US20010012815A1 - Piezoelectric ceramic and manufacturing method therefor - Google Patents
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- US20010012815A1 US20010012815A1 US09/773,398 US77339801A US2001012815A1 US 20010012815 A1 US20010012815 A1 US 20010012815A1 US 77339801 A US77339801 A US 77339801A US 2001012815 A1 US2001012815 A1 US 2001012815A1
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- 239000000919 ceramic Substances 0.000 title claims abstract description 65
- 238000004519 manufacturing process Methods 0.000 title claims description 15
- 239000002245 particle Substances 0.000 claims abstract description 49
- 239000013078 crystal Substances 0.000 claims abstract description 30
- NKZSPGSOXYXWQA-UHFFFAOYSA-N dioxido(oxo)titanium;lead(2+) Chemical compound [Pb+2].[O-][Ti]([O-])=O NKZSPGSOXYXWQA-UHFFFAOYSA-N 0.000 claims abstract description 19
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims abstract description 19
- 229910052721 tungsten Inorganic materials 0.000 claims abstract description 19
- 239000010937 tungsten Substances 0.000 claims abstract description 19
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 21
- 229910010293 ceramic material Inorganic materials 0.000 claims description 9
- 229910052681 coesite Inorganic materials 0.000 claims description 8
- 229910052906 cristobalite Inorganic materials 0.000 claims description 8
- 239000000377 silicon dioxide Substances 0.000 claims description 8
- 229910052682 stishovite Inorganic materials 0.000 claims description 8
- 229910052905 tridymite Inorganic materials 0.000 claims description 8
- 238000010304 firing Methods 0.000 claims description 7
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 5
- 230000000052 comparative effect Effects 0.000 description 19
- 238000009826 distribution Methods 0.000 description 10
- 239000000463 material Substances 0.000 description 9
- 238000005245 sintering Methods 0.000 description 9
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000001747 exhibiting effect Effects 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 238000001878 scanning electron micrograph Methods 0.000 description 3
- 229910003781 PbTiO3 Inorganic materials 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 238000010191 image analysis Methods 0.000 description 2
- MRELNEQAGSRDBK-UHFFFAOYSA-N lanthanum oxide Inorganic materials [O-2].[O-2].[O-2].[La+3].[La+3] MRELNEQAGSRDBK-UHFFFAOYSA-N 0.000 description 2
- HTUMBQDCCIXGCV-UHFFFAOYSA-N lead oxide Chemical compound [O-2].[Pb+2] HTUMBQDCCIXGCV-UHFFFAOYSA-N 0.000 description 2
- YEXPOXQUZXUXJW-UHFFFAOYSA-N lead(II) oxide Inorganic materials [Pb]=O YEXPOXQUZXUXJW-UHFFFAOYSA-N 0.000 description 2
- 239000011656 manganese carbonate Substances 0.000 description 2
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Chemical compound O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 description 2
- 229910000016 manganese(II) carbonate Inorganic materials 0.000 description 2
- KTUFCUMIWABKDW-UHFFFAOYSA-N oxo(oxolanthaniooxy)lanthanum Chemical compound O=[La]O[La]=O KTUFCUMIWABKDW-UHFFFAOYSA-N 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 239000007858 starting material Substances 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 238000007606 doctor blade method Methods 0.000 description 1
- 239000011363 dried mixture Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 238000013001 point bending Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/80—Constructional details
- H10N30/85—Piezoelectric or electrostrictive active materials
- H10N30/853—Ceramic compositions
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/46—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates
- C04B35/462—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates
- C04B35/472—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates based on lead titanates
Definitions
- the present invention relates to a piezoelectric ceramic and a manufacturing method therefor. More specifically, the present invention relates to a piezoelectric ceramic used for, for example, a ceramic resonator, a ceramic filter, an ultrasonic resonator and an acceleration sensor, and to a manufacturing method therefor.
- the PZT piezoelectric ceramics were, however, not appropriate as materials of piezoelectric elements used, in particular, in high frequency regions because the PZT piezoelectric ceramics had high dielectric constants in spite of having superior piezoelectric characteristics.
