JP2504176B2 - Ferroelectric composition containing lead oxide and piezoelectric element using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a lead oxide-containing ferroelectric ceramic composition, and in particular, a lead oxide-containing ferroelectric ceramic having a large electromechanical coupling coefficient and capable of low temperature sintering. The present invention relates to a composition and a piezoelectric element using the same.

(Prior Art) Generally, porcelain piezoelectric materials are applied to piezoelectric elements such as filters, piezoelectric buzzers, and bimorphs because they are excellent in workability, mass productivity, and characteristics. As this type of piezoelectric material, lead titanate-based ferroelectric porcelain, lead zirconate titanate-based ferroelectric porcelain, and barium titanate-based ferroelectric porcelain are put to practical use.

However, these ferroelectric porcelains have a sintering temperature of 1100 ° C.
Due to the above high temperatures, a composite integrated with a substrate such as a metal plate could not be obtained.

In addition, when the ferroelectric porcelain is a lead oxide-containing ferroelectric porcelain, since Pb is contained as a component thereof, part of the PbO is easily lost from the composition during firing, so that the reproducibility and uniformity of the characteristics can be improved. It was difficult to achieve.

Furthermore, these ferroelectric porcelains are used as oscillators (resonators).
When it is used as a filter, the electromechanical coupling coefficient is large, so that the bandwidth of the filter is not wide and partly lacks stability in use.

Therefore, in JP-A-58-204579, by adding 1 to 30 wt% of a silicate glass compound, a soda glass compound, or a lead glass compound to a piezoelectric ceramic,
A compound-containing piezoelectric ceramic has been proposed which has a narrow filter bandwidth and improved stability.

(Problems of Prior Art) However, the piezoelectric ceramic containing a glass compound has a problem that the energy conversion efficiency is lowered because the electromechanical coupling coefficient is remarkably lowered by the addition of the glass compound.

In addition, when the conventional ferroelectric ceramic composition is applied to a ceramic resonator in a spreading vibration mode, there is a problem that abnormal oscillation occurs due to spurious vibration that is thickness longitudinal vibration.

(Means for Solving Problems) The lead oxide-containing ferroelectric ceramic composition of the present invention is a Pb oxide and a Ge oxide with respect to the lead oxide-containing ferroelectric ceramics as the main component. Is added to each, and Pb oxide is added to Pb
In terms of O, converting the oxides of Ge to GeO _2, the general formula the molar ratio of PbO and GeO _2: when expressed as xPbO · yGeO ₂ x, y, respectively x = 1~6, y = 1~ 3 and the total amount of PbO and GeO ₂ added and contained is 0.01 to 30% by weight.

Further, the piezoelectric element of the present invention, a plate-shaped ferroelectric porcelain plate made of the above-mentioned lead oxide-containing ferroelectric porcelain composition, and electrodes formed on both main surfaces of the ferroelectric porcelain plate, It is characterized by consisting of.

Furthermore, in the piezoelectric element of the present invention, a thick film paste containing a calcined powder made of the above-described lead oxide-containing ferroelectric ceramic composition is applied on a metal substrate and baked to be integrated, and this baking is performed. An electrode is formed on the surface of the ferroelectric porcelain layer formed by.

Ferroelectric porcelain which is the main component of the lead oxide-containing ferroelectric porcelain composition of the present invention includes lead titanate-based ferroelectric porcelain, lead zirconate titanate-based ferroelectric porcelain, and lead metaniobate-based ferroelectric porcelain. Representative examples include dielectric porcelain and lead-containing composite perovskite porcelain, but the present invention is not limited to these.

The lead titanate-based ferroelectric porcelain means intrinsic and modified lead titanate, and modified lead titanate includes simple oxides such as Cr ₂ O ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , and Bi _2. Metal oxides such as O ₃ and MnO ₂ added, Pb sites containing Mg, Ca, Sr, Ba and La ₂ O ₃ , Nd
₂ O ₃ , Y ₂ O ₃ substituted with rare earths, and a two-component system in which a part of PbTiO ₃ is substituted with at least one complex perovskite compound represented by the following general formulas (I) to (VI), Includes ternary and other multi-component porcelain or combinations of these.

