JP3243874B2 - Dielectric porcelain composition - Google Patents

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 suitable as a material for a dielectric resonator or the like. The dielectric ceramic composition of the present invention can be applied to, for example, a dielectric substrate for microwave IC, a dielectric adjustment rod, and the like, in addition to the dielectric resonator material.

[0002]

2. Description of the Related Art In recent years, with the integration of microwave circuits, a small and high-performance dielectric resonator has been demanded. Such dielectric dielectric ceramic composition used in the resonator, the ratio is large dielectric constant epsilon _r, also the linearity of the temperature characteristics of stability and resonance frequency temperature coefficient tau _f of resonance frequency is excellent It is required that the no-load Q is large. As such a dielectric porcelain composition, Ti
Although those containing O ₂ , MgO—CaO—TiO ₂ as main components are known, the former has a problem that the temperature coefficient is large, and the latter has a small relative dielectric constant.

As an improved system, BaO-TiO ₂ -Nd
Proposal for ₂ O ₃ based dielectric porcelain composition [Ber. Dt.
eram.Ges.55 (1978) Nr.7; JP 60-35406 Publication], _{or, BaO-TiO 2 -Nd 2 O} 3 -B
Although proposals have been made for the i ₂ O ₃ system (Japanese Patent Application Laid-Open No. 62-72558), a smaller dielectric resonator is required, and therefore, development of a material having a higher dielectric constant is desired.

[0004]

An object of the present invention is to provide a dielectric ceramic composition having more excellent characteristics as a microwave dielectric resonator material, particularly a high dielectric constant, a large unloaded Q, and a small temperature change of the resonance frequency. An object of the present invention is to provide a dielectric ceramic composition.

[0005]

According to the present invention, there is provided a compound represented by the following formula:
_{a (Nd 1-xy Sm x} Bi y) 2 + A Ti 4 + B O
_{12 + 3A / 2 + 2B} (where 0 ≦ x ≦ 0.8, 0.2 ≦ y ≦ 0.
5. A dielectric ceramic composition comprising barium, neodymium, samarium, bismuth, titanium and oxygen represented by A = 0, B = 0 , where 0.2 ≦ x + y ≦ 1).

According to the present invention, the temperature change of the resonance frequency can be reduced while maintaining a large dielectric constant by replacing part or all of Nd with Sm in the BaNd ₂ Ti ₄ O ₁₂ structure. Further, by substituting a part of Nd with Bi, the permittivity can be further increased and the temperature change of the resonance frequency can be reduced. However, when the substitution amount of Nd increases, the Q value decreases, so the substitution amount y falls within the above range. Is set.

Further, the composition formula, Ba (Nd _1-xy Sm _x B)
i _y ) _{2 + A} Ti _{4 + B} O _{12 + 3A / 2 + 2B} , where A and B are
When A = 0 and B = 0 , respectively, BaNd ₂
A different phase other than the Ti ₄ O ₁₂ basic structure is easily formed, and one or more of the dielectric constant, the temperature coefficient of the resonance frequency, and the Q value are deteriorated. A = 0, B = 0
Such as greater outside the Bi from tends to leave at the time of firing, and the withdrawal amount that a prone to variation in electrical characteristics unstable. When A = 0 and B = 0, that is, in the BaNd ₂ Ti ₄ O ₁₂ structure, good characteristics are obtained.

The dielectric porcelain composition according to the present invention is calcined by mixing starting materials such as barium, neodymium, samarium, bismuth and titanium carbonate, oxides and the like, which become oxides by calcining and firing. Thereafter, it can be manufactured by a method of molding, firing and sintering.

First, barium carbonate, neodymium oxide, samarium oxide, bismuth oxide, and titanium oxide are wet-mixed by predetermined amounts with a solvent such as water or alcohol. Subsequently, after removing water, alcohol, and the like, pulverization is performed, and 900 to 1100 is placed in an oxygen-containing gas atmosphere (for example, air atmosphere).
Calcinate at about 1 to about 5 hours. The calcined product thus formed is pulverized by a wet or dry method, an organic binder such as polyvinyl alcohol is added, and the product is dried and pressed (at a pressure of about 100 to 1000 kg / cm ² ). As a molding method, in addition to uniaxial pressure molding, HIP, doctor molding, cast molding and the like may be used. When the obtained molded body is fired at 1200 to 1400 ° C. in an oxygen-containing gas atmosphere such as air, the above-mentioned dielectric ceramic composition is obtained.

