (Znt/s * N
bs+/a) 0x-Pb(Nit7a・Nb2/a
) Ox-PbTi03PbZrOs-based porcelain (hereinafter referred to as PZN
-PNN-PT-PZ) has been used and has been improved for various uses.

That is, in the above composition, a part of Pb is replaced by Ca.

Direct conversion with Sr, Ba, etc., or Cr 203 +
CO2O3*sno□I "120* The piezoelectric properties have been improved by adding oxides such as Na and O (including those that change to oxides by firing). However, each has its own characteristics. is the piezoelectric constant (hereinafter d
a1. (abbreviated as daa), electromechanical coupling coefficient (hereinafter referred to as K
B1. abbreviated as Na8), and dielectric constant (hereinafter ε, 3
There has been no piezoelectric ceramic material that has both a large value of /ε0) and a high Curie point (hereinafter abbreviated as Tc) and is excellent in all of the characteristics.

As a result of conducting four types of research on the four-component solid solution system porcelain of PZN-PNN-PT-PZ, the inventor discovered that the four-component system has a specific composition range, and that PZN-PNN-PT-PZ is within a specific composition range.
Part of i) is directly replaced with c, sr, Ba, etc.
Alternatively, ds+, da8. Ka++
8B, ε33/ε. It has been concluded that a piezoelectric ceramic composition having both thick (1,') and a high TC that does not cause any trouble in normal use can be obtained.

That is, PZN -PNN -PT shown in Figure 1 tC
-PZ four-component solid solution porcelain is N81. K,, a distribution trend and ε33/ε. Since the distribution trends are different, if a composition with a large N81 or I(2B is selected), ε33/ε.

is proportionally thicker (in some cases it is not thicker, and in other cases it is smaller).Also, if a composition in which ε, 3/ε. On the contrary, it may become smaller.Furthermore, PZ
There were problems such as a decrease in Tc when the N or PNN component was increased. Then, a part of c, pb is replaced with Ca and Sr.

When replaced with Ba etc. ε33/ε. increases, but Tc
Since Tc of the basic composition material before 1λ conversion decreases greatly,
If it is not large enough, there is a risk that the Tc after substitution will be so low as to cause problems in practical use.

In order to eliminate these various drawbacks, the inventor has been working hard on the current situation, and in order to eliminate these various drawbacks, the inventor studied the basic composition formula representing the four-component solid solution porcelain shown in FIG. As a result of doing this, we found that chemistry can be reduced from the theoretical value (A = 1.00), so da
t, daa, K3L, K8B + ε33/ε
. It has been found that a composition that can increase both of and Tc can be obtained.

To give an example, in the above basic composition formula, W=X=
0.225, Y=0.125, Z=0.225, the composition A of pb is reduced from the stoichiometric value, and A=
d88 when changed from 1.00 mol to 0.96 mol
+N88+'rc was measured. The results are shown in FIG.

From the results, composition A is 1. ,? As the value decreases,
It can be seen that d88p N88 a're all increase. However, if we pass the maximum point around A = 0.975 mol and further decrease, d88* Kss + Tc
In both cases, t decreases rapidly.

Based on this knowledge?T, (181 + daa + N9
1 + I(88*ε33/ε. are both large and T
If we include a composition range in which c is 1 higher than the base in normal use in the basic composition formula written in DiJ, 0.960≦A≦0.985 0≦W≦(1,70 0≦ X<0.50 However, 0.25≦W +X≦0.700.20≦Y≦
The composition range satisfies the following: 0.40 0.075≦Z≦0.375.

The basic composition of the present invention is a piezoelectric ceramic composition having such a composition range, which satisfies the pressure 7R characteristic and Tc.

In addition, in the above basic composition, less than 5 molar width of Pb is ca
, sr, and a piezoelectric ceramic composition containing at least one type of Ba atom. In this case as well, d81°d88*
N31 + N88 * C3, /ε0 are both large,
Moreover, it can be seen that a piezoelectric material having a high Tc that does not cause any practical problems can be obtained. Note that a part of Pb is replaced by Ca.

