JPH0612915A - Dielectric porcelain composition and its manufacture - Google Patents

Abstract

PURPOSE:To provide a dielectric porcelain composition, in which the permittivity is high and the quality coefficient Q is large and the temperature coefficient tauf is approximately 0 and which is suitable for a microwave region, and its manufacture. CONSTITUTION:This is a titanium, barium, praseodymium, neodymium, samarium, gadolinium dielectric porcelain composition being expressed by composition formula a.BaO.b.TiO2.c.{1.Pr2O11/3, m.Nd2O3, n.Sm2O3, o.Gd2O3} (among the formula, for a, b, c, l, m, n, and o, a+b+c=1, 0.1<a<0.2, 0.6<b<0.8, 0.1<c<0.2, 0.97<=l+m+n+o<=1, 0.005<l<0.20, 0.015<m<0.70, 0.02<n<0.95, 0.01<o<0.70) by mol ratio). And, the dielectric porcelain composition is manufactured, using a light rare earth mixture being obtained by extraction and separation process out of the original ore including a rare earth element, as the material of a rare earth element.

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 a method for producing the same.
In addition to the dielectric resonator material, the present invention is also applied to, for example, a dielectric substrate for microwave IC, a dielectric adjusting rod, a raw material of a composite material with an organic material, and the like.

[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 utilize radio waves in the microwave band from the MHz band to the GHz band.
The dielectric ceramic composition used for such a dielectric resonator has a large relative permittivity εr, a small temperature coefficient τf of resonance frequency, and a large quality coefficient Q (no load Q ₀ ). Characteristics are required.

Conventionally, as such a dielectric ceramic composition
_{TiO2, MgO-CaO-TiO 2} , ZrO 2 -TiO 2 -SnO 2, BaO-TiO 2, etc. is mainly composed are known, or large temperature coefficient, the 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 and 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). .epsilon.r = about 25 to 40), there is a problem that the resonator cannot be sufficiently miniaturized when it is used as a resonator used in the 0.1 to 4 GHz band, for example.

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 that the relative permittivity εr is 80 to 83, the quality factor Q is 1900 to 2650, and τf is 3
Although it is considerably improved to ~ 10, it is still insufficient and development of a dielectric ceramic composition having excellent characteristics is desired. Further, when a rare earth element is included as a part of the dielectric ceramic composition, it is general to use each rare earth oxide as a raw material, but the rare earth oxide raw material is expensive and practically used. Was the problem.

[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, there is a problem that there is no material having a higher relative permittivity εr and a higher quality factor Q and a smaller 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, and a method for producing the same. To provide.

[0008]

[Means for Solving the Problems] In order to solve the above problems, as a result of extensive studies on the composition of dielectric porcelain, it was found that an excellent dielectric can be obtained by using praseodymium, neodymium, samarium and gadolinium. The invention was completed. That is, the first invention, the composition formula _{a · BaO · b · TiO 2} · c · {l · Pr 2 O 11/3 · m ·
Nd ₂ O ₃ · n · Sm ₂ O ₃ · o · Gd ₂ O ₃ } (in the formula, a, b,
c, l, m, n, o are molar ratios, a + b + c = 1, 0.1 <a <
0.2, 0.6 <b <0.8, 0.1 <c <0.2, 0.97 ≦ l + m + n + o
≤ 1, 0.005 <l <0.20, 0.015 <m <0.70, 0.02 <n <0.9
5, 0.01 <o <0.70), which is a titanium, barium, praseodymium, neodymium, samarium, or gadolinium-based dielectric ceramic composition.

