JPH0971464A - Dielectric porcelain composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a dielecric porcelain composition having suitable dielectric constant, Q value and enabling the temperature coefficient of small resonance frequency to drift around zero by compounding the principal component expressed in specific general formula with one or more oxides of elements selected from Cr, Mn, Fe, etc. SOLUTION: The starting raw material of principal component comprises powders of Sm2 O3 , TiO2 , ZrO2 and Nb2 O5 powder by weighting them a according to the general formula of Sm(Ti1-x Zrx )NbO6 (0<=x<=0.7). One or more kinds of oxides selected from the oxides of Cr, Mn, Fe, Co, Ni and Cu in an amount of less than 1.0 pts.wt.(excluding 0 pts.wt.) based on Cr2 O3 , MnO2 , Fe2 O3 . Co2 O3 , NiO and CuO are added per 100 pts.wt. of this principal components. This composition is wet blended after addition of pure water, dried after anhydration, calcined at 1,100 deg.C in air. The calcined material is wet crushed with pure water, dried after anhydration, blended with an organic binder, sieved and regulated in particle size, press molded at 1 ton/cm<2> and the molded article is fired at 1,300-1,500 deg.C for 2-50hrs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric ceramic composition used as a dielectric resonator in a high frequency region such as a microwave and a millimeter wave, and a dielectric ceramic used as a temperature compensating ceramic capacitor for electronic equipment. It relates to a composition.

[0002]

2. Description of the Related Art In recent years, dielectric ceramics have been used as dielectric resonators, dielectric filters and the like in communication devices utilizing electromagnetic waves in the microwave range, such as automobile phones, mobile phones and satellite broadcasting. In order to use a dielectric porcelain composition for such a dielectric component, in addition to having an appropriate dielectric constant suitable for an application or a device, low loss in a microwave region, and temperature change of a resonance frequency are required. Is small, that is, the temperature change of the dielectric constant is small. Conventionally, BaO—TiO ₂ series materials have been known for such applications, and are disclosed in Japanese Patent Publication No. 58-20905. In addition, Ba (Zn _1/3 Ta _2/3 ) containing Nb and Ta
It is disclosed in JP-A-53-35454 that composite perovskite compounds represented by O ₃ exhibit particularly high Q.

[0003]

[Problems to be Solved by the Invention] However, the above B
In order to improve the Q value, the aO-TiO ₂ system requires a special and complicated manufacturing process in which the calcined product is treated with an acid solution or further annealed after firing. Further, the crystal phase is easily affected by the firing conditions, which causes a problem that the dielectric properties are likely to change, and it is difficult to control the properties. In addition, the above-mentioned Ba (Zn _1/3 Ta _2/3 )
The composite perovskite type typified by O ₃ has a small dielectric constant and has not sufficiently met the demand for miniaturization of the resonator. Further, since the firing temperature is as high as about 1500 ° C. or more and a long firing time of 50 hours or more is required, mass productivity is poor, and the manufacturing cost due to the energy required for firing is high. It was

The present invention solves the above-mentioned problems, and has an appropriately large dielectric constant, a high no-load Q value, and a small temperature coefficient of the resonance frequency, and the temperature coefficient of the resonance frequency is centered around zero. It is an object of the present invention to provide a dielectric porcelain composition that can be changed arbitrarily.

[0005]

[Means for Solving the Problems] To achieve this object
The dielectric ceramic composition of the present invention has the general formula Sm (Ti
_1-xZr_x) NbO₆Represented by (0 ≦ x ≦ 0.7)
It is.

[0006]

With the above structure, the dielectric constant (ε _r ) of 25 or more
And a Qf product of 25,000 or more, and an absolute value of 100 pp
It is possible to realize a dielectric ceramic composition having a resonance frequency temperature coefficient (τ _f ) of m / ° C. or less and capable of arbitrarily changing the resonance frequency temperature coefficient around zero.

[0007]

【Example】

Embodiment 1 Hereinafter, a first embodiment of the present invention will be described in detail.

