JPH08157259A - Production of ceramic dielectric - Google Patents

Abstract

PURPOSE: To produce a ceramic dielectric for a microwave having an increased Q value by annealing a dielectric. CONSTITUTION: A dielectric porcelain compsn. contg. 10-60mol% ZrO2 , 20-60mol% TiO2 and 1-70mol% oxide of one or more among Mg, Co, Ni, Zn, Mn, Sn, Nb, Ta and W is fired at 1,300-1,600 deg.C and the resultant fired dielectric is continuously held at 800-1,200 deg.C for 1-24hr at the time of cooling after firing.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for manufacturing a ceramic dielectric. More specifically, ZrO ₂ —TiO ₂
The present invention relates to a method of manufacturing a ceramic dielectric for microwaves containing as a main component.

[0002]

2. Description of the Related Art In recent years, with the spread of mobile communication such as mobile phones and car phones, the number of these communication devices and base stations has been increasing. However, mobile communication in the microwave region has a frequency band. Dielectric ceramics are widely used as resonators in pass (block) filters and the like.

The characteristic required for the dielectric resonator is that the dielectric loss in the microwave region is small, that is, the unloaded Q.
The value is large. In addition, as other required characteristics, when the same resonance mode is used, the size of the dielectric is inversely proportional to the square root of the dielectric constant, so that the relative dielectric constant is large with respect to the demand for miniaturization, and It is necessary that the temperature change of the resonance frequency is small, and further, the variation in each of the above characteristics is also small. In particular, a dielectric resonator for a base station is incorporated as a resonator for transmission and reception as a dielectric, but it is required to have a very low loss, that is, an unloaded Q value is very large. It

Generally, the product of the resonance frequency f of the microwave ceramic dielectric and the unloaded Q value is constant regardless of the size of the resonator element if the material is the same. . That is, if the same material is used, the resonance frequency f and the no-load Q value are in inverse proportion to each other. Therefore, the larger the shape of the dielectric element, the smaller the resonance frequency f and the larger the no-load Q value. However, especially the shape of the element becomes very large and the resonance frequency f becomes 1 GH.
When it becomes z or less, the increase of the Q value is small with respect to the decrease of f, and the value of the fQ product remarkably decreases. When used as a transmission filter in a base station dielectric, transmission power is consumed by the resonator, so heat generation becomes a problem when the Q value is low. When used for reception, a high Q value is required to realize a narrow band.

Conventionally, as a dielectric material used for this purpose, as a material containing ZrO ₂ --TiO ₂ as a main component, for example, those disclosed in JP-A-62-132769 and JP-A-2-192460 are known. Has been. However, since the value of the fQ product was remarkably reduced as the frequency was lowered, a higher Q material was needed. As materials having a higher Q, materials containing Ba (ZnTa) O ₃ (JP-A-53-60540) or Ba (MgTa) O ₃ (JP-A-53-60544) as main components are known. ing. Since Ta, whose raw material is expensive, is used as a main component, these are very expensive for a large-sized resonant element. Therefore, there has been a demand for a manufacturing method for obtaining a high Q containing ZrO ₂ —TiO ₂ as a main component.

[0006]

According to the studies made by the inventors, a material containing ZrO ₂ —TiO ₂ as a main component has a high Q value, so that the material should be kept for 48 hours or longer and 20 ° C./hr during firing.
Gradual cooling is required, but since firing takes a long time,
Utilities costs and electric furnace depreciation costs were high, leading to high costs.

The present invention solves such a problem by holding a dielectric material containing ZrO ₂ —TiO ₂ as a main component at a firing temperature and then continuously or at a temperature of 800 when firing the dielectric material. An object of the present invention is to provide a low-cost method for producing a ceramic dielectric, which can obtain a high Q value by firing in a short time by annealing at a temperature of ℃ to 1200 ℃.

[0008]

In order to solve this problem, the method for producing a ceramic dielectric of the first invention is as follows: (1) ZrO ₂ 10 to 60 mol%, TiO ₂ 20 to 60
mol%, {Mg, Co, Ni, Zn, Mn, Sn, N
a dielectric porcelain composition containing 1 to 70 mol% of at least one oxide composed of b, Ta, W} at 1300 ° C.
It is characterized in that it is baked at ˜1600 ° C. and continuously or at the time of temperature decrease after baking, or the baked dielectric is held at a temperature of 800 ° C. to 1200 ° C. for 1 to 24 hours.

