JPH0628919A - Dielectric porcelain composition - Google Patents

Abstract

PURPOSE:To provide a dielectric porcelain composition having a high dielectric constant, a large quality coefficient Q, and a temperature coefficient tauf of resonance frequency of almost zero, and suitable for a microwave region. CONSTITUTION:A titanium, barium, lead, lanthanum, samarium, and gadolinium dielectric porcelain composition is expressed by a formula: a.{(1-w).BaO, w.PbO}.b.TiO2.c.{x.La2O3, y.Sm2O3, z.Gd2O3}, wherein (a), (b), (c), (w), (x), (y), and (z) represent mole ratios; a+b+c=1; 0.1<a<0.2; 0.6<b<0.8; 0.1<c<0.2; 0.001<w<0.25; x+y+z=1; 0.02<x<0.75; 0.02<y<0.95; and 0.02<z<0.55.

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 and the like, and in addition to the dielectric resonator material, for example, a dielectric substrate for microwave IC, a dielectric adjusting rod and an organic material. It is also applied to the raw material of the composite material with.

[0002]

2. Description of the Related Art Recently, dielectric resonators have been widely used in mobile radios such as car phones and cordless phones that use radio waves in the microwave band from MHz band to GHz band. The dielectric ceramic composition used for such a dielectric resonator has characteristics such as a large relative permittivity εr, a small temperature coefficient τf of the resonance frequency, and a large quality coefficient Q (no load Q ₀ ). Is required.

Conventionally, as such a dielectric ceramic composition
It is known that TiO ₂ , MgO-CaO-TiO ₂ , ZrO ₂ -TiO ₂ -SnO ₂ , BaO-TiO ₂ etc. are the main components, but they have a large temperature coefficient or a quality factor in the microwave band. Since Q is small, it is difficult to put it into practical use.

Also, a proposal for a BaO-TiO ₂ -Nd ₂ O ₃ -based dielectric ceramic composition {Ber. Dt. Keram. Ges. 55 (1978) N
o. 7; Japanese Patent Laid-Open No. 60-35406, etc.}, but the quality factor Q is small and the relative dielectric constant εr is also small, which is not sufficient.

In addition, Ba (Mg _1/3 , Ta _2/3 ) O ₃ and Ba (Zn _1/3 , Ta
_2/3 ) O ₃ , Ba (Zn _1/3 , Nb _2/3 ) O ₃ -based dielectric ceramic compositions having a perovskite structure have been proposed, but their relative permittivity is small (relative permittivity). εr = about 25-40)
For example, when using a resonator used in the 0.1 to 4 GHz band,
There is a problem that the resonator cannot be downsized sufficiently.

As a means for solving this problem, Japanese Patent Laid-Open No.
62-72558 discloses a BaO—TiO ₂ —Nd ₂ O ₃ —BiO _2/3 based dielectric ceramic composition. Its characteristics are relative permittivity εr of 80 to 83, quality factor Q of 1900 to 2650, and τf of 3 to.
Although it is considerably improved to 10, it is still insufficient, and development of a dielectric ceramic composition having further excellent properties is desired.

[0007]

As described above,
In the conventional dielectric ceramic composition, any one of the characteristics that should be provided as a dielectric resonator material that has been recently required,
That is, the relative permittivity εr and the quality factor Q are higher,
In addition, there is a problem that there is no material that also has a small τf. The present invention has been made in view of these problems, and an object thereof is to provide a dielectric ceramic composition having a higher relative permittivity εr and a quality factor Q and a smaller τf. is there.

[0008]

[Means for Solving the Problems] In order to solve the above problems, as a result of extensive studies on the composition of dielectric ceramics, a part of barium was replaced by lead, and lanthanum, samarium and gadolinium were used to obtain an excellent dielectric property. It was found that the body was obtained, and the present invention was completed. That is, the present invention relates to the composition formula a · {(1-w) · BaO, w · PbO} ·.
b ・ TiO ₂・ c ・ {x ・ La ₂ O ₃ , y ・ Sm ₂ O ₃ , z ・ Gd ₂ O ₃ }
(In the formula, a, b, c, w, x, y, z are molar ratios, and a + b + c = 1
, 0.1 <a <0.2, 0.6 <b <0.8, 0.1 <c <0.2, 0.001 <w <0.2
5, x + y + z = 1, 0.02 <x <0.75, 0.02 <y <0.95, 0.02 <z <
0.55) is a titanium, barium, lead, lanthanum, samarium, and gadolinium-based dielectric ceramic composition.

