JPS6145509A - Dielectric porcelain composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a dielectric ceramic composition, and particularly to a dielectric ceramic composition suitable as a dielectric material for laminated capacitors and the like.

(Prior art) Conventionally, high dielectric constant porcelain compositions mainly composed of barium titanate, in which stannate, zirconate, titanate, etc. are dissolved, have been widely put into practical use. ing.

(Problems to be solved by the invention) Conventional barium titanate-based porcelain materials have an optimum firing temperature of 1300
The temperature is as high as ~1,400°C, which not only increases the firing cost, but also requires the use of a high-melting-point material such as palladium or platinum as an internal electrode polishing material when used as a dielectric material for a multilayer capacitor, for example.

Such a high-melting-point total bending material is expensive. Therefore, conventional barium titanate-based dielectric ceramic compositions have been a major obstacle in reducing the cost of, for example, multilayer capacitors.

Therefore, the main object of the present invention is to provide a dielectric ceramic composition having an optimum firing temperature of 950° C. or less and a high dielectric constant.

(Means for Solving the Problems) This invention consists of lead oxide, iron oxide, niobium oxide, tungsten oxide, and zinc oxide, and when these components are expressed by the following general formula, XPb (Fe1/2Nb1/ 2- YPb (Fe2
/3W+/3) 03 Z P b (Z n 17
2W+/2) 03Mole fractions X, Y and Z (however,
X+Y+Z=1.00) is the following points A, B, C, D,
In the range surrounded by a polygon with vertices E and F,
It is a dielectric ceramic composition.

X Y ZA
0.800,190,01 B 0. ,800,100,10 C0.600,100,30 D 0.400,300,30 E 0.400,500,10 F 0.500,490,01 (Effect of the invention) According to this invention, optimal firing Even if the temperature is 950"C or less, the dielectric constant is as large as 500 or more. Therefore, by using the dielectric ceramic composition obtained by the present invention, a small capacitor with a large capacity can be obtained. If the dielectric ceramic composition of the present invention is used as a ceramic material for a multilayer capacitor, the firing temperature will be 950''C.
Since it is as follows, a less expensive silver-based metal can be used as the electrode, and therefore the cost of such a multilayer capacitor can be reduced by 111iii.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

(Example) Output Qf”1 fee t!: ShiteP b304.F e 0
3, using Nb2o,,wo3 and ZnO,
Pb(Fe+z2N+/2) 03, Pb(F
e2/3W+/3) 03 Oyobi pb (Z n 1
/3)O2W1/3)O2)03, they were weighed so that their respective molar fractions would be the blending ratios shown in the table.

Then, these were wet mixed in a ball mill for 5 to 20 hours. After drying the IMed mixture, 650-850°
It was held at C for 2 hours and calcined to form a powder. The obtained calcined powder was kneaded with a binder containing 3% by weight of polyvinyl alcohol, granulated, and then molded into a disc having a diameter of IQms and a thickness of 1mm under a pressure of 200 kg/c+d. This disk,
It was fired at 900 to 950°C for 2 hours using an electric furnace with a lead atmosphere. Measurement samples 1 to 18 were prepared by baking silver electrodes on both sides of the obtained porcelain disk.

For each sample, the dielectric constant (ε) and the dielectric loss tangent (tan
δ) was measured and the values are shown in the table. In addition,
The dielectric constant and dielectric loss tangent are at a temperature of 25°C and a frequency of 1k.
It was measured under the condition of Hz.

(Left below blank) Samples marked with * in the table are outside the scope of this invention, and the remaining samples are within the scope of this invention. That is, in the table, sample number 1 4, 6, a, 14. 1s and 18 are outside the scope of the invention, and sample numbers 2, 3, and 5
, 7.9-13.16 and 17 are within the scope of the invention.

Based on the results of each experimental example shown in the table, a three-component composition diagram (ternary diagram) is shown in the drawing. In addition, the numbers marked with circles in this drawing represent each sample number. In this drawing, the areas representing the blending ratio within the scope of this invention are indicated by vertices A, B, C, and D.
, E and F. That is, the blending ratio in the above-mentioned three-component ceramic composition was changed to XPb (
Fe1/3)O2Nb172- YPb(Fe2z3
W+a- ZPb (Z n 1/3) O2WI/2
) 03 (where x, y, z represent the mole fraction of each component, and X + Y + Z = 1.00), the scope of this invention is A, B, C, D, E and X Y corresponding to the blending ratio within the range surrounded by polygon ABCDEF with F as the vertex
Z8 0.80 0.19
0.01s 0. I3o 0.100,
10C0.600,100,30D 0. /LO0.300,30E 0.
/10 0.50 0.10F 0.
500,490,01 The reason why the composition of the dielectric ceramic composition according to the present invention is limited as described above is as follows. In the drawing, line segment A
Outside B, outside line segment BC, outside line segment CD, D
Outside E, the dielectric constant is as low as 8000 or less, and the dielectric loss tangent is also as large as 2% or more. Also, line segment EF
Further outside, the dielectric constant is as low as 8000 or less, and outside the line segment FA, the dielectric loss tangent is as large as 2% or more, which are both unfavorable. On the other hand, in the sample band within the scope of this invention, which is located in the region surrounded by the polygon ABCDEF with points A, B, C, D, E, and F as vertices, the dielectric constant is 8.
000 or more, the dielectric loss tangent is as small as 2% or less, and the optimum firing temperature is also 950'C or less. For example, it is suitable as a dielectric material for ceramic capacitors.

[Brief explanation of the drawing]

The drawing is a ternary diagram showing the range of compounding ratios of the present invention.

Claims (1)

[Claims] Consisting of lead oxide, iron oxide, niobium oxide, tungsten oxide and zinc oxide, each of these components is represented by the following general formula: XPb(Fe_1_/_2Nb_1_/_2)O_3-
YPb(Fe_2_/_3W_1_/_3)O_3-Z
Pb(Zn_1_/_2W_1_/_2)O_3 mole fractions X, Y, and Z (X+Y+Z=1.00) form a polygon with the following points A, B, C, D, E, and F as vertices. A dielectric porcelain composition within the enclosed area. X Y Z A 0.80 0.19 0.01 B 0.80 0.10 0.10 C 0.60 0.10 0.30 D 0.40 0.30 0.30 E 0.40 0.50 0.10 F 0.50 0.49 0.01