JPS63116307A - Dielectric magnetic composition - Google Patents

Abstract

(57) [Abstract] 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 temperature-compensating dielectric ceramic composition that can be fired at a temperature of 1150° C. or lower.

Conventional Temperature Compensating Materials Used in Ceramic Capacitors include MgO-CaO-TiO2-based materials (e.g., JP-A-48-86097) and La203-Ti02-based materials (e.g., JP-A-Sho. 51-A). 30400), but these materials require a firing temperature of 1250~
Since the temperature is as high as 1400° C., expensive platinum or palladium electrodes are required as internal electrodes when used in multilayer ceramic capacitors.

On the other hand, among high dielectric constant materials, it has recently been discovered that composite perovskite materials mainly composed of PbO exhibit low firing temperatures of around 1000°C and excellent dielectric properties.
Many compositions have been proposed because cheaper silver thread electrodes can be used as electrodes. For example, JP-A-55-
Pb(Mg1zriNb2/3)03-Pb(Mgxz2Wl/2) disclosed in Publication No. 144470
In the OG system, the firing temperature is around 1000℃, and the dielectric constant is 30.
00 or more.

Problems to be Solved by the Invention Conventionally used temperature-compensating ceramic capacitor materials require expensive electrodes due to the high firing temperature. There is a strong need for dielectric materials that can be fired. Composite perovskite materials mainly composed of Pbo have a large temperature change in dielectric constant (although there are no known materials that can be used for temperature compensation capacitors).

In view of the current situation, an object of the present invention is to provide a dielectric ceramic composition having a low firing temperature and a small rate of temperature change.

Means for solving the problem Pb (Mgxzs Nb2z3> (Mg5tq
Wl/2).

+-y Part of Pb in the solid solution represented by 03 is replaced with Ca.

Effect P b (Mgxts Nb2/s )1□ (Mgt
By partially replacing pb in 12Wt/*)y03 with Ca, characteristics for temperature compensation can be obtained without impairing low-temperature sinterability.

Examples As starting materials, chemically high purity PbO, CaCo3
．． MgO, Nb2O5, and WO3 were used. After correcting the purity of these, a predetermined amount was weighed and mixed in a ball mill for 17 hours using agate cobblestones and pure water as a solvent. This is suction filtered to remove most of the moisture, dried, and then thoroughly crushed using a Raikai machine.
t% of water was added and molded into a cylindrical shape with a diameter of 60M and a height of about 50mm at a molding pressure of 500 kg/ci. Place this in an aluminum crucible, cover with the same material, and heat at 750℃~8
It was calcined at 80°C for 2 hours. Next, the calcined product was roughly crushed in an alumina mortar, and further crushed in a ball mill using agate cobblestones and pure water as a solvent for 17 hours, filtered under suction to remove most of the moisture, and then dried. After repeating the above calcining, crushing, and drying several times, this powder was mixed with polyvinyl alcohol 6W.
t% aqueous solution was added at 6h% of the powder amount, granulated through a 32 mesh sieve, and molded into a cylinder with a diameter of 13 m+++ and a height of about 5 m at a molding pressure of 1000 kg/cj. The molded product was heated to 700°C in air and held for 1 hour to burn out the polyvinyl alcohol content. After cooling, it was transferred to a Magnesia porcelain container, covered with a similar lid, and heated to a specified temperature in air at 400°C/ After increasing the temperature for 2 hours and holding it for 2 hours,
The temperature was lowered at a rate of 00°C/hr.

The fired product was cut into a disk shape with a thickness of 1+ nm, and both sides were coated with Cr-
Au was evaporated and the dielectric constant and Q were set to LMHz, IV/l.
Measurements were made under an electric field of lll11. Also, the resistivity is 20℃
A voltage of 1 kV/ya was determined from the value 1 minute after application.

The firing temperature was set to the temperature at which the density of the fired product was the highest.

Table 1 shows the composition range of the present invention, peripheral composition components, firing temperature, dielectric constant, temperature change rate of Q1 dielectric constant, and resistivity.

(Left space below) For compositions outside the scope of the invention, samples marked with an asterisk (*) in No. of Table 1 were cited as examples; however, if the Ca amount exceeds 0.6, the optimum firing temperature will exceed 1150°C, and 0. Below ゜2, the rate of change in dielectric constant will be over 11000pp/℃, or (
Mgs/+ Nbz/3) When the amount is 0.5 or less, Q is 10
It has some disadvantages such as being less than 00.

Effects of the Invention According to the dielectric ceramic composition of the present invention, a temperature change rate of dielectric constant of 11,000 pp/'C or less and a Q of 1,000 or more can be obtained, and furthermore, since it can be fired at a temperature of 1,150°C or less, lamination is possible. Ag-Pd as internal electrode of capacitor element
It is of great industrial value because it allows the use of similar materials and enables the realization of inexpensive multilayer capacitors.

Claims (1)

[Claims] (PbCa) (Mg_1_/_3Nb_2_/_3)O
_3 and (PbCa)(Mg_1_/_2W_1_/
_2) Pb_1_-_xCa_x(Mg_1_/_3Nb_2
___/_3)_1_-_y(Mg_1_/_2W_1_/
_2) A dielectric ceramic composition characterized in that, when expressed as _yO_3, x and y are in the ranges of 0.3≦x≦0.6 and 0.05≦y≦0.5, respectively.