 |
|
 |
| |
 |
Barium titanate base ceramic composition having a high dielectric constant |
| RE29484 |
Barium titanate base ceramic composition having a high dielectric constant
|
|
| Patent Drawings: | |
| Inventor: |
Utsumi, et al. |
| Date Issued: |
November 29, 1977 |
| Application: |
05/729,290 |
| Filed: |
October 4, 1976 |
| Inventors: |
Ohno; Tomeji (Tokyo, JA)
Tsubouchi; Norio (Tokyo, JA)
Utsumi; Kazuaki (Tokyo, JA)
|
| Assignee: |
Nippon Electric Company, Limited (Tokyo, JA) |
| Primary Examiner: |
Wyman; Daniel E. |
| Assistant Examiner: |
Waltz; Thomas A. |
| Attorney Or Agent: |
Hopgood, Calimafde, Kalil, Blaustein & Lieberman |
| U.S. Class: |
252/520.21; 501/138; 501/139 |
| Field Of Search: |
106/73.31; 106/73.32; 106/DIG.5; 252/520 |
| International Class: |
|
| U.S Patent Documents: |
2331444; 2836501; 2980546; 3373120; 3473958; 3474043; 3523028; 3529978; 3586642; 3666505; 3788867; 3975307 |
| Foreign Patent Documents: |
755,860 |
| Other References: |
"Three -Step Positive Temperature Coefficient of Resistivity...," Kuwabara et al., CA 79:71231t (1973).. |
|
| Abstract: |
A ceramic composition having a high dielectric constant which has good stability with temperature variation and the passage of time includes BaTiO.sub.3 in which the molecular ratio of Ba to Ti ranges from about 0.9 to 1.1 as the basic constituent and about 0.1 to 10 mol % of at least one compound selected from the group of Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5 and about 0.01 to 15 mol % of at least one compound selected from the group consisting of In.sub.2 O.sub.3, Ga.sub.2 O.sub.3, Tl.sub.2 O.sub.3, MgO, ZnO and NiO as sub constituents. |
| Claim: |
We claim:
1. A dielectric ceramic composition having a high dielectric constant, consisting of 77.5 to 99.79 mol % of BaTiO.sub.3 0.1 to 10 mol % of at least one of Nb.sub.2 O.sub.5 and Ta.sub.2O.sub.5, and about 0.01 to 15 mol % of at least one of the compounds In.sub.2 O.sub.3, Ga.sub.2 O.sub.3, and Tl.sub.2 O.sub.3.
2. A dielectric ceramic composition having a high dielectric constant, consisting of 77.5 to 99.79 mol % of BaTiO.sub.3, 0.1 to 10 mol % of at least one of Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5, about 0.01 to 15 mol % of at least one of thecompounds In.sub.2 O.sub.3, Ga.sub.2 O.sub.3, and Tl.sub.2 O.sub.3, and about 0.01 to 10 mol % of Al.sub.2 O.sub.3.
3. A dielectric ceramic composition, having a high dielectric constant, consisting of 77.5 to 99.79 mol % of BaTiO.sub.3 as a basic constituent, 0.5 to 5.0 mol % of Nb.sub.2 O.sub.5 as a sub constituent, and 0.05 to 5.0 mol % of at least one ofthe compounds In.sub.2 O.sub.3, Ga.sub.2 O.sub.3, and Tl.sub.2 O.sub.3 as another sub constituent.
4. A dielectric ceramic composition, having a high dielectric constant, consisting of 77.5 to 99.79 mol % of BaTiO.sub.3 as a basic constituent, 0.5 to 5.0 mol % of Nb.sub.2 O.sub.5 as one sub constituent, 0.05 to 5.0 mol % of at least one ofthe compounds In.sub.2 O.sub.3, Ga.sub.2 O.sub.3, and Tl.sub.2 O.sub.3 as a second sub constituent and 0.5 to 5.0 mol % of Al.sub.2 O.sub.3 as a third sub constituent, the total amount of said sub constituents being within a range of 1.05 to 10 mol %.
5. A dielectric ceramic composition, having a high dielectric constant, consisting of 77.5 to 99.79 mol % of BaTiO.sub.3 as a basic constituent, 0.5 to 5.0 mol % of Ta.sub.2 O.sub.5 as a sub constituent, and 0.05 to 5.0 mol % of at least one ofthe compounds In.sub.2 O.sub.5, Ga.sub.2 O.sub.3, and Tl.sub.2 O.sub.3 as another sub constituent.