If Sr and Ba atoms are replaced with only one type, the composition A in the basic composition formula will decrease, but the amount of A before substitution is the sum of the amount of substitution of AsR, Cai Sr, and BB atoms after G conversion. be equivalent to.

Substituted with at least one type, Li2O3 molar or less, Na2O5 molar or less, 5nO25 molar or less, Cr
2032 mole or less, co2032 mole or less, NiO
3 molti or less, zno 87 A/% Ja F, Nb
Including those containing at least one species of 2058 molt or less.

In this case, a material that generates the above oxide upon firing may be added. In this case as well, excellent piezoelectric properties and Tc can be obtained.

When producing the porcelain composition of this invention, P is used as a raw material.
bo, N i O, zno, Nb2o51 T
'io, * zr O21naco3.5rco3.
CaCO3, Cr1O1l+ CO2031SnO!
5Li20 and Na2O are blended to obtain the required composition.

Note that, if necessary, compounds that decompose into the above raw material oxides by heating, such as Pbo for pt)3o, NiO for NiCO3, CaC0 for Ca(HC03)2, cr
203 can be blended in the form of Cry, Li, 0 can be blended in the form of Li, CO3, etc., or compounds of these oxides can be used as raw materials.

In addition, zro2, one of the raw materials, often contains a small amount of H.
Since it contains f, it is thought that Hf atoms occupy some of the positions of tetravalent metal atoms in the mixed crystal, but Hf
Since it is more expensive than r, and its use in industrial production would cause a rise in cost, in this invention, we do not consider replacing one part of Zr with f (f), and we do not consider replacing one part of Zr with f.
(Ignore this and think about it.

Furthermore, Nb, 05 may be contaminated with Ta205 of a few degrees or less, but 'ra, o, is N1)20. and chemically show similar properties. Therefore, Nl), 50 of 05
The piezoelectric properties of the composition in which Ta205 is substituted with N
It is possible to obtain piezoelectric properties almost equivalent to those of a composition containing only b, 0, and 0. Infused Nb
Even if you use 2 o 3 o, no problem will occur in terms of formulation.

The reason why the composition range of the piezoelectric ceramic composition represented by the above basic composition formula in this invention is limited is as follows.

As is clear from FIG. 2, if A is less than 0.960 mol or more than 0.985 mol, the effect of improving piezoelectric properties and Curie point is not significant, so 0.960≦A≦0.98.
I gave it a 5.

In the range where Y is less than 0.20 mol and 2 is more than 0.875 mol, or in the range where Y is more than 9.4Q mol and 2 is less than 0.075, 8g or ε33/'0 becomes small. .

In the range where W exceeds 0.70 mol, Xo, and 50 mol, and (W+X) exceeds 0.7 mol, Tc decreases, and in the range where (W+X) is less than 0.25 mol, c,
3/ε. becomes smaller.

Therefore, as described above, the composition ranges of w, x, y, and z were limited as described above.

Ca, Sr, and Ba, which are substituted for a part of Pb, are limited to 5 moles or less because if the substitution amount exceeds 5 moles, the "8m K88 * TC" will be significantly lowered.

Li2O, Na2O, Snug, Cr2O3, Co2
02. NiO.

Both zno and Nb2O5 have the effect of improving e33/ε0, but Li2O, Na, o and SnO2
If each of Cr, OB, and CO2O exceeds 5 mol, and each exceeds 2 mol, the resistivity of the porcelain material decreases and the breaking point due to mechanical stress becomes low, which is not preferable. Also, Nip, zno and N1)20. are all components constituting the basic composition of the porcelain according to the invention, and since adding too much of these oxides would disturb the basic composition of the porcelain, each was limited to 8 molar proportion or less.

Next, embodiments of the invention will be described.

