JPH02263761A - Ferroelectric ceramic composition and piezoelectric element utilizing the same - Google Patents

Abstract

PURPOSE:To obtain the composition capable of being sintered at low temp. and having a large electromechanical coupling factor and large relative permittivity by incorporating specified amts. of Pb oxide and Ge oxide as the auxiliary component into a ferroelectric ceramic as the main component. CONSTITUTION:Pb oxide and Ge oxide are respectively incorporated into the ferroelectric ceramic (e.g. barium titanate-based ferroelectric ceramic, lead titanate-based ferroelectric ceramic, etc.) as the main component. In this case, the Pb oxide is expressed in terms of PbO, the Ge oxide is expressed in terms of GeO2, and the molar ratio of PbO to GeO2 is expressed by the formula xPbO.yGeO2 where (x)=1 to 6 and (y)=1 to 3. The total content of the PbO and GeO2 is controlled to 0.01 to 30wt.%. By this method, a ferroelectric ceramic capable of being sintered at a low temp. (about 850 to 100 deg.C) and having a large electromechanical coupling factor and large relative permittivity is obtained. Consequently, a piezoelectric element having high energy conversion efficiency can be produced.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a ferroelectric ceramic composition, particularly a ferroelectric ceramic composition that has a large electromechanical coupling coefficient and can be sintered at a low temperature, and a piezoelectric ceramic composition using the same. Regarding elements.

(Prior Art) Porcelain piezoelectric materials are generally used in piezoelectric elements such as filters, piezoelectric buzzers, and bimorphs because of their excellent workability, mass productivity, and characteristics. As this type of piezoelectric material, lead titanate-based ferroelectric ceramics, lead zirconate titanate-based ferroelectric ceramics, and barium titanate-based ferroelectric ceramics are in practical use.

However, these ferroelectric ceramics have a sintering temperature of 1100
Due to the high temperature of ℃ or higher, it was not possible to obtain a composite integrated with a substrate such as a metal plate.

In addition, when ferroelectric ceramics are lead oxide-containing ferroelectric ceramics/ceramics, since they contain volatile Pb as a component, part of the PbO is likely to be lost from the composition during firing, resulting in poor reproducibility of characteristics. It was difficult to achieve uniformity.

Furthermore, when these ferroelectric ceramics are used for an oscillator (resonator), the electromechanical coupling coefficient is large, so the bandwidth of the filter is not wide, and there is a lack of stability in use.

For this reason, in Japanese Patent Application Laid-Open No. 58-204579, piezoelectric ceramics are made of silicate glass compounds, soda glass compounds,
Alternatively, a compound-containing piezoelectric ceramic has been proposed in which the filter bandwidth is narrowed and the stability is improved by adding 1 to 30 wt % of a lead glass compound.

(Problems with the Prior Art) However, the glass compound-containing piezoelectric ceramic has a problem in that the addition of the glass compound significantly reduces the electromechanical coupling coefficient, resulting in a reduction in energy conversion efficiency.

Furthermore, when a conventional ferroelectric ceramic composition is applied to a ceramic resonator in a spread vibration mode, there is a problem in that abnormal oscillations occur due to spurious vibrations that are thickness longitudinal vibrations.

(Means for Solving the Problems) The ferroelectric ceramic composition of the present invention contains an oxide of Pb and an oxide of Ge, respectively, to the ferroelectric ceramic as the main component. When the oxide is converted to PbO, the Ge oxide is converted to GeO2, and the molar ratio of Pbo and GeO2 is expressed as the general formula: xPbO・yGe02, X?
y is x = 1 ~ a, y = x ~ 3, and the total amount of added and contained PbO and GeO2 is 0.01 ~ 3
It is characterized by being 0% by weight.

Further, the piezoelectric element of the present invention includes a plate-shaped ferroelectric ceramic plate made of the above-mentioned ferroelectric ceramic composition, and electrodes formed on both main surfaces of the ferroelectric ceramic plate. Features.

Furthermore, the piezoelectric element of the present invention is formed by applying a thick film paste containing calcined powder made of the above-mentioned ferroelectric ceramic composition onto a metal substrate and baking it into one piece. It is characterized by electrodes being formed on the surface of the ferroelectric ceramic layer.

