JP2003335576A - Dielectric ceramic composition, dielectric, and wave absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dielectric ceramic composition, a dielectric, and a wave absorber having a large dielectric tangent (tanδ), and an excellent wave absorbing effect. <P>SOLUTION: The dielectric ceramic composition, which does not contain Zr, but contains Ca, Ti, a Group 5A element, and Si, wherein Ca content is 22.0 to 57.0 mol percent, Ti content is 6.0 to 40.0 mol percent, the content of the Group 5A element (for example, Nb) is 0.2 to 16 mol percent, and Si content is 21.0 to 59.0 mol percent when total content of respective elements is 100 mol percent in conversion into oxides, and contains titanate solid solution. The dielectric is formed by mixing the composition and the other materials and then molding the mixture. Alternatively, it is formed by combining a compact comprising the composition with other materials. The wave absorber contains the composition. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a dielectric ceramic composition and a dielectric, and a radio wave absorber. For more details,
The present invention relates to a dielectric ceramic composition having a large dielectric loss tangent (tan δ) and an excellent radio wave absorption effect, a dielectric, and a radio wave absorber. INDUSTRIAL APPLICABILITY The dielectric ceramic composition, the dielectric and the radio wave absorber of the present invention can be widely used in various fields where radio wave absorption is required. For example, inside and outside walls of buildings, bridges,
It is used in tunnel ceilings, structures such as inner walls of space stations, peripheral parts of radar equipment, and inside and outside electronic equipment housings.

[0002]

2. Description of the Related Art Heretofore, as a radio wave absorbing material, a dielectric loss material or the like which absorbs a radio wave by a dielectric loss due to an interaction between a radio wave and an electric dipole moment of the material has been known. As such a dielectric loss material, for example, a ceramic dielectric material having titanite (CaTiSiO ₅ ) as a main crystal and having a large dielectric loss tangent in the millimeter wave frequency band is disclosed (Japanese Patent Laid-Open No. 2002-20168).
Issue). When using a dielectric loss material based on such a dielectric loss (hereinafter also referred to as a radio wave absorbing material) to make a radio wave absorber such as the inside and outside walls of a building, the complex permittivity obtained by solving Maxwell's electromagnetic field equation The “non-reflection curve” (see FIG. 1), which shows the correspondence between the real part and the imaginary part, serves as a design guide. Therefore, if a radio wave absorber is manufactured using a dielectric loss material having a complex dielectric constant on the line of the non-reflection curve and further above the non-reflection curve, a radio wave absorber having an excellent radio wave absorption effect can be obtained. Can be said.

[0003]

However, even though the conventional dielectric loss material has a large dielectric loss tangent,
Since the complex permittivity is such that it is located below the non-reflection curve, sufficient electromagnetic wave absorption effect was not obtained. Also, when a conventional dielectric loss material is mixed with a resin material or a glass plate to form a composite wave absorber in the form of paint, film, sheet, etc., which has a wide range of applications, the resin material is generally a dielectric material. Since the tangent was small, the complex permittivity of the prepared electromagnetic wave absorber was far away from the non-reflection curve, and a sufficient electromagnetic wave absorption effect was not obtained. The present invention is to solve the above problems, and an object thereof is to provide a dielectric ceramic composition, a dielectric, and a radio wave absorber having a large dielectric loss tangent (tan δ) and an excellent radio wave absorption effect. To do.

[0004]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made diligent studies in order to further improve the dielectric properties of titanite having a large dielectric loss tangent.
It has been found that the dielectric loss tangent can be further increased by substituting for the present invention, and the present invention has been completed.