- Most of conventional piezoelectric ceramics primarily including the PZT piezoelectric ceramics do not have very high mechanical strength and hardness as ceramic materials.
- requirements for miniaturization of electronic parts have intensified, and piezoelectric ceramic elements are also required to be compact and to exhibit sufficient characteristics. In the case in which compact elements are used in environments where shocks and vibrations are likely to be encountered, there is a problem in reliability of strength. The reason for this is that accompanying the miniaturization of elements, the effect of heterogeneity in ceramic microstructure increases so as to decrease the strength of the element as a whole.
- PT piezoelectric ceramics containing PbTiO 3 as a primary component have been used.
- the PT piezoelectric ceramics have the merits of having low dielectric constants, of being superior in response in high frequency regions, and, in addition, of exhibiting high strength compared to the PZT piezoelectric ceramics.
- objects of the present invention are to provide a piezoelectric ceramic having increased mechanical strength and which may be used for producing a piezoelectric element having sufficient strength and hardness in spite of compactness, and to provide a manufacturing method therefor.
- a piezoelectric ceramic according to the present invention contains lead titanate as a primary component and about 0.1 to 5% by weight of tungsten in terms of WO 3 relative to the primary component, in which about 75% or more of the crystal particles constituting the piezoelectric ceramic have particle diameters distributed in the range of about 0.2 ⁇ m to 0.8 ⁇ m.
- a piezoelectric ceramic according to the present invention may further contain about 2% or less by weight of silicon oxide in terms of SiO 2 relative to the primary component.
- a manufacturing method for a piezoelectric ceramic according to the present invention includes a step of firing a piezoelectric ceramic material at a temperature of more than about 1,080° C. and less than about 1,150° C., in which the piezoelectric ceramic material contains lead titanate as a primary component and about 0.1 to 5% by weight of tungsten in terms of WO 3 relative to the primary component.
- a manufacturing method for a piezoelectric ceramic according to the present invention includes the aforementioned step of firing, in which the piezoelectric ceramic material may further contain about 2% or less by weight of silicon oxide in terms of SiO 2 relative to said primary component.
- a piezoelectric ceramic containing lead titanate as a primary component when the piezoelectric ceramic contains less than about 0.1% by weight of tungsten in terms of WO 3 relative to the primary component, an effect as a sintering promoter cannot be seen, and the piezoelectric ceramic cannot be sintered at a low temperature. When the content exceeds about 5% by weight, the three-point flexural strength and Vickers hardness are decreased. Therefore, neither of the aforementioned cases is preferable.
- a piezoelectric ceramic containing lead titanate as a primary component and about 0.1 to 5% by weight of tungsten in terms of WO 3 relative to the primary component in which about 75% or more of crystal particles constituting the piezoelectric ceramic had particle diameters distributed in the range of about 0.2 ⁇ m to 0.8 ⁇ m, could be produced by firing a piezoelectric ceramic material containing lead titanate as a primary component and about 0.1 to 5% by weight of tungsten in terms of WO 3 relative to the primary component at a temperature of more than about 1,080° C. and less than about 1,150° C..
- the firing temperature is 1,080° C. or less, sintering does not sufficiently proceed, and when the firing temperature is 1,150° C. or more, growth of particles cannot be sufficiently suppressed. Therefore, neither of the aforementioned cases is preferable.
- the distribution of the diameters of crystal particles can be controlled.
- FIG. 1 is a graph showing the distribution of the diameters of crystal particles of Sample A
- FIG. 2 is a graph showing the distribution of the diameters of crystal particles of Comparative Sample B
- FIG. 3 is a graph showing the distribution of the diameters of crystal particles of Comparative Sample C.
- the present invention relates to a piezoelectric ceramic containing lead titanate as a primary component.
- the piezoelectric ceramic containing lead titanate as a primary component (Pb 0.865 La 0.09 )TiMn 0.016 O 3 , etc., may be mentioned.
