JPS61256971A - Ceramic 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 (Field of Industrial Application) The present invention relates to a ceramic composition, particularly a ceramic composition having a high dielectric constant that can be sintered at a low temperature of 1050° C. or lower and is suitable for a multilayer ceramic capacitor.

(Prior Art) It is well known that dielectric ceramic compositions containing barium titanate (BaTiO3) as a main component have been widely put into practical use as conventional dielectric ceramic compositions used in multilayer ceramic capacitors. However, BaTiOsk, whose main component is sintered at a high temperature of 1,300 to 1,400 degrees Celsius, is used in multilayer capacitors using materials that can withstand this sintering temperature, such as platinum or palladium, as internal electrodes. The drawback is that it requires the use of expensive precious metals such as aluminum and is expensive to manufacture. For this reason, it has been desired to lower the sintering temperature of porcelain as much as possible in order to make it possible to use inexpensive metals mainly composed of silver, nickel, etc.

Therefore, Pb(Fe8/3Wt/3)Os P
b(FeV2NbV2)O8 (Special Publication No. 55-34962
) and (Sr*Pb)Ti03-Pb(Mg1/2 wt
/2) What is the proposal for Os (Japanese Unexamined Patent Publication No. 52-21699)?

The present inventors searched for a promising porcelain composition different from these, and found that Pb(Co1/'3 Nb2/3)01 and Pb
It has been found that a three-component composition consisting of (Co1/2WIA)03 and PbTiOs can be sintered at a low temperature of 1050° C. or lower and has a high dielectric constant. However, these 3
The component porcelain composition has high dielectric loss and low resistivity, and improvements are desired for practical use.

(Objective of the Invention) An object of the present invention is to provide a ceramic composition for a multilayer capacitor that can be sintered at a low temperature of 1050° C. or lower, has a high dielectric constant, low dielectric loss, and high specific resistance.

(Structure of the Invention) The main component ceramic composition of the present invention is (P b (C, o 1/
3 Nb27/'3)Os]x[Pb(Co1/2 W
1/2) 03'), (PbTi0,1.karasu (friend x + y + z = 1.0), point in the ternary composition diagram, A,
B, C, D or A (x=0.89.y=0.01.

z=0.10), B(x=0.01, y=0.74.
z=0.25).

C(x=o, o 1 , y=0.34, z=0.
65), D(x=0.50°Y”0.05,
z = 0.45 ) on the line connecting the four points and in the main component composition surrounded by the four points, there are 0.08 times of manganese atoms as a subcomponent! It is characterized by the addition of 1 to 2.0% by weight.

(Explanation regarding the structure) The porcelain composition of the present invention contains manganese compounds such as Mn■3 and MnO as the main component raw materials, and the Mn atom is 0.08 times the main component! By including Chihiko in an amount of 2.0% by weight, specific resistance can be significantly improved and dielectric loss can be significantly reduced.

(Example) The present invention will be explained in detail below with reference to Examples.

Lead oxide (pbo) with a purity of 99% or more as a starting material.

Cobalt carbonate (coco), niobium oxide (NbtO3)
]-Tungsten oxide (WO3), titanium oxide (TiO
Z) and manganese carbonate (M n Co 3) are used and weighed to a predetermined mixing ratio.Next, they are wet mixed in a ball mill and then pre-fired at 750 to 800°C.Then, they are crushed in a ball mill, and dried door to door. After that, an organic binder was added and the particles were sized and pressed at 0.7 to V'ci. Diameter 161
fil.

Four disks with a thickness of about 2 m were made. Then 880 in the air
Sintering was carried out at 1040°C for 1 hour. Silver electrodes on the top and bottom surfaces of a sintered nine-disc plate? After baking at 600° C., the capacitance and dielectric loss (tan δ) were measured using a digital LCR meter at a frequency of 1 k[z and a current of IVrms, and the dielectric constant was calculated. Next, apply a voltage of 50V for 1 minute using a transcendental needle, measure the insulation resistance, and calculate the specific resistance. In each case, four samples were measured at room temperature,
Please note that the average value is a representative value.

The relationship between the properties thus obtained and the blending ratio is shown in the following table.

Input: No margin (effect of the invention) As is clear from the results shown in the table, the present invention
1/"5Nb2/"l"'0x-Pb(Co1/'2W
1/2) Os pb'rto, the dielectric loss (tan δ) 1 &
: Significantly improved, with significantly increased specific resistance, high dielectric constant, and low-temperature sintering. Therefore, it provides an excellent material as a ceramic composition for multilayer capacitors.

If the blending ratio of the main components is outside the range of the present invention, the dielectric constant will be low or the sintering temperature will be higher than 1050°C.

If the amount of manganese atoms added is less than 0.08% by weight, the effect of improving specific resistance and dielectric loss (tan δ) is small. If it exceeds 2% by weight, the effect of improving dielectric loss will be reduced.

In this embodiment, manganese carbonate was used as the manganese compound, but manganese oxides or oxides that decompose at high temperatures, such as oxalates, sulfates, and hydroxides, may also be used.

Claims (1)

[Claims] Cobalt, lead niobate [Pb (Co1/3Nb2/3
) O_3] and cobalt, lead tungstate [Pb(Co
1/2W1/2)O_3] and lead titanate [PbTiO_
3], a composition consisting of [Pb(Co1/3Nb2/3)
O_3]_x [Pb(Co1/2W1/2)O_3]_
When expressed as y[PbTiO_3]_z (where x
+y+z=1.00), points A and B in the ternary composition diagram
, C, D or A(x=0.89, y=0.01, z=0.10) B(
x=0.01, y=0.74, z=0.25)C(x=
0.01, y=0.34, z=0.65)D(x=0.
50, y=0.05, z=0.45) and the main component composition surrounded by the four points contains 0.08% to 2.0% by weight of manganese atoms as a subcomponent.
A porcelain composition characterized in that it is added.