JP2609362B2 - Dielectric ceramic material for microwave - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave dielectric having a high relative dielectric constant, a sufficiently high Q value (reciprocal of dielectric loss) and a small and stable temperature characteristic for practical use in the microwave region. Related to porcelain materials.

[0002]

2. Description of the Related Art Microwave dielectrics are widely used in resonators, filters, duplexers, microwave integrated circuit boards (MIC boards) and the like in communication equipment. It is very effective for stabilizing the frequency, improving the filter characteristics, and miniaturizing communication devices and circuits that have recently been particularly demanded. The characteristics required for such a dielectric include a high dielectric constant in the microwave frequency range (the size of the dielectric required for a dielectric application component is inversely proportional to the square root of the dielectric constant). Therefore, it is extremely effective for miniaturization of devices or components.), Low dielectric loss, and excellent temperature stability of resonance frequency.

[0003] Conventionally, as a dielectric material having the above-mentioned characteristics, there is a general formula: xBaO-
yTiO ₂ -zSm ₂ O ₃ (provided that the molar fraction is 5 ≦
x ≦ 23, 57 ≦ y ≦ 82.5, 2.5 ≦ z ≦ 37.5, x + y + z = 1
00) or the general formula of JP-A-63-294609: xBaO-yTiO ₂ -z ｛(1-m-
n) Sm ₂ O ₃ -m (SrO.CeO ₂ ) -n (CaO.
CeO ₂ )｝ (provided that the molar fraction is 0.1 ≦ x ≦ 0.25,
0.6 ≦ y ≦ 0.85, 0.05 ≦ z ≦ 0.30, 0 ≦ m ≦ 0.80, 0 ≦
n ≦ 0.8, x + y + z = 1.0, 0 <m + n ≦ 0.8).

[0004]

With the recent miniaturization and weight reduction of microwave communication equipment, it is necessary to reduce the size of individual components constituting the communication equipment. For the dielectric application parts, for the above-mentioned reason, it is essential to use a material having a higher relative permittivity than the conventional one for downsizing. It is extremely difficult to simultaneously achieve high relative dielectric constant, low dielectric loss, and small and stable temperature characteristics in a microwave dielectric ceramic material. The above-mentioned conventional dielectric material is an excellent material which shows a good value for both the Q value (1 / dielectric loss) and the temperature coefficient while showing a high relative dielectric constant of 84. However, in order to further reduce the size of dielectric application parts, the relative permittivity of conventional materials is not sufficient, and materials having higher values are required. At present, there are very few practical materials exhibiting higher dielectric constants than the conventional materials.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and in the microwave frequency region, has a higher relative dielectric constant, a sufficiently high Q value, and a small and stable temperature characteristic. It is an object of the present invention to supply a microwave dielectric ceramic material having the same.

[0006]

In order to solve the above-mentioned problems, the present invention has a general formula: (1-a) [xBaO-yTi
O ₂ -z ｛(1-mn) Sm ₂ O ₃ -m (SrO · Ce
O ₂ ) -n (CaO.CeO ₂ )}]-a.CaTiO ₃
In the composition formula represented by the following formula, the molar fraction is 0.1 ≦ x ≦ 0.25 0.6 ≦ y ≦ 0.85 0.05 ≦ z ≦ 0.30 ≦ m ≦ 0.80 ≦ n ≦ 0.8 x + y + z = 1 0 <m + n ≦ 0.80 <a ≦ 0.60 This is a dielectric porcelain material having a composition range as shown below and containing Mn ₂ O ₃ as an auxiliary component in an amount of 3% by weight or less based on the total weight.

[0007]

According to the present invention, the intended object can be achieved by using the material having the above composition, and BaO-TiO ₂ -S
By replacing a part of Sm ₂ O ₃ contained in the m ₂ O ₃ ceramic material with the components (SrO.CeO ₂ ) and (CaO.CeO ₂ ), the Q value was changed to include the component CaTiO _3. Greatly increases the relative permittivity, and further increases Mn ₂ O ₃
The sinterability is improved by the addition and addition of.

