JPH0891930A - Microwave dielectric ceramic composition and method for producing the same - Google Patents

Abstract

(57) [Abstract] [Purpose] ε _r (relative permittivity), Qu (unloaded Q) and τ
_{Disclosed is} a microwave dielectric ceramic composition that widely controls _f (resonance frequency temperature coefficient) within a practical characteristic range and maintains these characteristics in a well-balanced manner. [Composition] The composition is Bi (Nb _x Ta _1-x ) O.
₄ (provided that 0 <x ≦ 0.96) is used as a main component, and 2% by weight or less (0% by weight is added to 100% by weight of Bi (Nb _x Ta _1-x ) O ₄ ). V ₂ O ₅ (not included) and 1% by weight or less (not included 0% by weight) TiO ₂ is additionally contained. Particularly, the added amount of V ₂ O ₅ is 0.2 to 1.0% by weight, and the added amount of TiO ₂ is preferably 0.1 to 0.6% by weight. τf is -15 to +1
2 ppm / ° C., Qu 500-900, ε _r 42-5
It can be zero. The firing temperature is 875-950 ° C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave dielectric ceramic composition, and more specifically, it has a relative permittivity (hereinafter, simply referred to as ε _r ), an 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 each of these characteristics in a well-balanced manner, and a manufacturing method thereof. INDUSTRIAL APPLICABILITY The present invention is used for a dielectric resonator in a microwave region, a microwave integrated circuit substrate, impedance matching of various microwave circuits, and the like,
It is particularly suitable as an LC filter material.

[0002]

2. Description of the Related Art LC filter materials, dielectric resonators, dielectric substrates, etc., which are generally used in high frequency regions such as microwaves and millimeter waves, have high ε _r and high Qu, and τ _f
A small absolute value of is desired. That is, the microwave dielectric porcelain composition (hereinafter, simply referred to as a dielectric porcelain composition) tends to have a larger dielectric loss as the operating frequency becomes higher, so that ε _r and Qu, which are high in the microwave region, etc. A dielectric ceramic composition having excellent properties is 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.
Compositions belonging to the complex perovskite type structure such as a _2/3 ) O ₃ or BaO—TiO ₂ composition are used, but all have a high firing temperature of 1300 ° C. or higher.

When the firing temperature is high as described above, power consumption during firing increases, which causes a disadvantage in terms of production cost and production efficiency. In addition, copper (melting point; 1
(083 ° C.), silver (melting point; 961 ° C.) and the like, it is 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 drawbacks and provides a composition in which a predetermined amount of V ₂ O ₅ and TiO ₂ is added to a Bi (NbTa) O ₄ main component. To control ε _r , Qu, and τ _f widely within a practical characteristic range, and maintain the respective characteristics in a well-balanced manner, and to manufacture the composition by firing it at a relatively low temperature. The purpose is to provide a method.

[0005]

The present inventors have found that Bi (N
In the bTa) O ₄ composition, ε _r , Qu and τ _f are widely controlled within a practical property range, and various studies were conducted on the composition which can be produced by firing at low temperature. As a result, Nb ₂ By changing the ratio of O ₅ and Ta ₂ O ₅ ,
It has been found that the above object can be achieved by further adding a predetermined amount of V ₂ O ₅ and TiO ₂ thereto, and in particular, it has been found that τf can be controlled by adding TiO _2. Has been completed.

That is, the dielectric ceramic composition of the first invention is
Bi (Nb _x Ta _1-x ) O ₄ (where 0 <x ≦ 0.9
6) as a main component, to which Bi (N
b _x Ta _1-x ) O ₄ 100 wt% V ₂ O ₅ or less (not including 0 wt%) V ₂ O ₅ and 1 wt% or less (not including 0 wt%) TiO ₂ Is added and contained.

In the above composition, x is 0 <x ≦ 0.9.
The reason for setting 6 is that when x exceeds 0.96, Ta ₂
O ₅ component is substantially absent, and ε
_This is because it becomes difficult to control _r and τ _f . Also, Ta
By changing the addition amount of ₂ O ₅ , it is possible to easily control ε _r and τ _f , and particularly, by increasing the addition amount of Ta ₂ O ₅ , it is possible to achieve high ε _r and high Qu.