The dielectric ceramic composition of the present invention comprises Ca, T
i, Group 5A element and Si, Zr-free, acid
In terms of a compound, the Ca, the Ti, the 5A group element and the Si
When the total content of each of the above is 100 mol%, the Ca
Content of 22.0-57.0 mol%, content of the Ti
Is 6.0 to 40.0 mol%, and the content of the 5A group element is
0.2-16.0 mol%, the Si content is 21.0-
59.0 mol% and contains a solid solution of titanite
It is characterized by Other dielectric ceramic composition of the present invention,
Contains Ca, Ti, 5A group elements, Si and Zr, and oxidizes
The Ca, Ti, 5A group element, Si and
When the total content of each Zr is 100 mol%,
The content of Ca is 22.0 to 57.0 mol% and the content of Ti is
The content is 6.0 to 40.0 mol%, the content of the 5A group element
The amount is 0.2 to 16.0 mol%, and the Si content is 21.
0-59.0 mol%, the Zr content is 10.0 mol%
And is characterized by including a solid solution of titanite
And Here, the “5A group element” means V, Nb and
And Ta means three kinds of elements. In addition, this dielectric porcelain
The elements contained in the composition are usually solid solutions of titanite.
Contained as complex oxides such as
It In addition, oxidation of each element when "as oxide"
The items are "CaO" and "TiO", respectively._Two, "M
_TwoO ₅(M is a Group 5A element), “SiO_Two",
"ZrO_Two". Further, the group 5A element is Nb.
It can be a dielectric ceramic composition. Dielectric of the present invention
The body is a mixture of the above-mentioned dielectric ceramic composition and other materials.
And then molded. Other books
The dielectric material of the invention is a molded article made of the above dielectric ceramic composition.
Is characterized by being combined with other materials.
A radio wave absorber of the present invention contains the above dielectric ceramic composition.
It is characterized by

[0006]

The dielectric ceramic composition of the present invention has a large dielectric loss tangent (tan δ) and an excellent electromagnetic wave absorption effect. The other dielectric ceramic composition of the present invention has a large dielectric loss tangent and an excellent electromagnetic wave absorption effect. Furthermore, Z
Since r is contained, the dielectric constant is large, and the degree of freedom in designing the thickness and the like can be widened. Further, when the group 5A element is Nb, it has a large dielectric loss tangent,
It is possible to obtain a dielectric ceramic composition having a more excellent electromagnetic wave absorption effect. Since the dielectric of the present invention and other dielectrics of the present invention are formed by using the above-mentioned dielectric ceramic composition having excellent performance, mixing with a resin material or the like having a small dielectric loss tangent,
Or, it has an excellent electromagnetic wave absorption effect even when combined with other materials. Since the radio wave absorber of the present invention contains a dielectric ceramic composition having a large dielectric loss tangent, it has an excellent radio wave absorption effect.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. (1) In the dielectric porcelain composition of the present invention which does not contain Zr as an essential component, Ca, Ti, a 5A group element, and the dielectric porcelain composition of the present invention which contains Si as an essential component, the content of “Ca” is , Oxide, Ca, Ti, 5A group element and Si
When the total content of each of the above is 100 mol%, 22.
0-57.0 mol%, preferably 27.0-4
The content is 8.0 mol%, more preferably 30.0 to 38.0 mol%. If this content is less than 22.0 mol%, the amount of the titanite solid solution produced decreases, and the dielectric loss tangent decreases. On the other hand, when the content exceeds 57.0 mol%, the production amount of the titanite solid solution decreases, the dielectric loss tangent decreases, the amount liberated as CaO increases, and the dielectric constant of the dielectric ceramic composition decreases. Will end up.

The content of "Ti" is calculated as oxide.
6.0-40.0 mol%, preferably 10.0-37.
It is 0 mol%, and more preferably 18.0 to 33.0 mol%. If this content is less than 6.0 mol%, the amount of the titanite solid solution produced decreases, and the dielectric loss tangent decreases. On the other hand, if the content exceeds 40.0 mol%, the amount of the titanite solid solution produced decreases, the amount liberated as TiO ₂ increases, and the dielectric constant of the dielectric ceramic composition increases, but the electrostatic tangent Will be significantly reduced.

This dielectric ceramic composition contains at least one of the above "Group 5A elements". This makes it possible to obtain a dielectric ceramic composition having a large dielectric loss tangent and an excellent electromagnetic wave absorption effect. Among them, when the group 5A element is Nb, it is preferable because the dielectric ceramic composition has a larger dielectric loss tangent and a more excellent electromagnetic wave absorption effect. The content of the 5A group element is 0.2 to 16.0 mol% in terms of oxide, preferably 0.8 to 14.0 mol%, more preferably 1.5 to 12.0 mol%. Is. This content is 0.
If it is less than 2 mol%, a sufficient increase in dielectric loss tangent cannot be expected. On the other hand, when the content exceeds 16.0 mol%, M
_The amount released as ₂ O ₅ increases, and the dielectric constant of the dielectric ceramic composition decreases.

