JPS5884179A - Microwave 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 The present invention provides a dielectric ceramic composition in which microwave resonance characteristics are significantly improved by adding a small amount of antimony or niobium oxide to a BaO-TiO2-based dielectric material. It is about things. - As is well known, the size of microwave three-dimensional circuit elements is based on the wavelength of electromagnetic waves normally used. The wavelength of electromagnetic waves propagating in a microwave circuit using a dielectric is usually λ0/ρ7, where the permittivity of the dielectric is ε and the wavelength in vacuum is λ0.
The larger the dielectric constant ε, the more compact the circuit can be. In recent years, with the miniaturization of circuits in high frequency regions such as microwaves and millimeter waves, there has been a strong demand for the development of dielectric materials with high dielectric constant, low loss, and high stability.

Conventionally, BaO/nTiO2-based dielectric materials have a high dielectric constant,
Dielectric ceramic compositions are used as materials with low loss and a small resonant frequency temperature coefficient. However, when lower loss and higher stability are required, conventional BaO・
The nT i 02-based dielectric material had insufficient characteristics.

In addition, if you try to reduce the loss with this type of material,
Progress was not easy, as the firing temperature had to be raised to 1300~+aooC or hot press firing had to be carried out.

An object of the present invention is to provide a microwave piezoelectric ceramic composition that can further improve the properties of conventional BaO/TlO2-based dielectric materials and exhibit lower loss and higher stability. .

The present invention provides that by adding 0.1 to 0.7% by weight of 5b20a or NbaOa to an fja O/TiO2-based dielectric material, electrical characteristics in high frequency ranges such as microwaves and millimeter waves can be significantly improved. It has been completed based on this knowledge.

The present invention will be explained in more detail below.

The composition of the base HaO-Ti 02 dielectric material is 15 to 25 mol% of barium oxide (Bad),
It contains 75 to 85 moles of titanium oxide (Ti02) and has a composition of 6. The present invention is based on this base BaO
・For n T i 02, antimony oxide (Sb2
0a) or niobium oxide (Nb206) from Oj to 0.7
% by weight of the composition. The manufacturing method may be a conventional powder molding method. That is, the calcination temperature, which is sufficient to add an organic binder to the calcined powder, granulate it, press-form it into a predetermined shape, and then sinter it, may be 50 to 100 C lower than that of the conventional one. The atmosphere during firing may be in the air, but a more dense porcelain can be obtained if the firing is performed in oxygen.

The composition of the base BaO-TiO2 dielectric material is
BaO=15-25 mol%, Ti02=75-8
The reason for setting it to 5 mol% is that when the Ba0O amount exceeds 25 mol%, Q (= 1 / tan δ) decreases, and BaO
If the amount of 0O is less than 15 mol%, the decrease in Q is relatively small, but the temperature coefficient becomes large (which makes it unsuitable for practical use.However, in this type of composition, the amount of Ba0O is about 18.2 mol%, It is most preferable that the amount of TiO2 is about 81.2 mol%.The reason why the amount of 5baOa and Nb205 added is 0.1 to 0.7% by weight is because Q, 1% by weight or more is added. Approximately 20% more than without addition
The grade Q is improved, a clear addition effect appears, and 0.
This is because if it exceeds 7% by weight, Q will decrease rapidly and the temperature coefficient will also increase. Regarding the basis for these numerical limitations,
This will become clearer from the experimental examples described below.

Experimental Example 1 Each raw material of BaOO3, TiO2, and 5b203 was weighed to obtain 11 types of materials with different compositions. These materials are wet mixed using a ball mill, then dried and calcined at a temperature of 850 to 1200 C for 6 hours.

After that, it is finely ground again in a ball mill, dried, and granulated by adding a binder such as polyvinyl alcohol to it.
201itφ at a pressure of 1000~aoooKP/d,
Form into a cylindrical shape with a height of 2011m+. This molded body is 1
After baking for 6 hours at a temperature of 200-1+ooU, 111
Processed into 11φ x 5m11 cylinders, 11 types of samples (3
1 to S) were obtained.

The dielectric constant ε and dielectric loss ta are measured using the dielectric resonance method.
nδ, temperature coefficient of resonance frequency fO・TK (pPm/l:
, -40 to +80C). The measurement frequency is approximately 6.5 GHz. The composition and electrical properties of each sample are shown in Table 1. Note that here, Q=1/lan δ, and the main mouth indicates a composition outside the scope of the present invention. Also,
Sample numbers 81 to S6 are shown as graphs in Figure 1.

When adding Table 5b20a, it is preferable that the amount added be around 0.5% by weight, that is, 0.4 to 0.6% by weight, within the above-mentioned addition range, as can be seen from Figure 1. 0
This is because at around 0.06% by weight, Q has a maximum and the temperature coefficient of the resonance frequency becomes very close to zero.

Experimental Example 2 Regarding Nb2O6, seven types of samples (Nl-N7) were prepared in the same manner as in Experimental Example 1, and measurements were performed. The results are shown in Table 2. Further, the characteristics of sample numbers N1 to N6 are shown in graph form in Figure 2.

When adding 206, as shown in Figure 2, within the above addition range, especially the addition amount is 086.
% by weight, i.e. 0.5-0.7% by weight is preferred. This is because at around 0.6% by weight, Q is quite large and the temperature coefficient of the resonance frequency is very close to zero.

The present invention further reduces loss by adding a very small amount of antimony or niobium oxide to the BaO/TiO2 dielectric material, which originally has a high dielectric constant and low loss, as described above. In other words, it is possible to increase Q (Q can be increased by 20% or more compared to the case without additives), and not only can the temperature coefficient of the resonance frequency be kept low, but also the value of the temperature coefficient can be changed depending on the amount of addition. It is also possible to control the firing temperature, and in addition, the firing temperature can be lowered, making manufacturing easier.

[Brief explanation of the drawing]

Figure 1 is a graph showing the effect of adding 5b203 to 2BaO・9Ti02, Figure 2 is a graph showing the effect of adding 5b203 to 2BaO・9TiO2.
2 is a graph showing the effect of adding Nb2O5 to Figure 1 f; b20B 4, Mol (wt'A) 1M2 figure

Claims (1)

[Claims] 1. Ba0=15-25 molar ratio, Ti02=75
In contrast to a dielectric material with a composition of ~85 mol%, in the synchronous body table? A dielectric ceramic composition for use in microwaves, in which 0.1 to 0.7 weight percent of an oxide of an element in five periods of group V is added. 2. The composition according to claim 1, wherein the additive is 8b20a. 3. The composition according to claim 1, wherein the additive is Nb2O6.