JP3357479B2 - Microwave dielectric porcelain composition and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to a microwave dielectric ceramic composition and, more particularly, the dielectric constant (hereinafter, simply. As epsilon _r), unloaded Q (hereinafter, simply referred to as Qu.) And The present invention relates to a microwave dielectric ceramic composition that controls a temperature coefficient of resonance frequency (hereinafter simply referred to as τ _f ) widely within a practical characteristic range and maintains these characteristics in a well-balanced manner, and a method of manufacturing the same. INDUSTRIAL APPLICABILITY The present invention is used for a dielectric resonator, a microwave integrated circuit board, impedance matching of various microwave circuits, etc. in a microwave region,
Particularly, it is suitable as an LC filter material.

[0002]

2. Description of the Related Art Generally, an LC filter material, a dielectric resonator, a dielectric substrate and the like used in a high frequency region such as a microwave and a millimeter wave have a high ε _r and a high Qu, and have a high τ _f
It is desired that the absolute value of is small. In other words, the microwave dielectric porcelain composition (hereinafter simply referred to as dielectric porcelain composition) tends to have a higher dielectric loss as the operating frequency becomes higher, so that ε _r and Qu etc. in the microwave region are high. A dielectric porcelain composition having excellent properties has been desired. In recent years, Ba (Zn _1/3 Ta _2/3 ) O ₃ and Ba (Mg _1/3 T) have been used as such dielectric ceramic compositions.
a _2/3 ) A composition belonging to a complex perovskite structure such as O ₃ or a BaO—TiO ₂ composition is used, but the firing temperature is as high as 1300 ° C. or more.

[0003] As described above, when the firing temperature is high, there is a drawback that the power consumption during firing is increased, and disadvantages are caused in terms of production cost and production efficiency. Further, as in an LC filter, a strip line filter, etc., copper (melting point: 1) is used as an electrode.
083 ° C.) and silver (melting point: 961 ° C.), it is particularly advantageous that the firing temperature is lower than the melting point of the conductor.

[0004]

DISCLOSURE OF THE INVENTION The present invention overcomes the above-mentioned disadvantages and is directed to a composition comprising Bi (NbTa) O _{4 as a} main component and predetermined amounts of V ₂ O ₅ and TiO ₂ added thereto. Thereby, ε _r , Qu and τ _f are controlled in a wide range within a practical characteristic range, a microwave dielectric porcelain composition that maintains these characteristics in a well-balanced manner, and is manufactured by firing at a relatively low temperature. The aim is to provide a method.

[0005]

Means for Solving the Problems The present inventors have proposed Bi (N
In bTa) O ₄ system compositions, widely controlled within a practical characteristic range epsilon _r, Qu and tau _f, As a result of various investigations on the composition which can be produced by firing at a low temperature, Nb ₂ in the composition Changing the ratio of O ₅ and Ta ₂ O ₅ ,
It has been found that the above object can be achieved by adding a predetermined amount of V ₂ O ₅ and TiO ₂ to the composition, and particularly, it has been found that τf can be controlled by adding TiO _2. Was completed.

That is, the dielectric porcelain composition of the first invention is:
Bi (Nb _x Ta _1-x ) O ₄ (where 0 <x ≦ 0.9
6) as a main component, and the composition represented by Bi (N
b _x Ta _1-x ) 2% by weight or less (excluding 0% by weight) of V ₂ O ₅ and 1% by weight or less (excluding 0% by weight) of TiO _{2 based on} 100% by weight of O ₄ . Is added and contained.

In the above composition, x is 0 <x ≦ 0.9.
The reason is that when x exceeds 0.96, Ta ₂
O ₅ component is substantially absent, and ε
control of _r and τ _f is because it becomes difficult. Also, Ta
By changing the added amount of ₂ O ₅ , control of ε _r and τ _f is facilitated. In particular, by increasing the added amount of Ta ₂ O ₅ , higher ε _r and higher Qu can be achieved.

Furthermore, the addition amount of V ₂ O ₅ and 2% by weight or less than 0, since V ₂ O ₅ is acting as a sintering aid, can lower the sintering temperature by adding, performance Stabilization can be achieved, but adding more than 2% by weight causes a decrease in Qu and τ _f , and when V ₂ O ₅ is not added, sintering becomes insufficient and various properties are deteriorated. . The addition amount of V ₂ O ₅ is particularly 0.3 to 0.5% by weight.
(Especially around 0.4% by weight), a practical dielectric porcelain composition in which the properties are balanced is obtained, which is more preferable.

