JPH0737423A - Dielectric ceramic composition for high-frequency - Google Patents

Abstract

PURPOSE:To provide a dielectric ceramic composition for high-frequency in which a large epsilonr over a wide baking temperature scope, and a large Q-value and a small TCf in the microwave scope can be obtained, and furthermore, the variation scope of the TCf to the unevenness of the baking temperature is small, and the electric characteristics is stable and excellent. CONSTITUTION:The main components are a barium oxide, a titanium oxide, and a neodymium oxide, and when they are converted to BaO, TiO2, and Nd2O3, and shown as the composition formula: xBaO.yTiO2.zNd2O3, x+y+z=100mol%, and 8<=x<=19, 62<=y<=73, and 12<=z<=19. Furthermore, a bismuth oxide, a niobium oxide, and manganese oxide are contained, and when they are converted to Bi2O3, Nb2O5, and MnO, 2.5 to 11.3wt.% of Bi2O3, 0.05 to 1.5wt.% of Nb2O5, and 0.05 to 1.5wt.% of MnO are contained to the main component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency dielectric ceramic composition used as a material for a dielectric resonator mainly used in a microwave region.

[0002]

2. Description of the Related Art As the frequency range of use of dielectric resonators expands, there is a demand for miniaturization of dielectric resonators used in the microwave range. Therefore, various dielectric porcelain compositions have been developed so far, but the properties required for such compositions are high relative permittivity (εr) in order to enable downsizing and dielectric loss. Is high in order to keep low, and the resonance frequency temperature coefficient (TCf) is small in order to keep characteristic fluctuation due to temperature change low.

As a dielectric ceramic composition conventionally proposed for use for such a purpose, for example, B
Materials such as aO—TiO ₂ —Nd ₂ O ₃ —Bi ₂ O ₃ system are known. Further, in JP-A-2-275756 _{discloses, BaO-TiO 2 -Nd 2 O} 3 -Me-B
i ₂ O ₃ (However, Me is Dy ₂ O ₃ or 1 / 3Pr ₄ O
_11), or in JP-A 4-104949 _{discloses, BaO-TiO 2 -Nd 2 O} 3 -Pr 2 O 11/3 -B
Compositions such as i ₂ O ₃ have been disclosed.

However, when a high-frequency dielectric resonator is formed by using these compositions, the TCf characteristics greatly change due to a slight change in the firing temperature during the production of the dielectric ceramic. Furthermore, due to a slight decrease in the firing temperature, ε
r and Q may be greatly reduced. Therefore, it is difficult to obtain a dielectric ceramic with stable electric characteristics,
The defective rate of the product will also increase. Therefore, it is necessary to precisely control the firing temperature in order to obtain a dielectric porcelain having stable electric characteristics by using the conventional composition.

[0005]

The object of the present invention is to obtain a large relative permittivity εr, a large Q in the microwave region, and a small TCf in a wide firing temperature range, and further to a firing temperature change. Another object of the present invention is to provide a dielectric ceramic composition for high frequencies, which has a small change width of TCf and has stable and excellent electric characteristics.

[0006]

These objects are achieved by the present invention described in (1) to (5) below. (1) Contains barium oxide, titanium oxide, and neodymium oxide as main components, and contains barium oxide, titanium oxide, and neodymium oxide as BaO, TiO _2, and Nd ₂ O ₃ , respectively.
To the composition formula xBaO · yTiO ₂ ·
When expressed by zNd ₂ O ₃ , x ≦ y + z = 100 mol%, 8 ≦ x ≦ 19, 62 ≦ y ≦ 73 and 12 ≦
z ≦ 19, and when bismuth oxide, niobium oxide and manganese oxide are converted into Bi ₂ O ₃ , Nb ₂ O ₅ and MnO, respectively, Bi ₂ O ₃ is 2. 5 to 11.3% by weight, Nb ₂ O ₅ is 0.05 to 1.5% by weight, and MnO is 0.05 to 1.
A high-frequency dielectric ceramic composition containing 5% by weight. (2) 9 ≦ x ≦ 18, 65 ≦ y ≦ 73, 14 ≦ z ≦ 19
And Bi ₂ O ₃ is 3.0 to 11.0 wt%, Nb ₂
O ₅ is 0.1 to 1.0% by weight, MnO is 0.1 to 1.0
The high frequency dielectric ceramic composition according to the above (1), which is added by weight%. (3) A part of the neodymium oxide may be substituted with one or more of lanthanum oxide and praseodymium oxide,
Lanthanum oxide and praseodymium oxide were added to La ₂ respectively.
Converted to O ₃ and Pr ₂ O _11/3 , the main component is expressed by the composition formula xBaO · yTiO ₂ · z [(Nd ₂ O ₃ ) _1-mn (L
a ₂ O ₃ ) _m (Pr ₂ O _11/3 ) _n ]
The high frequency dielectric ceramic composition according to the above (1) or (2), wherein ≦ m ≦ 0.13 and 0 ≦ n ≦ 0.13. (4) The high frequency dielectric ceramic composition according to the above (3), wherein 0 ≦ m ≦ 0.1 and 0 ≦ n ≦ 0.1. (5) Dielectric constant εr at 4GHz is 60 or more, 4GHz
At no load in 1000 is 1000 or more, and further -40 to
Resonance frequency temperature coefficient TCf at 80 ℃ is 30ppm /
The dielectric ceramic composition for high frequencies according to any one of the above (1) to (4), which has a temperature equal to or lower than ° C.