The content of the above "Si" is, in terms of oxide,
21.0 to 59.0 mol%, preferably 30.0 to 5
0.0 mol%, more preferably 33.0 to 44.
It is 0 mol%. If this content is less than 21.0 mol%, the amount of the titanite solid solution produced decreases, and the dielectric loss tangent of the dielectric ceramic composition is lowered. On the other hand, when the content exceeds 59.0 mol%, the production amount of the titanite solid solution decreases, the dielectric loss tangent decreases, and the amount liberated as SiO ₂ increases, and the dielectric constant of the dielectric ceramic composition decreases. Resulting in.

(2) Another dielectric ceramic composition of the present invention containing Zr as an essential component In another dielectric ceramic composition of the present invention containing Ca, Ti, 5A group elements, Si and Zr as essential components, , Above "Z
By including "r", the dielectric constant of the dielectric ceramic composition can be increased, and when the electromagnetic wave absorber is used, the degree of freedom in designing the thickness and the like can be provided. The content of Zr is 1 when the total content of Ca, Ti, 5A group elements, Si and Zr is 100 mol% in terms of oxide.
0.0 mol% or less, preferably 7.0 to 0.01
Mol%, and more preferably 3.0 to 0.01 mol%. If this content exceeds 10.0 mol%, ZrO ₂
As a result, the amount liberated as is increased, and the dielectric constant of the dielectric ceramic composition decreases.

The Ca content is 22.0 in terms of oxide.
˜57.0 mol%, preferably 27.0 to 48.
It is 0 mol%, more preferably 30.0 to 38.0 mol%. The content of Ti is 6.0 to 40.
It is 0 mol%, preferably 10.0 to 37.0 mol%, and more preferably 18.0 to 33.0 mol%.
In addition, this dielectric ceramic composition contains at least one of Group 5A elements. This makes it possible to obtain a dielectric ceramic composition having a large dielectric loss tangent and an excellent electromagnetic wave absorption effect. Among them, when the group 5A element is Nb, it is preferable because the dielectric ceramic composition has a larger dielectric loss tangent and a more excellent electromagnetic wave absorption effect. The content of the Group 5A element is 0.2 to 16.0 mol% in terms of oxide, preferably 0.8 to 14.0 mol%, more preferably 1.5 to 1
It is 2.0 mol%. The content of Si, in terms of oxide,
21.0 to 59.0 mol%, preferably 30.0
˜50.0 mol%, more preferably 33.0 to 44.0.
Mol%. For the reason for limiting the contents of Ca, Ti, 5A group elements and Si, the above description of the present invention in which Zr is not an essential component can be applied as it is.

[0013] In (3) Taitanaito solid solution dielectric ceramic composition of the present invention, the "Taitanaito solid solution" is stoichiometric composition, i.e., the portion of an element in Group 5A of Ti contained in Taitanaito represented by CaTiSiO ₅ It has been replaced. Particularly, the proportion of the titanite solid solution is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably, when the total amount of the titanite solid solution and the oxides of the respective elements is 100% by mass. 80 mass% or more, particularly preferably 9
It is 0 mass% or more. The presence of the titanite solid solution can be confirmed by an X-ray diffraction method or the like. Furthermore,
The composition of the dielectric porcelain composition can be obtained by measuring the content of each element by a chemical analysis method, a fluorescent X-ray method, or the like, and based on this content, the molar ratio of each element as an oxide. The composition of the dielectric ceramic composition can also be determined from the raw material composition used.

(4) Components other than the solid solution of titanite In the dielectric ceramic composition of the present invention, each element (Ca, Ca, etc.) other than the solid solution of titanite is contained as long as desired dielectric properties (dielectric constant, dielectric loss tangent) are not impaired. Ti, 5A group element, Si
And a complex oxide other than the Zr) oxide and the titanite solid solution. Further, nitrides and composite nitrides of each of the above elements, further, oxides other than the above elements,
Ceramic components such as nitrides, composite oxides and composite nitrides may be contained. In addition, these components may be contained in only 1 type and may be contained in 2 or more types.

