GB2111968A - Dielectric ceramic composition - Google Patents
Dielectric ceramic composition Download PDFInfo
- Publication number
- GB2111968A GB2111968A GB08229556A GB8229556A GB2111968A GB 2111968 A GB2111968 A GB 2111968A GB 08229556 A GB08229556 A GB 08229556A GB 8229556 A GB8229556 A GB 8229556A GB 2111968 A GB2111968 A GB 2111968A
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- weight
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- dielectric ceramic
- dielectric
- ceramic composition
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/002—Details
- H01G4/018—Dielectrics
- H01G4/06—Solid dielectrics
- H01G4/08—Inorganic dielectrics
- H01G4/12—Ceramic dielectrics
- H01G4/1209—Ceramic dielectrics characterised by the ceramic dielectric material
- H01G4/1218—Ceramic dielectrics characterised by the ceramic dielectric material based on titanium oxides or titanates
- H01G4/1227—Ceramic dielectrics characterised by the ceramic dielectric material based on titanium oxides or titanates based on alkaline earth titanates
-
- 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
- C04B35/465—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 alkaline earth metal titanates
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Power Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Compositions Of Oxide Ceramics (AREA)
- Inorganic Insulating Materials (AREA)
- Ceramic Capacitors (AREA)
Abstract
In a microwave circuit, the components, such as a filter and a solid oscillator, consist of a dielectric ceramic composition. Known dielectric ceramic compositions, such as TiO2, MgTiO3-CaTiO3- La2O3 &cirf& 2TiO2, ZrO2-SnO2-TiO2, CaZrO3, and BaO &cirf& n TiO2 (n=4-4.5) cannot simultaneously attain high dielectric constant ( epsilon ) and small resonance frequency temperature coefficient Tcf. The dielectric ceramic composition of the present invention is expressed by xMgO-yCaO-zTiO2- wLa2O3, where 0.2</=x</=0.32, 0.002</=y</=0.035, 0.57</=z</=0.70, 0<w</=0.21, and x+y+z+w=1 part by weight, and is characterized by a small resonance frequency temperature coefficient Tcf.
Description
SPECIFICATION
Dielectric ceramic composition
The present invention relates to a dielectric ceramic composition. More particularly, it relates to a dielectric ceramic composition used at a high frequency or used as a temperaturecompensation ceramic capacitor.
Dielectric ceramics are used as various components of a microwave circuit, e.g., as a miniaturized filter, a solid oscillator having a stable oscillation frequency, a capacitor, and an impedance-matching component. Dielectric ceramics used for a microwave circuit should exhibit a relatively small resonance frequency temperature coefficient, a high dielectric constant (e), and a high no load 0. Also, it is necessary that the value of the dielectric constant () and the no load Q depend to a small degree upon the temperature at which a microwave circuit is used.
That is, a small variation in capacitance is necessary. The symbol Q indicates 1 /tan 8, wherein tan 8 is the dielectric loss tangent. Various dielectric ceramic compositions, such as TiO2, MgTiO3-CaTiO3-La203 2TiO2, Zr02-Sn02-Ti02, CaZr03, and Bay nTiO, (n = 4-4.5), have been developed so as to miniaturize the components of and reduce the cost of the components of a microwave circuit. At room temperature, the dielectric constant () of known dielectric ceramic compositions is high if the resonance frequency temperature coefficient is high. It is, therefore, impossible to simultaneously obtain at room temperature a high dielectric constant () and a small resonance frequency temperature coefficient.In addition, the properties of the known dielectric ceramic compositions are liable to be unstable depending upon the production conditions. The known dielectric ceramic compositions do not meet simultaneously all the requirements for use in a microwave circuit, including good and thermally stable electric properties and a low cost.
Dielectric ceramics used as a temperature-compensation ceramic capacitor should exhibit a small resonance frequency temperature coefficient, a high dielectric constant (e), a high no load
Q, and no dependency of the dielectric constant upon temperature. The known dielectric ceramic compositions for use as a temperature-compensation ceramic capacitor consist of TiO2,
BaO-nTiO2, or CaTiO3-MgTiO3-La203 2tit2. Good and thermally stable electric properties cannot be simultaneously attained in these dielectric ceramic compositions.