(2) Further, in the method for producing a ceramic dielectric of the second invention, the compositional formula is xZrO ₂ -yTiO ₂ -zA.
_{When represented by (1 + w) / 3} Nb _{(2-w) / 3} O _{(2-w / 2)} , the symbol A is at least one component selected from {Mg, Co, Ni, Zn, Mn} And a dielectric porcelain composition having x, y, z, w within the range represented by the following mathematical formula: 1300
Firing at ℃ ~ 1600 ℃, continuously during the temperature decrease after firing,
Alternatively, the fired dielectric is held at a temperature of 800 ° C. to 1200 ° C. for 1 to 24 hours (where x,
y and z are mole fractions, and w is a numerical value shown below).

X + y + z = 1 0.10 ≦ x ≦ 0.60 0.20 ≦ y ≦ 0.60 0.01 ≦ z ≦ 0.70 0 ≦ w ≦ 1.50

[0011]

As described above, the method for manufacturing the ceramic dielectric is
ZrO ₂ 10-60 mol%, TiO ₂ 20-60 mol%
, {Mg, Co, Ni, Zn, Mn, Sn, Nb, T
1 to 7 of at least one or more oxides composed of a, W}
Dielectric porcelain composition containing 0 mol% 1300 ℃ ~ 16
The dielectric is fired at 00 ° C. and continuously at the time of temperature decrease after firing, or at a temperature of 800 ° C. to 1200 ° C. for 1 to 2
Since it is held for 4 hours to be manufactured, it is possible to manufacture a ceramic dielectric material containing ZrO ₂ —TiO ₂ as a main component, which can obtain a very high Q value by firing for a short time.

Further, the method for producing a ceramic dielectric of the present invention comprises a compositional formula xZrO ₂ --yTiO ₂ --zA _{(1 + w) / 3} Nb.
_{(2-w) / 3} O _{(2-w / 2)} is used as a composition satisfying the above conditions, and annealing is performed under the above conditions. Therefore, a very high Q value can be easily obtained by firing for a short time. Ceramic dielectrics based on _2- TiO ₂ can be manufactured.

[0013]

EXAMPLE An example of the present invention will be described below. The starting materials are chemically high purity ZrO ₂ , TiO ₂ ,
MgO, CoO, NiO, ZnO, MnO ₂ , SnO,
After using each powder of Nb ₂ O ₅ , Ta ₂ O ₅ , and WO ₃ to correct the purity, a predetermined amount is weighed so that the composition ratios shown in Table 1, Table 2, Table 3, and Table 4 are obtained.

Mixing these powders, 800-1200 ° C
After calcining, crushing and granulating at 1000 kg / cm ² , diameter 13
mm Press-molded into a cylindrical shape with a thickness of 6 mm. Also, in order to see the characteristics at different frequencies, some of the samples were molded by changing the size of the cylinder.

The molded body is heated at 600 ° C. for 4 hours to incinerate the binder, then put in a sheath, and 1300 ° C. or higher depending on the composition.
Bake at 1600 ° C. for 4 hours and cool to room temperature. Then, the fired body was annealed at 700 ° C to 1300 ° C for 1 to 24 hours. The characteristics are measured by the dielectric resonator method,
The unloaded Q value and the resonance frequency before and after annealing were obtained. The results are shown in Tables 1 to 3 and Tables 6 and 7. The symbols x, y, A, z, and w in Tables 6 and 7 represent the symbols in the composition formula of the second invention described in the item (2) of the above-mentioned solving means.

After firing at 1300 ° C to 1600 ° C for 4 hours, the temperature is continuously lowered at 700 ° C to 1200 ° C for 1 hour.
Annealed for ~ 24 hours. The results are shown in Table 4.
Table 5 shows a comparative example in which the holding time during firing is 48 hours or longer and the slow cooling is performed at 20 ° C./hr. Sample numbers marked with * are comparative examples outside the scope of the present invention, and other examples are examples of the present invention.

For sample Nos. 48 to 53, the relationship between the Q value after firing, the Q value after annealing and the frequency is shown in FIG.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

As is clear from Tables 1 to 4, the ceramics annealed by firing for a short time all have improved Q values as compared with the Q values after firing, but as shown in FIG. The lower the resonance frequency, the greater the effect of improving the Q value. For example, sample numbers 48, 49, 51, 53
Then, 3% at 9 GHz, 6% at 4.5 GHz, 1.8 G
The Q value is improved by 10% at Hz and 23% at 0.80 GHz.