(5) Dielectric Properties of Dielectric Ceramic Composition In the dielectric ceramic composition of the present invention, the average value of the dielectric loss tangent (tan δ) measured by the free space method is 0.27 in the frequency band of 55 to 110 GHz. Above, in particular, 0.28 or more, and more preferably 0.30 or more. Also,
It may be 0.33 or more (usually 0.40 or less). The average value of the dielectric constant measured by the same method can be 18 or more, particularly 19 or more, and further 20 or more (usually 30 or less). Furthermore, by containing Zr, the average value of this dielectric constant is
It can be set to 25 or more, particularly 30 or more (usually 40 or less), and can have a wide range of design freedom such as thickness when used as a radio wave absorber.

Further, when the content of the 5A group element in the dielectric ceramic composition is, in terms of oxide, the total content of Ca, Ti, 5A group elements, Si and Zr, is 100 mol%, By setting the content to 0.5 mol% or more, the dielectric ceramic composition can have an average dielectric loss tangent value of 0.27 or more and an average dielectric constant value of 18 or more. In particular, by setting the content of the 5A group element to be 5.0 mol% or more, a dielectric ceramic composition having an average dielectric loss tangent value of 0.32 or more and an average dielectric constant value of 18 or more can be obtained. Further, by setting the content of the 5A group element to be 9.0 mol% or more, a dielectric ceramic composition having an average dielectric loss tangent value of 0.34 or more and an average dielectric constant value of 18 or more can be obtained. . The free space method is described in Osamu Hashimoto, "Introduction to Wave Absorbers," [Morikita Publishing Co., Ltd. (199
7)], and more specifically, a plane wave or a focused beam is incident on a plate-shaped test piece to determine its reflection / transmission characteristics, thereby obtaining a high frequency band (300 MHz-
It is possible to measure the dielectric loss tangent at 300 GHz, the dielectric constant, the radio wave absorption characteristics, and the like. The dielectric loss tangent of the dielectric material in the low frequency band (1 kHz to 1 MHz) can also be measured by various known methods such as an impedance analyzer, an LCR meter, and a cavity resonator method (perturbation method).

(6) Manufacture of Dielectric Ceramic Composition The method for manufacturing the dielectric ceramic composition of the present invention is not particularly limited, and the dielectric ceramic composition can be manufactured in the same manner as a known ceramic manufacturing method. Further, various manufacturing methods can be selected depending on the form of the dielectric ceramic composition. In order to obtain a powdery dielectric ceramic composition, a dropping melting decomposition method, an atomizing method, or the like can be adopted. A press molding method, an extrusion molding method, a casting molding method, or the like can be adopted to obtain the dielectric ceramic composition of the molded body. Further, in order to obtain a dielectric ceramic composition in the form of a thin film, a sputtering method, a thermal spraying method or the like can be adopted.

(7) Dielectric Material and Production Thereof The dielectric material of the present invention is obtained by mixing the dielectric ceramic composition with another material, and then molding the mixture. Examples of the form of the dielectric ceramic composition at this time include powder, granules, fibers and the like. The "other material" is not particularly limited, but examples thereof include ceramics such as titania, alumina, silica and silicon carbide, carbon, elastomers and resins. These can be used in the form of powder, particles, fibers and the like.
Further, it may be a suspension, a paste or the like composed of the material in each of these forms and a dispersion medium. Mixing means of the dielectric porcelain composition and other materials, and the molding means after mixing are not particularly limited, a general method can be used, and depending on the type of other materials, etc. You can choose.

Another dielectric of the present invention is a composite of a molded body made of the dielectric ceramic composition and another material. The molded body made of the dielectric ceramic composition at this time is not particularly limited, and examples thereof include a plate-shaped body and a film-shaped body. The molded body does not need to be composed of the dielectric ceramic composition alone, and may contain the other materials and the like as long as the dielectric properties of the dielectric ceramic composition are not impaired. Examples of the "other materials" include metal plates, plate glass, resin plates, wood, cement plates and woven cloth. Further, a surface layer of glaze, wax or the like may be formed on the surface of these. The means for forming the composite is not particularly limited and may be attached with an adhesive,
A general method such as baking by firing or spraying by thermal spraying can be used, and can be appropriately selected according to the type of other materials.

