JPH0891924A - Dielectric porcelain composition - Google Patents

Abstract

(57) [Summary] [Purpose] ε _r , Q × f, determined by composition
To provide a dielectric porcelain composition whose characteristics such as τ _f and T _min can be controlled relatively arbitrarily by additives. [Constitution] The dielectric ceramic composition is composed of barium oxide (Ba
O), Nd as essential components (R ₂ O
₃ ), bismuth oxide (Bi ₂ O ₃ ), and titanium oxide (TiO ₂ ) as main components, and the general formula, aBaO-bR ₂
Represented by O ₃ -cBi ₂ O ₃ -dTiO ₂ , a + b +
c + d = 100, c = 0.8 to 6.3, a, (b +
100 parts by weight of the dielectric ceramic composition in which c) and d are within the range formed by connecting the four points P, Q, R, and S in FIG. 0 parts by weight or less Z
rO ₂ was added and 85% or more in volume fraction was orthorhombic. 1 to 3.5 mol% of a part of this BaO
Substitution with SrO is also possible.

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, and more particularly to a dielectric material for a microwave filter used in communication and broadcasting equipment.

[0002]

2. Description of the Related Art Recent advances in communication technology have led to mobile communication such as car phones and mobile phones, and GPS (Global
Positioning System) etc. are rapidly spreading. However, these communication systems are simultaneously expanding the frequency range used and promoting frequency utilization in the microwave band.

Automotive telephones, mobile telephones, consumer GPs
A microwave filter using a dielectric resonator, a small dielectric resonator for stabilizing the frequency of an oscillator, or a circuit using a dielectric porcelain for the purpose of downsizing a device suitable for an S device or the like. Many efforts have been made to reduce the size, and it is reaching the stage of practical application.

The characteristics required of such a dielectric ceramic are that the permittivity (hereinafter, referred to as ε _r ) in the used frequency band is large and that the temperature coefficient of the resonance frequency (hereinafter, τ _f
Is called as close to zero as possible, and the dielectric loss in the microwave band {hereinafter referred to as tan δ (= 1 / Q)}
Is small. Since the size of the dielectric loss tan δ of the dielectric material used in the microwave band is usually expressed in the form of Q × f, this is used below. Therefore, a large value of Q × f is one of the indicators that the dielectric material is excellent. Note that f is the resonance frequency of the material at that time.

[0005]

Conventionally, as a microwave dielectric ceramic material having a high dielectric constant, BaO--Ti has been used.
O ₂ -rare earth oxide-based materials are known, but the materials having the compositions disclosed so far have a poor balance of ε _r and Q × f. In order to solve the drawback, the present inventors have found that BaO, SrO, Nd ₂ O ₃ , didymium oxide, Bi ₂ O.
₃ , the composition of TiO ₂ is limited and the volume fraction is 8
A dielectric ceramic in which 5% or more is orthorhombic has been proposed (Japanese Patent Application No. 6-171600, hereinafter referred to as Conventional Example 1). In this material, the resonance frequency changes so that it becomes the lowest at a certain temperature, and the temperature coefficient of the resonance frequency becomes small near that temperature. Therefore, it is practically important to have the minimum of this resonance frequency near the temperature actually used. Below, the temperature at which the resonance frequency becomes the lowest is T
_Call it _min . However, in the composition shown in Conventional Example 1,
ε _r , Q × f, τ _f , T _min are determined by the composition,
It had the drawback that it could not be operated arbitrarily. Especially T _min
Since it affects the value of τ _f in the practical temperature range, the fact that it cannot be controlled freely is a big negative in using materials.

Therefore, the technical problem of the present invention is to provide a dielectric ceramic composition in which the characteristics such as ε _r , Q × f, τ _f , and T _min , which are determined by the composition, can be controlled relatively arbitrarily by additives. To provide.

[0007]

As a dielectric ceramic material for solving the above-mentioned problems, the present invention provides barium oxide (Ba).
O), Nd as essential components (R ₂ O
₃ ), bismuth oxide (Bi ₂ O ₃ ), and titanium oxide (TiO ₂ ) as main components, and the general formula, aBaO-bR ₂
Represented by O ₃ -cBi ₂ O ₃ -dTiO ₂ , a + b +
c + d = 100 mol%, c is 0.8 ≦ c ≦ 6.3,
And the dielectric ceramic composition in which a, (b + c), and d are within the range formed by connecting the four points of P, Q, R, and S shown in Table 1 below is 100 parts by weight. On the other hand,
A dielectric porcelain composition was found in which 0.01 parts by weight or more and 1.0 parts by weight or less of ZrO ₂ is added, and 85% or more in volume fraction is orthorhombic. It was the invention.