- PbO, TiO 2 , La 2 O 3 and MnCO 3 are prepared as starting materials. These materials are weighed, mixed, calcined and pulverized. The resulting pulverized materials are fired after addition of, for example, 0.6% by weight of WO 3 and 0.3% by weight of SiO 2 as promoters, so as to produce a piezoelectric ceramic. Sintering at a low temperature become possible and growth of particles can be suppressed by controlling the additive amounts of the sintering promoters. Furthermore, the degree of the growth of the particles can be adjusted at a predetermined level by controlling the firing temperature.
- the aforementioned piezoelectric ceramic is controlled so that about 75% or more of crystal particles thereof have particle diameters distributed in the range of about 0.2 ⁇ m to 0.8 ⁇ m.
- the distribution of diameters of crystal particles is determined by image analysis of a SEM image.
- PbO, TiO 2 , La 2 O 3 , and MnCO 3 as starting materials, were weighed and were mixed so as to have a compositional formula (Pb 0.865 La 0.09 )TiMn 0.016 O 3 .
- This mixture was wet milled using a ball mill for 16 hours. The resulting mixture was dehydrated and dried. Thereafter, the dried mixture was calcined in air at a temperature of 850° C. for 2 hours. The calcined material was pulverized using the ball mill again.
- the resulting compact was fired in an oxygen atmosphere at 1,100° C. so as to produce Sample A.
- Another compact was produced using materials similar to those of Sample A, and in a manner similar to that of Sample A, and was fired in an oxygen atmosphere at 1,080° C. so as to produce Comparative Sample B.
- Another compact was produced using materials similar to those of Sample A without adding sintering promoters WO 3 and SiO 2 in the production of a slurry, and was fired in an oxygen atmosphere at 1,230° C. so as to produce Comparative Sample C.
- Sample A, Comparative Sample B, and Comparative Sample C were cut to form rectangular plate test pieces of 5 mm by 30 mm, and three-point bending destructive tests were made using a strength tester.
- the three-point flexural strength of each Sample determined based on breaking load and test piece size is shown in Table 1. Rectangular plate test pieces having mirror-finished surfaces were prepared and the Vickers hardness thereof were measured using a Vickers hardness tester. The results thereof are shown in Table 1. In the measurements of strength and hardness, 100 test pieces of each Sample were examined. TABLE 1 Three-Point Flexural Strength (MPa) Vickers Hardness Sample A 2.06 710 Comparative Sample B 1.27 720 Comparative Sample C 1.57 510
- Example 2 test pieces of Sample numbers 1 to 8 were prepared with variations in WO 3 content compared to Sample A in Example 1.
- test pieces of Sample numbers 1 and 2 containing less than 0. 1% by weight of tungsten in terms of WO 3 relative to the primary component do not exhibit an effect of sintering promotion so that the test pieces cannot be sintered, and in test pieces of Sample number 8 containing tungsten exceeding about 5% by weight in terms of WO 3 , the three-point flexural strength and Vickers hardness are decreased.
- a piezoelectric ceramic having increased mechanical strength in spite of compactness, having a high Vickers hardness, having a low dielectric constant and exhibiting superior response in high frequency regions can be provided.
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Abstract
Description
- 1. Field of the Invention
- The present invention relates to a piezoelectric ceramic and a manufacturing method therefor. More specifically, the present invention relates to a piezoelectric ceramic used for, for example, a ceramic resonator, a ceramic filter, an ultrasonic resonator and an acceleration sensor, and to a manufacturing method therefor.
- 2. Description of the Related Art
- Hitherto, PZT compositions containing PbZrO3-PbTiO3 as a primary component have been widely used as compositions for piezoelectric ceramics.
- Addition of metallic oxides, such as MnO2, and compound perovskite oxides, such as Pb(Nb⅔Mg,⅓)O3, to the primary component or substitution for the aforementioned oxides have been attempted to improve piezoelectric characteristics.