[0008]

An embodiment of the present invention will be described below.

The starting material used is BaCO of high chemical purity.
_{3, TiO 2, Sm 2 O} 3, CaCO 3, SrCO 3, CeO
₂ , Mn ₂ O ₃ and CaTiO ₃ were used. These raw materials are represented by the composition formula: (1-a) [xBaO-yTiO ₂ -z} (1-
_{m-n) Sm 2 O 3} -m (SrO · CeO 2) -n (Ca
O · CeO ₂ )}]-a · CaTiO ₃ , for each sample, so that the component composition in mole fraction is the value shown in Table 1.
They were weighed and mixed components other than CaTiO _3, 105 in the air
The reaction was performed at 0 ° C. for 2 hours and calcined. Then, the obtained calcined product is pulverized with a mortar, a ball mill, etc.
The aTiO ₃ component was similarly mixed. The mixed powder thus produced was molded at a molding pressure of 800 kg / cm ² and a diameter of 12 mm.
It was press-formed into a cylindrical shape with a height of 15 mm and a disk shape with a diameter of 12 mm and a height of 5 mm. The obtained molded body is placed in an oxygen atmosphere for about
It was kept at 1250-1450 ° C. for 4-50 hours and fired to obtain dielectric porcelain. The obtained dielectric porcelain was subjected to grinding processing, and the relative permittivity and the Q value were measured at 6 GHz by a parallel conductor plate type dielectric cylinder resonator method, and then the temperature coefficient was calculated at 1 MHz (temperature coefficient of relative permittivity: τ). _k ) was measured in the temperature range from -10 to 50 ° C.

The results are shown in Table 1. The relative dielectric samples Nos. 1 to 7 in Table 1 are out of the scope of the present invention and are listed as comparative examples. All others are within the scope of the present invention. Note that the temperature coefficient (τ _k ) of Comparative Sample No. 7 was not measured because the Q value was small.

[0011]

[Table 1]

[0012] The effect and the limit amount of each component exhibiting the desired characteristics appear in a complex and synergistic manner and are determined, so that it is difficult to specify the amount of each component. However, basically, from the comparison between Sample No. 4 and Comparative Sample No. 3 in Table 1,
The Q value is improved by the inclusion of the components (SrO.CeO ₂ ) and (CaO.CeO ₂ ). From the comparison between Sample Nos. 5, 6, 7, 9, and 10 and Comparative Sample No. 3, the inclusion of the component CaTiO ₃ It can be seen that the non-dielectric constant greatly increases. Sample Nos. 2, 3, 4, 9, 10, 11 and Comparative Sample No. 3
From the comparison with, the content of the component (SrO.CeO ₂ ) has τ _k on the minus side, the content of the component (CaO.CeO ₂ ) has τ _k on the plus side, and the content of the component CaTiO ₃ has τ _k on the minus side. It can be seen that they are respectively shifted to. That is,
The three components (SrO. CeO ₂ ), (CaO. Ce)
The temperature coefficient can be arbitrarily adjusted by O ₂ ) and CaTiO ₃ . Further, from the comparison between Sample Nos. 5 and 12, the auxiliary component Mn ₂
It can be seen that the relative dielectric constant slightly increases with the addition of O ₃ . As described above, the dielectric ceramic of the present invention has a large dielectric constant and a large Q value in a microwave frequency band, and can easily compensate for the temperature coefficient of the dielectric constant. Component Ba
When the mole fraction x of O is larger than 0.25 or the mole fraction y of the component TiO ₂ is smaller than 0.60, the relative dielectric constant and the Q value are reduced, and the mole fraction of the component CaTiO ₃ is 0.00
In such a case, the relative dielectric constant decreases, and the material becomes unsuitable as a dielectric ceramic material for microwaves. The decrease in the relative permittivity and the Q value is caused by the component (SrO.CeO ₂ ) and the component (CaO.Ce
It also occurs when the sum (m + n) of the molar fractions of O ₂ ) is greater than 0.8 and when the minor component Mn ₂ O ₃ is added in excess of 3% by weight. Also, the molar fraction x of the component BaO
Is less than 0.1 and the molar fraction y of the component TiO ₂ is greater than 0.85, or when the molar fraction of the component CaTiO ₃ exceeds 0.6, the absolute value of τ _k becomes larger,
It becomes difficult to apply as a part and becomes unsuitable as an industrial material.