Further, the lead zirconate titanate-based ferroelectric porcelain means intrinsic and modified lead zirconate titanate, and modified lead zirconate titanate includes Pb (Ti, Zr) O ₃ and Cr ₂ O ₃ , Nb ₂ O ₅ , T
Metal oxides such as a ₂ O ₅ , Bi ₂ O ₃ and MnO ₂ added, Pb
The site is replaced with alkaline earth metals such as Mg, Ca, Sr, Ba and La ₂ O ₃ , Nd.
Substituted with rare earth such as ₂ O ₃ , Y ₂ O ₃ and Pb (Ti, Zr)
Includes three-component, four-component and other multi-component porcelains in which a part of O ₃ is substituted with at least one compound perovskite compound represented by the following general formulas (I) to (VI), or a combination thereof. Be done.

Furthermore, the lead metaniobate-based ferroelectric porcelain means intrinsic and modified lead metaniobate, and modified lead metaniobate includes simple oxides such as Cr ₂ O ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , and Bi ₂ O ₃ ,
Metal oxides such as MnO ₂ added, Pb part of Mg, Ca,
Substituted with an alkaline earth metal such as Sr or Ba or a rare earth such as La ₂ O ₃ , Nd ₂ O ₃ or Y ₂ O ₃ , and lead metaniobate are represented by the following general formulas (I) to (VI). Included are two-component, three-component and other multi-component porcelains added with at least one compound perovskite compound.

The lead-containing composite perovskite-based porcelain contains, in addition to the lead-containing composite perovskite compounds represented by the general formulas (I) to (VI) described below, two or more of them or at least one of them and another composite perovskite compound. Consisting of 2
Includes component-based, two-component, and other multi-component porcelain. For example, one-component system such as Pb (Fe _2/3 W _1/3 ) O ₃ and Pb (Fe _1/2 Nb _1/2 ) O ₃ , Pb (Fe _1/2 Nb _1/2 ) O ₃ −Pb Binary system such as (Fe _2/3 W _1/3 ) O ₃ , Pb (Mn _1/3 Nb _2/3 ) O ₃ −Pb (Fe _1/2 Nb _1/2 ) O ₃ − Pb (Fe _{2 / 3} W _1/3 ) O ₃ , Pb (Zn _1/3 Nb _2/3 ) O ₃ −Pb (Fe _1/2 Nb _1/2 ) O ₃ − Pb (Fe _2/3 W _1/3 ) O ternary complex perovskite compounds such as _3.

A typical compound perovskite compound is a compound represented by the general formula (I): A ²⁺ (B ²⁺ _1/3 B ⁵⁺ _2/3 ) O ₃ , for example, Ba (Zn _1/3 Nb _2/3 ) O ₃ , Ba (Cd _1/3 Nb _2/3 ) O ₃ , Ba (Mg _1/3 Nb _2/3 ) O ₃ , Sr (Cd _1/3 Nb _2/3 ) O ₃ , Pb (Mg _1/3 Nb _2/3 ) O ₃ , Pb (Ni _1/3 Nb _2/3 ) O ₃ , Pb (Mn _1/3 Nb _2/3 ) O ₃ , Pb (Mg _1/3 Ta _{2 / 3} ) O ₃ , Pb (Ni _1/3 Ta _2/3 ) O ₃ , Pb (Cd _1/3 Nb _2/3 ) O ₃ ; General formula (II): A ²⁺ (B ³⁺ _1/2 Compounds represented by B ⁵⁺ _1/2 ) O ₃ , such as Ba (Fe _1/2 Nb _1/2 ) O ₃ , Ba (Sc _1/2 Nb _1/2 ) O ₃ , Ca (Cr _1/2 Nb _1/2 ) O ₃ , Pb (Fe _1/2 Nb _1/2 ) O ₃ , Pb (Fe _1/2 Ta _1/2 ) O ₃ , Pb (Sc _1/2 Nb _1/2 ) O ₃ , Pb (Sc _1/2 Ta _1/2 ) O ₃ , Pb (Yb _1/2 Nb _1/2 ) O ₃ , Pb (Yb _1/2 Ta _1/2 ) O ₃ , Pb (Lu _1/2 Nb _{1 / 2} ) O ₃ , Pb (In _1/2 Nb _1/2 ) O ₃ ; general formula (III): a compound represented by A ²⁺ (B ²⁺ _1/2 B ⁶⁺ _1/2 ) O ₃ , For example, Pb (Cd _1/2 W _1/2 ) O ₃ , Pb (Mn _1/2 W _1/2 ) O ₃ , Pb (Zn _1/2 W _1/2 ) O ₃ , Pb (Mg _1/2 W _1/2 ) O ₃ , Pb (Co _1/2 W _1/2 ) O ₃ , Pb (Ni _1/2 W _1/2 ) O ₃ , Pb (Mg _1/2 Te _1/2 ) O ₃ , Pb (Mn _1/2 Te _1/2 ) O ₃ , Pb (Co _1/2 Te _1/2 ) O ₃ ; general formula (IV): a compound represented by A ²⁺ (B ³⁺ _2/3 B ⁶⁺ _1/3 ) O ₃ , for example, Pb (Fe _{2 / 3} W _1/3 ) O ₃ ; a compound represented by the general formula (V): A ²⁺ (B ²⁺ _1/2 B ⁴⁺ _1/2 ) O ₃ , for example, Pb (Sn _1/2 Sb _{1 / 2} ) O ₃ , La (Mg _1/2 Ti _1/2 ) O ₃ , Nb (Mg _1/2 Ti _1/2 ) O ₃ ; and general formula (VI): A ⁺ _1/2 A ^{3 +} _{1 / 2} ) B ⁴⁺ O ₃ compound, for example, (Na _1/2 La _1/2 ) TiO ₃ , (K _1/2 La _1/2 ) TiO ₃ , (Na _1/2 Ce _1/2 ) TiO ₃ , (Na _1/2 Nd _1/2 ) TiO ₃ , (Nd _1/2 Bi _1/2 ) TiO ₃ , (K _1/2 Bi _1/2 ) TiO _{3 and the} like.