- The PZT piezoelectric ceramics were, however, not appropriate as materials of piezoelectric elements used, in particular, in high frequency regions because the PZT piezoelectric ceramics had high dielectric constants in spite of having superior piezoelectric characteristics. Most of conventional piezoelectric ceramics primarily including the PZT piezoelectric ceramics do not have very high mechanical strength and hardness as ceramic materials. In recent years, requirements for miniaturization of electronic parts have intensified, and piezoelectric ceramic elements are also required to be compact and to exhibit sufficient characteristics. In the case in which compact elements are used in environments where shocks and vibrations are likely to be encountered, there is a problem in reliability of strength. The reason for this is that accompanying the miniaturization of elements, the effect of heterogeneity in ceramic microstructure increases so as to decrease the strength of the element as a whole.
- Therefore, for the uses in high frequency regions, PT piezoelectric ceramics containing PbTiO3 as a primary component have been used. The PT piezoelectric ceramics have the merits of having low dielectric constants, of being superior in response in high frequency regions, and, in addition, of exhibiting high strength compared to the PZT piezoelectric ceramics.
- Accompanying substantial miniaturization of elements, however, in accordance with strong market requirements for compact and thin layer elements, even the PT piezoelectric ceramics are insufficient in their strength.
- Accordingly, objects of the present invention are to provide a piezoelectric ceramic having increased mechanical strength and which may be used for producing a piezoelectric element having sufficient strength and hardness in spite of compactness, and to provide a manufacturing method therefor.
- A piezoelectric ceramic according to the present invention contains lead titanate as a primary component and about 0.1 to 5% by weight of tungsten in terms of WO3 relative to the primary component, in which about 75% or more of the crystal particles constituting the piezoelectric ceramic have particle diameters distributed in the range of about 0.2 μm to 0.8 μm.
- A piezoelectric ceramic according to the present invention may further contain about 2% or less by weight of silicon oxide in terms of SiO2 relative to the primary component.
- A manufacturing method for a piezoelectric ceramic according to the present invention includes a step of firing a piezoelectric ceramic material at a temperature of more than about 1,080° C. and less than about 1,150° C., in which the piezoelectric ceramic material contains lead titanate as a primary component and about 0.1 to 5% by weight of tungsten in terms of WO3 relative to the primary component.
- A manufacturing method for a piezoelectric ceramic according to the present invention includes the aforementioned step of firing, in which the piezoelectric ceramic material may further contain about 2% or less by weight of silicon oxide in terms of SiO2 relative to said primary component.
- It was discovered that in a piezoelectric ceramic containing lead titanate as a primary component and about 0.1 to 5% by weight of tungsten in terms of WO3 relative to the primary component, when the diameters of the crystal particles were distributed in the range of about 0.2 μm to 0.8 μm and were not too small, the ceramic had increased strength, and the Vickers hardness thereof was increased by limiting the diameters of crystal particles to about 0.8 μm or less.
- In a piezoelectric ceramic containing lead titanate as a primary component, when the piezoelectric ceramic contains less than about 0.1% by weight of tungsten in terms of WO3 relative to the primary component, an effect as a sintering promoter cannot be seen, and the piezoelectric ceramic cannot be sintered at a low temperature. When the content exceeds about 5% by weight, the three-point flexural strength and Vickers hardness are decreased. Therefore, neither of the aforementioned cases is preferable.
- It was discovered that a piezoelectric ceramic containing lead titanate as a primary component and about 0.1 to 5% by weight of tungsten in terms of WO3 relative to the primary component, in which about 75% or more of crystal particles constituting the piezoelectric ceramic had particle diameters distributed in the range of about 0.2 μm to 0.8 μm, could be produced by firing a piezoelectric ceramic material containing lead titanate as a primary component and about 0.1 to 5% by weight of tungsten in terms of WO3 relative to the primary component at a temperature of more than about 1,080° C. and less than about 1,150° C.. Herein, when the firing temperature is 1,080° C. or less, sintering does not sufficiently proceed, and when the firing temperature is 1,150° C. or more, growth of particles cannot be sufficiently suppressed. Therefore, neither of the aforementioned cases is preferable.
