JPH0680467A - Dielectric ceramic composition - Google Patents

Abstract

PURPOSE:To produce a dielectric magnetic composition having excellent characteristics such as high dielectric constant (60-110), high no-load Q (>=2000) and low resonance frequency temperature factor (tauf) (<=100ppm/ deg.C) in dielectric resonators and electronic equipment used in microwave band. CONSTITUTION:A dielectric ceramic composition expressed by the formula xBaO.yTiO2.zNd2O3.tSm2O3.wBi2O3 having mole fractions in the following ranges: 0.06<=(x)<=0.155, 0.69<=(y)<=0.80, 0.05<=(z)<=0.18, 0<(t)<=0.07, 0<(w)<=0.05 [(x)+(y)+(z)+(t)+(w)=1]. In this composition, one or more kinds of Al2O3 and ZrO2, etc., may be added as additives or a part of Ba of the dielectric ceramic composition may be replaced with other element. The purity of Sm2O3 and Nd2O3 required is >=70wt.%.

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 material for a dielectric resonator and a dielectric substrate used for electronic equipment.

[0002]

2. Description of the Related Art Heretofore, in the high frequency region, dielectrics have been applied to impedance matching of microwave circuits, dielectric resonators and the like. In particular, as the technology for integrating microwave circuits has advanced in recent years, a dielectric resonator using a dielectric ceramic with a high dielectric constant and low loss is used for frequency stabilization of bandpass filters and oscillators. The miniaturization is being actively promoted, the high dielectric constant and the large unloaded Q,
There is a demand for a dielectric porcelain composition having a small resonance frequency temperature coefficient (τf) and capable of varying the respective characteristics in a wide range.

Therefore, as these dielectric materials, B
aO-TiO ₂ system dielectric ceramic [HMO, Bryan, Jr., Thomso
n, Jr.and JK Plourde: J.Am.Ceram.Soc.57 (1974) 450)
And a part of which is replaced with another element, and further, in order to adjust the resonance frequency temperature coefficient (τf), a combination of TiO ₂ having a negative value and a dielectric ceramic or glass having a positive value. Has been used.

[0004]

However, the above-mentioned conventional materials have various problems such as low permittivity and no-load Q, high resonance frequency temperature coefficient (τf), and the like, which are difficult to use in practice. . In order to solve this problem, BaO-T
iO ₂ -Nd ₂ O ₃ based dielectric ceramic composition (JP-B 60-4
1633 JP) or _{BaO-TiO 2 -Nd 2 O 3} -Bi 2
O ₃ -based dielectric ceramic compositions (Japanese Patent Publication No. 59-51091) and the like have been proposed. The former has a large resonance frequency temperature coefficient (τf), and the latter has no load Q with respect to the relative dielectric constant. It was not yet satisfactory to meet the diversification of required characteristics such as low.

The present invention solves the above-mentioned problems of the prior art, and has a high permittivity and a no-load Q, a small resonance frequency temperature coefficient (τf), and a required diversification of characteristics. , A dielectric constant, a no-load Q, and a temperature coefficient (τf) of a resonance frequency can be varied over a wide range.

[0006]

The dielectric ceramic composition of the present invention which achieves this object has a composition formula of xBaO.yTiO ₂ .zNd ₂ O ₃ .tSm ₂ O ₃ .wB
i ₂ O ₃ and the mole fraction of each is 0.06 ≦ x ≦ 0.
155, 0.69≤y≤0.80, 0.05≤z≤0.
18, 0 <t ≦ 0.07, 0 <w ≦ 0.05 (however, x
+ Y + z + t + w = 1) in the range,
Al ₂ O ₃ , F was added to 100 parts by weight of the dielectric ceramic composition.
e ₂ O ₃ , SnO ₂ , ZnO, NiO, MnO, CuO,
One or two or more of CoO, SiO ₂ , and ZrO ₂ may be added in an amount of 3 parts by weight or less, and a part of the Ba element in the dielectric ceramic composition may be contained in a mole fraction of 20 mol% or less S
A configuration in which one or more elements such as r, Ca, and Mg are substituted may be used. Furthermore, the purity of Sm ₂ O ₃ and Nd ₂ O _{3 in} the dielectric ceramic composition may be 70 wt% or more, and the chemical composition of impurities may be composed of other rare earth.