(Function) The present invention is applied to a ferroelectric ceramic such as a lead titanate-based, lead titanate zirconate-based, lead metaniobate-based, and lead-containing composite perovskite-based ferroelectric porcelain as a sub-component containing PbO as a subcomponent. Converted into GeO ₂ and converted into GeO ₂ and converted into PbO and GeO ₂
When the molar ratio of xPbO · yGeO ₂ is expressed as xPbO · yGeO ₂ , when x and y are added and contained so that x = 1 to 6 and y = 1 to 3 respectively, and fired, liquid phase sintering causes heterophase ceramics. By producing bulk, lead titanate-based
Enables sintering at a low temperature of 850 to 1000 ° C without lowering the electromechanical coupling coefficient originally possessed by ferroelectric porcelains such as lead zirconate titanate, lead metaniobate and lead-containing composite perovskite. As a result, it is possible to perform integral sintering with a metal substrate, which has been impossible in the past.

Further, the lead oxide-containing ferroelectric porcelain according to the present invention can be molded or processed by any method such as a screen printing method, a coating method, a press molding method, an extrusion molding method, a sheet molding method and a hot press method. By printing the thick film paste on the surface of the metal substrate by the screen printing method and sintering the paste, an integrally sintered piezoelectric element can be obtained.

Pb oxide and Ge oxide are added and contained as sub-components, respectively, and the Pb oxide is converted to PbO.
_When converted to ₂ , the molar ratio of PbO and GeO ₂ is represented by the general formula: xPbO · yGeO ₂ , where x and y are x = 1 to 6 and y = 1 to 3, respectively, and PbO added and contained. And the total amount of GeO ₂ is 0.01-3
If the amount is less than 0.01% by weight, the effect is not so expected, and if it exceeds 30% by weight, the sintering temperature becomes low, but the decrease in the electromechanical coupling coefficient becomes conspicuous. Is. Particularly, when the total amount of PbO and GeO ₂ added and contained is 0.1 to 10% by weight, a lead oxide-containing ferroelectric ceramic composition having a low sintering temperature and a large electromechanical coupling coefficient can be obtained. . In addition, the value of x, y is x = 1 to 6, y = 1
The reason for setting ~ 3 is that Pb is used to enable sintering at low temperature.
Oxides and Ge oxides whose melting points are below 850 ° C were selected. Furthermore, the lead oxide-containing ferroelectric ceramic composition according to the present invention exhibits high bending strength.
It is considered that this is because a chemical bonding force is generated between the lead oxide in the main component and the lead oxide in the sub-component, and the mechanical strength at the grain boundary is increased.

 Hereinafter, examples of the present invention will be described.