- Furthermore, in the piezoelectric ceramic containing lead titanate as a primary component according to the present invention and in the manufacturing method therefor, by further containing about 2% or less by weight of silicon oxide in terms of SiO2 relative to the primary component, the distribution of the diameters of crystal particles can be controlled.
- The aforementioned objects, further objects, features, and advantages of the present invention will be apparent from the following detailed explanations of embodiments according to the present invention with reference to the drawings.
- FIG. 1 is a graph showing the distribution of the diameters of crystal particles of Sample A;
- FIG. 2 is a graph showing the distribution of the diameters of crystal particles of Comparative Sample B;
- FIG. 3 is a graph showing the distribution of the diameters of crystal particles of Comparative Sample C.
- The present invention relates to a piezoelectric ceramic containing lead titanate as a primary component. As examples of the piezoelectric ceramic containing lead titanate as a primary component, (Pb0.865La0.09)TiMn0.016O3, etc., may be mentioned. In order to produce such a piezoelectric ceramic, for example, PbO, TiO2, La2O3 and MnCO3 are prepared as starting materials. These materials are weighed, mixed, calcined and pulverized. The resulting pulverized materials are fired after addition of, for example, 0.6% by weight of WO3 and 0.3% by weight of SiO2 as promoters, so as to produce a piezoelectric ceramic. Sintering at a low temperature become possible and growth of particles can be suppressed by controlling the additive amounts of the sintering promoters. Furthermore, the degree of the growth of the particles can be adjusted at a predetermined level by controlling the firing temperature.
- The aforementioned piezoelectric ceramic is controlled so that about 75% or more of crystal particles thereof have particle diameters distributed in the range of about 0.2 μm to 0.8 μm. The distribution of diameters of crystal particles is determined by image analysis of a SEM image. In order to increase mechanical strength of the piezoelectric ceramic, it is preferable that most diameters of crystal particles be distributed in the range about 1 μm or less. The reason for this is that diameters of crystal particles must be sufficiently small compared to size of an element so as to prevent stress from concentrating at physical defects in the surface of the element, which causes decrease in strength of the element. It is not preferable that the diameters of crystal particles be too small. The reason for this is that when the diameters of crystal particles are too small, toughness is decreased. In the present invention, it was discovered that a piezoelectric ceramic having sufficient strength and hardness in spite of compactness could be produced when the diameters of about 75% or more of crystal particles of the piezoelectric ceramic being distributed in the range of about 0.2 mm to 0.8 μm.
- PbO, TiO2, La2O3, and MnCO3, as starting materials, were weighed and were mixed so as to have a compositional formula (Pb0.865La0.09)TiMn0.016O3. This mixture was wet milled using a ball mill for 16 hours. The resulting mixture was dehydrated and dried. Thereafter, the dried mixture was calcined in air at a temperature of 850° C. for 2 hours. The calcined material was pulverized using the ball mill again. 0.6% by weight of WO3 and 0.3% by weight of SiO2 were added as sintering promoters to the resulting pulverized materials, and an organic binder, a dispersing agent, etc., were further blended so as to produce a slurry, and thereafter, green sheets were produced by the doctor blade method. Then, the green sheets having a size of 40 mm by 27 mm were stacked one on the other and were molded by thermocompression bonding so as to produce a compact 600 μm in thickness.
- The resulting compact was fired in an oxygen atmosphere at 1,100° C. so as to produce Sample A. Another compact was produced using materials similar to those of Sample A, and in a manner similar to that of Sample A, and was fired in an oxygen atmosphere at 1,080° C. so as to produce Comparative Sample B. Another compact was produced using materials similar to those of Sample A without adding sintering promoters WO3 and SiO2 in the production of a slurry, and was fired in an oxygen atmosphere at 1,230° C. so as to produce Comparative Sample C.
