JP3291780B2 - 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. Further, the dielectric ceramic composition of the present invention is 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]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a dielectric ceramic composition having more excellent properties as a dielectric resonator material, particularly a dielectric having a high dielectric constant, a large unloaded Q, and a small temperature change in the resonance frequency. It is to provide a porcelain composition.

[0005]

Means for Solving the Problems The present invention provides a composition represented by the following formula:
(Ba _1-X Pb _X ) (Nd _1-YZ La _Y Bi _Z ) ₂ Ti
₄ O ₁₂ (wherein 0.01 ≦ X ≦ 0.3, 0 ≦ Y ≦ 0.
3, 0.1 ≦ Z ≦ 0.3) and a dielectric ceramic composition comprising barium, lead, neodymium, lanthanum, bismuth, titanium and oxygen.

According to the present invention, by substituting a part of Ba with Pb in the BaNd ₂ Ti ₄ O ₁₂ structure,
The dielectric constant can be increased and the temperature coefficient of the resonance frequency can be reduced. If the replacement amount is too large, Q decreases, so the replacement amount X is set in the above range.

The dielectric constant can be increased by substituting a part of Nd with La. However, if the replacement amount is too large, the temperature coefficient of the resonance frequency increases, so the replacement amount Y is set in the above range. Furthermore, N
The dielectric constant can be further increased by substituting a part of d with Bi. However, when the substitution amount increases, Q decreases, so the substitution amount Z is set in the above range.

Further, (Ba)_1-XPb_X) (Nd
_1-YZLa_YBi_Z)_TwoTi_FourO₁₂Basic structure in
In other words, (Ba)_1-XPb_X) (Nd
_1-YZLa _YBi_Z)_{2 + A}Ti_{4 + B}O_{12 + 3A / 2 + 2B}Represents
The dielectric constant when A and B in the formula are not 0,
One of the temperature coefficient of resonance frequency, Q, or
Degrades two or more properties. Also, the stoichiometric ratio
Pb, Bi, etc. are easily released during firing,
In addition, the amount of departure is not stable, causing variations in electrical characteristics.
It is not preferable because it becomes easy.

The dielectric porcelain composition according to the present invention is prepared by mixing starting materials such as barium, lead, neodymium, lanthanum, bismuth and titanium carbonate, oxides and the like, which are converted to oxides by calcination and firing. After baking, it can be manufactured by a method of molding, baking and sintering.

First, barium carbonate, lead oxide, neodymium oxide, lanthanum oxide, bismuth oxide and titanium oxide are wet-mixed by predetermined amounts with a solvent such as water or alcohol. Then, after removing water, alcohol, etc., pulverize,
900 ~ under an oxygen-containing gas atmosphere (for example, air atmosphere)
Calcinate at 1100 ° C for about 1 to 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 ). Molding methods include uniaxial pressure molding, HI
P, doctor molding, cast molding and the like may be used. The obtained molded body was placed in an oxygen-containing gas atmosphere such as air at 1300-1000.
By firing at 1450 ° C., the above dielectric ceramic composition is obtained.

The thus obtained dielectric porcelain composition can be used as it is or, if necessary, processed into an appropriate shape and size to obtain a dielectric resonator, a microwave IC dielectric substrate, 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.

[0012]

The present invention will be described more specifically with reference to the following Examples and Comparative Examples. Example 1 Barium carbonate powder (BaCO ₃ ) 0.090 mol, lead oxide powder (PbO) 0.010 mol, neodymium oxide powder (Nd ₂ O ₃ ) 0.073 mol, lanthanum oxide powder (L
a ₂ O ₃₎ 0.008 mol, bismuth oxide powder (Bi ₂
O ₃ ) 0.019 mol, and titanium oxide powder (TiO 2)
₂ ) 0.400 mol was put into a ball mill together with ethanol and wet-mixed for 10 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. An appropriate amount of a polyvinyl alcohol solution was added to the pulverized product, dried, formed into pellets having a diameter of about 9 mm and a thickness of 4 mm, and fired and sintered at 1370 ° C. for 2 hours in an air atmosphere to obtain a dielectric ceramic composition of the present example. Material (Ba _0.9 Pb _0.1 ) (N
d _0.73 La _0.08 Bi _0.19 ) ₂ Ti ₄ O ₁₂ was obtained. The thus obtained porcelain composition of Example 1 was processed into a size of about 7 mm in diameter and about 2.5 mm in thickness, and then measured by a dielectric resonance method. The rate ε _r was determined. The temperature dependency of the resonance frequency was measured in the range of 0 ° C. to 50 ° C., and the temperature coefficient τ _f was obtained. Table 1 shows the results.

Examples 2 to 10 The charge ratio and the sintering temperature of the raw materials of Example 1 were 1350 to
A dielectric ceramic composition was manufactured in the same manner as in Example 1 except that the temperature was changed to 1390 ° C., and the characteristics were measured. Table 1 shows the results.
Shown in

Comparative Example 1 Barium carbonate (BaCO ₃ ), neodymium oxide (Nd ₂ O)
₃ ) and the titanium oxide (TiO ₂ ) powder were adjusted to have a molar ratio as shown in Table 1, and the firing temperature was set to 1390.
A dielectric ceramic composition was manufactured in the same manner as in Example 1 except that the temperature was changed to ° C., and the physical properties were measured. Table 1 shows the results. Comparative Examples 2 to 12 Barium carbonate (BaCO ₃ ), lead oxide (PbO), neodymium oxide (Nd ₂ O ₃ ), lanthanum oxide (La
₂ O ₃ ), bismuth oxide (Bi ₂ O ₃ ), and titanium oxide (TiO ₂ ) in the molar ratio shown in Table 1 and the firing temperature was changed to 1350-1390 ° C. A dielectric ceramic composition was manufactured in the same manner as in Example 1, and the physical properties were measured. Table 1 shows the results.

[0015]

[Table 1]

[0016]

The dielectric ceramic composition of the present invention has a large dielectric constant, a large unloaded Q, a small temperature coefficient of the resonance frequency, and a dielectric resonator material, especially from MHz to G.
It is suitable as a resonator material used in the Hz band. 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.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-78154 (JP, A) JP-A-62-56361 (JP, A) Industrial materials, Japan, Nikkan Kogyo Shimbun, Vol. 33, No. 4 (1985), p. 39−48 (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01B 3/12 303 H01B 3/12 311 C04B 35/46

Claims (1)

(57) [Claims] A composition formula (Ba)_1-XPb_X) (Nd
_1-YZLa_YBi_Z) _TwoTi_FourO₁₂(Where 0.01 ≦
X ≦ 0.3, 0 ≦ Y ≦ 0.3, 0.1 ≦ Z ≦ 0.3)
Barium, lead, neodymium, lanthanum, bismuth represented
A dielectric porcelain composition comprising titanium, titanium and oxygen.