[0007]

[Specific Configuration] The specific configuration of the present invention will be described in detail below.

The high frequency dielectric ceramic composition of the present invention contains barium oxide, titanium oxide and neodymium oxide as main components. The barium oxide, titanium oxide and neodymium oxide are converted into BaO, TiO ₂ and Nd ₂ O ₃ , respectively, and the main component is represented by the composition formula xBaO · yTiO ₂ · zN.
When represented by d ₂ O ₃ , x + y + z = 100 mol%, x is 8 ≦ x ≦ 19, and more preferably 9 ≦ x ≦ 1.
8 Further, y is 62 ≦ y ≦ 73, and more preferably 65 ≦ y ≦ 73. Furthermore, z is 12 ≦ z ≦ 1.
9, more preferably 14 ≦ z ≦ 19.

If x is too small, Q will be small. Further, if it is too large, Q becomes small, and if the firing temperature becomes high, TCf becomes large on the + side. When y is too small, the sinterability deteriorates, and both εr and Q become small. Further, if it is too large, both εr and Q become small. If z is too small, Q becomes small, and if too large, εr and Q
Both become smaller.

The high frequency dielectric ceramic composition of the present invention comprises:
Further, bismuth oxide, niobium oxide and manganese oxide are added to the main component. The addition amounts of bismuth oxide, niobium oxide and manganese oxide are Bi ₂
When converted into O ₃ , Nb ₂ O ₅ and MnO, the added amount of Bi ₂ O ₃ is 2.5 to 11.3% by weight, more preferably 3.0 to 11.0% by weight, based on the main component. , Especially 3.0 to 10.0% by weight. The amount of Nb ₂ O ₅ added is 0.05 to 1.5% by weight with respect to the main component,
More preferably, it is 0.1 to 1.0% by weight. further,
The amount of MnO added is 0.05 to 1.
It is 5% by weight, more preferably 0.1 to 1.0% by weight.

If the amount of bismuth oxide added is too small, TC
If f becomes large on the + side, and if it is too large, Q becomes small. When the amount of niobium oxide added is too small, TCf changes greatly depending on the firing temperature, and when the firing temperature is low, both εr and Q decrease. If too much, εr
Becomes smaller. If the amount of manganese oxide added is too small, the sinterability deteriorates and εr and Q decrease. If too much, both εr and Q become small, and
Cf increases toward the + side.

In the high frequency dielectric ceramic composition of the present invention, part of the neodymium oxide may be replaced with one or two of lanthanum oxide and praseodymium oxide.

When neodymium oxide is substituted by these, lanthanum oxide and praseodymium oxide are converted into La ₂ O ₃ and Pr ₂ O _11/3 , respectively, and the main component is represented by the composition formula xBaO.yTiO ₂ .z [( Nd ₂ O ₃ )
_1-mn (La ₂ O ₃ ) _m (Pr ₂ O _11/3 ) _n ], m + n> 0, 0 ≦ m ≦ 0.13, preferably 0
≦ m ≦ 0.1, 0 ≦ n ≦ 0.13, preferably 0 ≦ n ≦
0.1, and usually m + n is 0.01 or more.

When the substitution amount of lanthanum oxide in which a part of neodymium oxide is substituted is too large, both εr and Q become small and TCf becomes large on the + side. Further, even if the substitution amount of praseodymium oxide, which is a part of neodymium oxide, is too large, TCf increases to the + side.

Further, in addition to these composition components, silicon oxide, aluminum oxide, etc. due to components derived from raw materials or materials in the manufacturing process are 0.1% by weight of the total composition.
It may be included below the degree.

With such a composition, the high frequency dielectric ceramic composition of the present invention has a firing temperature of 125 at the time of manufacture.
Relative permittivity εr at 4 GHz is 60 or more at about 0 ℃,
Especially, 63 to 73, and Q at no load at 4 GHz is 1000 or more, especially 1000 to 1480, and further -40.
Resonance frequency temperature coefficient TCf at ~ 80 ℃ is 30ppm /
It has excellent electrical characteristics below ℃, especially +4 to +28 ppm / ℃. Further, the change width of TCf is 1220 at the firing temperature.
〜1380 ℃, especially 5pp in the range of 1250-1350 ℃
Within m / ° C, TCf has excellent stability against variations in firing temperature.