[0007]

[Action] This _{configuration, (1) BaO-TiO 2} -Nd 2 O 3 -Sm 2 O 3 -Bi 2 O
_{By using the 3-} based dielectric porcelain composition, it is possible to obtain a dielectric porcelain having a high dielectric constant and a no-load Q in the microwave region and a small resonance frequency temperature coefficient (τf). (2) By adding Al ₂ O ₃ or ZrO ₂ to the dielectric ceramic composition, the sinterability can be improved and the variation in the dielectric constant can be suppressed low. Especially with respect to ZrO ₂ , the mechanical strength of the dielectric ceramics can be greatly improved. (3) Ba element in the dielectric ceramic composition is Sr, C
Even if it is partially replaced with an element such as a or Mg, it can have the same characteristics as the Ba element and the application range can be expanded. (4) Regarding the purity of Sm ₂ O ₃ and Nd ₂ O ₃ , even a low-purity product can have characteristics close to those of a high-purity product, and the range of applications can be expanded.

[0008]

EXAMPLES The present invention will be described in more detail based on the following examples.

As a raw material, BaCO which is an industrial raw material₃，
TiO₂, Sm₂O₃, Nd₂O₃, Bi ₂O₃, Al₂O₃，
Fe₂O₃, SnO₂, ZnO, NiO, MnO, Cu
O, CoO, SiO₂, ZrO₂To use. Sm₂O₃，
Nd₂O₃For purity 65, 70, 80, 90, 9
A 9.9 wt% product was prepared.

The above raw material powders were weighed so as to have a predetermined composition, put into a urethane-lined ball mill equipped with agate balls together with pure water, and wet-mixed. After sufficiently drying this mixture, it was formed into pellets at a pressure of 400 kg / cm ² , and the formed body was calcined in the temperature range of 900 to 1000 ° C in the atmosphere. Then, the calcined product was put in a ball mill having the same structure as above together with pure water and wet-mixed.
The obtained pulverized product was dehydrated and dried, and then 8 v / w% of a polyvinyl alcohol solution having a concentration of 3 w / v% was added to the powder as an organic binder for granulation, followed by sizing with a 32 mesh sieve. Using a die and a hydraulic press, the sized powder is molded at a pressure of 800 kg / cm ² with a diameter of 20 mm and a thickness of 8 to 1.
It was molded into 2 mm pellets. The molded body was fired in a temperature range of 1200 to 1550 ° C. for 2 to 3 hours depending on the composition to obtain a target dielectric ceramic. The obtained dielectric porcelain was used as a dielectric resonator, and the unloaded Q and the resonance frequency temperature coefficient (τf) were measured. The permittivity was calculated from the resonance frequency and the size of the dielectric ceramic. Resonance frequency is 2
It was 4 GHz. The resonance frequency temperature coefficient (τf) is −
It measured in the temperature range of 25-50 degreeC.

Example 1 The dependence of the relative dielectric constant and the unloaded Q on the blending ratio (molar fraction) of each composition component was confirmed. The results are shown in FIGS. 1 and 2.

FIGS. 1 (a) and 1 (b) show these dependences on the BaO mole fraction (x), and FIGS. 2 (a) and 2 (b) show the TiO ₂ mole fraction. These dependences on (y), FIG. 3 (a) is the dependence of the relative permittivity on the mole fraction (z) of Nd ₂ O ₃ , and FIG. 3 (b) is Sm ₂
Dependence of relative permittivity on mole fraction (t) of O ₃ , FIG.
(A) and (b) show the dependence of the unloaded Q and the resonance frequency temperature coefficient (τf) on the mole fraction (w) of Bi ₂ O ₃ .

When confirming the dependence on each of the above-mentioned mole fractions, the raw materials other than the raw material for changing the mole fraction were made constant within the scope of the present invention.

As a method of illustration, a characteristic value corresponding to the sample (the composition number at the composition point of the target component is N = 20) was plotted, and the area was designated on the graph.
As is clear from FIGS. 1 and 2, the dielectric porcelain composed of the dielectric porcelain composition of the present invention has a large relative permittivity and no load Q at a frequency in the microwave region, and has a resonance frequency temperature coefficient (τf). It turns out that is small. In addition, as criteria for determination, no load Q ≧ 2000, relative permittivity ≧ 60, and resonance frequency temperature coefficient (τf) ≦ 100 ppm / ° C. The reason for the determination is that, when the unloaded Q is less than 2000, the insertion loss is large and it is difficult to use when used for a high frequency filter. Moreover, even if it is used as a circuit board, it has a bad influence on the circuit such as heat generation. Regarding the relative permittivity, if it is 60 or more, the size of the dielectric resonator becomes 5 mm or more in the frequency band of 1 to 2 GHz, which is out of the trend of miniaturization. Resonance frequency temperature coefficient (τf) is 100ppm / ℃
This is because, when the value exceeds, the resonance frequency of the resonator formed on the circuit shifts due to temperature, and matching on the circuit cannot be achieved.