The reason why the addition amount of TiO ₂ is set to 1% by weight or less is that each characteristic is remarkably deteriorated when the addition amount exceeds 1% by weight. TiO ₂ has the function of shifting τ _f from negative to positive by adding TiO _2.
A practical dielectric porcelain composition in which the respective properties are balanced is obtained at a content of 0.3 to 0.3% by weight (particularly 0.2% by weight), which is more preferable.

[0010] Further, the addition amount of V ₂ O ₅ is 0.2 to
1.0 wt%, amount of the TiO ₂ is 0.1
It can be 0.6% by weight. This is because in the case of these addition ranges, the performance balance of ε _r , Qu and τ _f is excellent. Further, according to the above composition, τf
Is −15 to +12 ppm / ° C., Qu is 500 to 900,
A practical performance balance of 42 to 50 can be obtained.

The method for producing a dielectric ceramic composition according to the fourth aspect of the present invention is characterized in that Bi (Nb _x Ta _1-x ) O ₄ (where 0 <x
≦ 0.96) as a main component, and 2% by weight or less (not including 0% by weight) of V _{2 with} respect to 100% by weight of Bi (Nb _x Ta _1-x ) O ₄ . Bismuth (III) oxide powder is added so as to have a composition containing O ₅ and 1% by weight or less (not including 0% by weight) of TiO ₂ .
Niobium oxide (V) powder, tantalum oxide (V) powder, vanadium oxide (V) powder and titanium oxide (II) powder are mixed, and then calcined at 600 to 800 ° C. to produce a calcined powder. The calcined powder is pulverized and formed into a predetermined shape,
It is characterized by firing at 875 to 950 ° C. still,
In the present invention, firing can be performed in either an air atmosphere or a reducing atmosphere. The reason for setting the firing temperature in the range of 875 to 950 ° C. is that if the temperature is lower than 875 ° C., the sintering may not be performed sufficiently. In this range, a sufficient sintering density can be ensured and stable performance is exhibited. is there. In addition, when co-sintering with a conductor like an LC filter, low-temperature baking is particularly preferable.

[0012]

The present invention will be specifically described below with reference to examples and comparative examples . Bi ₂ O ₃ powder (purity: 98.9%), Nb ₂ O ₅ powder (purity: 99.9%), Ta ₂ O ₅ powder (purity: 99.9%)
9%), V ₂ O ₅ powder (purity; 99.5%) and TiO
₂ powder (purity; 99.9%) as a starting material, as shown in Table 1, _{x of} Bi (Nb _x Ta _1-x ) O ₄ is 0 to
1.0, the addition amount (α% by weight) of V ₂ O ₅ is 0 to 3.0,
A predetermined amount (about 600 g in total) was weighed and mixed so that the composition in which the amount of TiO ₂ added (β wt%) varied in the range of 0 to 2.0. In Table 1, No.
1, 7, 8, 12, 16, 17, and 22 are comparative examples.
You.

[0013]

[Table 1]

Thereafter, the weighed and mixed raw material powder was put into a vibrating mill, subjected to primary pulverization (3 hours), and then calcined at 700 ° C. for 2 hours in an air atmosphere. Next, an appropriate amount of an organic binder (about 15 g) and water (3 g) were added to the calcined powder.
30 g), and the resulting mixture was subjected to secondary pulverization with a 20 mmφ alumina ball in a ball mill at 90 rpm for 23 hours.
Thereafter, granulation is performed by vacuum freeze-drying (pressure: about 0.4 Torr, freezing temperature: -20 to -40 ° C, drying temperature: 40 to 50 ° C, time: 20 hours), and the granulated raw material is used. 19mmφ × 10mm at a press pressure of 1 ton / cm ²
A columnar molded body of t (height) was obtained.