It is an object of the present invention to provide a high dielectric constant (+high no load Q dielectric ceramic composition in which the resonance frequency temperature coefficient can be optionally and stably controlled to O ppm/ C and adjusted to less than or more than 0 ppm/ C, if necessary.
In accordance with the present invention, there is provided a dielectric ceramic composition which is characterized by quaternary components, namely xMg0-yCa0-zTi02-wLa203, wherein x is not less than 0.2 parts by weight and not more than 0.32 parts by weight, y is not less than 0.002 parts by weight and not more than 0.035 parts by weight, z is not less than 0.57 parts by weight and not more than 0.70 parts by weight, and w is more than 0 but not more the 0.21 parts by weight, with the proviso that x + y + z + w = 1.
A ternary dielectric ceramic composition composed of Mg0-Ca0-Ti02 exhibits a high no load O. However, in such a ternary dielectric ceramic composition, the dielectric constant () is disadvantageously low and the resonance frequency temperature coefficient is disadvantageously large. The addition of La203 to the ternary dielectric ceramic composition composed of Mg0-Ca0-Ti02 can remove the disadvantages of said ternary dielectric composition.
A La203, 3Ti02 compound can be formed in the dielectric ceramic composition of the present invention. As a compound of La203 and TiO2, La2032Ti02, i.e., La2Ti207, is known as a ferrodielectric having a high Curie point. La2032Ti02, however, does not exhibit excellent highfrequency properties because the no load 0 is low in the wavelength range of a microwave. The resonance frequency temperature coefficient of La203 3Ti02 is positive while the resonance frequency temperature coefficient of La203 2Ti02 is negative. The resonance frequency temperature coefficient of a MgTiO3 compound which is present in the ceramic dielectric composition according to the present invention is negative.It is, therefore, possible to maintain the resonance frequency temperature coefficient at O ppm/ C by adjusting the content of MgTiO3 and La203 3tit2. in addition, since the no load Q of a MgTiO3 compound is high, it is possible to provide the dielectric ceramic composition with a high no load Q.
La203 3Ti02 can be formed by sintering La203 and TiO2 in a reducing atmosphere or in the presence of an alkaline earth oxide such as CaO.
Preferred dielectric compositions according to the present invention have the following x, y, and w values:
A. To obtain a very small absolute value of a resonance frequency temperature coefficient (Tcf) of less than 5 ppm/ C, x0.25, y = 0.006-0.012, and w = 0.110.16.
B. To obtain a resonance frequency temperature coefficient (Tcf) of zero, x = 0.25, y = 0.012, z = 0.607, and w = 0.131.
C. To obtain a very high no load Q of more than 7000 at 8 GHz, x = 0.236-0.279, y = 0.004--0.008, and w = 0.0092-0. 166.
The x, y, and z values of the dielectric ceramic composition according to the preferred composition B are approximately central values in the ranges of x, y, and z. The preferable amount of w is at least 0.047 parts by weight.
The dielectric ceramic composition of the present invention is appropriate for a miniaturized filter, a solid oscillator, an impedance-matching component, and other components of a microwave circuit of, for example, 400 Hz-40 GHz, because they exhibit a high dielectric constant, a high no load Q, a small-temperature resonance frequency coefficient, and a high iinearity of the resonance frequency temperature coefficient. In addition, it is possible to optionally adjust the resonance frequency temperature coefficient with a good reproducibility.
The dielectric ceramic composition of the present invention is also appropriate for a temperature-compensation ceramic capacitor.
The present invention is explained with reference to an example.