In the above embodiment, B was used as a starting material.
aCO ₃ , TiO ₂ , Sm ₂ O ₃ , CaCO ₃ , SrCO ₃ ,
Although CeO ₂ , Mn ₂ O ₃ , and CaTiO ₃ were used, they are not particularly limited to these raw materials, and if necessary, a compound containing each metal component or a composite oxide such as BaTiO ₃ may be used. Good.

[0014] Thus, as can be seen from Table 1, according to this embodiment, along with dielectric ceramic materials of compositions shown relative dielectric constant 85 to 93 will be _{obtained, BaO-TiO 2 -Sm 2 O} 3 based ceramic A part of the component Sm ₂ O _{3 in} the component (SrO · Ce)
O ₂ ) and (CaO · CeO ₂ ), and further containing CaTiO ₃ to provide a higher relative dielectric constant, a practically sufficient Q value, and a temperature coefficient that can be adjusted around 0 ppm / ° C. And a dielectric porcelain having
By adding and containing n ₂ O ₃ , sinterability can be improved and a dielectric ceramic having a higher relative dielectric constant can be obtained.

[0015]

As described above, the present invention provides a compound represented by the general formula: (1)
-A) [xBaO-yTiO ₂ -z ｛(1-mn) S
m ₂ O ₃ -m (SrO.CeO ₂ ) -n (CaO.Ce
O ₂ )｝]-a · CaTiO ₃ (wherein, by mole fraction, 0.1
≦ x ≦ 0.25, 0.6 ≦ y ≦ 0.85, 0.05 ≦ z ≦ 0.3, 0 ≦ m ≦
0.8, 0 ≦ n ≦ 0.8, x + y + z = 1, 0 <m + n ≦ 0.
8, 0 <a ≦ 0.60), an excellent microwave dielectric having a higher relative dielectric constant, a sufficiently high Q value for practical use, and a small and stable temperature coefficient in the microwave frequency range. A body porcelain material is obtained. Further, by adding and containing Mn ₂ O ₃ , sinterability is improved and a dielectric ceramic having a higher relative dielectric constant can be obtained. For example, the use of the dielectric porcelain of the present invention can promote the miniaturization and high performance of microwave application parts such as a dielectric resonator.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hisao Watai 8-1-1, Tsukaguchi-Honmachi, Amagasaki-shi Examiner, Materials Research Laboratory, Mitsubishi Electric Corporation Tomoyasu Sato (56) References JP-A-63-294609 (JP, A)

Claims (1)

(57) [Claims] 1. The general formula: (1-a) [xBaO-yTiO ₂ -z ｛(1-m-
n) Sm ₂ O ₃ -m (SrO.CeO ₂ ) -n (CaO.
CeO ₂ )｝]-a · CaTiO _{3 In} the composition formula, 0.1 ≦ x ≦ 0.25 0.6 ≦ y ≦ 0.85 0.05 ≦ z ≦ 0.30 ≦ m ≦ 0.80 ≦ n ≦ 0.8 x + y + z = 1 0 <m + n ≦ 0.8 0 <a ≦ 0.60 In the composition range, Mn ₂ O ₃ is added as an auxiliary component in an amount of 3% by weight or less based on the total weight, and is a dielectric ceramic for microwaves. material.