JPS6152097B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a high dielectric constant ceramic composition having a low sintering temperature and suitable as a material for ceramic capacitors. Conventional configurations and their problems The characteristics that dielectric materials should have vary depending on the application, but ceramic capacitors have a large dielectric constant;
In addition, a low sintering temperature is required. A high dielectric constant is an important condition for making the device compact. The low sintering temperature has great industrial value, as it allows the use of inexpensive furnace materials for the firing furnace and requires less energy for firing when firing porcelain materials. Furthermore, in a multilayer ceramic capacitor, if the sintering temperature is low, a relatively inexpensive electrode material containing silver as a main component can be used as the internal electrode, so the price of the capacitor can be significantly reduced. Barium titanate-based porcelain has traditionally been used as a material for high dielectric constant ceramic capacitors. However, this material has a sintering temperature of 1300~
Because the temperature is as high as 1,400°C, the manufacturing of multilayer ceramic capacitors had the disadvantage of having to use expensive internal electrodes whose main component was platinum or palladium, which was suitable for the sintering temperature. Purpose of the invention The present invention improves the above-mentioned drawbacks, and the sintering temperature is 1000
The object of the present invention is to provide a ceramic composition that has a low dielectric constant of less than 0.degree. C. and a large dielectric constant. Structure of the Invention The composition of the present invention comprises Pb(Ni _1/3 Nb _2/3 ) _x
(Fe _1/2 Nb _1/2 ) _y (Fe _2/3 W _1/3 ) _z In the composition represented by O ₃ , the blending ratio is 0.01≦x≦0.40, 0.45
≦y≦0.80 and 0.05≦z≦0.50 (however, x+
y+z=1). Description of Examples Raw materials include PbO, NiO, Fe ₂ O ₃ , Nb ₂ O ₅ ,
Using WO ₃ , these were weighed to the composition ratio shown in the table below, mixed wet, and dried at 750°C.
It was calcined for 2 hours. The obtained calcined product was wet-pulverized in a ball mill, dried, and then pressure-molded into a cylindrical shape with a diameter of 13 mm and a length of about 8 mm using an aqueous solution of polyvinyl alcohol as a binder. Then, after incinerating the binder, it was placed in a magnesia porcelain container and fired at a temperature of 880-1040°C for 2 hours. The fired porcelain is cut to a thickness of 1 mm, and both sides are coated with Cr-
After depositing Au, the dielectric constant ε _r and dielectric loss tangent D are
Measurements were made at 1 kHz and 1 V/mm at room temperature. The temperature change rate of ε _r was measured in the range of -25°C to 85°C with 20°C as a reference. Moreover, the specific resistance was measured at 1 kV/mm at room temperature. The results are shown in the table below.

[Table] In the above table, samples No. 1, 3, 5, 13, and 14 are outside the scope of the present invention, and samples No. 2, 4, 6 to 12 are examples of the present invention. As is clear from the above table, porcelain made of the composition within the scope of the present invention has a large dielectric constant (8230 to 23410).
In addition, the firing temperature is 880°C to 980°C, and sintering is possible at low temperatures. Also,
It exhibits features such as a small dielectric loss tangent D, a small temperature change rate of the dielectric constant ε _r , and a relatively high specific resistance. Note that compositions where x is less than 0.01 have a small resistivity, and compositions where x is more than 0.40 require firing temperatures of 1000°C or higher;
Compositions in the range of 0.05 and z > 0.50 have relatively small dielectric constants and are therefore excluded from the scope of the present invention.
The composition is limited to the above and has a large specific resistance. Effects of the Invention The composition of the present invention has a large dielectric constant, a relatively small temperature change rate of the dielectric constant, a relatively small dielectric loss tangent, and a large specific resistance, making it suitable as a material for ceramic capacitors and at low temperatures below 1000°C. Since the sintering temperature is low, when used in multilayer ceramic capacitors, which have great industrial value, such as being able to use inexpensive materials for the sintering furnace and requiring less energy for sintering, Since it is possible to use internal electrodes made of relatively inexpensive silver-based materials, the price of the capacitor can be reduced, which is of great industrial benefit.

Claims (1)

[Claims] 1 Pb (Ni _1/3 Nb _2/3 ) _x (Fe _1/2 Nb _1/2 ) _y
(Fe _2/3 W _1/3 ) _z In the composition represented by O ₃ , the blending ratio is 0.01≦x≦0.40, 0.45≦y≦0.80 and
A high dielectric constant ceramic composition characterized in that it is within the range of 0.05≦z≦0.50 (where x+y+z=1).