[0023]

[Table 5]

[0024]

[Table 6]

[0025]

[Table 7]

Further, as is clear from the results shown in Tables 6 and 7, the dielectric ceramic composition within the composition range of the second invention described in the item (2) is after annealing as compared with the Q value after firing. Q value of is greatly improved.

However, in Tables 1 to 4, if the annealing temperature is lower than 800 ° C. or higher than 1200 ° C., the Q value improvement rate by annealing is not necessarily large, and the effect of annealing is small. The object of the first invention described in the item (1) could not be achieved, and thus it was out of the scope of the invention.

Further, in Tables 6 and 7, when x is larger than 0.60 as in sample No. 76 or smaller than 0.10 as in sample No. 72, Q value is maintained even if annealing is performed. Remains low and is not suitable for practical use, so (2)
It is outside the scope of the invention described in the section.

Similarly, whether y becomes larger than 0.60 as in sample numbers 68 and 69, or sample numbers 77, 91 and 9 are obtained.
2, 93 is smaller than 0.20, z is larger than 0.70 like sample numbers 91, 92 and 93, and w is 1.50 like sample numbers 86 and 87.
Even when it becomes larger, the Q value remains low even if annealing is performed, and it is not suitable for practical use. Therefore, it was out of the range of the second invention described in the item (2).

[0030]

As is apparent from the above description, according to the present invention, in the method for producing a dielectric ceramic composition for microwaves containing ZrO ₂ —TiO ₂ as a main component, 1300 ° C. to 1 ° C.
By firing at 600 ° C. and continuously after firing or lowering the temperature of the fired dielectric at 800 ° C. to 1200 ° C. for 1 to 24 hours, the Q value can be greatly improved by firing in a short time. it can. In addition, a large element having a low resonance frequency that requires a large Q, such as a base station resonator, has a large improvement rate of the Q value, and this effect is very large.

Further, the present invention contains ZrO ₂ --TiO ₂ as a main component, and as compared with a ceramic containing Ta, which is an expensive raw material, as a main component, the cost can be greatly suppressed particularly in a large-sized resonant element. It is possible to supply an inexpensive large-sized resonant element.

Therefore, according to the manufacturing method of the present invention, the Q value of the ceramic dielectric can be greatly improved and the characteristics can be made very good. Therefore, the yield in mass production can be greatly improved. In addition, since the firing time is extremely short, utility costs and depreciation costs for electric furnaces can be significantly reduced, and since costly raw materials are not used as the main component, the cost can be greatly reduced, which is industrial. It is of great value.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the Q value after firing and the Q value after annealing and frequency of Examples Nos. 48 to 53 of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kojiro Okuyama 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Yoichiro Yokotani 1006 Kadoma, Kadoma City Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. ZrO ₂ 10 to 60 mol%, TiO ₂ 2
0-60 mol%, {Mg, Co, Ni, Zn, Mn, S
a dielectric ceramic composition containing 1 to 70 mol% of at least one oxide of n, Nb, Ta, W}.
A method for producing a ceramic dielectric, characterized by firing at 00 ° C to 1600 ° C, and continuously or at the time of cooling after firing, or holding the fired dielectric at a temperature of 800 ° C to 1200 ° C for 1 to 24 hours. . 2. The composition formula is xZrO ₂ —yTiO ₂ —zA.
_{When represented by (1 + w) / 3} Nb _{(2-w) / 3} O _{(2- w / 2)} , the symbol A is at least one component selected from {Mg, Co, Ni, Zn, Mn} And a dielectric porcelain composition having x, y, z, w within the range represented by the following mathematical formula: 1300
Firing at ℃ ~ 1600 ℃, continuously during the temperature decrease after firing,
Alternatively, the fired dielectric is held at a temperature of 800 ° C. to 1200 ° C. for 1 to 24 hours, wherein x, y, and z are mole fractions and w is represented by the following. Shows the numerical value). x + y + z = 1 0.10 ≦ x ≦ 0.60 0.20 ≦ y ≦ 0.60 0.01 ≦ z ≦ 0.70 0 ≦ w ≦ 1.50