The raw materials were weighed t1 to have the composition shown in Table 1, wet mixed in a ball mill, calcined at 850° C. for 2 hours, and then ground again in a ball mill to a particle size of about 1 μm. This pulverized powder was press-molded into a rectangular bar shape with dimensions of 5ffiX 5ffffX 12yqtn, and sintered at 1200"C for 1 hour.Ag electrodes were attached to both sides of the sintered crystal thus obtained, and 1
Polarization treatment was performed by applying a direct current field of 4 KV/gm for 30 minutes in silicone oil at 00°C.

The piezoelectric properties and Curie point of the product porcelain 24 hours after the polarization treatment were measured. The results are shown in Table 1. In addition, sample AI, 7゜1B, 27.8 marked with * in the table
8.86.59 is a porcelain whose composition falls outside the composition range of this invention and was given as a comparative example.

From the results shown in Table 1, compared to the comparative example, both d a
s T K2S +ε33/ε. is noticeably thicker (, also'
re is also very high. Therefore, by implementing the present invention, it is possible to produce a piezoelectric ceramic having excellent piezoelectric properties and a high Curie point, which could not be obtained conventionally.

(Margin below)

[Brief explanation of the drawing]

Figure 1 is a quaternary composition diagram of the basic composition in this invention;
The figure is a chart showing the relationship between composition A, piezoelectric properties (daa, K8m) and the Curie point (T, c). Applicant: Sumitomo Special Gold Pain Co., Ltd.

Claims (1)

[Claims] 1. The basic compositional formula is Pbi ((Znt/a ・Nbz/s)w・(Nit
/a ・Nb2/a) Piezoelectric ceramic composition. 0.960 ≦A ≦0.985 0≦W≦0,70 0≦X≦0.50 However, 0.25≦w+x≦o, 7゜0.20≦Y≦0.40 0.075≦2≦ 0.375 2 The basic composition formula is PbA((Znt/51Nb2/a)wIl(Ntt/
g″Nb2/g)x-TiyZrz)03, w
When +x+y+z=t, A that limits the composition range,
In a piezoelectric ceramic composition in which W, X, Y, and Z satisfy the following formula, up to 5 molar percentage of Pb is c
A piezoelectric ceramic composition characterized in that it is substituted with at least one of a, s, and na atoms. 0.960≦A≦0.985 0≦W≦0.70 0≦X≦+1.50 However, 0.25≦W+X ≦0.700.20≦Y
≦0.40 0.075≦2≦0.875 3 The basic composition formula is PbA((Znt7s°Nb2/g) w Il(N
i lrs°Nb2/a ) x TiyZrz)0. When expressed as W +
O25 molti or less, C "2032 molti or less, co2o
! 2 mol or less, Ni 0 8 mo/l/%, >-
Do, ZHO3 mo Iv% or less, NbxOs 8 mo/l/
A special feature of the porcelain composition is that it contains a small amount of Z or less (and one kind of material). 0.960≦A≦0.985 0≦W≦0.70 0≦X≦0.50 However, 0.25≦w+x≦0.70 0.20≦Y≦0.40 0.075≦2≦0.875 4 The basic composition formula is Pb ((Znt7s1Nb2/a)w(Nit/5l
lNb2/a)x″TiyZrz)03to, W+
When X + Y + Z = 1, in a piezoelectric ceramic composition having a composition in which A, W, X, Y, and Z that limit the composition range satisfy the following formula, up to 5 moles of Pb are replaced by ca, sr, and Ba atoms. direct conversion with at least one of the following, and Li2O3 mol or less, Na2O5 mol or less, s,
o25 molar ratio or less, Cr2032 molar ratio or less, co20
32 mol % or more F, Nio 3 mol % or more F. Zn0 3 molti or less, N1)20. 8 moles or less,
A piezoelectric ceramic composition characterized by containing at least one of the following. 0.960 ≦ A ≦ 0.985 0 ≦W ≦ 0.70 0 ≦X ≦-〇, 50 However, 0.25≦W + X≦0.700.20 ≦
Y ≦ 0440 0.075 ≦ 2 ≦ 0.375