Further, when the mole fraction (x) and the mole fraction (y) are 0.155 or more and 0.69 or less, respectively, Bi ₂ O ₃ is evaporated during firing and the characteristics are deteriorated. The mole fraction (x) and the mole fraction (y) are each 0.1
It is preferably 55 or less and 0.69 or more.

(Example 2) Next, xBaO.yTiO _{2
· ZNd 2 O 3 · tSm 2} O 3 · wBi 2 O 3 composition mole fraction of a dielectric ceramic composition having a composition formula, x = 0.12
2, y = 0.69, z = 0.141, t = 0.052
A predetermined amount of Al ₂ O ₃ and ZrO ₂ was added to 100 parts by weight of the composition adjusted so that w = 0.005, and the effect of the addition was confirmed. The results are shown in FIGS.

5 (a) and 5 (b) show the dependence of the coefficient of variation (%) of the relative permittivity and the unloaded Q on the added amount (parts by weight), and FIG. 6 shows that of ZrO ₂ . It shows the dependence of the three-point bending strength (kg / cm ² ) on the added amount (parts by weight).

As is apparent from FIGS. 5 (a) and 5 (b),
A decrease in the variation of the dielectric constant, which is considered to be a ripple effect from the improvement of the sinterability, is recognized. When the addition amount exceeds 3 parts by weight, the no-load Q is lowered, which is considered to be due to an increase in the glass layer formed near the crystal grain boundaries. Especially for ZrO ₂ , as is clear from FIG. 6, a remarkable increase in mechanical strength is observed. However, when it exceeds 3 parts by weight, the no-load Q tends to decrease as shown in FIGS. 5 (a) and 5 (b). Al ₂
The effect of the mixing ratio of O ₃ and ZrO ₂ was not so noticeable. Further, the same experiment was conducted by changing the composition mole fraction of the above composition within the range of the present invention, and similar results were obtained.

(Example 3) Next, using a sample having the same composition ratio as in Example 2 and using a composition in which Ba element was replaced by Sr, Ca, and Mg at a predetermined ratio, a relative permittivity and no load were applied. The dependency of Q was confirmed. The results are shown in FIGS. 7 (a) and 7 (b). As is clear from FIGS. 7A and 7B, Sr, C
It can be seen that when the substitution rate of a and Mg is 20 mol% or more, there is a tendency that the relative permittivity and the unloaded Q partially decrease. still,
Similar results were obtained when Sr, Ca, and Mg were replaced alone or as a mixture.

(Example 4) Next, using a sample having the same composition ratio as in Example 2, the effect of the purity of Sm ₂ O ₃ and Nd ₂ O ₃ on the relative dielectric constant was confirmed. The result is shown in FIG.

FIG. 8A shows the influence of the purity (wt%) of Sm ₂ O ₃ , and FIG. 8B shows the influence of the purity (wt%) of Nd ₂ O ₃ .

As is apparent from FIGS. 8 (a) and 8 (b),
It can be seen that when the purity of Sm ₂ O ₃ and Nd ₂ O ₃ is less than 70 wt%, the relative dielectric constant tends to decrease. Therefore,
From this, it can be said that industrially refined raw materials can be sufficiently used.

(Example 5) Next, the composition formula xBaO.yT
The composition mole fraction of iO ₂ · zNd ₂ O ₃ · tSm ₂ O ₃ · wBi ₂ O ₃ is 0.06 ≦ x ≦ 0.155 0.69 ≦ y ≦ 0.80 0.05 ≦ z ≦ 0. 18 0 <t ≤ 0.07 0 <w ≤ 0.05 (however, x + y + z + t + w = 1) When changing in the range, and for the composition of the composition ratio of the conventional example, no load Q with respect to relative permittivity, resonance The relationship between frequency temperature coefficient (τf) was confirmed. The result is shown in Figure 9.
Shown in (a) and (b).

FIG. 9A shows the dependence of the unloaded Q on the relative permittivity of each dielectric ceramic composition, and FIG. 9B shows the dependence of the resonance frequency temperature coefficient (τf).

As is apparent from FIGS. 9 (a) and 9 (b), in comparison with the conventional example, the present invention can obtain a higher unloaded Q and a lower resonance frequency temperature coefficient (τf) with respect to the relative permittivity. it can.