The first invention will be described in more detail below. The feature of the present invention resides in the use of barium, titanium, praseodymium, neodymium, samarium and gadolinium, and the composition ratio thereof, but is particularly characterized in praseodymium, neodymium, samarium and gadolinium. That is, the total molar ratio of Pr ₂ O _11/3 , Nd ₂ O ₃ , Sm ₂ O ₃ and Gd ₂ O _3.
c is 0.1 <c <0.2, and l indicating the ratio of Pr ₂ O _11/3 is 0.
005 <l <0.20, m showing the ratio of Nd ₂ O ₃ is 0.015 <m <0.70,
The quality factor Q5 750 to 6080 and the relative permittivity εr 87 due to the composition where n indicating the ratio of Sm ₂ O ₃ is 0.02 <n <0.95 and o indicating the ratio of Gd ₂ O ₃ is 0.01 <o <0.70. It is possible to obtain an excellent dielectric material suitable for a microwave band having a temperature coefficient .tau.f of .about.91 and a resonance frequency of -3 to +3.

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, and more preferably 0.12 <a <
It is 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 <b <0.2, and more preferably 0.12 <c <0.18.

When l is 0.005 or less or 0.20 or more, the temperature coefficient τf of the resonance frequency becomes large, which is not preferable. Therefore, l is in the range of 0.005 <l <0.20, and more preferably 0.005 <l <0.15. m is 0.015 or less or 0.70
In the above case, the temperature coefficient τf of the resonance frequency becomes large, which is not preferable. Therefore, m is in the range 0.015 <m <0.70, and
More preferably, 0.02 <m <0.50. When n is 0.02 or less or 0.95 or more, the temperature coefficient τf of the resonance frequency becomes large, which is not preferable. Therefore, n is in the range of 0.02 <n <0.95, and more preferably 0.02 <n <0.90. o is
Below 0.01 or above 0.70, the temperature coefficient of resonance frequency τ
f becomes large, which is not preferable. Therefore, o is 0.01 <o
The range is <0.70, and more preferably 0.02 <o <0.65.

The dielectric porcelain composition according to the present invention has only to finally become an oxide porcelain composition.
Barium (Ba), titanium (Ti), praseodymium (Pr) neodymium (Nd), samarium (Sm) and gadolinium (G
d) or other oxides, or carbonates, basic carbonates, nitrates, hydroxides, organic acid salts, and the like, which can be produced by a method of mixing and firing starting materials that become oxides by thermal decomposition . 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.

Further, the second invention is characterized in that a light rare earth mixture obtained from the raw ore containing rare earth elements in the extraction and separation step is used as the whole or a part of the starting materials of Pr and / or Nd. is there. The light rare earth mixture referred to here is a mixture obtained in the extraction step when producing rare earth elements by refining raw ores such as monazite and bastnasite containing rare earth elements in the processes of beneficiation, extraction and separation. , Praseodymium and neodymium as main components, and a compound or mixture containing yttrium, lanthanum, samarium and the like.

This light rare earth mixture contains praseodymium and neodymium, which are the main components of the rare earth used in the composition of the dielectric porcelain composition of the first invention, and further the dielectric porcelain composition of the first invention. The composition of the product is a composition suitable for using the composition of the light rare earth mixture as it is. Therefore, the light rare earth mixture can be used as it is as a part of the raw material of the first invention, it is not necessary to separate and purify each element, which is very advantageous in industrial production, and also praseodymium oxide, neodymium oxide and samarium oxide. Molar ratio of
Since the sum of l, m, n, and o is not always 1, and trace amounts of compounds of other elements contained in this light rare earth mixture, such as lanthanum oxide and yttrium oxide, can be included in the composition, impurities rare earth components are included in the composition. It is possible to manufacture dielectric porcelain with excellent characteristics even if included in, and the composition has a large allowable range, which is advantageous in production control. In addition, the composition of the first invention can be added and adjusted as a rare earth raw material separated and purified.

Also when the light rare earth mixture is used as a raw material, the usual method for producing a dielectric ceramic composition can be applied as described above. That is, the starting materials are weighed and mixed to obtain the target composition, calcined, and then molded,
An example is a method of sintering (a method applied in applications such as a resonator). Next, this method 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 carried out in an atmosphere containing oxygen gas such as an air atmosphere at a temperature of about 900 to 1300 ° C. If the calcination temperature is lower than 900 ° C., the solid-phase reaction due to calcination is not promoted, and if the calcination temperature exceeds 1300 ° C., the calcination powder agglomerates and the powder characteristics deteriorate, which is not preferable.

