JPH06139820A - Dielectric ceramic composition - Google Patents

Abstract

PURPOSE:To provide a dielectric ceramic composition having a large dielectric constant, a large no-load Q, and a small temperature coefficient of the resonance frequency and suitable for a dielectric resonator material. CONSTITUTION:A dielectric ceramic composition is constituted of barium, lead, neodymium, praseodymium, samarium, lanthanum, bismuth, titanium, and oxygen, and it is expressed by the composition formula (Ba1-x Pbx) (NdaPrbSmcLadBie)2 Ti4O12, where 0.01<=x<=0.4, 0.05<=a<=-0.95, 0.01<=b<=0.80, 0<=c<=0.6, 0<=d<=0.3, 0.04<=e<=0.5, and a+b+c+d+e=1.

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 is applied to, for example, a dielectric substrate for microwave IC, a high frequency capacitor, a dielectric adjusting rod, etc., in addition to the dielectric resonator material.

[0002]

2. Description of the Related Art In recent years, with the integration of microwave circuits, a compact and high-performance dielectric resonator is required. The dielectric ceramic composition used for such a dielectric resonator has a large relative permittivity ε _r, excellent stability of the temperature coefficient τ _f of the resonance frequency and linearity of the temperature characteristic of the resonance frequency. It is required that the unloaded Q be large. As such a dielectric ceramic composition, Ti
A material containing O ₂ , MgO-CaO-TiO ₂ or the like as a main component is known, but 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 is used.
Proposal of ₂ O ₃ based dielectric ceramic composition [Ber.Dt.K
eram.Ges.55 (1978) Nr.7; JP 60-35406 Publication], _{or, BaO-TiO 2 -Nd 2 O} 3 -B
Although a proposal has been made for the i ₂ O ₃ system (Japanese Patent Laid-Open No. 62-72558), a smaller dielectric resonator is required, and therefore, development of a material having a larger dielectric constant is desired.

[0004]

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

[0005]

The present invention provides a composition formula,
(Ba_1-xPb_x) (Nd_aPr_bSm_cLa_dB
i_e) ₂Ti_FourO₁₂(In the formula, 0.01 ≦ x ≦ 0.4,
0.05 ≦ a ≦ 0.95, 0.01 ≦ b ≦ 0.80, 0
≤c≤0.6, 0≤d≤0.3, 0.04≤e≤0.
5, barium represented by a + b + c + d + e = 1),
Lead, neodymium, praseodymium, samarium, lantern,
Dielectric ceramic composition composed of bismuth, titanium and oxygen
Regarding

According to the invention, by substituting part of Ba with Pb in the BaNd ₂ Ti ₄ O ₁₂ structure,
The permittivity can be increased and the temperature coefficient of resonance frequency can be reduced. If the substitution amount becomes too large, Q will decrease, so the substitution amount x is set within the above range.

By substituting Pr for Nd, the temperature change of the resonance frequency can be controlled in the positive direction. However, if the replacement amount becomes too large, the temperature change of the resonance frequency exceeds the practical range, so the replacement amount b is set within the above range. Further, by substituting with Sm, the Q value can be increased while maintaining a large permittivity, and the temperature change of the resonance frequency can be reduced. However, if the amount of substitution is too large, the dielectric constant decreases, so the amount of substitution c is set within the above range. Further, the dielectric constant can be increased by substituting a part of Nd with La, but if the substitution amount of La is too large, the temperature coefficient of the resonance frequency increases, so the substitution amount d is set within the above range. . Furthermore, the dielectric constant can be further increased by substituting a part of Nd with Bi. However, if the substitution amount becomes too large, Q decreases, so the substitution amount e is set within the above range.

Further, the composition formula, (Ba_1-xPb_x) (Nd
_aPr_bSm_cLa_dBi_e)₂Ti_FourO₁₂At
If deviated from this structure, that is, (Ba_1-xPb_x)
(Nd _aPr_bSm_cLa_dBi_e)_{2 + A}Ti_{4 + B}O
_{12 + 3A / 2 + 2B}When expressed as, A and B in the formula are not 0
Of the dielectric constant, temperature coefficient of resonance frequency, and Q
Either one or more than one characteristic is degraded. Well
Also, if the stoichiometric ratio deviates, Pb, Bi, etc. will be
It is easy to disengage, and the amount of disengagement is unstable and electrical.
It is not preferable because variation in characteristics is likely to occur.

The dielectric porcelain composition according to the present invention comprises barium, lead, neodymium, praseodymium, samarium, lanthanum, bismuth and titanium carbonates, oxides, acetates,
It can be manufactured by a method in which starting materials such as nitrates and fluorides that are calcined and fired to form oxides are mixed and calcined, and then molded, fired and sintered.