The present invention will be described in more detail below. The characteristics of the present invention reside in the use of barium, lead, titanium, lanthanum, samarium and gadolinium, and the composition ratio thereof, and are particularly characterized in barium, lead and lanthanum, and samarium and gadolinium. That is, BaO and Pb
The total molar ratio a of O is 0.1 <a <0.2, and BaO and PbO
The ratio of w is 0.001 <w <0.25, and La ₂ O ₃ and Sm ₂ O
The total molar ratio c of ₃ and Gd ₂ O ₃ is 0.1 <c <0.2,
X indicating the ratio of La ₂ O ₃ is 0.02 <x <0.75, y indicating the ratio of Sm ₂ O ₃ is 0.02 <y <0.95, z indicating the ratio of Gd ₂ O _3.
However, due to the composition represented by 0.02 <z <0.55, the quality factor Q 5820 to 6240, the relative permittivity εr 87 to 93, and the temperature coefficient τf of the resonance frequency are excellent in the microwave band of -4 to +5. A dielectric material is obtained.

The reason for limiting the composition range is as follows. a
When BaO is 0.1 or less, the relative dielectric constant εr is small, and when it is 0.2 or more, the quality factor Q is low, which is not preferable. Therefore,
a is in the range of 0.1 <a <0.2, more preferably 0.12 <a
<0.18. b is in the TiO ₂ is 0.6 or less sinterability is lowered, unfavorably large temperature coefficient τf of the resonance frequency is 0.8 or more. Therefore, b is in the range of 0.6 <b <0.8, and more preferably 0.64 <b <0.76. c is 0.1
Below, the relative permittivity εr is small, and above 0.2, both the relative permittivity εr and the quality factor Q are small, which is not preferable. Therefore, c is in the range of 0.1 <c <0.2, and more preferably 0.12 <c <0.18.

When w is 0.001 or less, the relative dielectric constant εr does not increase, and when w is 0.25 or more, the quality factor Q decreases, which is not preferable. Therefore, w is in the range of 0.001 <w <0.25, and more preferably 0.01 <w <0.2. When x is 0.02 or less or 0.75 or more, the temperature coefficient τf of the resonance frequency becomes large, which is not preferable. Therefore, x is in the range of 0.02 <x <0.75, and more preferably 0.05 <x <0.65. y is 0.
Below 02 or above 0.95, the temperature coefficient of resonance frequency τ
f becomes large, which is not preferable. Therefore, y is 0.02 <y
The range is <0.95, and more preferably 0.1 <y <0.95. When z is 0.02 or less or 0.55 or more, the temperature coefficient τf of the resonance frequency becomes large, which is not preferable. Therefore,
z is in the range of 0.02 <z <0.55, more preferably 0.02
<z <0.45.

The dielectric porcelain composition according to the present invention has only to finally become an oxide porcelain composition, and the production method thereof is usually performed such that barium (Ba), lead (Pb), titanium (Ti). , Oxides such as lanthanum (La) samarium (Sm) and gadolinium (Gd) or starting materials that become oxides by thermal decomposition of carbonates, basic carbonates, nitrates, hydroxides and organic acid salts Then, it can be manufactured by a method such as firing. In some cases, the starting raw materials may be mixed and calcined, and then the obtained calcined powder may be put into practical use by being combined with an organic material or the like as it is.

Next, a method of forming and sintering after mixing the starting materials and calcining (method applied in applications such as resonators) will be described. First, the starting materials are mixed in predetermined amounts. At the time of mixing, a method having a high mixing property such as a method of wet mixing with water, alcohol, other organic solvent or the like is preferable. When wet mixing is performed, the solvent is removed and then the obtained mixture is calcined. The calcination is preferably performed at a temperature of about 900 to 1300 ° C. in an oxygen gas-containing atmosphere such as an air atmosphere. If the calcination temperature is lower than 900 ° C, the solid-state reaction due to calcination is not promoted, and the calcination temperature is
If the temperature exceeds 1300 ° C, the calcined powder agglomerates and the powder properties deteriorate, which is not preferable.