[0008]

[Table 1]

In the dielectric ceramic of the present invention, the rare earth oxide (R ₂ O ₃ ) is neodymium oxide (Nd ₂ O).
₃ ) and a, (b + c), d are within the range of the above Table 1, and when this is 100 parts by weight, 0.01 parts by weight or more and 1.0 parts by weight or less of ZrO ₂ is added. It is preferable that the orthorhombic crystal has a volume fraction of 85% or more. In the dielectric ceramic of the present invention, the rare earth oxide (R ₂ O ₃ ) is didymium oxide {(Nd + Pr) ₂ O.
₃ } and a, (b + c), and d are within the range of the above Table 1, and when this is 100 parts by weight, 0.
It is preferable that ZrO ₂ is added in an amount of 01 parts by weight or more and 1.0 parts by weight or less, and that the volume fraction of 85% or more is orthorhombic.

[0010] In the dielectric ceramic composition of the present invention, the general formula _{aBaO-bR 2 O 3 -cBi 2} O 3 -
A general formula in which a part of barium oxide (BaO) in dTiO ₂ is replaced with strontium oxide (SrO), a′B
_{aO-eSrO-bR 2 O 3} -cNd 2 O 3 -dTiO
It is represented by ₂ , a '+ b + c + d + e = 100 mol%
Therefore, it is preferable that a = a ′ + e and e = 0.1 to 3.5 mol%.

[0011]

In the present invention, a microwave dielectric material is used,
The temperature at which the resonance frequency becomes the lowest is T _min .
By volume fraction BaO-R ₂ or more 85% orthorhombic
O ₃ -Bi ₂ O ₃ -TiO ₂ or BaO-SrO,
-Nd ₂ O ₃ -Bi ₂ O ₃ the -TiO ₂ of T _min can be controlled as desired by the addition of ZrO ₂ in a predetermined amount.

[0012]

EXAMPLES The present invention will be described in detail below based on examples.

The dielectric ceramic composition of the present invention comprises barium oxide (BaO), a rare earth oxide (R ₂ O ₃ ) containing Nd as an essential component, bismuth oxide (Bi ₂ O ₃ ), and titanium oxide (TiO _2). ) Is the main component. Then, the main component of the general _{formula, aBaO-bR 2 O 3 -cBi} 2 O
It is represented by _3- dTiO ₂ . Where a + b + c + d
= 100 mol%, c is 0.8 ≦ c ≦ 6.3, and a, (b + c), and d are P shown in Table 2 below.
It is within the range formed by connecting the four points of Q, R, and S. The range of this principal component is shown in a triangular diagram as shown in FIG. In the present invention, 100 parts by weight of this dielectric porcelain composition is used.
rO ₂ is added, and the orthorhombic crystal has a volume fraction of 85% or more with respect to the entire composition.

[0014]

[Table 2]

The dielectric ceramic composition of the present invention will be described in more detail below with reference to specific examples.

Example 1 First, BaCO ₃ , Nd ₂ O
Starting materials of ₃ , Bi ₂ O ₃ and TiO ₂ were weighed according to each composition and wet-mixed with a resin ball mill. After this mixture was dried, it was calcined at 1150 ° C. in the atmosphere. Further, a predetermined amount of ZrO ₂ was added to the calcined product, and the mixture of the calcined product and ZrO ₂ was wet pulverized by the ball mill, and then formed into a disk shape having a diameter of 15 mm and a thickness of about 6 mm, which was heated to 1300 to 1300 in the atmosphere. Sintering was performed at a temperature of 1400 ° C. to obtain porcelain having the composition shown in Table 2 below. The composition in Table 3 _{below, aBaO-bNd 2 O 3 -cBi} 2 O 3 -dTiO
₂ (mole%, a + b + c + d = 100).

Next, the dielectric resonator method was used to measure the temperature dependence of the dielectric constant, the dielectric loss, and the resonance frequency of these porcelains. The temperature T _min when the resonance frequency becomes the lowest was obtained by interpolating from the value when the resonance frequency was measured every 10 ° C. in the temperature range of −40 to + 120 ° C. The temperature coefficient of the resonance frequency was calculated from the difference of the resonance frequency f in the temperature range of 0 to + 40 ° C. by the following formula 1.

[0018]

[Equation 1] The resonance frequency was 2.5 to 3.2 GHz. The measurement results of the dielectric properties are shown in Table 3 below.

[0019]

[Table 3]

Example 2 Starting materials of BaCO ₃ , didymium oxide (Nd + Pr) ₂ O ₃ , Bi ₂ O ₃ and TiO ₂ were weighed according to each composition, and the same as in Example 1 The amount of Zr shown in Table 3 for each of the calcined powders obtained by the method
After adding O ₂ , it was mixed and crushed by the same ball mill as shown in Example 1, and then molded and sintered. Here, composition, aBaO-b (Nd + Pr ) 2 O 3 -cBi 2 O
_{It is} expressed as _3- dTiO ₂ (mol%, a + b + c + d = 100).

Then, the same measurements as those shown in Example 1 were performed on these porcelains, and the measurement results shown in Table 4 below were obtained. The analysis values of didymium oxide are shown in Table 5 below, and the weighing was performed by converting Pr ₂ O ₃ into 1 mol.