6. A dielectric ceramic composition, having a high dielectric constant, consisting of 77.5 to 99.79 mol % of BaTiO.sub.3 as a basic constituent, 0.5 to 5.0 mol % of Ta.sub.2 O.sub.5 as a sub constituent, 0.05 to 5.0 mol % of at least one of thecompounds In.sub.2 O.sub.5, Ga.sub.2 O.sub.3, and Tl.sub.2 O.sub.3 as another sub constituent and 0.5 to 5.0 mol % of Al.sub.2 O.sub.3 as a further sub constituent.
7. A dielectric ceramic composition, having a high dielectric constant, consisting of 77.5 to 99.79 mol % of non-stoichometric BaTiO.sub.3 in which the molecular ratio of Ba to Ti lies within the range of approximately 0.9 to 1.1, 0.1 to 10 mol% of at least one of Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5 ; and 0.01 to 15 mol % of at least one of the compounds In.sub.2 O.sub.3, Ga.sub.2 O.sub.3 and Tl.sub.2 O.sub.3.
8. A dielectric ceramic composition having a high dielectric constant, consisting of 77.5 to 99.79 mol % of non-stoichometric BaTiO.sub.3 in which the molecular ratio of Ba to Ti lies within the range of approximately 0.9 to 1.1, 0.1 to 10 mol %of at least one of Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5 ; 0.01 to 15 mol % of at least one of the compounds In.sub.2 O.sub.3, Ga.sub.2 O.sub.3 and Tl.sub.2 O.sub.3 ; and further including 0.01 to 10 mol % of Al.sub.2 O.sub.3. |
| Description: |
BACKGROUND OF THE INVENTION
The present invention relates to ceramic compositions containing BaTiO.sub.3 as the basic composition, and particularly to such ceramic compositions having a high dielectric constant and in which the dielectric constant remains substantiallystable despite temperature variation and the passage of time.
Ceramic compositions having the above described properties are suitable for use in various electronic devices, such as for instance ceramic capacitors. In order to be practical for use in ceramic capacitors, it is desirable that a material havea dielectric constant (.epsilon.) of up to 2,000. The dielectric constant should remain relatively stable over a wide temperature range, for example, from minus 55.degree. C to plus 125.degree. C and should have good stability over the passage oftime. It is also desirable that the dielectric loss (tan.delta.) of the material be low.
In order to fulfill these requirements, a variety of compositions have heretofore been prepared. Most of these prior art compositions, however, have only had a dielectric constant which was stable with reference to either temperature or time. Moreover, the temperature range of good dielectric constant stability has been very narrow, so that practical applications have been quite limited.
It has been recently found that ceramic compositions containing barium titanate (BaTiO.sub.3) as the basic component and Ce, La and Bi as additives have a good temperature stability of their dielectric constant over a temperature range of-55.degree. C to +125.degree. C. The stability of the dielectric constant of such materials is also good with respect to time. This fact is reported in detail, for example, by Johannes Just, in an article entitled "Eigenschaften vonhochtemperaturbestandigen Sonderkeramiken mit hoher Dielektrizitatskonstante," which appeared in `Technische Mitteilungen AEG-Telefunken Gesellschaft`, Vol. 60, No. 2, pages 125-126 (1970). However, in compositions of the type described in this articlehaving dielectric constants which have good stability with respect to time and temperature, the dielectric constant is degraded to below 1,000 in value. Moreover, since Bi which has a high vapor pressure and is very reactive is contained in thesecompositions, it is difficult to use them in the manufacture of ceramics. When for instance these compositions are used to manufacture a laminated ceramic capacitor, internal electrodes made of platinum or palladium are noticeably corroded.
An object of the present invention is to eliminate the disadvantages mentioned above.
Another object of the present invention is to provide ceramic compositions which have a high dielectric constant and exhibit good temperature stability over a wide temperature range together with good time stability.
A further object of the present invention is to provide ceramic compositions which contain BaTiO.sub.3 as a basic composition but contain no Bi, so that capacitor manufacture using these compositions is facilitated and these compositions providean optimum material for the manufacture of, for instance, laminated ceramic capacitors.
