JPS6065764A - Dielectric ceramics for microwave - 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] (Technical field of invention) The present invention relates to dielectric ceramics for microwave use.

(Description of Prior Art) Dielectric ceramics are used in dielectric resonators for microwave circuits, magnetic capacitors for temperature compensation, and the like.

For these applications, dielectric ceramics have a large relative dielectric constant (δ) and no-load Q, and the temperature coefficient of the resonant frequency (η,) takes into consideration the temperature coefficient of metals. Then, it is necessary to obtain an arbitrary positive or negative temperature coefficient centered around 0.

Conventionally, MgO-
Compositions such as Ti02-CaO were used. However, when dielectric resonators and capacitors are made using these compositions, the temperature coefficient (η,) is 0 (pp
The relative dielectric constant (mu) is as small as 20 to 40 in the vicinity of m/°C), and when dielectric resonance 2:(, etc.) is created using these materials, there is a drawback that the device becomes large.

(Objective of the Invention) In view of the above-mentioned conventional drawbacks, the object of the present invention is to obtain any positive or negative temperature coefficient centered on O (ppm/T3) by changing the composition, and to obtain a temperature coefficient of It is an object of the present invention to provide a dielectric ceramic material for microwave use that has a large relative permittivity (δ) and no-load Q even when pPffi/°C is around 0 (pPffi/°C).

(Structure of the Invention) In order to achieve this object, the dielectric ceramic of the present invention contains barium oxide (Bad) and titanium dioxide (Ti).
O2), cerium oxide (CeO2), and europium oxide (Euz03), and in terms of oxides, Bad: 14-19 mol% TiO2: 80-74 mol% CaO2: 3.8-18.5 mol %Eu2O3:L, in the range of 8 to 13 mol%.

(Explanation of Examples) Examples of the present invention will be described below.

First, the method for manufacturing dielectric ceramics of the present invention will be explained.

The starting material is chemically high-purity barium carbonate (BaCO
3) , titanium dioxide (Ti0z), cerium oxide (GeO2') and europium oxide (EL1203)
). First, these starting materials are mixed to have the composition ratios listed in Table 1.

Table 1 The prepared raw materials were mixed with pure water in a pot mill, dehydrated and dried, and then calcined at 1060°C for 2 hours in an air atmosphere.

Next, this calcined product was wet-pulverized with pure water in a pot mill, and then dehydrated and dried. Subsequently, a binder was added thereto, and the product was granulated through a 32-mesh sieve. In this case, the granulated powder is molded using a mold and a hydraulic press at a molding pressure of 1 to 3.
As ton/cm2, the diameter is 1 Elmm and the thickness is 9m.
It was molded into a disk shape of m. The molded body thus obtained was placed in a high-purity alumina box and fired at a temperature of 1200° C. to 1350° C. for 2 hours, thereby obtaining a dielectric ceramic.

The dielectric ceramic thus obtained was measured by the Coleman method to determine the dielectric constant (and) and the unloaded Q of the ceramic. Further, the temperature coefficient (η,) of the resonant frequency was determined from the value in the temperature range of -40'C+80'C with the resonant frequency at 20'C as a reference. The resonant frequency in these measurements is 3
~7 GHz.

Table 2 shows the results of such measurements. Note that this measurement result shows the characteristic measurement results of typical dielectric ceramics. In Table 2, sample numbers with wooden marks indicate comparative examples outside the scope of the present invention, and samples with other sample numbers are examples within the scope of the present invention.

Table 2 Next, the experimental results in Table 2 will be considered. That is, (Bao
)(Ti0z)The amount A of X is less than 76 mol% (A<7
5 mol%), the amount B of CeO2 is less than 3.8 mol% (B
<3.6 mol%) or EuzOs-EtC is 13
It can be seen that when the temperature coefficient is larger than mol % (13 mol %<C), the temperature coefficient becomes large and the relative permittivity (ε,) also decreases.

Also, whether (BaO)-(TiO2)icy)IA is thicker than 91 mol% (91 mol%<A) or Ce02(7)
ft B is greater than 18.5 mol% (18.5 mol%
<B) or Eu403 (7) If I C is less than 1.8 mol% (C< 1.8 mol%), the unloaded Q becomes small and the temperature coefficient becomes large, which is inappropriate. .

From the above experimental results, from a practical point of view, BaO is 14-
19 mol%, TlO2 is 80-74 mol%, CeO2
is 3.8-18.5 mol%, Eu403 is 1.8-13
It has been found that a range of mol % is suitable for dielectric ceramics for microwave use.

(Effects of the Invention) As is clear from the above, according to the microwave dielectric ceramic of the present invention, by changing the composition, the temperature coefficient (ηf) of the resonant frequency can be reduced to O (pp
It can be changed to any positive or negative value around m/'0), and in the microwave region,
Even when the temperature coefficient is 41, which is close to O (ppa/°C) 4·j, there is an advantage that the relative permittivity (δ) and the no-load Q are reasonable.

Therefore, the microwave dielectric ceramic according to the present invention can be used as a dielectric ceramic material for microwave dielectric resonators, temperature compensation capacitors, and the like.

Although the above-described embodiments have been described under preferred and specific conditions within the scope of the present invention, it is to be understood that these are merely illustrative and are not limited to the present invention or these embodiments. It is.

Claims (1)

[Claims] BaO, T i02, CeO2, and EL12
In terms of oxides, BaO: 14-19 mol% Ti0z: 80-74 mol% CeO2: 3.8-18.5 mol% Eu2O3: 1. ．． A dielectric ceramic for microwave use, characterized in that the content is in the range of 8 to 13%.