- Sample A, Comparative Sample B, and Comparative Sample C were cut to form rectangular plate test pieces of 5 mm by 30 mm, and three-point bending destructive tests were made using a strength tester. The three-point flexural strength of each Sample determined based on breaking load and test piece size is shown in Table 1. Rectangular plate test pieces having mirror-finished surfaces were prepared and the Vickers hardness thereof were measured using a Vickers hardness tester. The results thereof are shown in Table 1. In the measurements of strength and hardness, 100 test pieces of each Sample were examined.
TABLE 1 Three-Point Flexural Strength (MPa) Vickers Hardness Sample A 2.06 710 Comparative Sample B 1.27 720 Comparative Sample C 1.57 510 - As is clear from Table 1, the average strength of Sample A is about 1.6 times that of Comparative Sample B, and about 1.3 times that of Comparative Sample C. 1 0 It is clear that the Vickers hardness of Sample A is higher than that of Comparative Sample C and is nearly equivalent to that of Comparative Sample B.
- SEM images of fractured surfaces of Sample A, Comparative Sample B, and Comparative Sample C were examined. Distributions of the particle diameters of the crystal particles determined by image analysis of these SEM images are shown in FIG. 1, FIG. 2 and FIG. 3, respectively.
- As is clear from FIG. 1, 75% or more of crystal particles have particle diameters distributed in the range of about 0.2 μm to 0.8 μm in Sample A,. On the other hand, as is clear from FIG. 2, 25% or more of crystal particles having particle diameters less than 0.2 μm are observed in Comparative Sample B . As is clear from FIG. 3, 25% or more of crystal particles having a particle diameter exceeding 0.8 μm are observed in Comparative Sample C. In Comparative Sample B, however, sintering and growth of particles can also be accelerated by increasing an additive amount of WO3 as a sintering promoter so as to produce samples having a predetermined distribution of particle diameters.
- As is clear from the aforementioned results, about 75% or more of crystal particles have particle diameters distributed in the range of about 0.2 μm to 0.8 μm in Sample A, and therefore, Sample A exhibits superior mechanical characteristics, that is, the mechanical strength thereof is higher than that of Comparative Sample B in which diameters of crystal particles tend to be less than 0.2 μm, and the Vickers hardness of Sample A is higher than that of Comparative Sample C in which diameters of crystal particles tend to be more than 0.8 μm.
- In Example 2, test pieces of
Sample numbers 1 to 8 were prepared with variations in WO3 content compared to Sample A in Example 1. - In a manner similar to that of Example 1, distributions of the particle diameters of the crystal particles, three-point flexural strength and Vickers hardness of test pieces of
Sample numbers 1 to 8 were examined. The results thereof are shown in Table 2. In Table 2, the term “unsintered” in the column of Distribution of Diameters of Crystal Particles indicates that test pieces ofSample numbers 1 and 2 could not be sintered, and the term “within range” indicates that in test pieces of Sample numbers 3 to 8, 75% or more of crystal particles constituting the piezoelectric ceramic had particle diameters distributed in the range of about 0.2 μm to 0.8 μm.TABLE 2 Distribution of Three-Point Sample Content of WO3 Diameters of Flexural Strength Vickers Number (% by weight) Crystal Particles (MPa) Hardness 1 0.0 unsintered — — 2 0.05 unsintered — — 3 0.1 within range 1.86 710 4 1.0 within range 2.14 700 5 2.0 within range 2.08 720 6 4.0 within range 2.12 690 7 5.0 within range 2.02 600 8 5.5 within range 1.84 530 - As is clear from Table 2, among piezoelectric ceramics containing lead titanate as a primary component in which about 75% or more of crystal particles constituting the piezoelectric ceramic have particle diameters distributed in the range of about 2 μm to 0.8 μm, the test pieces of Sample numbers 3 to 7 containing about 0.1 to 5% by weight of tungsten in terms of WO3 relative to the primary component have high three-point flexural strength and Vickers hardness.