Examples of the ferroelectric porcelain that is the main component of the ferroelectric porcelain composition of the present invention include barium titanate-based ferroelectric porcelain, lead titanate-based ferroelectric porcelain, lead zirconate titanate-based ferroelectric porcelain, Typical examples include lead metaniobate-based ferroelectric porcelain and lead-containing composite perovskite-based porcelain, but are not limited to these.

Barium titanate-based ferroelectric porcelain includes intrinsic and modified barium titanate-based ferroelectric porcelain.

Lead titanate-based ferroelectric porcelain refers to genuine and modified lead titanate, and modified lead titanate includes simple oxides such as Cr2O3, Nb2O5, Ta205. Bi 203
．． Addition of metal oxide such as MnO2, Pb site is Mg, Ca.

Sr, Ba'PLa203. Those substituted with rare earth elements such as Nd2O3 and Y2O3, and two-component systems, three-component systems, and other various systems in which PbTiO3 is partially replaced with at least one kind of composite perovskite compound represented by general formulas (I) to (VI) described below. Includes component-based porcelain or a combination of these.

In addition, lead zirconate titanate-based ferroelectric porcelain refers to genuine and modified lead zirconate titanates, and modified lead zirconate titanates include Cr in Pb(Ti, Zr)03.
'203. Nb2O5, Ta205. B 1203
．． Added metal oxides such as MnO2, Pb sites added with alkaline earth metals such as Mg, Ca, Sr, Ba, etc.
A three-component component in which a rare earth element such as a2O3, Nd2O3, or Y2O3 is substituted, and a part of Pb(Ti, Zr)03 is substituted with at least one kind of composite perovskite compound represented by the general formulas (I) to (VI) described below. porcelain type, four-component type, multi-component type porcelain, or a combination thereof.

Furthermore, lead metaniobate-based ferroelectric porcelain refers to both intrinsic and modified lead metaniobate, and modified lead metaniobate includes simple oxides such as Cr2O3, Nb2O5°
05. Addition of metal oxides such as Bi2O3 and MnO2, MB with a part of Pb, alkaline earth metals such as Ca, Sr, Ba, La203eNd203tY203
etc., as well as binary, ternary and other multi-component porcelains in which lead metaniobate is added with at least one kind of composite perovskite compound represented by general formulas (I) to (■) below. included.

Lead-containing composite perovskite porcelain has the following general formula (
1) In addition to the lead-containing composite perovskite compounds represented by ~(Vl), 2 consisting of two or more thereof or at least one thereof and another composite perovskite compound.
Includes component type, three-component type, and other multi-component type porcelains. For example, Pb (Fe2zaWxz3) 03s Pb (Fe
One-component system such as 172Nb 1/2) 03, Pb(Fe
l/2Nbl/2)03-Pb(Fe2/3W1/3)
Two-component system such as 03, Pb (Mnx/aNJ/3) 0
s-Pb (Fe 1/2Nbl/2)03-Pb (
Fe2/aWx/3) Oat Pb(Zn1/3Nb2/3)03-Pb(Fe1/2
Nbl/2)03-Pb (Fe2/3W1/3)03
Examples include three-component composite herovskite compounds such as.

Typical examples of the composite velorskite compound include general formula (1): A''(B2+1/3B''2/3)(13
A compound represented by, for example, Ba(Zn1/Jb2/3)03tBa(Cdx/
Jt)+73)03sBa(Mg1/3Nb2/3)0
3s 5r(Cd1/aNb2/3)03sPb(Mg
1/3Nb2/3) 03Pb(Ni1/3Nb2/3
)03tPb(Mg1/3Nb2/3)03j Pb
(Mg1/3Ta2/3)03tPb(Ni t/3T
a2/3)03*Pb(Cd1/3Nb2/3)03;
General formula (11)=A”(B “1/2B”1/2)03
A compound represented by, for example, Ba(Fe1/2Nb1/2)03. Ba(Se1/2
Nb1/2)03+Ca(Cr1/2Nb1/2)03
．． Pb(Fe1/2Nb1/2)03°Pb(Fe1/
2Ta1/2)03. Pb(SC1/2Nb172)0
3°Pb(SC1/2Ta1/2)03. Pb(Yb1
/2Nb1/2)03°Pb(Yb172Ta1/2)
039Pb(Lu1/2Nb1/2)03IPb(In
x72Nb17z)03; General formula (111)'A2+(B"1/2B"1/2)0
3, for example, Pb(Cd1/2Wx/2) IPb(Mn1/2W
1/2) 03shiPb (Zn1/2 stomach 1/2) 03. Pb
(Mg1/2W1/2)03°Pb(Cd1/2Wx/
2) 03*Pb(Ni 1z2Wt/2)03sPb(
Mgt/2Tet72)03yPb(Mn1/2W1/
2) 03sPb(Cd1/2Wx/2)03; General formula (IV)=A2''(B''2/3B''1/3)03
A compound represented by, for example, Pb(Fe2/3W1/3)03; General formula (V) 2A2+(B2+1/2B4+1/2)0
3, for example, Pb(Sn1/2Sb1/2)03. La(Mg1/2
W1/2) 03°Wb (M8t/2Ti 1/2) 03
; and General formula (■Door (A"1/2A"172) B
A compound represented by 4+03, for example, (Na1/2La1/2)T1039(K1/2La1
/2) Ti03p (Nat/2Cet/2) TiQ3s
(Na17Jdt/2)TiO3'(Ndt/2Bi
x/2) Ti03 (K1/2Bi t/2) Ti0
Examples include 3.