The starting material is chemically high purity Sm ₂ O ₃ ,
TiO ₂ , ZrO ₂ and Nb ₂ O ₅ powders were weighed so as to have a predetermined composition ratio, put into a polyethylene ball mill, and then stabilized zirconia boulders and pure water were added and wet-mixed for about 20 hours. did. After wet mixing, dehydration and drying,
This dry powder was placed in a crucible of high alumina quality and calcined in air at 1100 ° C. for 2 hours. Next, this calcined powder was put into the same ball mill used for mixing together with pure water to obtain about 2
After 0 hour wet pulverization, dehydration and drying were performed. Next, an organic binder was added to this pulverized powder, and the mixture was homogeneously mixed, and then sized through a 32 mesh sieve, and a molding pressure of 1 ton / cm ² was used to obtain a diameter of 13 mm and a thickness of 5
Molded to ~ 7 mm. Then, the molded body is put into an alumina-based sheath coated with zirconia powder, and the mixture is placed in air at 1300
By firing at a firing temperature of ~ 1500 ° C for 2 to 50 hours, dielectric ceramics having the compositions shown in sample numbers 1 to 12 of (Table 1) were obtained.

[0009]

[Table 1]

Next, of the obtained sintered bodies, both surfaces of the sintered body which was fired at a temperature at which the density of the sintered body was the highest were polished, and the dielectric characteristics by microwave were measured. The measurement was performed using a dielectric resonator, and the dielectric constant (ε _r ), Q · f product, and temperature coefficient (τ _f ) of the resonance frequency were calculated. Dielectric constant and Q
In measurement of the value, the resonance frequency is 3.5-7.0 GHz
Met. The temperature coefficient (τ _f ) of the resonance frequency is -25 to 8
It was measured in the range of 5 ° C.

The above measurement results are shown in (Table 1) for each sample number of 1 to 12. In Table 1, those marked with * are comparative examples outside the scope of the claims of the present invention. The reason for limiting the composition range of the dielectric ceramic composition of the present invention will be described with reference to (Table 1). As is clear from (Table 1), when expressed as Sm (Ti _1-x Zr _x ) NbO ₆ as a general formula, by substituting a part of Ti with Zr, the dielectric constant is changed without greatly changing the Q value. It is possible to shift the rate from 45 to 25 and the temperature coefficient of the resonance frequency in the negative direction. Dielectric porcelain compositions (without an asterisk) having a Zr substitution amount (x) within the composition range of 0.00 ≦ x ≦ 0.70 have a dielectric constant of 25 or more and a high Q of 25,000 or more.・
It can be seen that the f product and the absolute value have a temperature coefficient of the resonance frequency in the range of 100 ppm / ° C. or less, and the temperature coefficient of the resonance frequency can be arbitrarily changed over a wide range around zero. In particular, the substitution amount (x) of Zr is 0.
When it is 40, the dielectric constant is 32.5 and the Q · f product is 306.
There is a composition in which the temperature coefficient of the resonance frequency is 00 (nearly zero (+0.4)). When the Zr substitution amount (x) exceeds 0.70, the sinterability is lowered and only porous porcelain can be obtained. At this time, the dielectric constant decreases to 25 or less, and the bending strength of the sintered body decreases to 1.0 t / cm ² or less, resulting in a large decrease in mechanical strength, which is not practical. In this way, the composition range is limited.

(Second Embodiment) The second embodiment of the present invention will be described in detail below.

The starting material is chemically high-purity Sm.₂O_Three,
TiO₂, ZrO₂, Nb₂O_Five, Cr ₂O_Three, MnO₂, F
e₂O_Three, Co₂O_Three, NiO and CuO powders to the specified composition
Weighed to a ratio and then, as in Example 1,
A sintered body was prepared and the characteristics were evaluated. The result is 13-2
It shows in (Table 2) according to the sample number of 7.

