JPH013044A - dielectric porcelain 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 high dielectric constant dielectric ceramic composition that is fired at a temperature of 1050°C or lower, and in particular a composition that can be fired in a low oxygen partial pressure atmosphere and has a high resistivity. Regarding.

BACKGROUND OF THE INVENTION In recent years, multilayer ceramic capacitors are rapidly becoming popular due to the demand for smaller elements and larger capacitance in ceramic capacitors. Junctional ceramic capacitors are typically manufactured by a process in which internal electrodes and ceramic are integrally fired. Barium titanate-based materials have traditionally been used as high-permittivity ceramic capacitor materials, but
Since the firing temperature is as high as about 1300° C., it is necessary to use expensive metals such as Pt and Pd as internal electrode materials.

On the other hand, lead composite perovskite materials that can be fired in air at temperatures below 1100°C and inexpensive Ag-based materials can be used as internal electrodes, and base metal materials such as Ni that can be fired in a low oxygen partial pressure atmosphere can be used as internal electrodes. Barium titanate-based materials have been developed that can be used as Regarding the former, Pb(
Mgxz3Nb2t3)Ora-Pb(Zntzs
Nb2. s) Dielectric ceramic compositions containing Oa are known. Regarding the latter, materials such as those described in Japanese Patent Publication No. 56-46641 are known. Pb(Mgszz
Nb*t3)03-Pb(Znt,s Nb2zs)
OCI solid solution can be fired at 000 to 1080°C and a high dielectric constant can be obtained.

Therefore, a multilayer capacitor made of this dielectric ceramic composition and an Ag-based internal electrode has the advantage of allowing the device to have a large capacity, be small in size, and be low in cost. However, in recent years, there has been a demand for the use of base metals such as Cu as internal electrodes, which can further reduce the cost of internal electrode materials.For this reason, it is necessary to create an atmosphere with a low oxygen partial pressure in which metals such as Cu do not oxidize when simultaneously fired. There is a need for materials that can be fired at high temperatures and have high resistivities.

Problem to be solved by the invention Pb (Mg5ts Nbs+, 3) 03 Pb
When a (Znl, 2Nbz3)03 solid solution is fired in a low oxygen partial pressure atmosphere, it does not sinter densely and tends to have a low resistivity.

The present invention provides Pb (Mg1z+ Nb2z3) OG
- The purpose of this invention is to provide a dielectric ceramic composition that has a high resistance value when fired in a low oxygen partial pressure atmosphere without impairing the high dielectric constant 7 low temperature sintering properties of the Pb (Nbzzs)03 system. There is.

Means for solving the problem Pb1+a (Mg1zs Nb2zz ) x (Zntz
3Nbs/s), -802+2, where a is in the range of 0.001≦a≦0.15,
Let X be 0.60≦X≦0.95.

Function: By adding an excessive amount of the A-site component to the composition of the present invention, a fired product can be obtained in a low oxygen partial pressure atmosphere at 1050° C. or lower, and a highly reliable device with high resistivity can be obtained.

Example The starting materials are chemically highly pure PbO and MgO.

Nb2O5, ZnO, BaC0a, SrCO3, CaC
o5. MnO2, Coo, and Cu2O were used. After correcting the purity of these, a predetermined amount was weighed and mixed in a ball mill using agate cobblestones and pure water as a solvent at 17:00. This is filtered by suction to remove most of the water, then dried, and then thoroughly crushed using a grinding machine. After adding 5 wt% of water to the powder, it is shaped into a cylinder with a diameter of 60 m and a height of about 50 m. Molding was carried out at a pressure of 500 kg/cm2. Place this in an aluminum crucible, cover with the same quality lid, and heat to 750℃~
It was calcined at 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, a 6 wt % aqueous solution of polyvinyl alcohol was added to the powder at 6 wt % of the powder amount, and the powder was granulated through a 32 mesh sieve at a compacting pressure of 1000 kg/cm2.
It was molded into a disk shape with a diameter of 131III and a thickness of about 1 m.

The molded product was heated to 700° C. in air and held for 1 hour to burn out the polyvinyl alcohol content. This was transferred to a Magnesia porcelain container in which about 1/3 of the volume of the above-mentioned calcined powder was spread, and 200 mesh ZrO2 powder was spread to a thickness of about 1 mm. After deaerating the inside of the reactor core tube with a rotary pump, it was replaced with N2-82 mixed gas, and the oxygen partial pressure (PO2) was 1.0x 10
A mixed gas was flowed while adjusting the mixing ratio of N2 and H2 gas to 0-8 at, and the temperature was raised to a predetermined temperature at a rate of 400°C/hr. After being maintained for 2 hours, the temperature was lowered at a rate of 400°C/hr. PO2 in the reactor core tube was measured by an inserted stabilized zirconia oxygen sensor.

Cr-Au was deposited on both sides of the fired disk, and the dielectric constant, t
anδ was measured at 1 kHz under an electric field of IV/rrtta. Further, the resistivity was determined from the value 1 minute after applying a voltage of 1 kV/nnm.

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

Table 11 Tables 2 and 3 show the composition range of the present invention and the peripheral composition components (a, x, P b ++ , (M g
t/3Nb2/9) (Zntzs Nb2/
s), -x02+), firing temperature when firing in a low oxygen partial pressure atmosphere, dielectric constant, tan δ
, resistivity.

Table 1 1 Comparative example outside the scope of the invention Table 1 (Continued) 1 Comparative example outside the scope of the invention For compositions outside the scope of the invention, if a is less than 1.001, firing in a low oxygen partial pressure atmosphere When this is done, it is difficult to obtain a dense sintered product or the resistivity becomes low.
．． If X is thicker than 150, the dielectric constant and resistivity will decrease.In addition, compositions where In addition, the low oxygen partial pressure atmosphere Po2 selected as the firing atmosphere: 1.OxlO-eatm is lower than the equilibrium oxygen partial pressure of copper at the firing temperature (it is assumed that the metal will hardly oxidize). Conceivable.

Effects of the Invention According to the present invention, a dense and highly resistive sintered body for obtaining high reliability as a multilayer capacitor element can be obtained by firing at 1050°C or lower in a low oxygen partial pressure atmosphere, and Cu is used as the internal electrode.
It is possible to obtain an excellent dielectric ceramic composition that makes it possible to use base metal materials such as.

Claims (3)

[Claims] (1) Pb_1_+_a(Mg_1_/_3Nb_2_
/_3)_x(Zn_1_/_3 Nb_2_/_3)_1_-_xO_2_+_a, a is in the range of 0.001≦a≦0.15, and x is 0.60≦X≦0. Dielectric ceramic composition in the range of 95. (2) The dielectric ceramic composition according to claim 1, wherein 15 mol% or less of Pb is replaced with one or more elements selected from the group consisting of Ba, Sr, and Ca. (3) The dielectric ceramic according to claim 1 or 2, wherein 0.4 wt% or less of one or more oxides selected from the group consisting of MnO_2, CoO, and Cu_2O is added. Composition.