(Function) The present invention adds Pb as a subcomponent to ferroelectric ceramics such as barium titanate, lead titanate, lead zirconate titanate, lead metaniobate, and lead-containing composite perovskite as main components. When the oxide of Ge is converted into Pbo, the oxide of Ge is converted into GeO2, and the molar ratio of Pbo and GeO2 is expressed as the general formula: xPbO-yGe02, x and y are respectively x=1 to 6. When added and contained so that y=l~3 and fired, a different phase ceramic bulk is generated by liquid phase sintering, and the main components barium titanate, lead titanate, and lead zirconate titanate are removed. This makes it possible to sinter ferroelectric ceramics such as lead metaniobate-based and lead-containing composite perovskite-based ceramics at a low temperature of 850 to 1000°C without reducing their inherent electromechanical coupling coefficient. This enables integral sintering with a metal substrate, which was previously possible.

Further, the ferroelectric ceramic according to the present invention can be produced by a screen printing method, a coating method, a press molding method, or an extrusion molding method.

It can be formed or processed by any method such as sheet molding or hot pressing. For example, by printing a thick film paste on the surface of a metal substrate using screen printing and sintering it, you can create an integrally sintered piezoelectric. It is possible to obtain the element.

An oxide of Pb and an oxide of Ge are added as subcomponents, and the oxide of Pb is converted to Pbo, the oxide of [re is converted to GeO2, and the molar ratio of PbO and Ge09 is determined by the general formula: xPbO -Xy when expressed as yGe02
3' are respectively x=1 to 6. y=l~3, and the total amount of added and contained Pbo and GeO2 is 0.01
-30% by weight is because if it is less than 0.01% by weight, the effect is not expected to be so great, and if it exceeds 30% by weight, the sintering temperature will be lower, but the electromechanical coupling coefficient will drop noticeably. This is because it becomes

In particular, the total amount of added and contained PbO and GeO2 is reduced to 0.
．． When the amount is 1 to 10% by weight, a ferroelectric ceramic composition having a low sintering temperature and a large electromechanical coupling coefficient can be obtained. In addition, the values of x and y are set to x=1-6ty=1-3 in order to enable sintering at low temperatures. I chose the following. Furthermore, the ferroelectric ceramic composition according to the present invention exhibits high flexural strength when its main component is lead oxide-containing ferroelectric ceramic. This is thought to be because a chemical bond is generated between the lead oxide in the main component and the lead oxide in the subcomponent, increasing the mechanical strength at the grain boundaries.

Examples of the present invention will be described below.

(Example 1) Pb3O4, Ti 02. as raw materials. Using ZrO2 and Nb2O5, these were converted into PbTi o, 48zr
0.5203-1, 0 wt%Nb2O5 as the main component, and Pb3O4 and GeO as the raw materials for the subcomponents.
2, convert Pb3O4 to Pbo, and convert GeO2 to G
Converting to eO2, the molar ratio of Pbo and GeO2 is expressed by the general formula:
They were added and contained in the proportions shown in Table 1 so that when expressed as xPbO・yGe02, X and Y were x = 1 to B and y = 1 to 3, respectively, and mixed for 20 hours to obtain a mixture. Ta.

Next, this mixture was dehydrated, dried, calcined at 850° C. for 2 hours, and then ground to obtain calcined powder.