[0014]

[Table 2]

In Table 2, those marked with * are comparative examples outside the scope of the claims of the present invention. As is clear from this (Table 2), the dielectric ceramic composition according to the present example is
By additionally containing at least one or more selected from the group consisting of oxides of Cr, Mn, Fe, Co, Ni and Cu as an accessory component, sinterability is improved and dense sintering is performed, It can be seen that a high dielectric constant can be achieved without lowering the Q · f product. Also, by adding subcomponents,
Compared with the case of no addition, the control range of the temperature coefficient of the resonance frequency is further expanded to the negative side, and the degree of freedom in device design is increased. The reason for limiting the composition range will be described with reference to (Table 2). First, the sinterability is improved by containing the subcomponent. For this reason, it becomes possible to obtain a dense sintered body up to the range of Zr substitution amount (x) = 0.80 in the main component composition. If part of Ti is replaced by Zr beyond this range, only porous porcelain can be obtained as in the first embodiment. The amount of the sub-component added is Cr ₂ O ₃ , MnO ₂ , Fe ₂ O ₃ , Co ₂ O ₃ or NiO.
Also, when converted to CuO and within a range of 1.0 parts by weight (excluding 0 parts by weight) or less, there is an effect that a high dielectric constant can be obtained without significantly changing the Q · f product and the temperature characteristics. Although not shown in the examples, even if two or more auxiliary components are added, the same effect can be obtained as long as the total amount is 1.0 part by weight or less. In the examples, when the Zr substitution amount (x) is 0.40, the dielectric constant is 35.8 and the Q · f product is 2
At 9600, the temperature coefficient of resonance frequency is almost zero (+1.0)
There is a composition of. If the amount of addition of the accessory component exceeds 1.0 part by weight, the secondary phase will precipitate from the grain boundary portion and the Q · f product will greatly decrease, so the amount of addition will be limited. In this way, the composition range is limited. The same effect can be obtained even if the main component is calcined in advance and the subcomponent is added.

Further, in the method of manufacturing the dielectric ceramics in the examples, Sm ₂ O ₃ , TiO ₂ , ZrO ₂ , Nb ₂ O ₅ and Cr are used.
₂ O ₃ , MnO ₂ , Fe ₂ O ₃ , Co ₂ O ₃ , NiO and Cu
O was used, but is not limited to this method,
Even if a compound such as Sm ₂ Ti ₂ O ₇ or a carbonate, a hydroxide or the like is used so as to have a desired composition ratio, the same characteristics can be obtained.

Furthermore, when the amount of the subcomponents added is small, it is easy to uniformly mix them by adding them as an aqueous solution.

[0018]

As described above, according to the present invention, when Sm (Ti _1-x Zr _x ) NbO ₆ is represented by the general formula, x
In the composition region limited to the range of 0.00 ≦ x ≦ 0.70, a dielectric constant of 25 or more, a Q · f product of 25,000 or more, and a temperature coefficient of a small resonance frequency of 100 ppm / ° C. or less in absolute value are set. The excellent dielectric ceramic composition of the present invention can be realized.

Therefore, the microwave dielectric resonator and the temperature compensating ceramic capacitor using the dielectric ceramic composition of the present invention contribute to downsizing and high performance of communication equipment and electric equipment.

Claims (2)

[Claims] 1. The general formula Sm (Ti _1-x Zr _x ) NbO ₆
(Where 0 ≦ x ≦ 0.7) a dielectric ceramic composition. 2. The general formula Sm (Ti _1-x Zr _x ) NbO ₆
With respect to 100 parts by weight of the main component represented by (0 ≦ x ≦ 0.8), at least one or more oxides of Cr, Mn, Fe, Co, Ni, and Cu are added as sub-components, respectively.
₂ O ₃ , MnO ₂ , Fe ₂ O ₃ , Co ₂ O ₃ , NiO and Cu
Converted to O, 1.0 parts by weight (excluding 0 parts by weight)
A dielectric ceramic composition contained in the following range.