JPH0587006B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a dielectric ceramic composition that has a high dielectric constant, a small temperature coefficient, excellent quality, and high insulation resistance. BACKGROUND ART A dielectric material with a small temperature coefficient has been required as a capacitor element, and the following systems are known as dielectric ceramic compositions. MgO−TiO ₂ −CoO system La ₂ O ₃ −2TiO ₂ −CaTiO ₃ −2MgO−TiO ₂ system TiO ₂ −BaTiO ₃ −Bi ₂ O ₃ −La ₂ O ₃ system SrZrO ₃ −SrO−Nb ₂ O ₅ −CaTiO Problems to be solved by the ₃ -system invention However, these compositions have a low dielectric constant, and
The SrZrO ₃ −SrO−Nb ₂ O ₅ −CaTiO ₃ system also had poor quality. Furthermore, there is a problem in that Pd cannot be used as the internal electrode of a multilayer ceramic capacitor containing Bi ₂ O ₃ . The object of the present invention is to obtain a dielectric ceramic having a high dielectric constant, a small temperature coefficient, excellent quality, and high insulation resistance. _Means for Solving the Problem In order to _solve this problem _, the present invention provides _{the following formula : o} (Sm ₂ O ₃ )n] Where, x+y+z=1.00 o<m≦0.25 0.05≦n<1.00 x, y, z are each point a, b, c, d expressed below
This is a dielectric ceramic composition characterized in that the main component is a composition having a molar ratio within the range surrounded by .

[Table] FIG. 1 is a triangular diagram showing the composition range of the main components of the composition according to the present invention, and the reason for limiting the composition range of the main components will be explained with reference to the figure. In region A, sintering becomes difficult and the dielectric constant, quality Q, and insulation resistance decrease. In region B, the temperature coefficient becomes too large on one side, making it impractical. In region C, the temperature coefficient becomes large on the + side and the dielectric constant is also small. In region D, sintering becomes difficult, and the dielectric constant, quality Q, and insulation resistance decrease. Further, in the range of o<m≦0.25, increasing m shifts the temperature coefficient to the + side, and by selecting an appropriate composition, a composition with a large dielectric constant near the temperature coefficient NPO can be obtained. When m exceeds 0.25, sintering becomes difficult, and the dielectric constant, quality Q, and insulation resistance decrease. Also, in the range of 0.05≦n<1.00, n
When the temperature coefficient is increased, the temperature coefficient shifts to the + side, and by selecting an appropriate composition, a composition with a large dielectric constant near the temperature coefficient NPO can be obtained. When n is less than 0.05, the temperature coefficient increases to one side, making it impractical. The present invention further provides manganese,
At least one selected from the group consisting of oxides of chromium, iron, nickel, and cobalt, each converted into MnO ₂ , Cr ₂ O ₃ , FeO, NiO, and CoO, has a content of 0.05 to 0.05 of the main component. It can be configured such that 1.00% by weight is added. These additives have the effect of improving the sinterability of porcelain, and their addition amount is 0.05
If it is less than 1.00% by weight, there is no effect of addition, and if it exceeds 1.00% by weight, the dielectric constant decreases. Function The dielectric ceramic composition of the present invention makes it possible to obtain a dielectric ceramic having a high dielectric constant, a small temperature coefficient, excellent quality, and high insulation resistance. Examples Specific examples will be explained below. (Example 1) Starting materials include chemically highly purified BaCO ₃ , TiO ₂ ,
ZrO ₂ , Nd ₂ O ₃ , and Sm ₂ O ₃ powders were weighed to have the composition shown in Table 1, and placed in a rubber-lined ball mill equipped with an agate ball together with pure water.
Wet mixed. After dehydrating and drying this mixture, 9% by weight of a 5% concentration polyvinyl alcohol solution was added to the powder as a binder to make it homogeneous.
The grains were sized through a 32 mesh sieve. The sized powder was molded into a diameter of 15 mm and a thickness of 0.4 mm using a mold and a hydraulic press at a molding pressure of 1 ton/cm ² , and the molded product was placed in a high-purity alumina sagger and placed in air as shown in Table 1. The mixture was fired at the temperature shown for 2 hours to obtain dielectric porcelain having the composition shown in Table 1. The electrical properties of these samples are determined by baking silver electrodes on both sides of the sample, and the dielectric constant, goodness Q, and temperature coefficient are
Using YHP digital LCR meter model 4275A,
Measurement temperature 25℃, measurement voltage 1.0Vrms, measurement frequency
Obtained by measurement at 1MHz. Furthermore, the temperature coefficient is
Based on the capacitance value at 25°C, it was calculated using the following formula. Temperature coefficient = (C ₈₅ ℃ - C ₂₅ ℃) / (C ₂₅ ℃ × 60) ×
10 ⁶ (ppm/°C) Insulation resistance was measured using YHPHR meter model 4329A at voltage D. C. It was determined by measurement at 50V for 1 minute. Test conditions and results are shown in Table 1. (Example 2) Starting materials include chemically highly purified BaCO ₃ , TiO ₂ ,
ZrO ₂ , Nd ₂ O ₃ , Sm ₂ O ₃ , MnO ₂ , Cr ₂ O ₃ , FeO,
NiO and CoO powders were weighed to have the compositions shown in Table 2, and thereafter treated in the same manner as in Example 1 to obtain dielectric porcelain having the compositions shown in Table 2. The test methods for these samples were the same as in Example 1, and the test conditions and results are shown in Table 2.

【table】

【table】

[Table] Effects of the invention As described above, according to the present invention, the dielectric constant is high;
Dielectric ceramics with a small temperature coefficient, excellent quality Q, and high insulation resistance can be obtained. Furthermore, the firing temperature can be lowered by adding oxides of manganese, chromium, iron, nickel, and cobalt. Furthermore, since the obtained dielectric ceramic has a high dielectric constant, the element body can be made extremely small, and it is effective for miniaturizing circuits, and is particularly useful for making into thin plates for applications such as laminated ceramic capacitors and hybrid microcircuits. suitable for

[Brief explanation of the drawing]

The figure is a triangular diagram showing the composition range of the main components according to the present invention.

Claims (1)

[Claims] 1 When expressed as the general formula ×BaO−y[(TiO ₂ ) _1-n (ZrO ₂ ) _n ]−z[Nd ₂ O ₃ ) _1-o (Sm ₂ O ₃ )n] , However, x+y+z=1.00 o<m≦0.25 0.05≦n<1.00 x, y, z are each point a, b, c,
A dielectric ceramic composition characterized in that the main component is a composition having a molar ratio within the range surrounded by d. [Table] 2 At least one selected from the group consisting of oxides of manganese, chromium, iron, nickel, and cobalt is added to MnO ₂ , Cr ₂ O ₃ , FeO, and NiO, respectively.
The dielectric ceramic composition according to claim 1, further comprising 0.05 to 1.00% by weight of the main component in terms of CoO.