Next, 10% by weight of an organic binder consisting of a resin and a solvent was mixed with the obtained calcined powder to prepare a thick film paste.

Next, the prepared thick film paste was coated with a diameter of 20 mm and a thickness of 0.
After screen-printing a circle with a diameter of 18m+n on a substrate made of a heat-resistant metal of 1mIIIl, such as Ni-Cr metal, it is fired at the firing temperature shown in Table 1 to form a 50μ
A monolithically sintered composite with a thickness of 1/3 was obtained.

Next, a silver electrode was formed on the ceramic surface of the obtained composite by a baking method, and an 8.
A DC voltage of 3 to 4 KV/mm was applied at 0°C and polarization was performed for 30 minutes to prepare porcelain piezoelectric samples (sample numbers 1 to 6).
t- got it.

For each sample, the relative dielectric constant (Cr) and the electromechanical coupling coefficient (Kv) of the bending vibration of the disk were measured, and the results are shown in Table 1.

In addition, Table 1 shows, as comparative examples, a sample (sample number 7) in which the subcomponents Pb3O4 and GeO2 were not added;
bTi 0.4BZrO05203-1,0wt%Nb
Pbo:132o3- as a subcomponent in the calcined powder of 2O5
Sample prepared using a thick film paste prepared by adding 0.1 wt% of sio2-based glass compound (sample number 3)
, and PbTi0.48zr0.5203=1.0wt%Nb
Ma2O, B2O3,
Similar measurements were also performed on a sample (sample number 9) prepared using a thick film paste prepared by adding 5 wt % of a 5i02-based glass compound, and the results are also shown.

(Example 2) First, using Pb3O4 and GeO2 as raw materials for subcomponents, converting them into Pt1sOat)'bo, and converting GeO2 into GeO2
2, and the molar ratio of Pbo and GeO'2 is expressed by the general formula: x
When expressed as PbO・yGe02, Xyy is x=5. Set y to 3, and add the main ingredients at the mixing ratio shown in Table 2.

A calcined powder was obtained in the same manner as in Example 1 except that the powder was added.

Next, 2 to 3% by weight of an organic binder is added to the obtained calcined powder.
Add, granulate for 20 hours, press mold)4
, 5 mm x 10 mm x 20 mc square plates were formed, and the square plates were fired for 2 hours at the temperatures shown in Table 2 to obtain porcelain square plate samples (sample numbers 10 to 16).

Three-point bending test method for each sample (distance between support points: 11 m
The bending strength (kg/cm2) was measured according to M), and the results are shown in Table 2.

Note that sample number to, 13.16 is outside the scope of the present invention.

(Example 3) First, Pb3O4, TiO2, ZrO2,5 as raw materials
Using n02,5b203 and MnO2, 0.05P
b(Sn,,2Sb1,2)03-0,47PbTf0
Calcined powder was obtained in the same manner as in Example 1, except that it was weighed so as to obtain a ferroelectric porcelain having a composition of 3-0.48PbZr03-0.7wt%MnO2, and the calcining temperature was 900°C. Ta. Table 3 shows the molar ratio of PbO and GeO2, and the total amount of PbO and GeO2 added to the main components (wt%).

Next, 6 to 7 wt% of an organic binder is added to the obtained calcined powder.
After being layered for 20 hours, it was formed into a sheet using a doctor blade method and punched into a sheet with a diameter of 20 mm and a thickness of 0.
A 1 mm disk was formed, and this disk was fired for 2 hours at the firing temperature shown in Table 3 to obtain a porcelain disk. Next, silver electrodes were baked on both main surfaces of the obtained porcelain disk, and an 8°0
A DC voltage of 3 to 4 KV/mm was applied at ℃ to perform polarization treatment for 30 minutes, and porcelain piezoelectric samples (sample numbers 18 to 22
) was obtained.

For each sample, the relative dielectric constant (εr) and the electromechanical coupling coefficient (Kp) of the spreading vibration of the disk were measured, and the results are shown in Table 3.