Commercially available MgO, CaO, TiO2, and La203 as the raw materials were weighed according to the weight percentage of the oxides given in the table below and then were wet mixed in a ball mill for 20 hours. The resultant mixtures were dehydrated, calcined, and preliminarily shaped at a pressure of 0.5 t/cm2. The preliminarily shaped bodies were calcined at a temperature of 1150"C for 2 hours and then the calcined bodies were water-ground in a ball mill for 20 hours. The resultant powder was dehydrated and calcined, followed by granulation with an appropriate amount of a binder. The resultant grains were shaped to form discs having a diameter of 1 5 mm and a height of 10 mm. The discs were sintered at a temperature of from 1260"C to 1400"C for 2 hours.The resultant dielectric ceramic compositions in the form of a disc were machined, and samples having a diameter of 10 mm and a height of 5 mm were obtained. The dielectic constant (e) and no load Q at 8 GHz, as well as the resonance frequency temperature coefficient Tcf, of the samples were measured. In the measurement of the resonance frequency temperature coefficient, the resonance frequency of the samples was measured at a temperature ranging from - 40"C to + 80"C, and the variance (Af) of the resonance frequency in the range of from - 40"C to 80"C was calculated. The samples were sandwiched between a pair of metal plates at the top and bottom surfaces, and the metal plates were connected to a current source so as to produce a dielectric oscillator. The dielectric constant (), the no load 0, and the resonance frequency temperature coefficient Tcf were measured according to the dielectric cylinder transmission method when the oscillator was in the TE011 mode. The results of measurement are given in the table.
Table
Electric Properties
Oxides (Wt%) Dielectric Temperature
Sample Constant No-Load Q Coefficient
No. MgO CaO TiO2 La2O3 () (8GHz) Tcf (ppm/"C) 1 21.9 0.3 58.2 19.6 28.1 6,500 + 7
2 23.7 0.3 59.4 16.6 25.9 7,000 - 6 3 25.6 0.3 60.9 13.2 23.4 7,400 - 18 4 27.9 0.4 62.5 9.2 22.1 8,100 -22 5 22.1 0.5 59.1 18.3 27.9 6,400 + 11
6 24.0 0.5 59.7 15.7 25.7 6,700 - 2 7 26.5 0.6 61.6 11.3 23.3 7,100 - 15 8 22.5 0.7 58.7 18.1 27.2 5,500 + 15
9 23.4 0.7 59.4 16.5 26.8 5,600 + 9 10 24.3 0.7 60.1 14.9 25.8 5,800 + 2 11 25.3 0.7 60.8 13.2 24.8 5,900 - 3 12 26.4 0.8 61.6 11.2 23.8 6,100 - 9 13 21.6 1.0 59.1 18.3 28.7 4,800 +21 14 23.1 1.1 59.3 16.5 25.5 5,000 +11 15 25.0 1.2 60.7 13.1 23.9 5,100 0 16 27.2 1.2 62.3 9.3 22.6 4,900 - 15 17 21.1 1.8 58.9 18.2 29.7 3,900 + 28 18 22.5 1.9 59.1 16.5 27.5 4,000 +21 19 24.4 2.0 60.6 13.0 25.6 4,200 + 7 20 26.6 2.1 62.2 9.1 23.7 4,500 - 6 21 21.9 2.6 59.0 16.5 28.0 3,900 +31 22 23.8 2.8 60.4 13.0 26.8 4,000 + 25 23 25.9 3.0 62.0 9.1 24.9 4,200 + 18 24 28.3 3.2 63.8 4.7 22.5 4,400 + 12 25 22.2 0.5 61.3 16.0 27.4 6,600 + 7 26 22.9 0.6 62.0 14.5 26.6 6,700 + 3 27 23.6 0.7 62.7 13.0 25.8 6,900 1 28 24.1 0.7 63.8 11.4 25.3 7,000 - 3 29 24.7 0.8 64.7 9.8 24.5 7,200 - 7 30 35.9 4.8 59.3 0.0 20.0 7,800 + 20 31 23.0 1.0 54.0 22.0 31.2 2,900 + 31 32 22.0 1.0 52.0 25.0 33.3 2,200 + 40 33 19.0 1.0 62.0 18.0 31.0 5,600 + 40 34 33.0 1.0 48.0 18.0 27.0 6,500 - 52 35 22.1 0.1 57.8 20.0 27.5 6,400 + 8 36 28.3 3.6 64.0 4.1 21.0 3,100 + 20 37 22.0 0.8 56.0 21.2 29.1 5,600 + 10 38 22.0 1.0 71.0 6.0 26.0 5,200 -24 Sample Nos. 1 through 29 have the composition of the present invention while the compositions of Sample Nos. 30 through 38 are outside the present invention. The contents of MgO, CaO, TiO2, and La203 are given by weight percentage.
As is apparent from the table, when the content of La203 exceeds 21% (w > 0.21), the resonance frequency temperature coefficient (Tcf) has a high positive value and the no load 0 is very low (Sample No. 31) and when the content of CaO exceeds 3.5% (y > 0.035), the no load O is very low (Sample No. 36).