The resulting calcined product is crushed and then molded. As a molding method, pressure molding, extrusion molding, sheet molding, injection molding and the like, which are general methods for molding ceramic powder, 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, is processed into a suitable 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.

[0018]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples. [Examples 1 to 17 and Comparative Examples 1 to 12] High purity BaCO ₃ as a starting _{material, Pb 3 O 4, TiO 2} , Sm 2 O 3, Gd 2 O 3 powder and Pr
As the raw materials for Nd and Nd, Pr ₆ O ₁₁ is 22.6 wt% and Nd ₂ O ₃ is 76.4 wt%.
%, Sm ₂ O ₃ 0.53 wt%, La ₂ O ₃ 0.37 wt%
, A light rare earth mixed oxide powder containing 0.1 wt% of Y ₂ O ₃ was used.
In addition, although the light rare earth mixed oxide powder was mainly used also in the comparative example, the deficiency of the Pr ₂ O _11/3 or Nd ₂ O ₃ composition was adjusted by adding each of the individual oxide raw materials.
These starting materials were weighed so as to have the predetermined composition ratio shown in Table 1, and then the starting materials were wet mixed for 20 hours using a ball mill. After this slurry was dried by heating, it was calcined in air at a temperature of 1050 ° C. for 2 hours, and the obtained calcined product was wet-ground again for 20 hours using a ball mill. 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. The granulated powder was pressure-molded at a molding pressure of 800 kg / cm ² and fired in air at a temperature of 1350 ° C to 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. Regarding the characteristics of this sintered body, εr, quality factor Q and τf were measured in the GHz band by a transmission method using a cavity type resonator. The measurement is a Yokogawa Hewlett-Packard network analyzer (model number: YHP 85
10) and a measuring jig manufactured by Murata Manufacturing Co., Ltd. (model number: DRG 8553). The resonance mode used was the TE01δ mode. The resonance frequency of the sample was 3 to 4 GHz.
In general, when measuring 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 methods 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.

[0020]

[Table 1]

[0021]

The dielectric porcelain composition of the present invention has a high relative permittivity εr and a high quality factor Q by using praseodymium, neodymium, samarium and gadolinium as main components in addition to barium and titanium. The stability of τf is good, and it is particularly suitable as a dielectric material used in the 0.1 to 4 GHz band and exhibits excellent effects. Furthermore, by using a light rare earth mixture as a part of the starting material, the range of the main component composition of rare earth elements is widened, quality control is facilitated, and it can be manufactured at low cost, which is very advantageous in industrial production. is there.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ameya Kohei 3-5-1, Asahimachi, Machida-shi, Tokyo Denka Kagaku Kogyo Co., Ltd.

Claims (2)

[Claims] 1. The composition formula: a.BaO.b.TiO ₂ .c. {L
・ Pr ₂ O _11/3・ m ・ Nd ₂ O ₃・ n ・ Sm ₂ O ₃・ o ・ Gd ₂ O ₃ }
(In the formula, a, b, c, l, m, n, and o are molar ratios, and a +
b + c = 1, 0.1 <a <0.2, 0.6 <b <0.8, 0.1 <c <0.2, 0.97 ≦
l + m + n + o ≦ 1, 0.005 <l <0.20, 0.015 <m <0.70
, 0.02 <n <0.95, 0.01 <o <0.70), titanium, barium, praseodymium, neodymium, samarium,
Gadolinium-based dielectric ceramic composition. 2. The method for producing a dielectric porcelain composition according to claim 1, wherein a light rare earth mixture obtained from an ore containing rare earth elements in an extraction and separation step is used as a raw material for rare earth elements.