In addition, Table 3 shows, as comparative examples, a sample in which the subcomponents Pb3O4 and GeO2 were not added (sample number 17),
, 05Pb (Sn 172Sb 1/2) 03-0
, 47P bT 103-0.48P bZr03-
PbO is added to the calcined powder of 0.7 wt% MnO2 as a subcomponent.
-A sample prepared in the same manner as in Example 8 with the addition of 5 wt% of B2O3.5i02-based galame vitrification (sample number 24)
), and 0,05Pb (Sn 1/2sb 1z2
) 03-0.47PbT 1o3-0.48PbZr
03-0.1w of Na204203-3i02-based glass compound as a subcomponent to 0.7wt%MnO2 calcined powder
A sample (sample number 25) prepared in the same manner as in Example 8 with the addition of t% was also subjected to similar measurements, and the results are also shown.

Moreover, sample number 23 in Table 3 is outside the scope of the present invention.

(Example 4) First, Pb3O4 and GeO□ are used as raw materials for subcomponents, Pb3O4 is converted to Pbo, GeO2 is converted to GeO2, and the molar ratio of Pbo and GeO2 is determined by the general formula: xPbO
・When expressed as yGe02, each of X+Y is x=5
．． y = 3, and the main components were added at the mixing ratio shown in Table 4.

A calcined powder was obtained in the same manner as in Example 3, except that the powder was added, and then ceramic square plate samples (sample numbers 26 to 32) were obtained in the same manner as in Example 2.

Three-point bending test method (distance between support points: I
The bending strength (kg/C111'') was measured by Imm), and the results are shown in Table 4 along with the firing temperature.

Note that sample numbers 26, 29, and 32 are outside the scope of the present invention.

(Example 5) First, Pb3O4, TiO2, ZrO2, M
0.05Pb (Mn1
z3Nb273)03-0.45PbTi03-0,5
A calcined powder was obtained in the same manner as in Example 3, except that the weight was weighed so as to obtain a ferroelectric ceramic having a composition of 0PbZr03. Table 5 shows the molar ratio of PbO and GeO2, and the total amount of PbO and GeO2 added to the main components (wt%).

Next, 2 to 3 wt% of an organic binder is added to the obtained calcined powder.
In addition, after being layered for 20 hours, it was granulated and press-molded to form a disk with a diameter of 15 mm and a thickness of 1 mm, and this disk was fired for 2 hours at the firing temperature shown in Table 5 to obtain a porcelain disk. I got it.

Next, silver electrodes were baked on both main surfaces of the obtained porcelain disk,
A DC voltage of 3 to 4 KV/mm was applied between both electrodes at 80° C. to perform polarization treatment for 30 minutes to obtain porcelain piezoelectric samples (sample numbers 34 to 33).

For each sample, the relative dielectric constant (εr) and the electromechanical coupling coefficient (Kp) of the spreading vibration of the disk were measured, and the results are shown in Table 5.

Table 5 shows, as comparative examples, samples in which the subcomponents Pb30''4 and GeO2 were not added (sample number 33);
0,05Pb (t4n173Nb2y3) 03-0
．． 45PbTi03-0.50A sample (sample number 40) prepared in the same manner as in Example 5 by adding O, 1 wt% of a Pbo/B2O3/Si02-based glass compound as a subcomponent to the calcined powder of PbZr03, and 0, 05Pb (Mn173Nb273) 03-0.
Similar measurements were also performed on a sample (sample number 41) prepared in the same manner as in Example 5 by adding 5 wt% of Na20-B2O3/St02-based glass compound as a subcomponent to the calcined powder of 45PbTi03-0.50PbZr03. The results are also shown.

Moreover, sample number 39 in Table 5 is outside the scope of the present invention.

(Example 6) First, in Example 5, 0.05Pb(t4nt/3Nb2z
s) O3-0.45PbTi03-0.50PbZr0
In addition, using Pb3O4 and GeO2 as raw materials for subcomponents, Pb3O4 was
o, convert GeO2 to GeO2, general formula:
Let the molar ratio of xPbO-yGe02 be x=5. A calcined powder was obtained in the same manner as in Example 5, except that y = 3 and the main components were added and contained in the blending ratio shown in Table 6. Porcelain square plate samples (sample numbers 42 to 43) were obtained in the same manner.

Three-point bending test method for each sample (distance between support points @=11m
The bending strength (kg/Cm2) was measured by m), and the results are shown in Table 6 together with the firing temperature.

Note that sample numbers 42, 45, and 4B are outside the scope of the present invention.