SUMMARY OF THE INVENTION
The ceramic compositions of the present invention contain BaTiO.sub.3 as the basic constituent, in which the molecular ratio of Ba to Ti is within the range from about 0.9 to 1.1. These compositions further contain about 0.1 to 10 mol % of atleast one compound selected from the group consisting of Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5 and about 0.01 to 15 mol % of at least one compound selected from the group consisting of In.sub.2 O.sub.3, Ga.sub.2 O.sub.3, Tl.sub.2 O.sub.3, MgO, ZnO, andNiO as sub constituents. If desired, compositions within the above composition ranges may also contain about 0.01 to 10 mol % of Al.sub.2 O.sub.3 as another sub constituent to provide even greater improvement in both the temperature stability and thetime stability of the dielectric constant.
DESCRIPTION OF THE INVENTION
The ceramic compositions of the present invention have BaTiO.sub.3 as their basic constituent. The BaTiO.sub.3 is manufactured so that the molecular ratio of Ba to Ti is within the range of about 0.9 to 1.1. In addition, these ceramiccompositions contain about 0.1 to 10 mol % of at least one of Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5 and about 0.01 to 15 mol % of at least one of In.sub.2 O.sub.3, Ga.sub.2 O.sub.3, Tl.sub.2 O.sub.3, MgO, Zno, and NiO as sub constituents. Thesecompositions may also contain about 0.01 to 10 mol % of Al.sub.2 O.sub.3 as a further sub constituent.
If the content of Nb.sub.2 O.sub.5 and/or Ta.sub.2 O.sub.5 is less than 0.1 mol % in these ceramic compositions, tan .delta. will become large. While, if the content of Nb.sub.2 O.sub.5 and/or Ta.sub.2 O.sub.5 is more than 10 mol % or if thecontent of one or more of In.sub.2 O.sub.3, Ga.sub.2 O.sub.3, Tl.sub.2 O.sub.3, MgO, ZnO and NiO is less than 0.01 mol %, the temperature stability of the dielectric constant will be .[.degreaded.]. .Iadd.degraded.Iaddend.. If the content of one ormore of In.sub.2 O.sub.3, Ga.sub.2 O.sub.3, Tl.sub.2 O.sub.3, MgO, ZnO and NiO is more than 15 mol % or if the content of Al.sub.2 O.sub.3 is more than 10 mol %, the value of the dielectric constant will become low, e.g., below 1,500.
According to a first example of the present invention, a ceramic composition is made containing BaTiO.sub.3, about 0.1 to 10 mol % and preferably about 0.5 to 5.0 mol %, of Nb.sub.2 O.sub.5 and/or Ta.sub.2 O.sub.5 and about 0.01 to 15 mol % andpreferably about 0.05 to 5.0 mol % of at least one of In.sub.2 O.sub.3, Ga.sub.2 O.sub.3, and Tl.sub.2 O.sub.3. Less than 10 mol %, and preferably about 0.5 to 5.0 mol % Al.sub.2 O.sub.3 may be added to the composition. It is preferable that the totalamount of sub constituents in the composition be about 1.05 to 10 mol %.
According to a second example of the present invention, a ceramic composition contains BaTiO.sub.3, about 0.1 to 10 mol % and preferably about 0.5 to 5.0 mol % of Nb.sub.2 O.sub.5 and/or Ta.sub.2 O.sub.5, about 0.001 to 10 mol % and preferablyabout 0.5 to 5.0 mol % of MgO, ZnO, or NiO, and about 0.1 to 10 mol % and preferably about 0.5 to 5.0 mol % of Al.sub.2 O.sub.3. This composition may also contain at least one of TiO.sub.2, SiO.sub.2, SnO.sub.2, GeO.sub.2 and ZrO.sub.2 in an amount ofabout 0.01 to 10 mol % and preferably about 0.1 to 5.0 mol %. It is preferable that the total amount of sub constituents in the composition be about 1.6 to 10.0 mol %.
The ceramic compositions of the present invention have a high dielectric constant which is for example in the range of 1,500 to 3,500. The dielectric constant of these compositions has good stability over a wide temperature range, varying onlyin the range of +15% to -20% over a temperature range of -55.degree. C to +125.degree. C. The dielectric constant of these compositions also has good stability with respect to time.
