JPS6050009B2 - High dielectric constant porcelain composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a high dielectric constant ceramic composition having a low sintering temperature and suitable as a material for a ceramic capacitor.

Conventional Structures and Problems The characteristics that dielectric materials should have vary depending on the application, but ceramic capacitors are required to have a large dielectric constant and resistivity, a small dielectric loss tangent, and a low sintering temperature.

A high dielectric constant is an important condition for miniaturizing devices. 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. Conventionally, barium titanate-based porcelain has been used as a material for high dielectric constant ceramic capacitors.

However, this material has a high sintering temperature of 1,300 to 1,400°C, so when manufacturing multilayer ceramic capacitors, it is necessary to use expensive internal electrodes that are suitable for the sintering temperature and whose main component is platinum or palladium. There were some unavoidable flaws. OBJECTS OF THE INVENTION It is an object of the present invention to improve the above-mentioned drawbacks and to provide a high dielectric constant ceramic composition having a low sintering temperature of 1000° C. or less and a high specific resistance.

Constitution of the Invention The composition of the present invention comprises Pb(Ni, I.

Nb. I. )x(Fe, /2NY), 1,)y(Fe2
/3W, Ia) ZO, and the composition ratio is 0.0
1≦X≦0.40, 0.45≦y≦0.80, and 0
．． The main component is a composition within the range of 05≦z≦0.50 (however, xfy+z=1), and further contains manganese (Mn), 9chromium (Cr), 9cobalt (Co) as subcomponents.
, and oxides (MnO., Cr.O., CoO, Li2O) of at least one element in lithium (Li).
The above objective was achieved by containing 0.01 to 1.5% by weight calculated as weight. Examples Raw materials include PbO, NiO, Fe2O3, Nb2q,
WO3, MnO2, cr2O3, cOO and Li2C
Using O3, these were weighed to have the composition ratio shown in the table below and wet mixed.

After drying, each of the mixtures was calcined at 750° C. for 2 hours, and then wet-pulverized using a ball mill. After drying, using an aqueous solution of polyvinyl alcohol as a binder, it was pressure-molded into a cylindrical shape with a diameter of 137wt and a length of about 87WE, and after the binder was incinerated, it was placed in a magnesia porcelain container and 840~G
It was fired for 2 hours at a temperature within the range of 8O<0>C. After cutting the fired porcelain into pieces of one thickness and depositing Cr-Au on both sides, the dielectric constant εr and the dielectric loss tangent D were set at 1 KHz, 1 V/
Measurements were made on TlOn at room temperature. Also, the specific resistance is 1KV/Tn at room temperature! Measured at n. The results are shown in the table below. Show above NO. l, 6, ll, l6, 23, 27, 3O
, 36, 38, 4O, 4l, and 45 are outside the scope of the present invention. 2-5, 7-10, 12-1
5, 17-22, 24-26, 28, 29, 31-35
, 37, 39, 42-44, 46-49. Each sample is an example within the scope of the present invention. As is clear from the above table, the porcelain made of the composition within the scope of the present invention can have a lower specific resistance by containing one or more elements among Mn, CrCO, and Li as a subcomponent to the main component. It is possible to increase the dielectric loss tangent and reduce the dielectric loss tangent. Furthermore, the composition of the present invention has a large dielectric constant (814
0-24100) and low firing temperature (840-980
'C) also maintains the characteristics of the main component composition. In addition,
A composition in which the content of subcomponents exceeds 1.5% by weight and 0.5% by weight.
If the composition is less than 0.01% by weight, it is not effective in improving specific resistance and is therefore excluded from the scope of the present invention.

In addition, the composition range of the main component is such that a dielectric constant of 8000 or more is obtained and the sintering temperature is 1000°C or less (x = 0.0
1~0.40, y=0.45~0.80, z=0.05
~0.50). Although the above-mentioned materials were used as raw materials in the examples, it goes without saying that the same effect can be obtained by using other oxides or raw materials that become oxides by firing, such as carbonates.

Effects of the Invention The composition of the present invention has a large dielectric constant, a relatively small dielectric loss tangent, and a large specific resistance, so it is suitable as a material for ceramic capacitors, and it can be fired at a low temperature of 10,000 C or less, so it can be fired in a firing furnace. It has great industrial value as it allows the use of inexpensive furnace materials and requires less energy for firing.

Claims (1)

[Claims] 1 Pb(Ni_1/_3Nb_2/3)_x(Fe_
1/_2Nb_1/_2)_y(Fe_2/_3W_1
/_3)_zO_3, and the composition ratio is 0.01≦x
≦0.40, 0.45≦y≦0.80 and 0.05≦
The main component is a composition within the range of z≦0.50 (x+y+z=1), and further contains manganese (Mn), chromium (Cr), cobalt (Co), and lithium (Li).
) with at least one element as a subcomponent (
A high dielectric constant ceramic composition containing 0.01 to 1.5% by weight of MnO_2, Cr_2O_3, CoO, Li_2O).