(Example 7) First, using Pb3O4, TlO2, La2O3 and MnO2 as raw materials, Pbo, 55La (1,10T
A calcined powder was obtained in the same manner as in Example 1, except that the weight was weighed so as to obtain a ferroelectric ceramic having a composition of i03-0.7 wt% MnO2, and the calcining temperature was 950°C. In addition, Table 7 shows the molar ratio of PbO and GeO2, and the Pb
The total amount of O and GeO2 added to the main components (wt
%).

Next, 4 to 5 wt of organic binder is added to the obtained calcined powder.
% and layered for 20 hours, extrusion molded to obtain a green sheet, which was punched to a diameter of 10 mm.

A disk with a thickness of 0.5 mm was formed, and this disk was fired at the firing temperature shown in Table 7 for 2 hours to obtain a porcelain disk.

Next 1. Silver electrodes were baked on both main surfaces of the obtained porcelain disc, and a DC voltage of 3 to 4 KV/mm was applied between the two electrodes at 80°C for 30 minutes to polarize the porcelain piezoelectric sample (
Sample numbers 50 to 54) were obtained.

For each sample, the relative dielectric constant (εr) and the electromechanical coupling coefficient (Kt) of vibration in the thickness direction of the disk were measured, and the results are shown in Table 7.

In addition, Table 7 shows a sample (sample number 49) in which the subcomponents Pb3O4 and GaO2 are not added, and Pb3O4 and GaO2 as comparative examples.
b□, 85Lao, 10TIO3-0,7wt%M
PbO・8203・S as a subcomponent in the calcined powder of nO2
A sample prepared in the same manner as in Example 7 with the addition of iO□-based galame glass compound tχ (sample number 56), and Pb
O,8!5LaO,t,'rto3-o, 7wt%M
Na2O, B2O3,
Similar measurements were also performed on a sample (sample number 57) prepared in the same manner as in Example 7 with the addition of 10 wt % of the 5i02-based vitrified metal, and the results are also shown.

Moreover, sample number 55 in Table 7 is outside the scope of the present invention.

(Example 3) First, in Example 7, Pb□, 85Lao, 1(, Ti
03-For the main component weighed to have a composition of 0.7 wt% MnO2, Pb3O4 and G are added as raw materials for the subcomponents.
Using eO2, Pb3O4 is Pb.

Convert GeO2 to GeO2, general formula: x
The molar ratio of PbO・yGeO2 is x=5. Porcelain square plate samples (sample numbers 58 to 64) were obtained in the same manner as in Example 2, except that y was set to 3 and the ingredients were added and contained in the blending ratios shown in Table 8.

Three-point bending test method for each sample (distance between support points: 11 m
The bending strength (kg/Cm2) was measured by m), and the results are shown in Table 8 along with the firing temperature.

Note that sample numbers 5B and 61.64 are outside the scope of the present invention.

(Example 9) First, BaCO3, Ti02. CaCf13
and MnO2, these are (BaO,92ca0
．． 06) Ti03-Weighed so as to obtain ferroelectric porcelain having a composition of 0.2wt%MnO2, and set the calcination temperature to 1.
A calcined powder was obtained in the same manner as in Example 1 except that the temperature was 100°C. Table 9 shows the molar ratio of Pbo and GeO2 and the total amount of Pbo and GeO2 added to the main components (wt%).

Next, 6 to 7 wt of organic binder is added to the obtained calcined powder.
% and layered for 20 hours to prepare a thick film paste.

Next, the prepared thick film paste was formed into a sheet using a doctor blade method, and punched to a diameter of 10@button and a thickness of 0.
．． A 1 mm disk was formed, and this disk was fired for 2 hours at the firing temperature shown in Table 9 to obtain a porcelain disk.

Next, silver electrodes were baked on both main surfaces of the obtained porcelain disk,
A DC voltage of 3 to 4 KV/n+m was applied between both electrodes at 80° C. to perform polarization treatment for 30 minutes to obtain porcelain piezoelectric samples (sample numbers 66 to 63).

For each sample, the relative dielectric constant (εr) and the electromechanical coupling coefficient (Kp) of the spreading vibration of the disk were measured, and the results are shown in Table 8.

In addition, Table 9 shows, as comparative examples, a sample (sample number 65) in which the subcomponents Pb3O4 and GeO2 were not added;
BaO,92Ca0. oθ)'rio3-o, 2w
t%MnO2 calcined powder with PbO-B2O as an accessory component
3.5 A sample prepared in the same manner as in Example 9 with the addition of 1 wt% of i02-based galame vitrification (sample number 69), and (Ba□, 92Cao, o3)'r;o3-o,
2wt% MnO3 calcined powder with Na2O as a subcomponent.
A sample prepared in the same manner as in Example 9 by adding wt% of B2O3/SiO□-based galame glass compound (sample number 70)
) were also measured in the same way, and the results are also shown.