The high frequency dielectric porcelain composition of the present invention is usually obtained by subjecting such a composition to treatments such as mixing, calcination, pulverization, kneading, molding and firing. Etc. are not particularly limited, and the conditions and the like may be appropriately selected from known conditions.

The raw materials to be used are not particularly limited, but it is usually preferable to mix and use raw material powders containing the metal component elements forming the above oxides. At this time, the raw material powder is an oxide or an oxide which is formed by subsequent firing. That is, it may be selected from, for example, oxides, carbonates, hydroxides, etc., which usually contain the elements constituting the above oxides.

The raw material powders used have an average particle size of preferably 5 μm or less, more preferably 0.5 to 3.0 μm.
Is.

[0020] Such raw material powders are weighed and mixed so that the final composition is the above composition, but there is no particular limitation on the mixing method or time, and the method and time for sufficiently dispersing the components can be selected. It doesn't matter. When the mixing is performed by a wet method, water, lower alcohols or the like may be used as a solvent alone or in combination of two or more kinds.

The mixture thus obtained may be dehydrated and dried by an appropriate method, and then usually calcined. The calcination is usually performed in air at a temperature of about 1000 to 1200 ° C. for 2 to
Do about 4 hours. Further, the calcined product obtained by calcination is coarsely pulverized by an appropriate method, and then the average particle size is 0.5 to
The particles may be pulverized to about 3.0 μm, and when wet pulverization is performed at this time, one or more of the solvents used in the wet mixing may be mixed and used.

Usually, 2.0 to 5.0 parts by weight of a binder is added to the pulverized powder with respect to 100 parts by weight of the powder, and the mixture is mixed and then pressure-molded. As the binder, polyvinyl alcohol or the like is usually used. The pressure molding may be carried out, for example, by filling a mold of an appropriate size with the powder mixed with a binder and the like, and at a molding pressure of about ² to 5 t / cm ² .

The firing is carried out at a temperature rise rate of about 50 to 300 ° C./h and a temperature fall rate of about 50 to 300 ° C./h, at 1250 to 1250.
It may be performed at about 1350 ° C. for about 1 to 5 hours in an oxygen atmosphere such as the air.

The thus obtained fired body, BaNd ₂ Ti ₅ O ₁₄ phase as a main phase, also, Ba ₂ as subphase
It has Ti ₉ O ₂₀ . Such a phase is an X-ray diffraction (XR
It can be confirmed by D).

The fired body thus obtained usually has a main phase having a grain size of about 1 to 3 μm, a secondary phase having a grain size of about 3 to 10 μm, and a boundary phase of about 1 μm or less.

Such a high frequency dielectric ceramic composition of the present invention is usually preferably used in a frequency band of about 800 MHz to 3 GHz. Examples of typical applications include materials for resonance elements such as car telephone duplexers and bandpass filter voltage controlled oscillators represented by interstage filters. Furthermore, it can also be used as a microwave integrated circuit board and a capacitor material for high frequency power.

[0027]

EXAMPLES The present invention will be described in more detail below by showing specific examples of the present invention.

Example 1 As starting materials, BaCO ₃ , TiO ₂ , Nd ₂ O ₃ ,
Using powders of Bi ₂ O ₃ , Nb ₂ O ₅ and MnO, each component powder was weighed so that the final composition after sintering would be the composition of each sample number shown in Table 1 and Table 2, and in a ball mill, Water was used as a solvent for 20 hours of wet mixing, followed by dehydration and drying to obtain a mixture.

This mixture was calcined at 1000 to 1200 ° C. for 2 hours, the obtained calcined product was roughly pulverized, and then wet pulverized in a ball mill together with zirconia balls using water as a solvent.

Polyvinyl alcohol was added as a binder to the obtained pulverized product, and the mixture was mixed and granulated to give a diameter of 12.7 mm,
After pressure molding into a cylinder with a height of 7 mm, 1250 ° C, 1
It was fired at each temperature of 300 ° C. and 1350 ° C. for 2 hours to obtain a dielectric ceramic.

The obtained dielectric porcelain has a diameter of 10 mm and a height of 5
processed into mm and sample numbers 1 to 13 and 21 to 3 respectively
4, each of the cylindrical dielectric ceramic samples was sandwiched between two parallel metal plates to form a resonator, and various characteristics were measured by the following methods. The obtained results are summarized in Tables 1 and 2. In addition, in Table 1 and Table 2, the composition of the additive component is shown by weight% with respect to the main component.