Next, this molded body is heated at 500 ° C. in the air.
It was degreased for 3 hours, and then fired at 850 to 950 ° C. for 2 hours to obtain a sintered body. Finally, the both end faces of this sintered body were
Polished into a cylindrical shape of mmφ × 8 mmt (height), further washed with ethanol, and a dielectric sample (Nos. 1 to 22 in Table 1)
And The heating rate in the calcining step was 200 ° C.
/ H and the cooling rate were -200 ° C / h, the heating rate in the degreasing step was 50 ° C / h, and the heating rate in the firing step was 100 ° C / h and the cooling rate was -100 ° C / h.

For each of the above samples, τ _f , τ _f , and _{t were determined} by a parallel conductor plate type dielectric cylinder resonator method (TE ₀₁₁ MODE) or the like.
ε _r , Qu and sintered density were measured. Note that τ _f is 25 to
Measured in a temperature range of 80 ° C., τ _f = (f ₈₀ −f ₂₅ ) /
(F ₂₅ × ΔT), ΔT = 80−25 = 55 ° C. The resonance frequency at the time of measurement is as shown in Table 1 (f ₀ ). These results are shown in Table 1 and FIGS.
6 is shown in the graph.

These results show that the addition of TiO ₂ greatly improves τf and makes it easier to control τf (FIG. 3). However, since the addition of TiO ₂ lowers ε _r and Qu (FIGS. 1 and 2),
Large amounts of TiO ₂ are not preferred. V ₂ O ₅
When no is added (No. 12), sintering becomes insufficient,
Measurement of each characteristic becomes impossible. By this addition epsilon _r increases (Fig. 5), since τf is decreased (Fig. 7),
τf can be adjusted. However, since Qu decreases with its addition (FIG. 6), it is not preferable to add a large amount of V ₂ O ₅ .

Further, τf increases as the x value of Bi (Nb _x Ta _1-x ) O ₄ increases (FIG. 11), so that τf can be adjusted by changing this x value. Further, with this increase, ε _r and Qu also increase (FIGS. 9 and 1).
0), although preferable in terms of these physical properties, the sintering density is reduced (FIG. 12). In addition, even if x is 1.0, a sintered density of 7.0 kg / m ³ or more can be secured (FIG. 12). On the other hand, when the firing temperature is 850 ° C. (No. 8), the sintering becomes insufficient and the measurement of each characteristic becomes impossible. On the other hand, 87
5 to 950 ° C. (x = 0.8, V ₂ O ₅ = 0.4% by weight,
TiO ₂ = 0.2% by weight), the sintered density is 7.36 to
It is as large as 7.52 kg / m ³ (FIG. 16), and the physical properties are stable (FIGS. 13 to 15).

As described above, the characteristics are V ₂ O ₅ and TiO ₂
Varies with the addition amount and the sintering temperature, but within the range of the present invention, each characteristic is within a range in which there is no practical problem. For example, of these, x = 0.8 to 0.96, V ₂
O ₅ = 0.4 to 1.0 wt%, TiO ₂ = 0.2~1.
In the case of 0% by weight, ε _r = 43.3-47.7, Qu =
370 to 910, τf = −13 to +11 ppm / ° C. In particular, when x = 0.8, V ₂ O ₅ = 0.4 wt%, and TiO ₂ = 0.2 to 0.4 wt%, ε _r =
45.4-47.7, Qu = 680-910, τf = −
13 to -9 ppm / ° C, and has an excellent performance balance. In addition, No. As can be seen from the results of 17 to 20,
In the present invention, when x is as small as 0.2 to 0.6, τ _f tends to increase on the negative side (−55 to −30 ppm / ° C.), but ε _r is 42.0 to 47.2. , Qu is 510
730, which is a practically sufficient characteristic. In the present invention, the present invention is not limited to the specific examples described above,
Various embodiments can be made within the scope of the present invention depending on the application.

[0020]

According to the dielectric ceramic composition of the present invention, ε _r ,
Qu and τ _f are within a practical characteristic range, and these characteristics are maintained in a well-balanced manner. Therefore, it is suitable as an LC filter material. Further, according to the present manufacturing method, the useful dielectric ceramic composition as described above can be manufactured by firing at a relatively low temperature of 850 to 950 ° C. This low-temperature sintering is particularly advantageous in the case of an LC filter co-sintered with a conductor.

[Brief description of the drawings]

FIG. 1 shows that a main component represented by Bi (Nb _0.8 Ta _0.2 ) O ₄ is added with 0.4% by weight of V ₂ O ₅ and a sintering temperature is 9%.
In the case of 00 ° C., which is a graph showing the relationship between the added amount β and epsilon _r of TiO _2.

