JPH04357619A - Dielectric porcelain composition - Google Patents

Abstract

PURPOSE:To provide a porcelain composition having a high dielectric constant, a low dielectric loss, a large dielectric voltage, large insulating resistance, and a small diameter of a crystalline particle by using a compound having a specific composition including Ba, Mg, Ti, and rare earth oxide. CONSTITUTION:A composition expressed by Formula (x)>>(BaO)(1-m).(MgO)m].(y) TiO2.(z)(R(1-t)Met)O3/2 is used, wherein R represents one kind or more of La, Pr, Nd and Sm; Me, a rare earth element other than La, Pr, Nd and Sm; and (m) ranges from 0.01 to 0.50; and (t), from 0.01 to 0.20. (x)+(y)+(z)=1. 0.3-5.0 parts by weight of niobium in a form of Nb2O5 are incorporated into 100 parts by weight of a main component within a range of mol ratios surrounded by a point (a) of (x)=0.15. (y)=0.50, and (z)=0.35, a point (b) of (x)=0.16, (y)=0.61, and (z)=0.23, a point (c) of (x)=0.10, (y)=0.67, and (z)=0.23, a point (d) of (x)=0.09, (y)=0.60, and (z)=0.31, a point (e) of (x)=0.02, (y)=0.58, and (z)=0.40, and a point (f) of (x)=0.02, (y)=0.52, and (z)=0.46.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric ceramic composition for a fixed ceramic capacitor for electronic equipment.

0002

BACKGROUND OF THE INVENTION Conventional dielectric ceramic compositions will be explained below. The following systems are known as dielectric ceramic compositions.

[0003] BaO・TiO2・Nd2O3 system BaO・
TiO2/Sm2O3 system e.g. 0.09BaO/0.56TiO2/0.35N
A dielectric ceramic disk was prepared using a dielectric ceramic composition having a composition ratio of dO3/2, and its electrical properties were measured. Dielectric constant: 67, capacitance temperature coefficient: N40 ppm/℃, Q
: 3000, insulation resistance: 8.0×10 12 Ω, and dielectric breakdown strength: 30 kv/mm.

0004

However, the above-mentioned conventional structure has the problems of low insulation resistance and low dielectric breakdown strength.

The present invention solves the above-mentioned conventional problems, and aims to provide a dielectric porcelain composition capable of obtaining dielectric porcelain having high insulation resistance and dielectric breakdown strength.

[0006]

[Means for Solving the Problem] In order to solve this problem, the dielectric ceramic composition of the present invention has the general formula x[(BaO)
(1-m)(MgO)m]・yTiO2・z(R(1-
t)Met)O3/2, where R is La, Pr,
One or more rare earth elements selected from Nd, Sm, Me
is one or more rare earth elements selected from rare earth elements excluding La, Pr, Nd, and Sm, and the values of m and t are 0.
It has a composition in the range of 01≦m≦0.50 and 0.01≦t≦0.20, and x, y, and z represent the molar ratio, and the values of x, y, and z are x+y+z=1. , a is x=0.15, y=0.50, z=0.35, b is x=0.16, y=0.61, z=0.23, c is x=
0.10, y=0.67, z=0.23, d is x=0.
09, y=0.60, z=0.31, e is x=0.02
, y=0.58, z=0.40, f is x=0.02, y
=0.52, z=0.46, a, b, c, d, e
, f, and 0.3 to 5.0 parts by weight of niobium in the form of Nb2O5.

[0007] Also, instead of niobium, tantalum can be used as Ta2.
It is contained in an amount of 0.1 to 10.0 parts by weight in terms of O5 form.

Furthermore, instead of niobium, vanadium is contained in an amount of 0.005 to 1.000 parts by weight in the form of V2O5.

Furthermore, in place of niobium, two or more selected from niobium, tantalum, and vanadium are Nb2O5.
, Ta2O5, V2O5 in total is 0.00
It contains 1 to 0.010 mole part.

0010

[Operation] With this configuration, R can be changed to La, Pr, Nd, S
By selecting from m, the capacitance temperature coefficient shifts in the positive direction in the order of La, Pr, Nd, and Sm.

[0011] Further, a part of one or more rare earth elements selected from La, Pr, Nd, and Sm may be replaced by La, Pr, Nd,
Q can be increased by substituting with one or more rare earth elements selected from rare earth elements other than Sm.

Furthermore, by substituting BaO with MgO, the temperature coefficient of capacitance is shifted to the positive direction, and the insulation resistance is increased.