[0022]

[Table 4]

[0023]

[Table 5]

(Embodiment 3) BaCO ₃ , SrCO ₃ , N
Starting materials of d ₂ O ₃ , Bi ₂ O ₃ , and TiO ₂ were weighed according to each composition, and the amounts shown in Table 5 were calculated for the calcined powder obtained by the same method as that shown in Example 1. ZrO ₂ was added and mixed in a ball mill similar to that shown in Example 1.
After crushing, it was molded and sintered. Here, the composition is a'B
_{aO-eSrO-bNd 2 O 3} -cBi 2 O 3 -dTi
It is expressed as O ₂ (mol%, a '+ b + c + d + e = 100).

Then, the same measurements as those shown in Example 1 were performed on these porcelains, and the measurement results shown in Table 6 below were obtained.

[0026]

[Table 6]

Example 4 BaCO ₃ , SrCO ₃ , didymium oxide (Nd + Pr) ₂ O ₃ , Bi ₂ O ₃ , TiO ₂
The _second starting materials are weighed according to each composition, relative to calcined powder obtained in the same manner as shown in Example 1, after adding ZrO ₂ in an amount shown in each of Table 6, Example The same ball mill as shown in 1 was mixed and crushed, and then molded and sintered. Here, the composition is a'BaO-eSrO-bNd _{2
O 3 -cBi 2 O 3 -dTiO 2} ( mole%, a '+ b +
c + d = 100). The didymium oxide is the same as that shown in Table 5 used in Example 2,
The weighing was performed by converting Pr ₂ O ₃ into 1 mol.

Then, the same measurements as those shown in Example 1 were performed on these porcelains, and the measurement results shown in Table 7 below were obtained.

[0029]

[Table 7]

Here, the reason for limiting the composition in the present invention will be specifically described. In the present invention, BaO—R ₂ O ₃ —Bi ₂ O ₃ is added by adding ZrO _2.
-TiO ₂ or _{BaO-SrO-R 2 O 3} -Ti,
The temperature T _min when the resonance frequency of the dielectric material containing O ₂ as the main component becomes the lowest can be arbitrarily limited, but when the main component is 100 parts by weight, the amount of ZrO ₂ added is 0. If it is less than 01 parts by weight, the effect is not recognized. Further, when the amount of ZrO ₂ added exceeds 1.0 part by weight,
ε _r , Q × f markedly deteriorates and is not suitable. This deterioration of ε _r and Q × f is not a problem at all when the ZrO ₂ addition amount is small, but the addition amount is 0.5
It begins to become more noticeable from around the weight part. Therefore, the added amount of ZrO ₂ is 0.01 part by weight or more,
It is suitable to be 1.0 part by weight or less, more preferably 0.5 part by weight or less.

[0031]

As described above, in the present invention, there is provided a dielectric ceramic composition in which the temperature T _{min at} which the resonance frequency of the dielectric material becomes the lowest can be arbitrarily controlled by adding ZrO _2. can do.

[Brief description of drawings]

FIG. 1 is a triangular diagram showing an example of the composition of a dielectric ceramic composition of the present invention.

Claims (4)

[Claims] 1. Barium oxide (BaO), a rare earth oxide (R ₂ O ₃ ), which contains Nd as an essential component, bismuth oxide (Bi ₂ O ₃ ), and titanium oxide (TiO ₂ ) as main components, and a general formula _{, aBaO-bR 2 O 3 -cBi} 2 O 3 -
Represented by dTiO ₂ , a + b + c + d = 100 mol
%, C = 0.8 to 6.3, and 100 parts by weight of the dielectric porcelain composition in which a, (b + c), and d are in a range formed by connecting the following four points P, Q, R, and S. Section, for which 0.
A dielectric porcelain composition comprising: 01 parts by weight or more and 1.0 parts by weight or less of ZrO ₂ and 85% or more in volume fraction being orthorhombic. ab + c d P 18.0 mol% 15.0 mol% 67.0 mol% Q 18.0 mol% 17.0 mol% 65.0 mol% R 12.6 mol% 19.7 mol% 67.7 mol% S 12.6 mol% 17.7 mol% 69.7 mol% 2. The dielectric ceramic composition according to claim 1, wherein the rare earth oxide (R ₂ O ₃ ) is neodymium oxide (Nd ₂ O ₃ ). 3. The dielectric ceramic composition according to claim 1, wherein the rare earth oxide (R ₂ O ₃ ) is composed of didymium oxide {(Nd + Pr) ₂ O ₃ }. Stuff. 4. The dielectric ceramic composition according to claim 1, wherein the general formula aBaO-b is used.
A part of barium oxide (BaO) in R ₂ O ₃ -cBi ₂ O ₃ -dTiO ₂ is replaced with strontium oxide (Sr
A'BaO-eSrO-bR in the general formula substituted with O)
Represented by _{2 O 3 -cBi 2 O 3 -dTiO} 2, a '+
b + c + d + e = 100 mol%, a = a ′ + e, e
= 0.1 to 3.5 mol%, a dielectric ceramic composition.