- As is clear from Table 2, among piezoelectric ceramics containing lead titanate as a primary component, test pieces of
Sample numbers 1 and 2 containing less than 0. 1% by weight of tungsten in terms of WO3 relative to the primary component, do not exhibit an effect of sintering promotion so that the test pieces cannot be sintered, and in test pieces of Sample number 8 containing tungsten exceeding about 5% by weight in terms of WO3, the three-point flexural strength and Vickers hardness are decreased. - Even when materials other than the ceramic materials shown in the aforementioned Examples 1 and 2 are used, as long as the materials are piezoelectric ceramics containing lead titanate as a primary component and about 0.1 to 5% by weight of tungsten in terms of WO3 relative to the primary component is used, by making the particle diameters of 75% or more of crystal particles distributed in the range of about 0.2 μm to 0.8 μm, piezoelectric ceramics having high mechanical strength and hardness can be produced. Furthermore, a piezoelectric ceramic having a low dielectric constant and exhibiting superior response in high frequency regions compared to the PZT piezoelectric ceramics can be produced.
- According to the present invention, a piezoelectric ceramic having increased mechanical strength in spite of compactness, having a high Vickers hardness, having a low dielectric constant and exhibiting superior response in high frequency regions can be provided.
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JP4283730B2 (en) * | 2004-05-24 | 2009-06-24 | Tdk株式会社 | Piezoelectric ceramic and piezoelectric element manufacturing method, method for lowering the firing temperature in the firing step in piezoelectric ceramic manufacturing, and piezoelectric element |
CN114853466B (en) * | 2022-04-27 | 2023-06-23 | 苏州思萃电子功能材料技术研究所有限公司 | Bismuth scandium-lead titanate-based high-temperature piezoelectric ceramic with low-high Wen Sunhao property and preparation method thereof |
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JPS63217674A (en) * | 1987-03-06 | 1988-09-09 | Meidensha Electric Mfg Co Ltd | Composite piezoelectric material |
KR910006178A (en) * | 1989-09-30 | 1991-04-27 | 서주인 | Piezoceramic Compositions with Excellent Electrical Properties |
JPH05290625A (en) * | 1992-04-14 | 1993-11-05 | Tdk Corp | Dielectric porcelain composition and manufacture thereof |
DE69511050T2 (en) * | 1994-11-30 | 2000-02-24 | Sumitomo Chemical Co., Ltd. | Process for the production of double metal oxide powders |
JP3119138B2 (en) * | 1995-10-06 | 2000-12-18 | 株式会社村田製作所 | Piezoelectric ceramic and manufacturing method thereof |
KR100345332B1 (en) * | 1995-12-29 | 2002-11-29 | 삼성전자 주식회사 | Recycled erbium doped fiber amplifier |
-
2001
- 2001-01-19 TW TW090101284A patent/TW516251B/en not_active IP Right Cessation
- 2001-01-26 DE DE10103519A patent/DE10103519B4/en not_active Expired - Fee Related
- 2001-01-31 KR KR10-2001-0004539A patent/KR100426319B1/en not_active IP Right Cessation
- 2001-01-31 US US09/773,398 patent/US6444141B2/en not_active Expired - Fee Related
- 2001-01-31 CN CNB011033894A patent/CN1139554C/en not_active Expired - Fee Related
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20100038999A1 (en) * | 2007-05-14 | 2010-02-18 | Murata Manufacturing Co., Ltd. | Piezoelectric ceramic composition and piezoelectric part |
US7944127B2 (en) | 2007-05-14 | 2011-05-17 | Murata Manufacturing Co., Ltd. | Piezoelectric ceramic composition and piezoelectric part |
Also Published As
Publication number | Publication date |
---|---|
KR100426319B1 (en) | 2004-04-08 |
DE10103519B4 (en) | 2007-02-08 |
DE10103519A1 (en) | 2001-08-23 |
TW516251B (en) | 2003-01-01 |
KR20010078201A (en) | 2001-08-20 |
US6444141B2 (en) | 2002-09-03 |
CN1139554C (en) | 2004-02-25 |
CN1306950A (en) | 2001-08-08 |
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