JPS63166107A - Dielectric 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 temperature-compensating dielectric ceramic composition that can be fired at a temperature of 1150° C. or lower.

Conventional technology Temperature compensation materials used in ceramic capacitors include MgO-CaO-TiO2-based materials (for example, Japanese Patent Application Laid-Open No. 48-86097), La203-TiO2, etc.
2-based materials (for example, Japanese Patent Application Laid-Open No. 30400/1986) have been used, but since these materials have a high firing temperature of 1250 to 1400°C, when used in multilayer ceramic capacitors, the internal electrode As such, expensive platinum or palladium electrodes are required.

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(Mg!z3
Nb2z3) Os-P'o<Mgtt2W1t* >0
3 series and the PbTi0s-Pb (Nisz2Wl/2)OG series disclosed in JP-A-59-57954 have a firing temperature of around iooo°C, but are high dielectric constant materials.

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 herovskite materials mainly composed of PbO have a large temperature change in dielectric constant, and 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 to solve the problem Pb (Mgt〆s Nb*13) (Nitz2W
l/2).

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

Effect Pb (Mgt/3Nb2t3) (Nisz2W
l/! 2).

By partially replacing Pb in +-y O3 with Ca, characteristics for temperature compensation can be obtained without impairing low-temperature sinterability.

Examples Starting materials include chemically high-purity PbO, CaCO3
, MgO, Nb2O5, Nip, and WO3. 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 was filtered by suction to remove most of the water, then dried, and then thoroughly crushed in a Raikai machine. After adding 5 wt% of water to the powder amount, a molding pressure of 500 kg/
c! It was molded into a cylindrical shape with a diameter of 60 and a height of about 50 mm. Place this in an aluminum pot and cover with the same material, 7
Calcining was performed at 50°C to 880°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 -1, a 6 wt % aqueous solution of polyvinyl alcohol was added to the powder in an amount of 6 wt %.
The mixture was granulated through a 2-mesh sieve and molded into a cylindrical shape with a diameter of 13 cm and a height of 5 cm at a molding pressure of 1000 +r/cwt. 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, homogenized, and heated to a specified temperature of 400°C in air. /hr to raise the temperature 2
After holding for a period of time, the temperature was lowered at 400°C/hr.

The fired product was cut into a disk shape with a thickness of 3 ml, and both sides were coated with C.
r-Au was evaporated and the dielectric constant and Q were set to I MHz, IV/
www(7) Measured under an electric field. Further, the resistivity was determined from the value 1 minute after applying a voltage of 1 kV/IIIm at 20°C.

The firing temperature was set at 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.

(The following is a blank space) Regarding compositions outside the scope of the invention, samples marked with * in Table 1 are given as examples, but if Caft exceeds 0°5! & If the appropriate firing temperature exceeds 1150°C and is below 0°3, the rate of change in dielectric constant will be more than 11000 pp/°C, or if the amount of (Mg + zs Nb2ts) is less than 0.5, Q will be less than 1000. have.

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)(Ni_1_/_2W_1_/
_2) Pb_1_-_xCa_x(Mg_1_/_3Nb_2
＿／＿３）＿１＿－＿y（Ni＿１＿／＿２W＿１＿／
_2) A dielectric ceramic composition characterized in that, when expressed as _yO_3, x and y are each in the range of 0.3≦x≦0.5 and 0.1≦y≦0.5.