The calcined material obtained is crushed and then molded.
As a molding method, pressure molding, extrusion molding, sheet molding, injection molding and the like, which are general ceramic powder molding methods, are applied. At this time, usual organic binders such as polyvinyl alcohol, and additive components such as a plasticizer and a dispersant are added as necessary. The obtained molded body is sintered. Sintering is preferably performed at a temperature of about 1300 to 1600 ° C. in an oxygen gas-containing atmosphere such as an air atmosphere.

The sintered body of the dielectric ceramic composition thus obtained is processed as it is, or if necessary, processed into an appropriate shape and size to obtain a dielectric resonator, a dielectric substrate for microwave IC and a dielectric. It can be used as a material for body adjusting rods and the like, and exhibits an excellent effect particularly when used as a dielectric resonator used in the 0.1 to 4 GHz band.

[0016]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples. [Examples 1 to 21 and Comparative Examples 1 to 10] High purity BaCO ₃ as a starting _{material, Pb 3 O 4, TiO 2} , La 2 O 3, Sm 2 O 3, Gd 2 O 3 powder with Table 1 After being weighed so as to have a predetermined composition ratio shown in, the mixture was wet-mixed for 20 hours using a ball mill. After heating and drying this slurry, it was dried in air at a temperature of 1050 ° C for 2 hours.
Calcined for a period of time, and the resulting calcined product is again used with a ball mill.
It was wet-milled for 20 hours. The obtained slurry was dried by heating, then an appropriate amount of polyvinyl alcohol was added and kneading was performed, and the mixture was granulated with a 32 mesh sieve. Pressure for forming granulated powder
Pressure-molded at 800 kg / cm ² , and temperature in air 1300 ° C ~
It was baked at 1500 ° C for 5 hours.

The sintered body thus obtained has a diameter of about 10 mm and a height of about 4 mm.
It was processed into a cylindrical shape of mm. The characteristics of this sintered body were evaluated by the transmission method using a cavity type resonator in the GHz band εr, quality factor Q,
τf was measured. The measurement is a Yokogawa Hewlett-Packard network analyzer (model number: YHP 851
No. 0) and a measuring jig manufactured by Murata Manufacturing Co., Ltd. (model number: DRG 8553). As the resonance mode, TE01δ mode was used. The resonance frequency of the sample was 3 to 4 GHz.
In general, when measuring the dielectric properties in the GHz band, the measured values often differ depending on the measuring method, and it is necessary to give due consideration to the measuring method when comparing the measured values. In particular, care must be taken when measuring the quality factor Q. Regarding the temperature dependence of the resonance frequency fo, from -30 ℃
The temperature coefficient τf was obtained by measuring in the range of + 80 ° C. The experimental results are shown in Table 1. The value of the quality factor Q in the table is converted to a value at 1 GHz by using the relational expression fo × Q = constant relation between the resonance frequency fo and the quality factor Q.

[0018]

[Table 1]

[0019]

The dielectric porcelain composition of the present invention contains, in addition to barium and titanium, lead, lanthanum, samarium, and gadolinium as main components, thereby obtaining a relative dielectric constant ε.
It has a high r, a large quality factor Q, a good stability of τf, is particularly suitable as a dielectric material used in the 0.1 to 4 GHz band, and exhibits excellent effects.

Front page continuation (72) Inventor Ameya Kohei 3-5-1, Asahimachi, Machida-shi, Tokyo Denka Kagaku Kogyo Co., Ltd.

Claims (1)

[Claims] 1. Compositional formula a. {(1-w). BaO, w. PbO}.
b ・ TiO ₂・ c ・ {x ・ La ₂ O ₃ , y ・ Sm ₂ O ₃ , z ・ Gd ₂ O ₃ }
(In the formula, a, b, c, w, x, y, z are molar ratios, and a + b + c = 1
, 0.1 <a <0.2, 0.6 <b <0.8, 0.1 <c <0.2, 0.001 <w <0.2
5, x + y + z = 1, 0.02 <x <0.75, 0.02 <y <0.95, 0.02 <z <0.
55) A titanium, barium, lead, lanthanum, samarium, gadolinium-based dielectric ceramic composition represented by 55).