Since the dielectric porcelain composition of the present invention and the dielectric using the same are electrical insulators, there is no risk of electric leakage or electric shock, there is little restriction on the place of use, and the field of application is wide. For example, it can be used as a radio wave absorber.
Such a radio wave absorber is particularly suitable for the millimeter wave band (30 to 3).
(00 GHz) radio wave absorber. The radio wave absorber is specifically used as a radio wave blocking material. The radio wave blocking material can be used for preventing leakage of radio waves from an electric device or as a blocking material for blocking intrusion of radio waves from the outside. In particular, it can be used as a material for preventing electromagnetic waves from entering from the outside, such as a structure such as a building, a structure for aviation and space, a casing of precision electronic equipment, and the like. Further, a reflection layer can be provided on the radio wave absorber. In this case, the radio wave absorption can be further enhanced,
It is suitable for applications where radio waves need to be completely absorbed.
The reflective layer may be any material as long as it can sufficiently reflect radio waves, and its material, shape, thickness, etc. are not particularly limited. As the reflection layer, a metal plate such as an aluminum plate, a stainless steel plate, a copper plate, or a metal foil such as an aluminum foil, a stainless steel foil, a copper foil, or a gold foil can be used. Further, a resin plate or resin sheet containing metal powder, a resin plate or resin sheet having metal deposited on its surface, or the like can also be used.

[0021]

EXAMPLES The present invention will be described in more detail below with reference to examples.
To do. (1) Dielectric ceramic composition Manufacture of dielectric ceramic composition As raw material powder, CaCO_Three(Special grade reagent), TiO
_Two(Special grade reagent), Nb_TwoO ₅(Special grade reagent), SiO
_Two(Purity 99.8%), ZrO_Two(Reagent special grade)
Each of the contained in the dielectric ceramic composition obtained by using the powder
Raw materials so that the values shown in Table 1 in terms of oxide conversion of elements are obtained.
Was compounded. ZrO_TwoThe powder was distributed only to Experimental Example 15.
It matched. Further, only in Experimental Example 16, Nb_TwoO₅Mix powder
I didn't. Then, these raw material powders (100 g)
And pure water (180 ml) with zirconia sphere (diameter 10
mm, 1000 g) and 40 r by ball mill
Mix for 24 hours at a speed of pm. Then freeze-dry,
It was calcined at 1100 ° C. for 3 hours to obtain a calcined powder. Next
Then, the obtained calcined powder and pure water (160 ml) were added to the above.
40 rpm by ball mill using zirconia ball stone
And mixed for 48 hours. After that, poly vinyl as a binder
1% by weight of alcohol is added and mixed to dissolve
Then, a slurry was prepared. Then the resulting slurry
Was lyophilized and granulated through a 60 mesh screen
After that, the uniaxial molding method of 25 MPa and the cold static of 250 MPa
Molded by hydraulic press (CIP) method
mm × width 75 mm × thickness 5 mm) was obtained. Then got
The formed body was fired at each firing temperature shown in Table 1 to obtain a sintered body.
Was obtained, and this sintered body was ground, and the length was 55 mm and the width was 55 m.
m × 2.3 mm thick test piece made of dielectric ceramic composition
(Experimental Examples 1 to 16) were obtained.

Confirmation of Composition of Dielectric Porcelain Composition The composition of each obtained porcelain composition was confirmed by an X-ray diffraction method (X-ray diffractometer; manufactured by Rigaku Denki Kogyo KK, model "RU-200T"). As a result, it was confirmed that each porcelain composition contained a titanite solid solution. Also,
FIG. 2 shows an explanatory diagram of the X-ray diffraction chart of Experimental Example 5. In addition, "+" in FIG. 2 shows the diffraction peak of the titanite solid solution.

Dielectric Property Test In each of the obtained test pieces of Experimental Examples 1 to 16, the dielectric constant, dielectric loss tangent (tan δ), and porcelain density (g / c)
m ³ ) was measured by the following method, and these results are shown in Table 1.
Also described in. In addition, "*" in the composition column in Table 1 indicates that it is outside the scope of the invention. (Measurement of dielectric constant and dielectric loss tangent) The dielectric constant and dielectric loss tangent are
It was measured by the free space method and shown as an average value of 55 to 110 GHz. (Measurement of Porcelain Density) Porcelain density was calculated from volume and mass.