FIG. 2 shows TiO _{2 at the} composition and firing temperature shown in FIG.
Is a graph showing the relationship between the added amount β and Qu.

FIG. 3 shows TiO _{2 at the} composition and firing temperature shown in FIG.
It is a graph showing the relationship between the added amount β and tau _f.

FIG. 4 shows TiO _{2 at the} composition and firing temperature shown in FIG.
3 is a graph showing the relationship between the amount β of sintering and the sintering density.

FIG. 5: TiO ₂ is added to a main component represented by Bi (Nb _0.8 Ta _0.2 ) O ₄ by 0.2% by weight, and the sintering temperature is 9
In the case of 00 ° C., which is a graph showing the relationship between the mixing amount α and epsilon _r of V ₂ O _5.

FIG. 6 shows V ₂ O _{5 at the} composition and firing temperature shown in FIG.
Is a graph showing the relationship between the amount of addition α and Qu.

FIG. 7 shows V ₂ O _{5 at the} composition and firing temperature shown in FIG.
4 is a graph showing the relationship between the added amount α and τ _f .

FIG. 8 shows V ₂ O _{5 at the} composition and firing temperature shown in FIG.
3 is a graph showing the relationship between the amount α of sintering and the sintering density.

FIG. 9: 0.4% by weight of V ₂ O ₅ and 0.2% by weight of TiO ₂ are added to the main component represented by Bi (Nb _x Ta _1-x ) O ₄ , and the sintering temperature is 900 ° C. in the case of a graph showing the relationship between x and epsilon _r.

10 shows x and Q at the composition and firing temperature shown in FIG.
6 is a graph showing a relationship with u.

11 shows x and τ at the composition and firing temperature shown in FIG.
It is a graph which shows the relationship with _f .

12 is a graph showing the relationship between x and the sintering density at the composition and firing temperature shown in FIG.

FIG. 13 shows the sintering temperature, ε _r, and the temperature when 0.4% by weight of V ₂ O ₅ and 0.2% by weight of TiO ₂ are added to the main component represented by Bi (Nb _0.8 Ta _0.2 ) O _4. 6 is a graph showing the relationship of.

FIG. 14 is a graph showing the relationship between the firing temperature and Qu in the composition shown in FIG.

FIG. 15 is a graph showing the relationship between the firing temperature and τ _{f in the} composition shown in FIG.

FIG. 16 is a graph showing the relationship between the sintering temperature and the sintering density in the composition shown in FIG.

Claims (4)

(57) [Claims] 1. Bi (Nb _x Ta _1-x ) O ₄ (where 0
<X ≦ 0.96) as a main component, and 2% by weight or less (not including 0% by weight) based on 100% by weight of Bi (Nb _x Ta _1-x ) O ₄ . A microwave dielectric ceramic composition comprising V ₂ O ₅ and 1% by weight or less (not including 0% by weight) of TiO ₂ . _2. The addition amount of V ₂ O ₅ is 0.2 to 1.0.
Weight%, and the amount of the TiO ₂ is 0.1 to 0.6
2. The microwave dielectric porcelain composition according to claim 1, wherein the composition is by weight. 3. The temperature coefficient of the resonance frequency is -15 to +12.
The microwave dielectric ceramic composition according to claim 1, wherein the unloaded Q is 500 to 900, and the relative dielectric constant is 42 to 50. 4. 4. Bi (Nb _x Ta _1-x ) O ₄ (where 0
<X ≦ 0.96) as a main component, and 2% by weight or less (not including 0% by weight) based on 100% by weight of Bi (Nb _x Ta _1-x ) O ₄ . Bismuth (III) oxide powder, niobium oxide (V) powder, tantalum oxide (V) so that V ₂ O ₅ and 1% by weight or less (excluding 0% by weight) of TiO ₂ are added and contained. ) Powder, vanadium oxide (V) powder and titanium oxide (II) powder are mixed, then calcined at 600 to 800 ° C. to produce a calcined powder, and the calcined powder is pulverized into a predetermined shape. A method for producing a microwave dielectric porcelain composition, comprising forming and then firing at 875 to 950 ° C.