As starting materials for making the basic constituent of the ceramic compositions of the present invention, BaCO.sub.3 and TiO.sub.2 powders of at least 99% purity were used. Powders of Nb.sub.2 O.sub.5, Ta.sub.2 O.sub.5, In.sub.2 O.sub.3,Ga.sub.2 O.sub.3, Tl.sub.2 O.sub.3, Al.sub.2 O.sub.3, MgO, ZnO, NiO, TiO.sub.2, SnO.sub.2, SiO.sub.2, GeO.sub.2, and ZrO.sub.2 of at least 99% purity were employed as the sub constituents. The BaCO.sub.3 and TiO.sub.2 were added together in equal mols,and were mixed by means of a ball mill. This mixture was thereafter pre-sintered at 1,000.degree. to 1,200.degree. C. It was determined by the powder X-ray diffraction method that the pre-sintering caused the powder to be thoroughly transformed intoBaTiO.sub.3. The pre-sintered BaTiO.sub.3 powder and the starting materials of subconstituents were weighed to obtain the necessary quantities, and were mixed by means of a ball mill. After filtration and drying, the mixture was pressure-molded intodiscs having a diameter of 16mm. These discs were sintered then at 1,300.degree. to 1,450.degree. C for 1 hour.
Silver electrodes were then provided on both the principal surfaces of the resultant ceramic discs by burning at 600.degree. C. The dielectric constant (.epsilon.) and the dielectric loss (tan.delta.) were then measured with a capacitance bridgeby applying an alternating current of 1 KHz to the ceramic discs at a temperature of 20.degree. C. The temperature stability of the dielectric constant was estimated by measuring it at various temperatures within the range of -55.degree. C and+125.degree. C and calculating the rate of temperature variation of the dielectric constant with reference to the value of the dielectric constant at +20.degree. C. The temperature stability of the dielectric constant can then be represented by:##EQU1## where .epsilon..sub.20 denotes the value of .epsilon. at +20.degree. C, while .epsilon..sub.max and .epsilon..sub.min respectively denote the maximum and the minimum values of the dielectric constant within the temperature range of -55.degree. C to +125.degree. C.
In order to estimate the time stability of the dielectric constant, the value of the dielectric constant was measured several times over a period of time from 12 hours to 1,000 hours after the provision of the silver electrodes by burning. Therate of variation (A.sub..epsilon.) of the dielectric constant with respect to time was calculated by the following equation: ##EQU2## where t: elapsed time,
.epsilon..sub.t0 : the value of .epsilon. at a time 12 hours after the provision of the electrodes by burning, and .epsilon..sub.t : the value of .epsilon. after an elapsed time of t hours.
Typical examples of the results obtained are listed in Tables 1, 2 and 3. Specimens shown with an asterisk in the tables are compositions outside the scope of the present invention.