Further, as shown in FIG. 3, Experimental Examples 1 to 16
The complex permittivity of each of the dielectric ceramic compositions of (1) was plotted, the positional relationship (upper or lower) with respect to the non-reflection curve was investigated, and the results are also shown in Table 1. The numbers in FIG. 3 correspond to the numbers in the experimental example. Here, the non-reflection curve is a curve showing the correspondence between the real part and the imaginary part of the complex permittivity obtained by solving Maxwell's electromagnetic field equation, and a material having a complex permittivity on this curve is , Has a sufficiently effective electromagnetic wave absorption effect.

[0025]

[Table 1]

Effects of Examples According to Table 1, in Experimental Example 16 containing no Nb, the permittivity was 22 and the dielectric loss tangent was 0.09, which were both small, and the positional relationship with the non-reflection curve was also low. Met. Also,
Experimental Example 6 in which the content of Ti is too small as 4.07 mol%,
Experimental example 10 in which the content of Ca is excessively low at 13.39 mol% and the content of Si is excessively high at 73.63 mol% C
In Experimental Example 11 in which the content of a was 63.81 mol% and the content of Ti was 5.26 mol%, the dielectric constant was 12 to 16 and the dielectric loss tangent was 0.18 to 0. .2
6 and both were small, and the positional relationship with the non-reflection curve was all downward. Furthermore, Experimental Example 9 in which the Nb content is excessively 18.37 mol%, and the Si content is 19.72 mol%
And Experimental Example 12 in which the content of Ca is too small as 21.55 mol% and Experimental Example 13 in which the content of Ti is too large as 51.73 mol% and the content of Nb is 0.13 mol. %
In Experimental Example 14, which is too small, the dielectric constant is 19 to 2
Although there was no problem with 5, the dielectric loss tangent was 0.13 to 0.26.
And the positional relationship with the non-reflection curve was all downward.

On the other hand, Ca, Ti, Nb and Si
In Experimental Examples 1 to 5 and Experimental Examples 7 and 8 in which the content of is within the scope of the invention, the dielectric constant is 19 to 23, and the dielectric loss tangent is 0.28 to 0.36, both of which are sufficiently large, The positional relationship with the non-reflection curve was also upward. Further, in Experimental Example 15 containing Zr, the dielectric constant was as large as 33, the dielectric loss tangent was sufficiently large as 0.30, and the positional relationship with the antireflection curve was also high. Therefore, these dielectric porcelain compositions have excellent dielectric properties, and even when mixed or compounded with another material having a small dielectric loss tangent, a sufficient radio wave absorption effect can be obtained.

(2) Dielectric (Mixed Sheet) Using the same raw material powder as that used in the preparation of the mixed sheet (1), the content of each element contained in the obtained dielectric ceramic composition was oxidized. The raw materials were blended so as to have a composition similar to that of Experimental Example 2 shown in Table 1. Then, these raw material powders (12
0 g) and pure water (180 ml) were mixed with zirconia ball stone (diameter 10 mm, 1000 g) by a ball mill at 40 rpm for 24 hours. Then, the freeze-dried product was put into a high alumina porcelain crucible and calcined at 1185 ° C. for 3 hours to obtain a calcined powder. Next, the obtained calcined powder and pure water (160 ml) were mixed with the zirconia spheres by a ball mill at 40 rpm for 48 hours. Then, it was freeze-dried and powdered. Then, the obtained powder (94.6 g), polyvinyl butyral resin (6.4 g), ethanol (30 ml), and methyl ethyl ketone (53 ml) were mixed with zirconia spheres (diameter: 10).
mm, 500 g) and 40 rp by a ball mill
mixed for 24 hours. After that, a sheet was prepared by a doctor blade method and dried to obtain a mixed sheet having a thickness of 1.9 mm.