First, barium carbonate, lead oxide, neodymium oxide, praseodymium acetate, samarium oxide, lanthanum oxide, bismuth oxide and titanium oxide each in a predetermined amount in water,
Wet mix with a solvent such as alcohol. Then water
After removing alcohol and the like, the product is pulverized, and then, in an oxygen-containing gas atmosphere (for example, an air atmosphere) at 900 to 1100 ° C., about 1
Calcination for 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, dried and then pressure-molded (pressure of about 100 to 1000 kg / cm ² ). The molding method may be uniaxial pressure molding, HIP, doctor molding, cast molding, or the like. The dielectric ceramic composition is obtained by firing the obtained molded body at 1300 to 1450 ° C. in an oxygen-containing gas atmosphere such as air.

The dielectric ceramic composition thus obtained is processed as it is or, if necessary, into an appropriate shape and size to obtain a dielectric resonator, a microwave IC dielectric substrate, a high frequency capacitor, a dielectric. It can be used as a material for adjusting rods and the like, and particularly when used in the MHz to GHz band, an excellent effect is exhibited.

[0012]

EXAMPLES The present invention will be described more specifically by showing Examples and Comparative Examples below. Example 1 0.080 mol of barium carbonate powder (BaCO ₃ ), 0.020 mol of lead oxide powder (PbO), 0.070 mol of neodymium oxide powder (Nd ₂ O ₃ ) and praseodymium acetate (Pr).
_{(CH 3 CO 2) 3 ·} 2H 2 O) 0.01 mole, samarium oxide powder (Sm ₂ O ₃₎ 0.005 mol, bismuth oxide powder (B
i ₂ O ₃ ) 0.020 mol, and titanium oxide powder (T
0.400 mol of iO ₂ ) was put into a ball mill together with ethanol and wet-mixed for 10 hours. The solvent ethanol was evaporated and the mixture was crushed for 1 hour with a mulcher. The crushed product was calcined in an air atmosphere at 1100 ° C., and then crushed again for 1 hour with a mashing machine. An appropriate amount of a polyvinyl alcohol solution was added to this pulverized product, which was dried, and then formed into pellets having a diameter of about 9 mm and a thickness of 4 mm, which were fired and sintered at 1350 ° C. for 2 hours in an air atmosphere and sintered to obtain the dielectric ceramic composition of this example. Thing (Ba _0.8 Pb _0.2 )
(Nd _0.70 Pr _0.05 Sm _0.05 Bi _0.20 ) 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 the dielectric resonance method to find no load Q and relative dielectric constant at the resonance frequency (4 to 5 GHz). The rate ε _r was determined. The temperature dependence of the resonance frequency was measured in the range of 0 ° C to 50 ° C to obtain the temperature coefficient τ _f . The results are shown in Table 1.

Examples 2 to 9 The charging ratio of the raw materials of Example 1 and the firing temperature were set to 1300.
A dielectric ceramic composition was produced in the same manner as in Example 1 except that the temperature was changed to 1400 ° C., and the characteristics were measured. The results are shown in Table 1.
Shown in.

Comparative Example 1 Barium carbonate (BaCO ₃ ), neodymium oxide (Nd ₂ O)
₃ ) and titanium oxide (TiO ₂ ) powders in a molar ratio as shown in Table 1, and a firing temperature of 1480.
A dielectric ceramic composition was produced in the same manner as in Example 1 except that the temperature was changed to ° C, and the physical properties were measured. The results are shown in Table 1. Comparative Examples 2-3 Barium carbonate (BaCO ₃ ), lead oxide (PbO), neodymium oxide (Nd ₂ O ₃ ), praseodymium acetate (Pr (CH ₃ C)
_{O 2) 3 · 2H 2 O} ), samarium oxide (Sm ₂ O _3), lanthanum oxide (La ₂ O _3), bismuth oxide (Bi
₂ O ₃ ) and titanium oxide (TiO ₂ ) powders are set to have a molar ratio as shown in Table 1, and the firing temperature is set to 13
A dielectric ceramic composition was produced in the same manner as in Example 1 except that the temperature was changed to 00 to 1400 ° C., and the physical properties were measured. The results are shown in Table 1.

[0015]

[Table 1]

[0016]

INDUSTRIAL APPLICABILITY The dielectric ceramic composition of the present invention has a large permittivity, a large no-load Q, and can control the temperature coefficient of the resonance frequency, and is used in dielectric resonator materials, particularly in the MHz to GHz band. It is suitable as a resonator material. In addition to the dielectric resonator material, the dielectric ceramic composition of the present invention can be applied to, for example, a dielectric substrate for microwave IC, a high frequency capacitor, a dielectric adjusting rod, and the like.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masataka Fujinaga 5 1978, Kozugushi, Ube City, Yamaguchi Prefecture, Ube Kosan Co., Ltd.

Claims (1)

[Claims] 1. A composition formula, (Ba _1-x Pb _x ) (Nd _{a
Pr b Sm c La d Bi e} ) 2 Ti 4 O 12 ( wherein, 0.
01 ≦ x ≦ 0.4, 0.05 ≦ a ≦ 0.95, 0.01
≤b≤0.80, 0≤c≤0.6, 0≤d≤0.3,
0.04 ≦ e ≦ 0.5, a + b + c + d + e = 1) A dielectric ceramic composition represented by barium, lead, neodymium, praseodymium, samarium, lanthanum, bismuth, titanium and oxygen.