JP3225577B2 - Dielectric porcelain composition - Google Patents

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 having a high dielectric constant, a small change in temperature, a small dielectric loss, a small dielectric loss when a signal voltage is applied, and an excellent sinterability. .

[0002]

2. Description of the Related Art Hitherto, as a material for a high dielectric constant ceramic capacitor, a dielectric ceramic composition containing barium titanate as a main component has been widely used. Among them, as the material having a small change in the dielectric constant with temperature, many compositions are known, including barium titanate-bismuth system, barium titanate-niobium pentoxide-manganese dioxide system (JP-A-51-76597). Have been.

Further, in order to meet the recent demand for a multilayer ceramic capacitor having a small size and a large capacity, the dielectric constant of a dielectric material and the thickness of a dielectric layer are rapidly progressing. Therefore, with a high dielectric constant, the temperature change of the dielectric constant is small,
The demand for a dielectric material having a small dielectric loss has become extremely large.

[0004]

However, most of the above-mentioned conventional dielectric porcelain compositions use barium titanate obtained by a solid-phase reaction from barium carbonate and titanium oxide as a raw material. The dielectric constant is 3000 or less.

In general, in a ferroelectric material such as barium titanate, as the applied electric field intensity increases, the change in the dielectric constant increases and the dielectric loss also increases. Since the characteristics of the capacitor are evaluated at a signal voltage of 1 Vrms, a high signal electric field is applied as the dielectric layer becomes thinner, and the signal voltage characteristics of the conventional dielectric ceramic composition are poor. However, there has been a problem that the dielectric loss rapidly increases with an increase in the signal voltage, and the standard cannot be satisfied.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems. It is an object of the present invention to provide a dielectric ceramic composition having a high dielectric constant, a small change in temperature, a small dielectric loss, and a good signal voltage characteristic. Aim.

[0007]

SUMMARY OF THE INVENTION To achieve this object, the present invention provides a barium titanate, niobium pentoxide,
Dielectric consisting of nickel, manganese oxide and silicon dioxide
100 parts by weight of barium titanate in the body porcelain composition
0.8 to 1.5 parts by weight of niobium pentoxide,
0.05 to 0.30 parts by weight of silicon, nickel oxide and acid
Manganese oxide in a total amount of 0.1 parts by weight or more, and pentaacid
The weight ratio of niobium oxide, nickel oxide and manganese oxide is 3
≤ Niobium pentoxide / (nickel oxide + manganese oxide)
(However, nickel oxide 0 parts by weight, manganese oxide 0 weight
Excluding parts by mass)
Which has a high dielectric constant and the temperature of this dielectric constant
The change is small, the dielectric loss is small, and the
Dielectric ceramic composition with low electric loss and excellent sinterability
You can get things.

[0008]

(Example 1) This example corresponds to the invention described in claim 1, and a specific amount of niobium pentoxide is added to barium titanate produced by a hydrothermal synthesis method and having a specific surface area adjusted by heat treatment. The problem was solved by adding nickel oxide, manganese oxide, and silicon dioxide.

First, a particle size of 0.1 produced by the hydrothermal synthesis method is used.
Barium titanate fine powder having a thickness of 9 μm or more and a purity of 99.99% or more was calcined at 900 to 1150 ° C, and barium titanate whose specific surface area was adjusted to 0.4 to 2.6 m ² / g was used. Then, as shown in (Table 1), niobium pentoxide was added to N 2 with respect to 100 parts by weight of the barium titanate.
Nickel oxide was converted to NiO, manganese oxide was converted to MnO ₂ , and silicon dioxide was converted to SiO _{2 in} terms of b ₂ O ₅ . In Table 1, niobium pentoxide, nickel oxide, manganese oxide, and silicon dioxide are referred to as Nb and N, respectively.
i, Mn, and Si.