Example 1 Pb ₃ O ₄ , TiO ₂ , ZrO ₂ and Nb ₂ O ₅ were used as raw materials, and these were used as a main component having a composition of PbTi _0.48 Zr _0.52 O ₃ 1.0 wt% Nb ₂ O ₅ together weighed as sexual porcelain is obtained, using a Pb ₃ O _4, and GeO ₂ as subcomponent materials, Pb ₃
O ₄ was converted to PbO, converting the GeO ₂ into GeO _2, the general formula the molar ratio of PbO and GeO _2: when expressed as xPbO · yGeO ₂ x, y, respectively x = 1~6, y = 1 In order to obtain ~ 3, it was added and contained in the ratio shown in Table 1, and wet mixed for 20 hours to obtain a mixture.

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

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

Next, the prepared thick film paste was screen-printed as a circle having a diameter of 18 mm on a substrate made of a heat-resistant metal having a diameter of 20 mm and a thickness of 0.1 mm, for example, a Ni-Cr-based metal, and then fired as shown in Table 1. It was fired at a temperature to obtain a 50 μm thick integrally sintered type composite body.

Next, a silver electrode is formed on the ceramic surface of the obtained composite by a baking method, and the silver electrode is formed between the silver electrode and the metal substrate.
A DC voltage of 3 to 4 KV / mm was applied at 80 ° C. and polarization treatment was performed for 30 minutes to obtain a sample of a porcelain piezoelectric material (sample numbers 1 to 6).

For each sample, the relative permittivity (εr) and the electromechanical coupling coefficient (Kv) of the flexural vibration of the disk were measured, and the results are shown in Table 1.

In Table 1, as a comparative example, a sample (Sample No. 7) in which Pb ₃ O ₄ and GeO ₂ as secondary components were not added, PbTi _0.48
Zr _0.52 O ₃ −1.0 wt% Nb ₂ O ₅ calcined powder with PbO
・ Sample (Sample No. 8) prepared using a thick film paste prepared by adding 0.1 wt% of B ₂ O ₃・ SiO ₂ glass compound, and PbTi _0.48 Zr _0.52 O ₃ -1.0 wt% Nb ₂ O _The same applies to the sample (Sample No. 9) prepared by using the thick film paste prepared by adding 5 wt% of Na ₂ O ・ B ₂ O ₃・ SiO ₂ glass compound as a subcomponent to the calcined powder of 5 The measurement was performed and the results are also shown.

(Example 2) First, Pb ₃ O ₄ and GeO ₂ were used as raw materials for the subcomponents, and Pb ₃ O ₄ was used.
The terms of PbO, converting the GeO ₂ into GeO _2, the general formula the molar ratio of PbO and GeO _2: when expressed as xPbO · yGeO ₂ x, with y is respectively x = 5, y = 3, A calcined powder was obtained in the same manner as in Example 1 except that the main component was added and contained at the compounding ratio shown in Table 2.

Next, 2-3 wt% of an organic binder is added to the obtained calcined powder, and the mixture is mixed for 20 hours, granulated, and press-molded for 1-1.
A square plate of 5 mm x 10 mm x 20 mm is formed, and this square plate is fired at the temperature shown in Table 2 for 2 hours to obtain a sample of a porcelain square plate (Sample No. 10
~ 16) was obtained.

3-point bending test method for each sample (distance between supporting points: 11 m
The bending strength (kg / cm ² ) was measured by m) and the results are shown in Table 2.

 The sample numbers 10, 13, 16 are out of the scope of the present invention.

(Example 3) First, using a _{Pb 3 O 4, TiO 2,} ZrO 2, SnO 2, Sb 2 O 3 and MnO ₂ as a raw _{material, 0.05Pb (Sn 1/2 Sb 1/2)} O 3 -0.47PbTiO ₃
-0.48PbZrO ₃ were weighed so as ferroelectric ceramics having a composition of -0.7wt% MnO ₂ is obtained, except that the calcining temperature was 900 ° C., to obtain a calcined powder in the same manner as in Example 1 . Note that Table 3 shows the molar ratio of PbO and GeO _2, and PbO and amount to the total amount of the main component of the GeO ₂ a (wt%).