Further, the addition amount of V ₂ O ₅ exceeding 0 and 2% by weight or less is because V ₂ O ₅ acts as a sintering aid, so that the addition of V ₂ O ₅ can lower the firing temperature and improve the performance. Stabilization can be achieved, but if it is added in excess of 2% by weight, Qu and τ _f will be decreased, and _if V ₂ O ₅ is not added, sintering will be insufficient and each property will be deteriorated. . The amount of V ₂ O ₅ added is especially 0.3 to 0.5% by weight.
(Especially around 0.4% by weight) is more preferable because a practical dielectric ceramic composition in which each property is balanced can be obtained.

The reason why the amount of TiO ₂ added is 1% by weight or less is that each property remarkably deteriorates when the amount added exceeds 1% by weight. TiO ₂ has a function of shifting τ _f from negative to positive by adding, and
It is more preferable that a practical dielectric ceramic composition in which the respective properties are well balanced is obtained at ˜0.3 wt% (particularly 0.2 wt%).

Further, the amount of V ₂ O ₅ added is 0.2 to
1.0% by weight, and the addition amount of 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 εr 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 Bi (Nb _x Ta _1-x ) O ₄ (where 0 <x
≦ 0.96) as a main component, and V _{2 of 2} % by weight or less (not including 0% by weight) based on 100% by weight of Bi (Nb _x Ta _1-x ) O ₄ described above. O ₅ and bismuth (III) oxide powder so as to have a composition containing 1% by weight or less (not including 0% by weight) of TiO ₂ ,
Niobium (V) oxide powder, tantalum (V) oxide powder, vanadium oxide (V) powder and titanium (II) oxide powder are mixed, and then calcined at 600 to 800 ° C. to produce a calcined powder, The calcined powder is crushed, shaped into a predetermined shape, and then
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. This firing temperature is set in the range of 875 to 950 ° C. because it may not sinter sufficiently below 875 ° C. In this range, a sufficient sintering density can be secured and stable performance is exhibited. is there. In the case of simultaneous sintering with a conductor such as an LC filter, low temperature firing is particularly preferable.

[0012]

EXAMPLES The present invention will be specifically described below with reference to examples. Bi ₂ O ₃ powder (purity; 98.9%), Nb ₂ O ₅
Powder (purity; 99.9%), Ta ₂ O ₅ powder (purity; 9
9.9%), V ₂ O ₅ powder (purity; 99.5%) and T
As shown in Table 1, BiO (Nb _x Ta _1-x ) O ₄ x was set to 0, using iO ₂ powder (purity: 99.9%) as a starting material.
1.0, the addition amount of V ₂ O ₅ a (alpha wt%) 0-3.
A predetermined amount (all about 600 g in total amount) was weighed and mixed so that the composition was such that the addition amount of 0 and TiO ₂ (β wt%) varied in the range of 0 to 2.0.

[0013]

[Table 1]

Then, the raw material powders weighed and mixed as described above were put into a vibration mill, subjected to primary pulverization (3 hours), and then calcined at 700 ° C. for 2 hours in an air atmosphere. Next, a suitable amount of organic binder (about 15 g) and water (3
30 g) was added, and secondary pulverization was performed in a ball mill with an alumina ball of 20 mmφ at 90 rpm for 23 hours.
Then, it is granulated 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 this granulated raw material is used. 19 mmφ × 10 mm at a press pressure of 1 ton / cm ^2.
A columnar shaped body of t (height) was obtained.

Next, the molded body was exposed to the air at 500 ° C.
It was degreased for 3 hours and then fired at 850 to 950 ° C. for 2 hours to obtain a sintered body. Finally, remove both ends of this sintered body by about 16
mmφ × 8 mmt (height) columnar, polished and further washed with ethanol to obtain a dielectric sample (Nos. 1 to 22 in Table 1).
And The rate of temperature rise in the calcination step was 200 ° C.
/ H and the temperature decreasing rate were −200 ° C./h, the temperature increasing rate in the degreasing step was 50 ° C./h, and the temperature increasing rate in the firing step was 100 ° C./h and the temperature decreasing rate was −100 ° C./h.

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

These results show that the addition of TiO ₂ greatly improves τf and facilitates the control of τf (FIG. 3). However, since the addition of TiO ₂ lowers ε _r and Qu (FIGS. 1 and 2),
Addition of a large amount of TiO ₂ is not preferable. Also, V ₂ O ₅
When No is added (No. 12), sintering becomes insufficient,
Measurement of each characteristic becomes impossible. And, with this addition, ε _r increases (FIG. 5) and τ f decreases (FIG. 7),
τf can be adjusted. However, addition of a large amount of V ₂ O ₅ is not preferable, since Qu is lowered by the addition thereof (FIG. 6).