Table 1 __________________________________________________________________________ rate rate of temp. of time variation variation Spec- tan .delta. of .epsilon. (%) of .epsilon. [A] imen Composition (mol %) .epsilon. (%) [-55.degree. C (%/ No. BaTiO.sub.3 Nb.sub.2 O.sub.5 Al.sub.2 O.sub.3 Other Subconstituents [20.degree. C] [20.degree. C] to +125.degree. C] decade) __________________________________________________________________________ 1* 95 2.5 2.5 -- -- -- -- 3130 6.40 +4 .about. -42 -1.5 2* 96 2.5 1.5 -- -- -- -- 2310 0.78 +19 .about. -30 -1.0 3* 96.5 1.5 2.0 -- -- -- -- 2770 0.36 0 .about. -40 -0.8 4 96 1.5 2.49 In.sub.2 O.sub.3 0.01 -- -- 2540 0.45 0 .about. -19 -0.8 5 96 1.5 2.40 " 0.10 -- -- 2450 0.40 0 .about. -16 -1.2 6 96 1.5 2.25 " 0.25 -- -- 2040 0.35 +1 .about. -8 -1.2 7 96 1.5 2.00 " 0.50 -- -- 2270 0.55 +15 .about. -10 -1.0 8 96 1.5 1.50 " 1.00 -- -- 1820 0.55 +15 .about. -10 -1.5 9 97 1.0 -- " 2.0 -- -- 2620 0.40 0.about. -16 -1.1 10 99.79 0.1 0.1 " 0.1 -- -- 2510 1.92 +7 .about. -11 -1.8 11 84.8 10.0 5.0 " 0.2 -- -- 1980 0.98 +10 .about. -6 -0.7 12 77.5 5.0 2.5 " 15.0 -- -- 1750 0.48 +9 .about. -19 -0.8 13 92.5 2.0 5.0 " 0.5 -- -- 1510 0.36 +8.about. -6 -1.3 14 96.7 2.0 1.0 " 0.3 -- -- 3000 0.33 +4 .about. -9 -1.2 15 97.8 1.5 0.5 " 0.2 -- -- 3100 0.41 +8 .about. -10 -1.0 16 78.0 7.0 -- Ga.sub.2 O.sub.3 15.0 -- -- 1770 0.86 +12 .about. -18 -1.0 17 97.2 1.5 1.0 " 0.3 - - 2200 0.42 +4 .about. -10 -1.2 18 97.2 1.5 1.2 " 0.1 -- -- 2460 0.67 0 .about. -17 -0.8 19 78.0 7.0 -- Tl.sub.2 O.sub.3 15.0 -- -- 1650 0.79 +11 .about. -18 -0.9 20 97.2 1.5 1.0 " 0.3 -- -- 2110 0.51 +8 .about. -6 -1.3 21 97.2 1.5 1.2 " 0.1 ---- 2300 0.39 0 .about. -13 -1.0 22 94.0 2.5 3.0 MgO 0.5 -- -- 2500 0.51 +14 .about. -12 -1.5 23 79.8 0.1 0.1 " 10.00 TiO.sub.2 10.0 3000 2.10 +5 .about. -15 -0.7 24 83.0 10.0 5.0 " 1.0 " 1.0 2530 1.00 +13 .about. -14 -1.0 25 83.0 5.010.0 " 1.0 " 1.0 2100 0.89 +12 .about. -13 -1.2 26 97.98 1.0 1.0 " 0.01 " 0.01 2300 0.43 +13 .about. -15 -1.5 27 95.0 2.5 1.5 " 0.5 " 0.5 1860 0.45 +10 .about. -13 -1.5 28 95.0 2.0 2.0 " 0.5 " 0.5 2560 0.50 +12 .about. -9 -1.2 29 94.51.0 1.5 " 1.5 " 1.5 1820 0.60 +17 .about. -12 -1.0 30 97.99 1.0 1.0 ZnO 0.01 -- -- 2400 0.83 +4 .about. -13 -1.3 31 93.0 1.0 1.0 ZnO 2.5 TiO.sub.2 2.5 2750 0.90 +6 .about. -13 -1.0 32 92.0 1.0 1.0 " 3.0 " 3.0 2530 1.10 +5 .about. -12-2.0 33 78.0 1.0 1.0 " 10.0 " 10.0 1650 0.53 +7 .about. -11 -1.0 34 93.5 2.5 2.0 " 1.0 SnO.sub.2 1.0 2300 0.73 +9 .about. -10 -1.5 35 78.0 1.0 1.0 " 10.0 " 10.0 1700 0.62 +3 .about. -7 -1.4 36 95.5 1.0 1.5 " 1.0 SiO.sub.2 1.0 2400 0.65 +7 .about. -8 -0.9 37 78.0 1.0 1.0 " 10.0 " 10.0 1730 0.55 +9 .about. -4 -0.7 38 95.5 1.0 1.5 " 1.0 GeO.sub.2 1.0 2630 0.43 +10 .about. -7 -1.3 39 78.0 1.0 1.0 " 10.0 " 10.0 1560 0.41 +3 .about. -6 -2.0 40 94.5 2.0 1.5 " 1.0ZrO.sub.2 1.0 2120 0.81 +4 .about. -10 -1.7 41 78.0 1.0 1.0 " 10.0 " 10.0 1770 0.91 +7 .about. -9 -2.0 42 97.0 1.0 1.5 NiO 0.5 -- -- 2440 0.83 +3 .about. -11 -0.7 43 95.98 2.0 2.0 " 0.01 TiO.sub.2 0.01 2510 0.75 +4 .about. -9 -1.2 44 95.0 1.5 1.5 " 1.0 " 1.0 2320 0.91 +7 .about. -7 -1.3 45 78.0 1.0 1.0 " 10.0 " 10.0 1600 1.01 +11 .about. -4 -1.1 46 97.99 1.0 1.0 In.sub.2 O.sub.3 0.005 Ga.sub.2 O.sub.3 0.005 2830