Next, an organic binder is added to the obtained calcined powder in an amount of 6 to 7% by weight.
In addition, after mixing for 20 hours, a sheet was formed by the doctor blade method and punched to form a disc having a diameter of 20 mm and a thickness of 0.1 mm, and the disc was fired at the firing temperature shown in Table 3 for 2 hours. I got a porcelain disc. Next, silver electrodes were baked on both main surfaces of the obtained porcelain disk, a DC voltage of 3-4 KV / mm was applied between both electrodes at 80 ° C, and polarization treatment was performed for 30 minutes to obtain a porcelain piezoelectric sample. (Sample Nos. 18 to 22) were obtained.

The relative permittivity (εr) and the electromechanical coupling coefficient (Kp) of the expansion vibration of the disk were measured for each sample, and the results are shown in Table 3.

In addition, in Table 3, as a comparative example, Pb ₃ O ₄ and G which are sub-components are included.
Sample without addition of eO ₂ (Sample No. 17), 0.05Pb (Sn
_1/2 Sb _1/2 ) O ₃ −0.47PbTiO ₃ −0.48PbZrO ₃ −0.7 wt% To the calcined powder of MnO ₂ , 5 wt% of PbO ・ B ₂ O ₃・ SiO ₂ glass compound was added as an accessory component. And a sample prepared in the same manner as in Example 3 (Sample No. 24), and 0.05Pb (Sn _1/2 Sb _1/2 ) O ₃ −0.47
Prepared in the same manner as _{PbTiO 3 -0.48PbZrO 3 -0.7wt% MnO Na} 2 as calcined powder subcomponent ₂ O · B ₂ O ₃ · a SiO ₂ -based glass compound by adding 0.1 wt% Example 3 Sample (Sample No. 2
The same measurement was performed for 5), and the results are also shown.

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

Example 4 First, Pb ₃ O ₄ and GeO ₂ were used as raw materials for the subcomponents, and Pb ₃ O ₄ was used.
The terms of PbO, converting the GeO ₂ into GeO _2, the general formula the molar ratio of PbO and GeO _2: when expressed as xPbO · yGeO ₂ x, with y is respectively x = 5, y = 3, After the calcined powder was obtained in the same manner as in Example 3 except that the main component was added and contained at the compounding ratio shown in Table 4, the porcelain angle was obtained in the same manner as in Example 2. Plate samples (Sample Nos. 26-32) were obtained.

3-point bending test method for each sample (distance between supporting points: 11 m
The bending strength (kg / cm ² ) was measured by m), and the results are shown in Table 4 together with the firing temperature.

 The sample numbers 26, 29 and 32 are out of the scope of the present invention.

Example 5 First, as raw materials, Pb ₃ O ₄ , TiO ₂ , ZrO ₂ , MnO ₂ and Nb _{2 were used.}
Using O ₅ 0.05Pb (Mn _1/3 Nb _2/3 ) O ₃ −0.45PbTiO ₃ −0.50PbZ
A calcined powder was obtained in the same manner as in Example 3 except that the ferroelectric porcelain having the composition of rO ₃ was weighed so as to obtain the porcelain. Note that Table 5, the molar ratio of PbO and GeO _2, and PbO and GeO ₂
And the addition amount (wt%) with respect to the main component of the total amount.

Next, the obtained calcined powder is mixed with an organic binder in an amount of 2 to 3% by weight.
In addition, after mixing for 20 hours, granulate, press mold and
A disc having a thickness of 15 mm and a thickness of 1 mm was formed, and the disc was fired at the firing temperature shown in Table 5 for 2 hours to obtain a porcelain disc.

Next, 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 both electrodes at 80 ° C to perform polarization treatment for 30 minutes to obtain a porcelain piezoelectric material. Sample (Sample number
34-38) was obtained.

With respect to each sample, the relative permittivity (εr) and the electromechanical coupling coefficient (Kp) of the expansion vibration of the disk were measured, and the results are shown in Table 5.

In Table 5, as a comparative example, Pb ₃ O ₄ and G which are sub-components are used.
Sample without addition of eO ₂ (Sample No. 33), 0.05Pb (Mn
_1/3 Nb _2/3 ) O ₃ −0.45PbTiO ₃ −0.50PbZrO ₃ calcination powder with PbO / B ₂ O ₃ / SiO ₂ system glass compound 0.1 wt% added as a sub-component Samples prepared in the same way (sample number
40), and 0.05Pb (Mn _1/3 Nb _2/3 ) O ₃ −0.45PbTiO ₃ −0.50PbZrO ₃ calcined powder with Na ₂ O ・ B ₂ O ₃・ SiO ₂ based glass compound as an accessory component.
The same measurement was performed on a sample (Sample No. 41) manufactured by adding 5 wt% in the same manner as in Example 5, and the results are also shown.