By containing niobium, tantalum, vanadium, or two or more selected from these as subcomponents, the insulation resistance and dielectric breakdown strength can be increased.

[0014]

[Embodiment] An embodiment of the present invention will be described below.

(Example 1) Chemically high-purity Nb2O5, La2O3, Pr6O11, Nd2O3 are used as starting materials.
, Sm2O3, CeO2, Gd2O3, Dy2O3, T
iO2, MgO and BaCO3 powders as shown below (Table 1)
The mixture was weighed so as to have the composition ratio shown in , and put into a rubber-lined ball mill equipped with agate balls together with pure water, and after wet mixing, it was dehydrated and dried. This dry powder was placed in a high alumina crucible and calcined in air at 1100°C for 2 hours. This calcined powder was put into a rubber-lined ball mill equipped with agate balls together with pure water, wet-pulverized, and then dehydrated and dried. After adding an organic binder to this pulverized powder and making it homogeneous, it was sized through a 32-mesh sieve, and the diameter was 15 mm using a mold and a hydraulic press at a molding pressure of 1 ton/cm2.
mm, thickness 0.4 mm. Next, the thus obtained molded disks were placed in an alumina pod covered with zirconia powder, and fired in air at the firing temperatures shown in Table 1 for 2 hours. A dielectric ceramic disk having the composition ratio shown in was obtained.

[0016]

[Table 1]

The thickness and diameter of the dielectric ceramic disk thus obtained were measured, and a sample for measuring the dielectric constant, Q, and capacitance temperature coefficient was prepared using silver electrodes on both sides of the dielectric ceramic disk. A sample for measuring insulation resistance and dielectric breakdown strength was prepared by providing a 1 mm wide portion without a silver electrode inside the outer periphery of a dielectric ceramic disk, and baking a silver electrode thereon. And the dielectric constant, Q,
The capacitance temperature coefficient was determined using a digital LCR meter model 4275A manufactured by Yokogawa-Hewlett-Packard Co., Ltd. at a measurement temperature of 20° C., a measurement voltage of 1.0 Vrms, and a measurement frequency of 1 MHz. The capacitance temperature coefficient was determined by measuring capacitance at 20° C. and 85° C. using the following formula.

TC=(C-Co)/Co×1/65×106TC: Temperature coefficient of capacitance (ppm/°C) Co: Capacitance at 20°C (pF) C: Capacitance at 85°C (pF) Further, the dielectric constant was determined from the following formula.

K=143.8×Co×t/D2K: Dielectric constant Co: Capacitance at 20°C (pF) D: Diameter of dielectric ceramic (mm) t: Thickness of dielectric ceramic (mm) Further , insulation resistance was measured using Yokogawa-Hewlett-Packard Co., Ltd. HR meter model 4329A, and the measurement voltage was 50V. D. C. , was determined from measurements with a measurement time of 1 minute.

[0020]The dielectric breakdown strength was determined by Kikusui Electronics (
Using a high voltage power supply model PHS35K-3 manufactured by Co., Ltd., the sample was placed in silicone oil, and the dielectric breakdown voltage determined at a voltage increase rate of 50 V/sec was divided by the dielectric thickness to obtain the dielectric breakdown strength per 1 mm.

The above measurement results are shown separately for sample numbers 1 to 10 (Table 2).

[0022]

[Table 2]

FIG. 1 is a ternary 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 FIG. That is, sintering is extremely difficult in region A. Further, in region B, Q is small and becomes impractical. Furthermore, in regions C and D, the capacitance temperature coefficient becomes too large on the negative side, making it impractical. In region E, the temperature coefficient of capacitance shifts to a positive direction, but the dielectric constant is too small to be practical. In addition, by selecting R from La, Pr, Nd, and Sm, it is possible to shift the capacitance temperature coefficient in the positive direction without significantly lowering the dielectric constant in the order of La, Pr, Nd, and Sm. , La, Pr, Nd, and Sm, or a combination thereof, the capacitance temperature coefficient can be adjusted.

[0024] Further, a part of one or more rare earth elements selected from La, Pr, Nd, and Sm is
, substitution with one or more rare earth elements selected from rare earth elements other than Sm has the effect of increasing Q, but if the substitution rate t is less than 0.01, there is no substitution effect; If it exceeds .20, the dielectric constant becomes too small to be practical.

