JPH0571538B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a dielectric ceramic composition, particularly a dielectric ceramic composition containing strontium oxide (SrO), barium oxide (BaO), titanium oxide (TiO ₂ ), and neodymium oxide (Nd ₂ O ₃ ) as main components. A dielectric ceramic composition composed of a dielectric material having a large relative permittivity (ε), a small temperature coefficient (TC), and a dielectric material having a large no-load Q value at high frequencies. Relating to a porcelain composition. [Prior art] Traditionally, dielectric ceramics include MgTiO ₃ ,
CaTiO ₃ , SrTiO ₃ , CaTiO ₃ −La ₂ O ₃・2TiO ₂ −
Compositions such as MgTiO ₂ are used, and by using these compositions, the relative permittivity (ε) can be increased.
15 to 280, and its temperature coefficient (TC) is +100 to -
It is known that dielectric ceramics with a temperature range of 3000 ppm/°C can be obtained. [Problems to be Solved by the Invention] However, in the compositions provided conventionally, as the relative dielectric constant increases, the absolute value of the temperature coefficient also increases, and if the absolute value of the temperature coefficient is to be decreased, the relative dielectric constant increases. This method has the disadvantage that only dielectric ceramics with a small dielectric constant can be obtained, and a dielectric ceramic composition with good relative permittivity and temperature coefficient has not been obtained. The present invention solves the above conventional problems and provides a dielectric ceramic composition that has a high dielectric constant, a relatively small absolute value of its temperature coefficient, and a large no-load Q value at high frequencies. The purpose is to provide something. [Means for Solving the Problems] The dielectric ceramic composition of the present invention contains strontium oxide (SrO), barium oxide (BaO), titanium oxide (TiO ₂ ), and neodymium oxide (Nd ₂ O ₃ ) as main components. _A composition comprising _{the general formula [} ] In the TiO ₂ −Nd ₂ O ₃ system, x, y,
It is characterized in that z is within the range formed by connecting the following five points A to E, and it contains bismuth oxide (Bi ₂ O ₃ ) in an amount of 15% by weight or less based on the main component.