The dielectric ceramic composition thus obtained can be used as it is or by processing it into an appropriate shape and size as needed to obtain a dielectric resonator, a dielectric substrate for microwave IC, a dielectric adjustment rod, and the like. It can be used as a material, and exhibits an excellent effect particularly when used in the MHz to GHz band.

[0011]

The present invention will be described more specifically with reference to the following Examples and Comparative Examples. Example 1 0.100 mol of barium carbonate powder (BaCO ₃ ), 0.075 mol of neodymium oxide powder (Nd ₂ O ₃ ), 0.025 mol of bismuth oxide powder (Bi ₂ O ₃ ), and titanium oxide powder (TiO ₂₎ ) 0.400 mol was put into a ball mill together with ethanol and wet-mixed for 12 hours. Ethanol as a solvent was evaporated, and the mixture was pulverized for 1 hour with a crusher. The pulverized material was calcined at 1000 ° C. in an air atmosphere, and then pulverized again with a crusher for 1 hour. After adding an appropriate amount of polyvinyl alcohol solution to the pulverized material and drying, a diameter of about 9 mm and a thickness of 4 mm
, And fired and sintered at 1290 ° C. for 2 hours in an air atmosphere to obtain a dielectric ceramic composition Ba (N
d _0.81 Bi _0.19 ) ₂ Ti ₄ O ₁₂ was obtained. The thus obtained porcelain composition was processed into a pellet having a diameter of about 7 mm and a thickness of about 2 mm, and then measured by a dielectric resonance method to obtain a resonance frequency (4
Unloaded Q and relative permittivity ε _r at 5 GHz) were determined. Regarding the temperature dependence of the resonance frequency, 0 ° C.
To 50 ° C. to determine the temperature coefficient τ _f . The results are shown in Tables 1 and 2.

Examples 2 to 13 and Comparative Examples 1 to 8 Barium carbonate powder (BaCO ₃ ), neodymium oxide powder (Nd ₂ O ₃ ), samarium oxide powder (Sm ₂ O ₃ ), bismuth oxide powder (Bi ₂ O ₃₎ ), And titanium oxide powder (T
The raw material charge ratio of iO ₂ ) and the sintering temperature were 1250-1.
A dielectric ceramic composition was manufactured in the same manner as in Example 1 except that the temperature was changed to 350 ° C., and the characteristics were measured. Table 1 shows the results.
The results are shown in Tables 2, 3 and 4.

Comparative Example 9 The barium carbonate powder (BaCO ₃ ), neodymium oxide powder (Nd ₂ O ₃ ), and titanium oxide powder (TiO ₂ ) were adjusted to have the molar ratios shown in Table 3, and the firing temperature was 13
A dielectric ceramic composition was manufactured in the same manner as in Example 1 except that the temperature was changed to 50 ° C., and the physical properties were measured. The results are shown in Tables 3 and 4.

Comparative Examples 10-13 Barium carbonate powder (BaCO3), neodymium oxide powder (Nd2O3), samarium oxide powder (Sm2O3),
The raw material charging ratio of bismuth oxide powder (Bi2 O3) and titanium oxide powder (TiO2) and the sintering temperature were set to 125.
A dielectric ceramic composition was manufactured in the same manner as in Example 1 except that the temperature was changed to 0 to 1350 ° C., and the physical properties were measured. The results are shown in Tables 3 and 4.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3]

[0018]

[Table 4]

[0019]

Industrial Applicability The dielectric ceramic composition of the present invention has a particularly high dielectric constant, a large unloaded Q, a small change in resonance frequency with temperature, and is used in a dielectric resonator material, especially in the MHz to GHz band. It is suitable as a resonator material. Further, the dielectric ceramic composition of the present invention can be applied to, for example, a dielectric substrate for microwave IC, a dielectric adjustment rod, and the like, in addition to the dielectric resonator material.

Continuation of the front page (56) References JP-A-57-156367 (JP, A) JP-A-62-19066 (JP, A) JP-A-4-104946 (JP, A) JP-A-4-240158 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01B 3/12 303 C04B 35/46 H01P 7/10

Claims (1)

(57) [Claims] 1. A composition _{formula, Ba (Nd 1-xy Sm} x Bi y) 2 + A
Ti _{4 + B} O _{12 + 3A / 2 + 2B} (where 0 ≦ x ≦ 0.8, 0.2
≦ y ≦ 0.5, A = 0, B = 0 , but 0.2 ≦ x + y
≦ 1) A dielectric porcelain composition comprising barium, neodymium, samarium, bismuth, titanium and oxygen.