[0025] By replacing BaO with MgO, it is possible to shift the capacitance temperature coefficient in the positive direction and increase the insulation resistance without significantly changing the dielectric constant, Q, and dielectric breakdown strength. However, the replacement rate m
If it is less than 0.01, there will be no substitution effect, while if it exceeds 0.50, the dielectric constant will be too small to be practical.

[0026] Also, with respect to the main component, Nb as a subcomponent
Containing 2O5 has the effect of increasing insulation resistance and dielectric breakdown strength, but if the content of Nb2O5 is less than 0.3 parts by weight per 100 parts by weight of the main component, the dielectric breakdown strength is not so high. Therefore, it is excluded from the scope of this invention. On the other hand, the content of Nb2O5 is 5% compared to the main component.
．． If the amount exceeds 0 parts by weight, the insulation resistance (Q) decreases, and the temperature coefficient of capacitance increases to the negative side, making it impractical.

(Example 2) High-purity Ta2O5 powder was used in place of high-purity Nb2O5 in the raw materials of Example 1, and the composition ratios shown in Table 3 below were weighed. Dielectric ceramic disks having the composition ratios shown in sample numbers 11 to 20 in Table 3 were obtained by processing the steps in the same manner as in Example 1, and the results were obtained by processing in the same manner as in Example 1 and measuring the characteristics. Sample number 1
1 to 20 (Table 4).

[0028]

[Table 3]

[0029]

[Table 4]

[0030] Here, the reason for limiting the composition range and structure of the main components is the same as in Example 1, so the explanation will be omitted. The addition of Ta2O5 as a subcomponent to the main component has the effect of increasing insulation resistance and dielectric breakdown strength;
If the amount is less than 0.1 part by weight, the dielectric breakdown strength is not so large and it is excluded from the scope of the present invention. On the other hand, if the content of Ta2O5 exceeds 10.0 parts by weight based on the main component, the insulation resistance (Q) decreases and the temperature coefficient of capacitance increases to the negative side, making it impractical.

(Example 3) High-purity V2O5 powder was used in place of high-purity Nb2O5 among the raw materials in Example 1, and the composition ratio was as shown in Table 5 below. Dielectric ceramic disks having the composition ratios shown in sample numbers 21 to 30 in Table 5 were obtained by processing the steps in the same manner as in Example 1, and the results were obtained by processing in the same manner as in Example 1 and measuring the characteristics. Sample number 21
~30 separately (Table 6).

[0032]

[Table 5]

[0033]

[Table 6]

[0034] Here, the reason for limiting the composition range and structure of the main components is the same as in Example 1, so the explanation will be omitted. By containing V2O5 as a subcomponent to the main component, it has the effect of increasing insulation resistance and dielectric breakdown strength, but the content of V2O5 is 100% of the main component.
If the amount is less than 0.005 parts by weight, the dielectric breakdown strength is not so high and it is excluded from the scope of the present invention. On the other hand, if the content of V2O5 exceeds 1.000 parts by weight based on the main component, the insulation resistance will decrease, making it impractical.

(Example 4) In place of high-purity Nb2O5 among the raw materials of Example 1, high-purity Nb2O5, Ta2O
5 and V2O5 powder were weighed so as to have the composition ratio shown in Table 7 below, and the subsequent steps were performed in the same manner as in Example 1 to obtain the compositions shown in sample numbers 31 to 40 (Table 7). Dielectric ceramic disks of different proportions were obtained, treated in the same manner as in Example 1, and their characteristics were measured. The results are shown in Table 8 for sample numbers 31 to 40.

[0036]

[Table 7]

[0037]

[Table 8]

[0038] Here, the reason for limiting the composition range and structure of the main components is the same as in Example 1, so the explanation will be omitted. Then, with respect to the main component, Nb2O5 and T as subcomponents
By containing a2O5 and V2O5, insulation resistance,
Although it has the effect of increasing dielectric breakdown strength, Nb2
The total content of O5, Ta2O5, and V2O5 is the main component 1
If the amount is less than 0.001 parts by mole, the dielectric breakdown strength is not so large and is excluded from the scope of the present invention. On the other hand, if the total content of Nb2O5, Ta2O5, and V2O5 exceeds 0.010 mole part based on the main components, Q,
The insulation resistance becomes small and the temperature coefficient of capacitance becomes large on the negative side, making it impractical. Also, Nb2O5,T
By containing two or more types selected from a2O5 and V2O5, the dielectric constant, Q, insulation resistance, and dielectric breakdown strength are higher than those containing one type selected from Nb2O5, Ta2O5, and V2O5, and the capacitance temperature is lower. The coefficient can be made smaller.