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

Example 6 First, in Example 5, 0.05Pb (Mn _1/3 Nb _2/3 ) O ₃ −0.45PbTiO ₃
Together weighed so as to have the composition of -0.50PbZrO _3, using a Pb ₃ O ₄ and GeO ₂ as a subcomponent material, converts the Pb ₃ O ₄ to PbO, converting the GeO ₂ into GeO _2, the general formula The molar ratio of: xPbO · yGeO ₂ is x = 5, y = 3, and
Except that it was added and contained at the compounding ratio shown in Table 6,
After obtaining the calcined powder in the same manner as in Example 5, samples of the porcelain square plates (Sample Nos. 42 to 48) were obtained in the same manner as in Example 2.

3-point bending test method for each sample (distance between supporting points: 11 m
The bending strength (kg / cm ² ) was measured by m), and the results are shown in Table 6 together with the firing temperature.

 Note that sample numbers 42, 45, and 48 are outside the scope of the present invention.

Example 7 First, a ferroelectric ceramic having a composition of Pb _0.85 La _0.10 TiO ₃ −0.7 wt% MnO ₂ is obtained by using Pb ₃ O ₄ , TiO ₂ , La ₂ O ₃ and MnO ₂ as raw materials. The calcination temperature at 950 ℃
A calcinated powder was obtained in the same manner as in Example 1 except that
Table 7 shows the molar ratio of PbO and GeO ₂ , and PbO and GeO _2.
The addition amount (wt%) to the main component of the total amount with O ₂ is shown.

Next, the obtained calcined powder is mixed with 4 to 5 wt% of an organic binder.
% And mixed for 20 hours, then extrusion-molded to obtain a green sheet, which is punched to form a disc having a diameter of 10 mm and a thickness of 0.5 mm, and the disc is baked at a firing temperature shown in Table 7. It was fired for a time to obtain a porcelain disc.

Next, silver electrodes were baked on both main surfaces of the obtained porcelain disk, and 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 a porcelain piezoelectric material. Sample (Sample number
50-54) was obtained.

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

In Table 7, as comparative examples, Pb ₃ O ₄ and G which are sub-components are used.
Sample without eO ₂ addition (Sample No. 49), Pb _0.85 La
_0.10 TiO ₃ −0.7 wt% MnO ₂ calcined powder with PbO
Example 7 in which 1 wt% of B ₂ O ₃ .SiO ₂ glass compound was added
Sample (Sample No. 56) prepared in the same manner as in, and Pb
Sample prepared in the same manner as in Example 7 by adding 10 wt% of Na ₂ O · B ₂ O ₃ · SiO ₂ based glass compound as a subcomponent to a calcined powder of _0.85 La _0.10 TiO ₃ −0.7 wt% MnO _2. The same measurement was performed for (Sample No. 57), and the results are also shown.

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

(Example 8) First, the weighed main component so as to have the composition of _{Pb 0.85 La 0.10 TiO 3 -0.7wt%} MnO 2 in Example 7, the Pb ₃ O ₄ and GeO ₂ as a subcomponent material Using Pb ₃ O ₄ converted to PbO, GeO
₂ is converted to GeO ₂ and the molar ratio of the general formula: xPbO · yGeO ₂ is x
= 5, 5 and y = 3, and samples (sample numbers 58 to 64) of porcelain square plates were obtained in the same manner as in Example 2 except that the compounding ratios shown in Table 8 were added and contained. .

3-point bending test method for each sample (distance between supporting points: 11 m
The bending strength (kg / cm ² ) was measured by m), and the results are shown in Table 8 together with the firing temperature.

 The sample numbers 58, 61 and 64 are out of the scope of the present invention.

As is clear from the results of Tables 1 to 8, the lead oxide-containing ferroelectric ceramic composition according to the present invention is 100 ° C. to 400 ° C. higher than the lead oxide-containing ferroelectric ceramic containing no subcomponents. It can be sintered at a firing temperature as low as 0 ° C., and exhibits almost the same electromechanical coupling coefficient and relative permittivity.

