JPH0465019A - Dielectric ceramic compound - Google Patents

Abstract

PURPOSE:To have a large specific dielectric constant (epsilonr) and a small temperature coefficient (tauf) of a resonance frequency by specifying (a-d) of mol% when (a-d) are expressed as the respective mol% of CaO, SrO, BiO and TiO2, and adding at least one kind of iron oxide, nickel oxide, leak oxide (PbO) to the main gradient. CONSTITUTION:A dielectric ceramic compound comprising a compound of (a) mol% of CaO, (b) mol% of SrO, (c) mol% of Bi2O3 and (d) mol% of TiO2, wherein the composition ranges are respectively defined as 0<=(a)<30, 0<(b)<=20, 10<=(c)<=50, 40<=(d)<=80 and at least one kind of 5wt.% or less of lead oxide (Fe2O3), 1wt.% of nickel oxide (NiO) and 5wt.% of lead oxide (PbO) is added to the main gradient of 0<a+b<=30. It is thus possible have 100 or more of specific dielectric constant (epsilonr) and the temperature coefficient (tauf) of resonance frequency in the microwave range from Nhz band to Ghz band.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a dielectric ceramic composition that has a large dielectric constant (εr) and a temperature coefficient (τf) of a resonant frequency that can be controlled over a small and wide range. It is something.

(Prior art) Ceramic filters have recently come to be widely used in mobile radio equipment such as car phones and cordless phones that use radio waves in the microwave band from the Z band to the GHz band. The dielectric material that makes up the filter has a large relative dielectric constant (εr).

It has an unloaded Q (QO) and a temperature coefficient of the resonant frequency (τ
This is due to the fact that the value of f) can be freely controlled in both positive and negative directions around 0 depending on the composition of the dielectric material.

Conventionally, as the above dielectric material, MgO-CaO-T
iO2 series, ZrO□-TiOz-5n02 series, Bad-
A Tie□-lanthanide oxide system was used.

(Problem to be solved by the invention) However, these materials have an εr of at most 100 or less, and when a resonant element is created, it is difficult to miniaturize it (1/i
r) naturally had its limits.

Therefore, a dielectric ceramic composition with a high εr has been desired.

(Means for Solving the Problems) The present inventors have discovered that [r is 100 or more and
prn/℃ or less, and Q. In order to obtain a composition with CaOd of 100 or more, we investigated various composition systems and found that CaOd
mol%, 5rOb mol%, Bi2O,c mol%.

Tie, consists of a composition system of d mol%, and each composition range is O≦a<30. O< b≦2010≦c≦50
．． 40≦d≦80 However, O< a + b≦30 The main components include 5% by weight or less of iron oxide (Fezes) and nickel oxide (NiO
) and at least one of lead oxide (PbO) and lead oxide (PbO) in an amount of 5% by weight or less, the desired characteristics can be obtained.

In the present invention, Cab, 5rO1Bi2o,, T
If the composition of ie2 is outside this range, Q will be 100 or less, which is not practical.

Furthermore, if the amount of Fe2O added exceeds 5% by weight, the Qo
becomes 100 or less, and τf also increases on the negative side.

In addition, if the amount of NxO added is more than 1% by weight, or pb
When the amount of o added is more than 5% by weight.

Q becomes 100 or less, and τf also becomes large on the plus side, making it unsuitable for practical use.

Note that the dielectric ceramic composition of the present invention can be finally made into an oxide ceramic composition by mixing and firing a predetermined amount of raw materials, and the raw materials are carbonic acid that is thermally decomposed to become an oxide. Salts, nitrates, organic acid salts, etc. may also be used.

(Example) CaCO31SrCO3HBx2031 TjOz +
Fe2O3+ N101 pb.

Each composition shown in Table 1 was weighed out, put into a polyethylene pot containing an agate ball together with acetone, and mixed for 16 hours.

After heating and drying this slurry, it was sized through a 5-mesh sieve, and calcined in air at 1000°C for 2 hours.
Again, the agate balls were placed in a polyethylene pot together with acetone and ground for 16 hours.

After the obtained slurry was dried by heating, an aqueous polyvinyl alcohol solution was added to perform cross-mixing, and the mixture was granulated using a 32-mesh sieve.

The granulated powder was molded at it/cd and heated to 1200 m in air.
It was fired at ~1400°C for 4 hours. The obtained fired body was processed to have a diameter of about 30 m and a height of about 15 nm, and εr and Q were measured at the peak of the TEo1x mode occurring at about I GHz. was calculated, and then τf was determined from the change in resonance frequency from -20°C to +60°C.

Each characteristic is shown in Table 1. The samples within the composition range of the present invention were classified as Example 1 and the samples outside the composition range of the present invention were classified as Comparative Examples.

(Effects of the Invention) As described above, the present invention provides εr
is large, Qo is also high, and the value of τf is different from CaO and SrO.
It can be adjusted widely by changing the composition ratio of Fe2O3, Nip, and PbO, and can be used for microwave dielectrics, temperature compensation capacitors, etc.
It has high industrial value.

Claims (1)

[Claims] Calcium oxide (CaO), strontium oxide (Sr
O), bismuth oxide (Bi_2O_3) and titanium oxide (TiO_2) are the constituent components, and the composition formula is aCaO・b SrO・c Bi_2O_3・d Ti
When expressed as O_2, a, b, c, and d are mol%, respectively, from the range of 0≦a<30, 0<b≦20, 10≦c≦50, 40≦d≦80, but 0<a+b≦30. The main components include at least one of iron oxide (Fe_2O_3) of 5% by weight or less, nickel oxide (NiO) of 1% by weight or less, and lead oxide (PbO) of 5% by weight or less.
A dielectric ceramic composition characterized by the addition of various types.