(Leaving space below) As is clear from the results in Tables 1 to 9, the ferroelectric ceramic composition according to the present invention contains no subcomponents. It can be sintered at a sintering temperature 100 to 400 degrees Celsius lower than that of ferroelectric porcelain that does not contain ferroelectric porcelain, and exhibits an electromechanical coupling coefficient and relative permittivity that are approximately the same.

Furthermore, the ferroelectric ceramic composition according to the present invention has xPbO.
Pb3O4 and GaO2 as subcomponents added to have a molar ratio of yGe02 (x=1 to 6.y=1-3)
The electromechanical coupling coefficient and dielectric constant decrease with the increase in the amount of PbO・B2O3
2-based glass compounds and Na2O・B2O3・S 1-02
It is significantly less than when a glass compound is added.

(Example 10) First, Pb3O4, TiO2, ZrO2, M
Using nO2 and Nb2O5, 0,1Pb(Mn,3Nb273)03-0.52Pb
Weighed so as to obtain ferroelectric porcelain having a composition of Tt03-0.38PbZr03, and added P as a raw material for the subcomponent.
Using b3O4 and GeO2, Pb3O4 is converted to Pbo, GeO2 is converted to GeO2, and the general formula: *PbO・
Let the molar ratio of yGe02 be x=5. y = 3, and added at the mixing ratio shown in Table 10 to the main ingredients.

A calcined powder was obtained in the same manner as in Example 3 except that it was added.

Next, 2 to 3 wt% of an organic binder is added to the obtained calcined powder.
In addition, after being layered for 20 hours, it was granulated and press-molded to form a square plate, and this square plate was fired for 2 hours at the firing temperature shown in Table 10 to form a square plate with a - side of 5 mm and a thickness of 0. A porcelain square plate of 5 mm was obtained.

Next, silver electrodes were baked on both main surfaces of the obtained porcelain square plate,
A DC voltage of 3 to 4 KV/mm was applied between both electrodes at 80°C, and polarization treatment was performed for 30 minutes to obtain oscillator (resonator) samples (sample numbers 71 to 73) polarized in the vertical direction in the plane. )
I got it.

Each sample was connected to the oscillation circuit shown in FIG. 1, and oscillated at an oscillation frequency of 455 K)Iz. In the figure, 1 is an oscillator, I
C1 is an inverting amplifier, R4 is a resistor, and CL1 and Cu2 are capacitors. Each sample was operated with this oscillation circuit 100 times, and Table 10 shows the number of times the oscillation frequency changed from 455 KHz to 4.5 MHz out of the 100 times.

Note that sample numbers 71, 73, 75, and 77 in Table 10 are outside the scope of the present invention.

(Left below) Table 10 As is clear from the results in Table 10, no abnormal oscillation was observed in the oscillator using the ferroelectric ceramic composition according to the present invention, but it does not contain subcomponents. In the case outside the scope of the present invention, as shown in FIG. 2, spurious vibrations due to thickness longitudinal vibration occurred and abnormal light i around 4.5 MHz was observed.

This is because the subcomponents added to ferroelectric porcelain not only increase the strength of grain boundaries, but also reduce spurious thickness longitudinal vibrations when used as an oscillator without adversely affecting the main vibration. It is believed that there is.

Therefore, the ferroelectric ceramic composition according to the present invention is advantageous in damping vibrations higher than the fundamental oscillation frequency. Incidentally, such an effect was observed not only in oscillators that utilize spread vibration, but also in ferroelectric ceramic compositions used as materials for oscillators and the like that utilize edge vibration.

(Example 11) First, as raw materials Pb3O4, Fe2O3, Nb2O5
and WO3, 0.70Pb(Fe172Nb172)03-0.30
Weighed so as to obtain a ferroelectric ceramic having a composition of Pb(Fe2z3L73)03, and added Pb as a raw material for the subcomponent.
Using 3O4 and GeO2, Pb3O4 is converted to Pbo, GeO2 is converted to GeO2, and the general formula: xPbo・
Let the molar ratio of yGe02 be x=5. Set y to 3 and add to the main ingredients at the mixing ratio shown in Table 11.