[0039] In the method for manufacturing dielectric ceramic in the above embodiment, V2O5, Ta2O5, Nb2O5, La
2O3, Pr6O11, Nd2O3, Sm2O3, Ce
Although O2, Gd2O3, Dy2O3, TiO2, MgO, and BaCO3 were used, the method is not limited to this method. Compounds such as BaTiO3, carbonates, hydroxides, etc. V2O5, Ta2O5, Nb2O5, La
2O3, Pr6O11, Nd2O3, Sm2O3, Ce
Even when compounds such as O2, Gd2O3, Dy2O3, TiO2, MgO and BaO are used, properties comparable to those of the examples can be obtained.

Further, even if the main component is calcined in advance and subcomponents are added, properties comparable to those of the examples can be obtained.

Furthermore, titanium dioxide, an industrial raw material commonly used for dielectric ceramics, such as titanium dioxide KA-10C manufactured by Titan Kogyo Co., Ltd. and titanium dioxide FA-55W manufactured by Furukawa Mining Co., Ltd., has a maximum of 0. 45% by weight Nb2
Although O5 is included, even if the dielectric ceramic having the main component of Example 1 is made using these titanium dioxides, the main component is 100%.
The content of Nb2O5 is at most 0.23 in terms of parts by weight.
Although it is a part by weight and is outside the scope of this invention, considering the amount of Nb2O5 in titanium dioxide, which is an industrial raw material, the shortage of N
By containing b2O5, properties comparable to those of the examples can be obtained.

[0042] In addition to the above basic composition, SiO2
, MnO2, Fe2O3, ZnO, Al2O3, and other salts and oxides that are generally considered to be fluxes.
It can also be added within a range that does not impair the characteristics.

[0043]

Effects of the Invention As is clear from the description of the examples above, the present invention provides the following advantages:
)m]・yTiO2・z(R(1-t)Met)O3/
2, where R is one or more rare earth elements selected from La, Pr, Nd, and Sm, and Me is La, Pr, and Nd.
, one or more rare earth elements selected from rare earth elements excluding Sm, and the values of m and t are 0.01≦m≦0.50.
and has a composition in the range of 0.01≦t≦0.20, and x, y and z represent molar ratios, and x+y+z=
1, the values of x, y, z are a, b, c, which indicate predetermined numerical values.
A dielectric ceramic composition containing niobium, tantalum, vanadium, or two or more selected from them as a subcomponent has a composition in the molar ratio range surrounded by d, e, and f as a main component. It is possible to obtain a dielectric ceramic having a large coefficient, Q, insulation resistance, and dielectric breakdown strength, and a small temperature coefficient of capacitance.

[Brief explanation of the drawing]

FIG. 1 is a ternary diagram illustrating the composition range of the main components of a dielectric ceramic composition in one embodiment of the present invention.

Claims (4)

[Claims] Claim 1: The general formula is x[(BaO)(1-m)(
MgO)m]・yTiO2・z(R(1-t)Met)
O3/2, where R is one or more rare earth elements selected from La, Pr, Nd, and Sm, and Me is La, Pr.
, Nd, and one or more rare earth elements selected from rare earth elements excluding Sm, and the values of m and t are 0.01≦m≦0.
．． 50 and in the range of 0.01≦t≦0.20,
And x, y, and z represent the molar ratio, and the values of x, y, and z are x+y+z=1, a is x=0.15, y=0.50, z=0.35, and b is x=0. .16, y=0.61, z=0.23, c is x=
0.10, y=0.67, z=0.23, d is x=0.
09, y=0.60, z=0.31, e is x=0.02
, y=0.58, z=0.40, f is x=0.02, y
=0.52, z=0.46, a, b, c, d, e
, f, and 0.3 to 5.0 parts by weight of niobium in the form of Nb2O5. 2. The dielectric ceramic composition according to claim 1, containing 0.1 to 10.0 parts by weight of tantalum in the form of Ta2O5 instead of niobium. 3. The dielectric ceramic composition according to claim 1, which contains 0.005 to 1.000 parts by weight of vanadium in the form of V2O5 in place of niobium. Claim 4: Instead of niobium, two or more selected from niobium, tantalum, and vanadium are Nb2O5, Ta2O5
, 0.001 to 0.01 in total when converted to V2O5 form
The dielectric ceramic composition according to claim 1, wherein the dielectric ceramic composition contains 0 mole part.