Dielectric Properties of Mixed Sheet The obtained mixed sheet was cut into a size of 70 mm × 70 mm, and the dielectric properties were measured by the free space method as described above. As a result, the dielectric constant is 20 and the dielectric loss tangent is 0.285.
The positional relationship with the non-reflection curve shown in FIG. 1 was linear. Then, again, similarly, a sheet with a thickness of 0.24 mm was created by the doctor blade method, and a metal plate (metal type; aluminum, thickness; 0.5 mm) was cut behind the mixed sheet cut into a size of 70 mm × 70 mm. ),
Radio wave absorption characteristics were measured by the free space method. As a result, return loss occurs at a frequency of 70 GHz, and the return loss is 32 dB.
And a practical level (25 to 30 dB) could be satisfied. From the above, it was found that even a dielectric obtained by compounding a dielectric ceramic composition in the form of a powder with a resin having a low radio wave absorption effect can have excellent dielectric properties. . Furthermore, it was found that a dielectric having excellent electromagnetic wave absorption characteristics can be obtained by using it.

(3) Dielectric (Composite Plate) Preparation of Composite Plate The test piece obtained in Experimental Example 4 was ground to a thickness of 2.0 mm, and then put on a commercially available plate glass (50 to 110 GH).
In z, a dielectric constant: 5.8, dielectric loss tangent: 0.03) ground to a thickness of 0.8 mm was placed, and the temperature was 500 ° C.
The plate glass was baked on the dielectric ceramic composition by heating in an electric furnace for 30 minutes to prepare a composite plate. Dielectric properties of composite plate Metal plate (type of metal; copper,
The thickness; 1 mm) was applied, and the electromagnetic wave absorption characteristics were measured by the free space method. As a result, return loss occurred at a frequency of 82 GHz, and the return loss amount was 33 dB, which was a practical level. From the above, it is possible to obtain an excellent dielectric property even in the case of a dielectric obtained by combining the dielectric ceramic composition in the form of a plate with a plate glass having a low radio wave absorption effect. I understood. Furthermore, it was found that a dielectric having excellent electromagnetic wave absorption characteristics can be obtained by using it.

The present invention is not limited to the specific examples described above, but various modifications may be made within the scope of the present invention according to the purpose and application. For example, the dielectric ceramic composition of the present invention can also be used as a dielectric component such as a heating element. Examples of the heating element include high-frequency (especially millimeter wave) heating elements for various heating devices.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a non-reflection curve.

FIG. 2 is an explanatory diagram with a chart showing an X-ray diffraction result of Experimental Example 5.

FIG. 3 is an explanatory diagram in which the complex permittivity of each dielectric ceramic composition of Experimental Examples 1 to 16 is plotted.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yutaka Higashida             2-4-1 Rokuno, Atsuta-ku, Nagoya-shi Foundation             Corporate Fine Ceramics Center F-term (reference) 4G030 AA08 AA15 AA16 AA20 AA37                       BA09 CA01 CA08                 4G031 AA04 AA10 AA11 AA14 AA30                       BA09 CA01 CA08                 5E321 AA01 AA41 AA44 BB21 BB31                       GG11

Claims (6)

[Claims] 1. Ca, Ti, a Group 5A element and Si are contained, Zr is not contained, and the Ca, Ti, and
When the total content of each of the Group 5A element and the Si is 100 mol%, the content of Ca is 22.0 to 57.0.
Mol%, the Ti content is 6.0 to 40.0 mol%, the 5A group element content is 0.2 to 16.0 mol%, the Si
Content of 21.0-59.0 mol%, and a titanite solid solution is contained, The dielectric ceramic composition characterized by the above-mentioned. 2. Ca, Ti, 5A group elements, Si and Zr
And the total content of each of the Ca, the Ti, the 5A group element, the Si, and the Zr is 100 mol% in terms of oxide.
In this case, the Ca content is 22.0 to 57.0 mol%, the Ti content is 6.0 to 40.0 mol%,
The content of the group A element is 0.2 to 16.0 mol%, the content of Si is 21.0 to 59.0 mol%, the content of Zr is 10.0 mol% or less, and the titanite is A dielectric porcelain composition comprising a solid solution. 3. The dielectric ceramic composition according to claim 1, wherein the Group 5A element is Nb. 4. A dielectric material, characterized in that the dielectric ceramic composition according to any one of claims 1 to 3 is mixed with another material and then molded. 5. A dielectric body comprising a molded body made of the dielectric ceramic composition according to claim 1 and another material. 6. A radio wave absorber comprising the dielectric ceramic composition according to any one of claims 1 to 3.