A calcined powder was obtained in the same manner as in Example 3 except that it was added.

Next, 2 to 3 wt of organic binder is added to the obtained calcined powder.
% and layered for 20 hours to form granules, press-molded to form a disk, which was fired at the firing temperature shown in Table 11 for 2 hours to form a 10 mm diameter, 1.0 mm thick disk. A porcelain disc was obtained.

Next, silver electrodes were baked on both main surfaces of the obtained porcelain disk to obtain capacitor samples (sample numbers 79 to 84).

For each sample, relative dielectric constant (εr) and bending strength (k
g/cm was measured and the results are shown in Table 11.

Note that sample numbers 79, 81, and 83 are outside the scope of the present invention.

(Example 12) First, Pb3O4, ZnO, Nb2O5, F as raw materials
e2O3, WO3 and 0.16Pb (Zn
1/3Nb273) 03-0, 48Pb (Fe1/2
Nb17z) 03-0.36Pb(Fe2/5Wt7
3) A calcined powder was obtained in the same manner as in Example 8 by weighing so as to obtain a ferroelectric ceramic having a composition of 03.

Next, 2 to 3 wt of organic binder is added to the obtained calcined powder.
After layering and granulating χ for 20 hours, press molding was performed to form a disk, which was then fired for 2 hours at the firing temperature shown in Table 12 to give a diameter of 10 mI! A porcelain disk with a thickness of 1.0 mm was obtained.

Next, silver electrodes were baked on both main surfaces of the obtained porcelain disk to obtain capacitor samples (sample numbers 85 to 83).

For each sample, relative dielectric constant (εr) and bending strength (k
glc, l112) was measured and the results are shown in Table 12.

Note that sample number 85.87 in Table 12 is outside the scope of the present invention.

(Left below) As is clear from the results in Tables 11 and 12, for composite perovskite capacitor materials containing lead oxide, Pb oxides are converted to PbO, and Ge oxides are converted to GeO2. , the molar ratio of PbO and GeO2 is expressed by the general formula: xPbO・yGe02 (x=1-6. y=1-3)
By adding and containing these as subcomponents in an amount of 0.01 to 30% by weight, the dielectric constant and the bending strength can be improved.

(Effect of the invention) As is clear from the above explanation, according to the present invention, 85
Since ferroelectric porcelain can be sintered at a low firing temperature of 0 to 1000° C. and has a large electromechanical coupling coefficient and a large dielectric constant, piezoelectric elements with high energy conversion efficiency can be manufactured.

In addition, since the sintering temperature is low, integral sintering with a metal substrate is possible, which not only makes it possible to manufacture integrally sintered buzzers and electrostrictive elements such as bimorphs, but also eliminates the need to adjust the PbO atmosphere during firing. Excellent effects can be obtained, such as prolonging the life of boxes and kilns, and saving energy.

Furthermore, the bending strength is not reduced, and when used in an oscillator, generation of spurious waves can be prevented.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an oscillation circuit including a ceramic oscillator, and FIG. 2 is a diagram showing the spread vibration, which is the main vibration, and the thickness longitudinal vibration, which is the spurious vibration, in the oscillation circuit of FIG. 1. 1...Ceramic resonator IC1...Inverting amplifier R1...Resistors CLl, Cl3...Capacitors.

Claims (3)

[Claims] (1) Pb oxide and Ge oxide are added as subcomponents to ferroelectric ceramic, which is the main component, and Pb oxide is converted to PbO, and Ge oxide is converted to Ge.
In terms of O_2, when the molar ratio of PbO and GeO_2 is expressed as the general formula: xPbO・yGeO_2, x and y are x = 1 to 6 and y = 1 to 3, respectively, and the added and contained PbO and GeO_2 A ferroelectric ceramic composition characterized in that the total amount of is 0.01 to 30% by weight. (2) Consisting of a plate-shaped ferroelectric porcelain plate made of the ferroelectric porcelain composition according to claim (1), and electrodes formed on both main surfaces of the ferroelectric porcelain plate. Features a piezoelectric element. (3) A thick film paste containing a calcined powder made of the ferroelectric ceramic composition according to claim (1) is applied onto a metal substrate and baked into an integrated product, and is formed by this baking. A piezoelectric element characterized by having electrodes formed on the surface of a ferroelectric ceramic layer.