[0026]

The present invention as described above, according to the present invention _{is, (1) BaO-TiO 2} -Nd 2 O 3 -Sm 2 O 3 -Bi 2 O
By using the _3- based composition, it is possible to obtain a dielectric porcelain having a high dielectric constant and a no-load Q in the microwave region and a small resonance frequency temperature coefficient (τf). (2) By adding Al ₂ O ₃ or ZrO ₂ or the like, it is possible to improve sinterability and suppress variations in dielectric constant to a low level. Especially with respect to ZrO ₂ , the mechanical strength of the dielectric ceramics can be greatly improved. (3) Even if Ba is partially replaced with Sr, Ca, Mg, Ba
It can have the same characteristics as, and can cope with the diversification of raw materials. (4) Sm ₂ O ₃ and Nd ₂ O ₃ provide an excellent dielectric porcelain composition that can have characteristics close to those of a high-purity product even if it is a low-purity product.

[Brief description of drawings]

1A is a characteristic diagram of a main composition of a dielectric ceramic composition according to a first embodiment of the present invention, and FIG. 1B is a main composition of a dielectric ceramic composition according to a first embodiment of the present invention. Characteristic diagram of object

FIG. 2 (a) is a characteristic diagram of the main composition of the dielectric ceramic composition in the first embodiment of the present invention. FIG. 2 (b) is a main composition of the dielectric ceramic composition in the first embodiment of the present invention. Characteristic diagram of object

FIG. 3A is a characteristic diagram of a main composition of a dielectric ceramic composition according to the first embodiment of the present invention, and FIG. 3B is a main composition of a dielectric ceramic composition according to the first embodiment of the present invention. Characteristic diagram of object

FIG. 4A is a characteristic diagram of a main composition of a dielectric ceramic composition according to the first embodiment of the present invention, and FIG. 4B is a main composition of a dielectric ceramic composition according to the first embodiment of the present invention. Characteristic diagram of object

5 (a) is a characteristic diagram showing the effect of adding the second component of the dielectric ceramic composition in the second embodiment of the present invention. FIG. 5 (b) is a dielectric ceramic composition in the second embodiment of the present invention. Characteristic diagram showing the effect of adding the second component of the product

FIG. 6 is a characteristic diagram showing the effect of adding the second component of the dielectric ceramic composition in the second example of the present invention.

7A is a characteristic diagram of a dielectric ceramic composition according to a third embodiment of the present invention, and FIG. 7B is a characteristic diagram of a dielectric ceramic composition according to a third embodiment of the present invention.

FIG. 8A is a characteristic diagram of the influence of the Sm ₂ O ₃ purity of the dielectric ceramic composition of the fourth embodiment of the present invention on the relative dielectric constant. FIG. 8B is the fourth embodiment of the present invention. Of the influence of the Nd ₂ O ₃ purity of the dielectric ceramic composition on the relative permittivity in

9 (a) is a characteristic comparison diagram of the dielectric ceramic composition in the fifth embodiment of the present invention and the composition of the conventional example, and FIG. 9 (b) is a dielectric ceramic composition in the fifth embodiment of the present invention. Comparison chart of properties of conventional and conventional compositions

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiromitsu Taki 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. The composition formula is xBaO.yTiO ₂ .zNd ₂
A dielectric ceramic composition comprising O ₃ · tSm ₂ O ₃ · wBi ₂ O ₃ , wherein when the composition range is expressed by a mole fraction, 0.06 ≦ x ≦ 0.155 0.69 ≦ y A dielectric ceramic composition characterized by being in the range of ≦ 0.80 0.05 ≦ z ≦ 0.18 0 <t ≦ 0.07 0 <w ≦ 0.05 (where x + y + z + t + w = 1). 2. With respect to 100 parts by weight of the dielectric ceramic composition,
Al ₂ O ₃ , Fe ₂ O ₃ , SnO ₂ , ZnO, NiO, Mn
O, claim characterized CuO, CoO, and it has added SiO _2, of ZrO ₂ one or more kinds of 3 parts by weight or less 1
The dielectric porcelain composition described in 1. 3. A part of Ba has a molar fraction of 20 mol% or less S
The dielectric ceramic composition according to any one of claims 1 and 2, which is substituted with one or more of r, Ca, and Mg. 4. The method according to claim 1, wherein the purity of Sm ₂ O ₃ and Nd ₂ O ₃ is 70 wt% or more and the chemical component of impurities is other rare earth. The dielectric ceramic composition of.