Further, since τf increases as the x value of Bi (Nb _x Ta _1-x ) O ₄ increases (FIG. 11), τf can be adjusted by changing the x value. Also, with this increase, ε _r and Qu also increase (see FIGS. 9 and 1).
0), although preferable in terms of this physical property, the sintered density is lowered (FIG. 12). It should be noted that a sintered density of 7.0 kg / m ³ or more can be secured even when x is 1.0 (FIG. 12). Moreover, when the firing temperature is 850 ° C. (No. 8), the sintering becomes insufficient and it becomes impossible to measure each characteristic. 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
Although it changes variously with the addition amount and the firing temperature, each characteristic is within the range of practically no problem within the range of the present invention. For example, among these, x = 0.8 to 0.96, V ₂
O ₅ = 0.4 to 1.0% by weight, TiO ₂ = 0.2 to 1.
In the case of 0% by weight, ε _r = 43.3 to 47.7, Qu =
It is 370-910 and (tau) f = -13- + 11 ppm / degreeC. Further, particularly when x = 0.8, V ₂ O ₅ = 0.4% by weight, and TiO ₂ = 0.2 to 0.4% by weight, ε _r =
45.4-47.7, Qu = 680-910, τf =-
It is 13 to -9 ppm / ° C and has an excellent performance balance. Incidentally, No. As you can see from the results of 17-20,
In the present invention, when x is as small as 0.2 to 0.6, τ _f tends to increase to 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. Incidentally, the present invention is not limited to those shown in the above specific examples, and the purpose,
Various modifications 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 the practical characteristic range, and each of these characteristics is maintained in a well-balanced manner. Therefore, it is suitable as an LC filter material. Further, according to the present production method, the useful dielectric ceramic composition as shown above can be produced by firing at a relatively low temperature of 850 to 950 ° C. And, this low temperature firing is particularly convenient in the case of an LC filter that is co-sintered with the conductor.

[Brief description of drawings]

FIG. 1 is obtained by adding 0.4% by weight of V ₂ O ₅ to a main component represented by Bi (Nb _0.8 Ta _0.2 ) O ₄ and firing temperature of 9
6 is a graph showing the relationship between the addition amount β of TiO ₂ and ε _{r at} 00 ° C.

FIG. 2 shows TiO _{2 at the} composition and firing temperature shown in FIG.
5 is a graph showing the relationship between the addition amount β of P and Qu.

FIG. 3 shows TiO _{2 at the} composition and firing temperature shown in FIG.
5 is a graph showing the relationship between the addition amount β and τ _{f of} .

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

5 is a main component represented by Bi (Nb _0.8 Ta _0.2 ) O ₄ with 0.2% by weight of TiO ₂ added and a firing temperature of 9;
6 is a graph showing the relationship between the addition amount α of V ₂ O ₅ and ε _{r at} 00 ° C.

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

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

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 addition amount α of α and the sintered density.

FIG. 9: V ₂ O ₅ 0.4 wt% and TiO ₂ 0.2 wt% were added to the main component represented by Bi (Nb _x Ta _1-x ) O ₄ , and the firing temperature was 900 ° C. 6 is a graph showing the relationship between x and ε _{r in} the case of.

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

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

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

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

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 firing temperature and τ _{f in the} composition shown in FIG.

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

Claims (4)

[Claims] 1. Bi (Nb _x Ta _1-x ) O ₄ (however, 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 described above. A microwave dielectric ceramic composition comprising V ₂ O ₅ and 1% by weight or less (not including 0% by weight) of TiO ₂ added. 2. The amount of V ₂ O ₅ added is 0.2 to 1.0.
% By weight, and the amount of TiO ₂ added is 0.1 to 0.6.
The microwave dielectric ceramic composition according to claim 1, wherein the microwave dielectric ceramic composition is in a weight percentage. 3. The temperature coefficient of resonance frequency is -15 to +12.
The microwave dielectric ceramic composition according to claim 1 or 2, wherein the unloaded Q is 500 to 900, and the relative dielectric constant is 42 to 50. 4. Bi (Nb _x Ta _1-x ) O ₄ (however, 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 described above. V ₂ O ₅ and 1% by weight or less (not including 0% by weight) of TiO ₂ are added so that the composition is such that bismuth (III) oxide powder, niobium (V) oxide powder, and 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, and the calcined powder is crushed into a predetermined shape. A method for producing a microwave dielectric ceramic composition, which comprises molding and then firing at 875 to 950 ° C.