Further, the lead oxide-containing ferroelectric ceramic composition according to the present invention is Pb _{3 which} is an auxiliary component added so as to have a molar ratio of xPbO · yGeO ₂ (x = 1 to 6, y = 1 to 3). The electromechanical coupling coefficient and the relative permittivity decrease with the increase of the amounts of O ₄ and GeO ₂ , but the degree of the decrease depends on the amount of PbO ・ B ₂ O ₃・ SiO ₂ glass compound or Na ₂ O ・ B ₂ O ₃・. Remarkably less than in the case of adding a SiO ₂ glass compound.

Example 9 First, as raw materials, Pb ₃ O ₄ , TiO ₂ , ZrO ₂ , MnO ₂ and Nb _{2 were used.}
Using O ₅ , weighed so as to obtain a ferroelectric porcelain having a composition of 0.1Pb (Mn _1/3 Nb _2/3 ) O ₃ −0.52PbTiO ₃ −0.38PbZrO ₃ , and used Pb ₃ as a raw material for the subcomponent. using O ₄ and GeO _2, converts the Pb ₃ O ₄ to PbO, converting the GeO ₂ into GeO _2, the general formula: the xPbO · yGeO molar ratio of ₂ with an x = 5, y = 3, the main 9th component
A calcined powder was obtained in the same manner as in Example 3 except that the compounding ratios shown in the table were added and contained.

Next, the obtained calcined powder is mixed with an organic binder in an amount of 2 to 3% by weight.
In addition, after mixing for 20 hours, it is granulated, press-formed to form a square plate, and this square plate is baked at the baking temperature shown in Table 9 for 2 hours to obtain a porcelain piece with a side of 5 mm and a thickness of 0.5 mm. I got a square plate.

Next, silver electrodes are baked on both main surfaces of the obtained porcelain square plate, a DC voltage of 3 to 4 KV / mm is applied between both electrodes at 80 ° C, and polarization treatment is performed for 30 minutes to make it perpendicular to the plane. Samples (sample numbers 71 to 78) of oscillators (resonators) polarized in the directions were obtained.

Each sample was connected to the oscillation circuit of FIG. 1 and oscillated at an oscillation frequency of 455 KHz. In the figure, 1 is an oscillator, IC ₁ is an inverting amplifier, R ₁ is a resistor, and CL ₁ and CL ₂ are capacitors. Then, for each sample, operate the oscillator circuit 100 times, and the oscillation frequency is 455KHz to 4.5MHz out of 100 times.
Table 9 shows the number of occurrences of abnormal oscillation in the.

The sample numbers 71, 73, 75, 77 in Table 9 are out of the scope of the present invention.

As is clear from the results shown in Table 9, in the oscillator using the lead oxide-containing ferroelectric ceramic composition according to the present invention, no abnormal oscillation was observed, but according to the present invention containing no subcomponents. Outside the range, as shown in Fig. 2, spurious of thickness longitudinal vibration occurred and abnormal oscillation near 4.5MHz was observed.

This is because when the accessory component added to the ferroelectric porcelain not only enhances the strength of the crystal grain boundary, but is also used as an oscillator,
It is considered that this is to reduce the spurious of the thickness longitudinal vibration without adversely affecting the main vibration.

Therefore, the lead oxide-containing ferroelectric ceramic composition according to the present invention is advantageous for damping vibrations higher than the fundamental oscillation frequency. It should be noted that such an effect was observed not only in the oscillator using the spreading vibration but also in the lead oxide-containing ferroelectric ceramic composition as a material of the oscillator using the side vibration.

(Example 10) First, Pb ₃ O ₄ , Fe ₂ O ₃ , Nb ₂ O ₅ and WO ₃ were used as raw materials, and 0.70Pb (Fe _1/2 Nb _1/2 ) O ₃ −0.30Pb (Fe _{2 / 3} W _1/3 ) O ₃ was weighed so as to obtain a ferroelectric porcelain, Pb ₃ O ₄ and GeO ₂ were used as raw materials for the subcomponents, and Pb ₃ O ₄ was converted to PbO.
Converting eO ₂ to GeO ₂ , the molar ratio of the general formula: xPbO · yGeO ₂ is set to x = 5, y = 3, and added to the main component in the compounding ratio as shown in Table 10, A calcined powder was obtained in the same manner as in Example 3 except that the calcined powder was added.