[Table] That is, as a result of various studies by the present inventors on materials that overcome the above-mentioned conventional drawbacks, in the composition represented by the above general formula [], x, y, and z satisfy the above five points A to E. The main components are those found within the bound area, and this includes bismuth oxide (Bi ₂ O ₃ ).
It has been discovered that by containing 15% by weight or less of the dielectric material, a dielectric ceramic having a large relative dielectric constant (ε), a small temperature coefficient (TC), and a large no-load Q value at high frequencies can be obtained, and the present invention has been made based on this discovery. Completed. The present invention will be explained in detail below. First, the reason for limiting the range of the main component composition of the dielectric ceramic composition of the present invention will be explained with reference to FIG. In FIG. 1, first, in the a region outside the above range, the dielectric constant becomes so small that it is not practical. In region b, the C·IR product becomes small, which is also not practical.
In region c, the dielectric constant is small and its temperature change becomes large. In the d region, the relative dielectric constant changes with temperature too much. Furthermore, in the e region, sintering becomes difficult and dense porcelain cannot be obtained. For this reason,
It is appropriate that x, y, and z be in the range surrounded by the five points A to E described above. Regarding p, if it is 0, a high dielectric constant, which is the object of the present invention, cannot be obtained. Therefore, 0<
Let p≦1. Regarding the addition of Bi ₂ O ₃ , as its content increases, the dielectric constant increases and the temperature coefficient can be improved, but if it is added in an amount exceeding 15% by weight of the main component, the no-load Q decreases. . For this reason, Bi ₂ O ₃
The amount added shall be 15% by weight or less. In the present invention, it is also possible to add SiO ₂ , MnCO ₃ , etc., which are commonly used as sintering aids, as long as the composition and properties of the main components are not changed. In this case, it is preferable to add SiO ₂ and MnCO ₃ in an amount of about 0.1 to 0.3% by weight of the main components. In order to manufacture such a dielectric ceramic composition of the present invention, for example, strontium oxide (SrO),
Specified powders of strontium carbonate (SrCO ₃ ), barium oxide (BaO), titanium oxide (TiO ₂ ), barium titanate (BaTiO ₃ ), neodymium oxide (Nd ₂ O ₃ ), bismuth oxide (Bi ₂ O ₃ ), etc. Weigh and mix thoroughly using a wet ball mill or the like. Next, after drying this mixture, if necessary, it is calcined at a temperature in the range of 1000 to 1100°C for several hours.
Although it is not necessary to perform this calcination, it tends to make the particles more uniform and improve the dielectric properties. When calcining is performed, the calcined product is further crushed using a wet ball mill, etc., and after drying,
A suitable organic binder such as polyvinyl alcohol is added to form granules, which are pressed into a predetermined shape and then fired. This firing is from 1250~
It is carried out at a temperature range of 1400℃ for about 0.5 to several hours. (Of course, these manufacturing conditions are the most suitable values, and the porcelain composition of the present invention may be manufactured under conditions or methods other than those described above.) [Examples] The present invention will be described in Examples below. The present invention will be described in more detail by citing the following examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. Example 1 As a starting material, chemically highly purified BaTiO ₃ ,
_{SrCO3 , TiO2} , _Nd2O3 , _Bi2O3 and _{SiO2 ,}
Using MnCO ₃ , these raw materials were weighed so as to have the compounding ratio shown in Table 1, and wet-milled with pure water using a ball mill for about 18 hours. After drying the mixed and pulverized raw materials, they were pre-calcined in the air at about 1075°C for 4 hours, and wet-pulverized again with pure water in a ball mill for about 18 hours. After drying the obtained pulverized product, a binder (a 13% by weight aqueous solution of polyvinyl alcohol) was added to granulate it, and it was press-molded into a disk shape with a diameter of about 16 mm and a thickness of about 0.7 mm. This disk-shaped sample was fired for 1 hour at the firing temperature shown in Table 1 to obtain dielectric porcelain Nos. 1 to 34 having the compositions shown in Table 1 and FIG. Silver paste was coated on both sides of the dielectric ceramic thus obtained, and after drying, it was baked at about 810°C for 3 minutes to form a parallel plate capacitor, and its electrical properties were evaluated. The results are shown in Table 1. Note that the dielectric constant ε and no-load Q are at 25℃, 1MHz.
It was measured with In addition, the temperature coefficient (TC) of the dielectric constant is
It was determined from measurements at 100 KHz in the temperature range of -55°C to +125°C. Insulation resistance (IR) was measured at 100 V DC for 60 seconds at room temperature. As is clear from Table 1, the dielectric ceramic composition within the scope of the present invention has a large relative dielectric constant (ε),
It also has excellent properties such as a relatively small temperature coefficient (TC) and a large no-load Q at high frequencies, making it suitable as a material for temperature compensation, high frequencies, etc.

【table】

[Table] [Effects of the Invention] As detailed above, the dielectric ceramic composition of the present invention has a high dielectric constant, a relatively small absolute value of its temperature coefficient, and a low no-load Q at high frequencies.
A dielectric porcelain with a high value is provided. Therefore, the dielectric ceramic composition of the present invention is extremely useful as a dielectric ceramic for temperature compensation, high frequency use, and the like. In particular, in the present invention, since bismuth oxide (Bi ₂ O ₃ ) is contained in an amount of 15% by weight or less of the main component, the comparative electrical conductivity can be increased and the temperature coefficient can be improved.

[Brief explanation of drawings]

FIG. 1 is a ternary composition diagram illustrating the composition of the dielectric ceramic composition of the present invention.

Claims (1)

[Scope of Claims] 1. A composition containing strontium oxide (SrO), barium oxide (BaO), titanium oxide (TiO ₂ ), and neodymium oxide (Nd ₂ O ₃ ) as main components, which has the general formula [ ] xMO −yTiO ₂ −zNd ₂ O ₃ ...[] {However, when expressed as M=Ba _1-p Sr _P (0<p≦1)}, in the MO-TiO ₂ −Nd ₂ O ₃ system, x, y,
A dielectric material characterized in that z is within the range formed by connecting the following five points A to E, and contains bismuth oxide (Bi ₂ O ₃ ) in an amount of 15% by weight or less based on the main component: Porcelain composition. 【table】