[0010]

[Table 1]

These are placed in a polyethylene container with a diameter of 5 m.
The mixture was mixed with pure water for 20 hours by a ball mill containing zirconia balls of m. After mixing, the slurry was granulated by adding 9% by weight of a 5% PVA (polyvinyl alcohol) aqueous solution to the dried powder. Then, the granulated powder was put into a mold, and 1 to 15 mm-diameter and 0.5 mm-thick discs were formed.
It was molded at a pressure of n / cm ² . The molded body thus obtained was fired at 1300 ° C. to 1400 ° C. for 2 hours, and silver electrodes were baked on both surfaces of the fired body to obtain a sample for measurement.
Samples whose sintering density did not reach 95% of the theoretical density at a sintering temperature of 1400 ° C. or less were not sintered, and the measurement of the following electrical characteristics was omitted. Then, at room temperature, the capacitance and dielectric loss of the sample were measured at 1 Vrms and 1 kHz, and the dielectric constant was determined from the capacitance. On the other hand, the signal voltage characteristic of dielectric loss is 1 k
Hz signal was applied at 50 Vrms for measurement. Further, the temperature characteristic of the dielectric constant is set to 1 V in the range of −60 ° C. to + 135 ° C.
rms, measured at 1 kHz. The results (Table 2)
Table 3 shows the dielectric constant at room temperature, dielectric loss, signal voltage characteristics of dielectric loss, and each temperature (−55 ° C., −25 ° C., + 85 ° C.).
° C, + 125 ° C). (Table 1),
In Tables 2 and 3, samples marked with # are out of the scope of the present invention and are comparative examples.

[0012]

[Table 2]

As is clear from Table 2, the amount of niobium pentoxide added is 0.1 to 100 parts by weight of barium titanate.
If the amount is less than 8 parts by weight, the sinterability is poor. On the other hand, if the amount exceeds 1.5 parts by weight, the dielectric constant becomes low. If the total amount of nickel oxide and manganese oxide is less than 0.1 parts by weight, the sinterability becomes poor. Is bad. When the weight ratio of niobium pentoxide / (nickel oxide + manganese oxide) is smaller than 3, the temperature change of the dielectric constant is large. Therefore, based on 100 parts by weight of barium titanate, 0.8 to 1.5 parts by weight of niobium pentoxide, 0.1 parts by weight or more of nickel oxide and manganese oxide in total, and niobium pentoxide, nickel oxide , Manganese oxide, and the relationship of 3 ≦ niobium pentoxide / (nickel oxide + manganese oxide) is defined. Table 3 shows the results of adding a specified amount of silicon dioxide to further improve sinterability.
Shown in

[0014]

[Table 3]

As is clear from Table 3, the sintered body obtained by adding 0.05 parts by weight or more of silicon dioxide to 100 parts by weight of barium titanate has a stable sintering density and a sintering temperature. A sintered density with little variation is obtained at both 1330 ° C. and 1300 ° C., and dielectric loss when a signal voltage of 50 Vrms / mm is applied is also good. However, when the added amount of silicon dioxide exceeds 0.3 parts by weight, the dielectric constant is significantly reduced.

Therefore, silicon dioxide is added in an amount of 0.05 to 0.3.
The dielectric porcelain composition of the present invention obtained by adding 0 parts by weight can widen the allowable range of the sintering temperature without greatly impairing the sinterability even if the sintering temperature varies, and can improve the electrical characteristics such as dielectric constant and dielectric loss. Etc. can be prevented.

[0017]

The dielectric porcelain composition of the present invention is 2700
With a high dielectric constant up to about 4000, the temperature change of the dielectric constant is small, the dielectric loss when a signal voltage of 50 Vrms / mm is applied is good, and the sinterability is improved. Is not greatly impaired, the allowable range of the sintering temperature can be widened, and deterioration of electric characteristics such as dielectric constant and dielectric loss can be prevented.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-44061 (JP, A) JP-A-2-92865 (JP, A) JP-A-1-315904 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01B 3/12 303 C04B 35/46 H01G 4/12 415

Claims (1)

(57) [Claims] 1. A barium titanate having an adjusted by Ri specific surface <br/> product to the generated heat treated with the hydrothermal synthesis method 0.8~2.4m ² / g, niobium pentoxide, nickel oxide, Manganese oxide, two
It consists of a silicon oxide, niobium pentoxide from 0.8 to 1.5 parts by per 100 parts by weight of barium titanate dioxide Ke
0.05 to 0.30 parts by weight of iodine, nickel oxide and oxidation
The total amount of manganese is 0.1 parts by weight or more , and the weight ratio of niobium pentoxide, nickel oxide, and manganese oxide is 3 ≦
Niobium pentoxide / (nickel oxide + manganese oxide ) relationship (however, nickel oxide 0 parts by weight , manganese oxide 0 parts by weight)
Part ) ( excluding parts ).