The presence of La203 3Ti02 in Sample Nos. 1 through 29 was detected by means of X-ray diffractometry. In Sample No. 35 having a CaO content of 0.1 % (y = 0.001), however, the presence of La2033Ti02 could not be confirmed.
The figure is a graph illustrating the Af/f20.c (x 10-6) of sample No. 10 (the present invention) and sample No. 30 (comparative example). The resonance frequency temperature variation in terms of Af/f2o.c (x 10-6) was very small and the linearity of Af/f2o.c (x 10-6) was high in the sample of the present invention.
Claims (7)
1. A dielectric ceramic composition which is characterized by quaternary components, namely xMgO-yCaO-zTiO2-wLa203, wherein x is not less than 0.2 parts by weight and not more than 0.32 parts by weight, y is not less than 0.002 parts by weight and not more than 0.035 parts by weight, z is not less than 0.57 parts by weight and not more than 0.70 parts by weight, and w is more than 0 but not more than 0.21 parts by weight, with the proviso that x+y+z+w= 1.
2. A dielectric ceramic composition according to claim 1, wherein x is not more than 0.25 parts by weight, y is from 0.006 to 0.012 parts by weight, and w is from 0.11 to 0.16 parts by weight.
3. A dielectric ceramic composition according to claim 2, wherein xis 0.25, y is 0.012, z is 0.607, and w is 0.131.
4. A dielectric ceramic composition according to claim 1, wherein x is from 0.236 to 0.279 parts by weight, y is from 0.004 to 0.008 parts by weight, and w is from 0.0092 to 0.166 parts by weight.
5. A dielectric ceramic composition according to claim 1, wherein said composition includes a La203 3TiO2 compound.
6. A ceramic dielectric composition according to claim 1, characterized by being used as a component of a microwave circuit of from 400 Hz to 40 GHz.
7. A ceramic dielectric composition according to claim 1, characterized by being used as a temperature-compensation ceramic capacitor.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56172480A JPS5873907A (en) | 1981-10-28 | 1981-10-28 | High frequency dielectric porcelain composition |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2111968A true GB2111968A (en) | 1983-07-13 |
| GB2111968B GB2111968B (en) | 1984-11-21 |
Family
ID=15942762
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08229556A Expired GB2111968B (en) | 1981-10-28 | 1982-10-15 | Dielectric ceramic composition |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS5873907A (en) |
| DE (1) | DE3238545A1 (en) |
| GB (1) | GB2111968B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0727789A4 (en) * | 1994-09-07 | 1997-08-13 | Sumitomo Metal Ind | DIELECTRIC PORCELAIN COMPOSITION AND THEIR PRODUCTION |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0687367B2 (en) * | 1984-11-27 | 1994-11-02 | 京セラ株式会社 | Dielectric porcelain composition |
| JPH07187772A (en) * | 1993-12-24 | 1995-07-25 | Fuji Elelctrochem Co Ltd | Ceramic dielectric material |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3431124A (en) * | 1964-06-10 | 1969-03-04 | Tdk Electronics Co Ltd | Ceramic dielectric |
| JPS6024070B2 (en) * | 1978-04-19 | 1985-06-11 | 株式会社村田製作所 | Microwave dielectric ceramic composition |
| JPS5654272A (en) * | 1979-10-05 | 1981-05-14 | Tdk Electronics Co Ltd | Dielectric ceramic composition for microwave |
-
1981
- 1981-10-28 JP JP56172480A patent/JPS5873907A/en active Granted
-
1982
- 1982-10-15 GB GB08229556A patent/GB2111968B/en not_active Expired
- 1982-10-18 DE DE19823238545 patent/DE3238545A1/en not_active Ceased
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0727789A4 (en) * | 1994-09-07 | 1997-08-13 | Sumitomo Metal Ind | DIELECTRIC PORCELAIN COMPOSITION AND THEIR PRODUCTION |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5873907A (en) | 1983-05-04 |
| DE3238545A1 (en) | 1983-05-05 |
| JPH0237645B2 (en) | 1990-08-27 |
| GB2111968B (en) | 1984-11-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PE20 | Patent expired after termination of 20 years |
Effective date: 20021014 |