[0032]

[Table 1]

[0033]

[Table 2]

<Method of Measuring Dielectric Properties> The relative permittivity εr and Q were measured by the dielectric resonator method (Hakki and Coleman's method) to measure the TE ₀₁ δ mode resonance at about 4 GHz with a network analyzer. The measuring temperature is 25 ± 10 ° C., the measuring humidity is 25 to 85% RH, and the measuring instrument is a network analyzer made by Hewlett-Packard: HP8510B.
It was used.

<Resonance Frequency Temperature Coefficient TCf Measuring Method> The change of the resonance frequency fr at the measuring temperature of -40 to 80 ° C. was measured by the dielectric resonator method (Hakki and Coleman's method), and TCf was calculated by the equation (1). .

[0036]

[Equation 1]

Example 2 As starting materials, BaCO ₃ , TiO ₂ , Nd ₂ O ₃ ,
La ₂ O ₃ , Pr ₂ O _11/3 , Bi ₂ O ₃ , Nb ₂ O ₅ ,
Using MnO powder, each component powder was weighed so that the final composition after sintering would be the composition of each sample number shown in Table 3, and otherwise the same as in Example 1 to treat sample numbers 41 to 50. Obtained.
However, the additive amount of the additive component is Bi ₂ O ₃ , Nb ₂ O ₅
And 7.5% by weight in terms of MnO and 0.2, respectively.
% And 0.1% by weight. Various properties of each of the obtained samples were measured in the same manner as in Example 1. The results obtained are summarized in Table 3. In Table 3, the composition of the substituting component is shown by the molar ratio of the substituting amount with respect to Nd ₂ O ₃ .

[0038]

[Table 3]

[0039]

As is clear from the measurement results of the electrical characteristics shown in Tables 1, 2 and 3, the high frequency dielectric ceramic composition of the present invention has a large εr and a relatively small TCf, and therefore has a conventional value. It is possible to meet the demand for frequency temperature stability which is more severe than that of the dielectric ceramic composition. Furthermore, Nb
_{Since the} stable firing temperature range was expanded by the addition of ₂ O ₅ , it became easy to control the firing temperature during manufacturing, and the precise temperature control equipment of the firing furnace became unnecessary. Further, by changing the addition amount of Bi ₂ O ₃ , it became possible to control the TCf value to 30 ppm / ° C. or less. Further, the addition of MnO improved the sinterability, and the reduction of the Q value due to the addition of Nb ₂ O ₅ could be prevented. That is, a high frequency dielectric ceramic composition having excellent electrical characteristics can be stably manufactured.

Claims (5)

[Claims] 1. Barium oxide, titanium oxide and neodymium oxide are contained as main components, and barium oxide, titanium oxide and neodymium oxide are contained in BaO, TiO ₂ and N, respectively.
Converted to d ₂ O ₃ , the main component is expressed by the composition formula xBaO · yT
When expressed as iO ₂ · zNd ₂ O ₃ , x + y + z = 1
00 mol%, 8 ≦ x ≦ 19, 62 ≦ y ≦ 73 and 12 ≦ z ≦ 19. Further, bismuth oxide, niobium oxide and manganese oxide are converted into Bi ₂ O ₃ , Nb ₂ O ₅ and MnO, respectively. when, Bi ₂ O ₃ is 2.5 to 11.3 wt% with respect to the main component of the composition formula, Nb ₂ O ₅ is 0.05.
A dielectric ceramic composition for high frequencies, containing 5% by weight and 0.05 to 1.5% by weight of MnO. 2. 9 ≦ x ≦ 18, 65 ≦ y ≦ 73, 14 ≦
z ≦ 19, Bi ₂ O ₃ is 3.0 to 11.0% by weight, Nb ₂ O ₅ is 0.1 to 1.0% by weight, and MnO is 0.
The high frequency dielectric ceramic composition according to claim 1, wherein the dielectric ceramic composition is added in an amount of 1 to 1.0% by weight. 3. A part of the neodymium oxide may be substituted with one or more kinds of lanthanum oxide and praseodymium oxide, and the lanthanum oxide and praseodymium oxide are converted into La ₂ O ₃ and Pr ₂ O _11/3 , respectively. The composition of the main component is xBaO · yTiO ₂ · z [(Nd ₂ O ₃ ).
_1-mn (La ₂ O ₃ ) _m (Pr ₂ O _11/3 ) _n ], 0 ≦ m ≦ 0.13 and 0 ≦ n ≦ 0.13. Dielectric porcelain composition. 4. The high frequency dielectric ceramic composition according to claim 3, wherein 0 ≦ m ≦ 0.1 and 0 ≦ n ≦ 0.1. 5. The relative permittivity εr at 4 GHz is 60 or more, the unloaded Q at 4 GHz is 1000 or more, and the resonance frequency temperature coefficient TCf at −40 to 80 ° C. is 30 ppm / ° C. or less. 2. A high-frequency dielectric ceramic composition according to any one of 1.