0.35 +1 .about. -13 -0.7 47 97.90 1.0 1.0 " 0.05 " 0.05 2540 0.41 +3 .about. -11 -1.1 48 97.75 1.0 1.0 " 0.125 " 0.125 2500 0.35 +5 .about. -10 -1.2 49 97.50 1.0 1.0 " 0.25 " 0.25 2380 0.51 +8 .about. -9 -0.9 50 97.00 1.0 1.0 " 0.5 " 0.5 2320 0.72 + 10 .about. -5 -0.8 51 97.00 1.0 -- " 1.0 " 1.0 2330 0.63 +5 .about. -8 -1.0 52 99.79 0.01 0.1 " 0.05 " 0.05 2960 0.91 +4 .about. -10 -1.3 53 88.80 10.0 1.0 " 0.1 " 0.1 1820 0.21 +1 .about. -13 -0.7 54 83.90 1.0 0.1 " 7.5 " 7.5 1550 0.32 +7 .about. -11 -0.9 55 88.50 1.0 10.0 " 0.25 " 0.25 1920 0.43 +5 .about. -10 -0.8 56 97.70 1.5 0.5 " 0.15 " 0.15 2480 0.38 +8 .about. -7 -0.9 57 84.00 1.0 -- -- Tl.sub.2 O.sub.3 7.5 " 7.5 1630 0.55 +3 .about. -14 -1.1 58 97.20 1.5 1.0 " 0.15 " 0.15 2210 0.61 +9 .about. -7 -1.2 59 97.29 1.5 1.2 " 0.005 " 0.005 2350 0.48 +2 .about. -12 -0.7 60 84.00 1.0 -- " 7.5 In.sub.2 O.sub.3 7.5 1610 0.65 +5 .about. -13 -0.9 61 97.20 1.5 1.0 " 0.15 " 0.15 2280 0.54 +7 .about. -9 -0.8 62 97.29 1.5 1.2 Tl.sub.2 O.sub.3 0.005 In.sub.2 O.sub.3 0.005 2310 0.37 +4 .about. -9 -1.1 63 92.00 1.0 -- " 2.0 " 3.0 2120 0.71 0 .about. -15 -1.0 Ga.sub.2 O.sub.3 2.0 64 97.20 1.5 1.0 Tl.sub.2 O.sub.3 0.1 " 0.03 2430 0.62 +11 .about. -5 -1.0 Ga.sub.2 O.sub.3 0.17 65 97.29 1.5 1.2 Tl.sub.2 O.sub.3 0.002 " 0.003 2510 0.53 +3 .about. -7 -0.9 Ga.sub.2 O.sub.3 0.005 __________________________________________________________________________
Table 2 __________________________________________________________________________ rate rate of of temp. time vari- variation ation of tan .delta. of .epsilon. (%) .epsilon.[A.sub.. epsilon. ] Specimen Composition (mol %) .epsilon. (%)[-55.degree. C (%/ No. BaTiO.sub.3 Ta.sub.2 O.sub.5 Al.sub.2 O.sub.3 In.sub.2 O.sub.3 Ga.sub.2 O.sub.3 Tl.sub.2 O.sub.3 [20.degree. C] [20.degree. C] to +125.degree. C] decade) __________________________________________________________________________ 66* 99.0 1.0 -- -- -- -- 2800 4.8 +30 .about. -40 -3.0 67 98.99 1.0 0.01 -- -- -- 2720 0.64 0 .about. -17 -1.0 68 98.0 1.0 1.0 -- -- -- 2540 0.35 0 .about. -20 -1.6 69 84.01.0 1.5 -- -- -- 1500 0.82 +11 .about. -4 -1.8 70 98.49 1.5 -- 0.01 -- -- 2380 0.67 0 .about. -13 -1.5 71 97.5 1.5 -- 1.0 -- -- 2300 0.71 +4 .about. -3 -1.5 72 84.0 1.0 -- 1.5 -- -- 1510 0.73 +3 .about. -6 -1.7 73 98.49 1.5 -- -- 0.01 -- 27400.61 +4 .about. -8 -1.4 74 98.0 1.0 -- -- 1.0 -- 3190 0.65 +11 .about. -4 -2.0 75 84.0 1.0 -- -- 1.5 -- 1500 0.79 +9 .about. -3 -2.1 76 98.49 1.5 -- -- -- 0.01 2710 0.84 +5 .about. -9 -0.9 77 97.5 1.5 -- -- -- 1.0 2650 0.71 +9 .about. -10 -1.1 78 84.0 1.0 -- -- -- 1.5 1530 0.62 +10 .about. -12 -1.3 79 98.87 0.1 1.0 0.03 -- -- 2630 0.73 +11 .about. -8 -0.8 80 97.5 1.0 1.0 0.5 -- -- 2410 0.52 +8 .about. -9 -1.1 81 96.47 1.5 2.0 0.03 -- -- 2260 0.43 +7 .about. -7 -1.5 82 93.9 5.0 1.00.1 -- -- 2080 0.44 +3 .about. -12 -1.6 83 88.9 10.0 1.0 0.1 -- -- 1610 0.76 +0 .about. -15 -1.8 84 98.0 1.0 0.5 -- 0.5 -- 2580 0.71 +0 .about. -14 -2.0 85 97.5 1.0 1.0 -- -- 0.5 2540 0.65 +0 .about. -17 -2.1 86 97.5 1.0 -- -- 1.0 0.5 2420 0.56+3 .about. -13 -1.3 87 98.0 1.0 -- 0.5 -- 0.5 2680 0.81 +1 .about. -11 -1.2 88 97.5 1.0 -- 0.5 1.0 -- 2370 0.77 +2 .about. -11 -1.5 89 97.47 1.0 -- 0.03 1.0 0.5 2330 0.69 +5 .about. -9 -1.7 90 97.97 1.0 0.5 -- 0.5 0.03 2410 0.53 +4 .about. -12-1.9 91 97.47 1.0 1.0 0.03 -- 0.5 2330 0.55 +7 .about. -10 -1.1 92 95.95 1.5 1.5 0.05 1.0 -- 2150 0.62 +6 .about. -9 -0.8 93 96.3 1.5 0.5 0.1 1.5 0.1 2470 0.71 +5 .about. -5 - __________________________________________________________________________ 0.6
Table 3 __________________________________________________________________________ rate of rate of tan .delta. temp. variation time variation Specimen Composition (mol %) .epsilon. (%) of .epsilon. (%) of .epsilon. [A.sub..epsilon. ] No. BaTiO.sub.3 Nb.sub.2 O.sub.5 Ta.sub.2 O.sub.5 Al.sub.2 O.sub.3 In.sub.2 O.sub.3 [20.degree. C] [20.degree. C] [-55.degree. C to +125.degree. C] (%/decade) __________________________________________________________________________ 94 96.0 0.51.0 2.25 0.25 2130 0.38 +2 .about. -7 -1.0 95 97.5 0.5 0.5 1.0 0.5 2380 0.45 +6 .about. -7 -0.9 96 96.47 1.0 0.5 2.0 0.03 2280 0.45 +3 .about. -7 -0.8 __________________________________________________________________________
The specimens numbered 1, 2, 3 and 66 indicate results for compositions outside the scope of the present invention for comparison. Results for specimens 1, 2, 3 and 66 show wide percentage variation of the dielectric constant of the testcompositions within the range of temperatures tested. By contrast from Tables 1 to 3, the example specimens numbered 4 through 65 and 67 through 96 have compositions within the scope of the present invention, and these compositions show a relativelysmaller variation in dielectric constant with variation in temperature. The rate of variation of dielectric constant with time of these compositions is also small. Moreover, the compositions of the present invention have dielectric constants ofsufficiently large values and superior values of dielectric loss (tan.delta.).
While almost all of the foregoing examples have been described as employing, as the basic constituent, BaTiO.sub.3 in which Ba and Ti are used in equimolecular amounts, similar effects can be achieved utilizing BaTiO.sub.3 in which the molecularratio of Ba to Ti (Ba/Ti) ranges from about 0.9 to 1.1, as shown by the results for specimens 50, 56, 71 and 80 in Tables 1 and 2. The specimens numbered 50 and 71 indicate results for compositions in which the molecular ratio of Ba to Ti (Ba/Ti) is0.9. While, the specimens 56 and 80 indicate results for compositions in which the molecular ratio of Ba to Ti is 1.1.
* * * * * |
|
|
|
 |
|
 |
|
| |
Randomly Featured Patents |
|