Next, add 2-3 wt% of organic binder to the obtained calcined powder.
%, Mixed and granulated for 20 hours, press-molded to form a disk, which was then baked at the baking temperature shown in Table 10 for 2 hours to obtain a porcelain disk with a diameter of 10 mm and a thickness of 1.0 mm. Got

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

The relative permittivity (εr) and bending strength (kg / cm ² ) of each sample were measured, and the results are shown in Table 10.

 The sample numbers 79, 81 and 83 are out of the scope of the present invention.

(Example 11) First, Pb ₃ O _4, ZnO, and _{Nb 2 O 5, Fe 2 O} 3, WO 3 is used as a raw material, these _{0.16Pb (Zn 1/3 Nb 2/3) O} 3 -0.48Pb (Fe _1/2 Nb
_{1/2) O 3 -0.36Pb (Fe 2/3} W 1/3) were weighed so as ferroelectric ceramics having a composition of O ₃ is obtained, to obtain a calcined powder in the same manner as in Example 3 .

Next, add 2-3 wt% of organic binder to the obtained calcined powder.
%, Mixed and granulated for 20 hours, press-molded to form a disc, which was then fired at the firing temperature shown in Table 11 for 2 hours to give a porcelain disc with a diameter of 10 mm and a thickness of 1.0 mm. Got

Next, silver electrodes were baked on both main surfaces of the obtained porcelain disk to obtain a capacitor sample (Sample No. 85-88).

The relative permittivity (εr) and bending strength (kg / cm ² ) of each sample were measured, and the results are shown in Table 11.

The sample numbers 85 and 87 in Table 11 are out of the scope of the present invention.

As is clear from the results in Tables 10 and 11, for the composite perovskite-based capacitor material containing lead oxide, the oxide of Pb was converted to PbO, the oxide of Ge was converted to GeO ₂ , and PbO The molar ratio of GeO ₂ is expressed by the general formula: xPbO · yGeO ₂ (x =
1-6, y = 1-3), and 0.01
Addition of up to 30% by weight makes it possible to improve the relative dielectric constant and flexural strength.

(Effects of the Invention) As apparent from the above description, according to the present invention, 85
It is possible to manufacture a piezoelectric element with high energy conversion efficiency because it is possible to obtain a lead oxide-containing ferroelectric porcelain having a large electromechanical coupling coefficient and a large relative dielectric constant, which is sintered at a low firing temperature of 0 to 1000 ° C. .

In addition, since the sintering temperature is low, it is possible to integrally sinter with a metal substrate, not only can an electrostrictive element such as an integrally sintered buzzer or bimorph be manufactured, but also PbO atmosphere adjustment is not required during firing. It is possible to obtain excellent effects such as prolonging the life of the box and the firing furnace and saving energy.

Furthermore, without lowering the bending strength,
When used as an oscillator, it is possible to prevent spurious emission.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an oscillation circuit including a ceramic oscillator, and FIG. 2 is a diagram showing thickness vibrations of spreading vibration and spurious vibration which are main vibrations in the oscillation circuit of FIG. 1 ... Ceramic oscillator IC ₁ ... Inverting amplifier R ₁ ... Resistors CL ₁ , CL ₂ ... Capacitors.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C04B 35/00 J H01L 41/18 101J

Claims (3)

(57) [Claims] 1. A Pb oxide and a Ge oxide are added as sub-components to a lead oxide-containing ferroelectric porcelain, which is the main component, and the Pb oxide is converted to PbO. of oxide in terms of GeO _2, the general formula the molar ratio of PbO and GeO _2: xPbO ·
When expressed as yGeO ₂ , x and y are x = 1 to 6 and y = 1, respectively.
The lead oxide-containing ferroelectric ceramic composition is characterized in that the total amount of PbO and GeO ₂ added is 0.01 to 30% by weight. 2. A plate-shaped ferroelectric porcelain plate made of the lead oxide-containing ferroelectric porcelain composition according to claim 1, and electrodes formed on both main surfaces of the ferroelectric porcelain plate. And a piezoelectric element. 3. A thick film paste containing a calcined powder made of the lead oxide-containing ferroelectric ceramic composition according to claim 1 is applied and baked on a metal substrate to be integrated,
A piezoelectric element having an electrode formed on the surface of a ferroelectric ceramic layer formed by this baking.