JPH02188427A - Inorganic composition - Google Patents

Abstract

PURPOSE:To obtain an inorg. compsn. having a small particle size and suitable for a ceramic dielectric material in the form of titanate type perovskite contg. at least two kinds of alkaline earth metals by calcining a specified compd. and a Ti compd. CONSTITUTION:A compd. represented by formula I (where M is Sr and/or Ca and X is 0-1) is wet-mixed with a Ti compd. such as TiO2 and water. This mixture is dried and calcined at 900-1,030 deg.C for about 2hr to obtain an inorg. compsn. in the form of titanate type perovskite contg. at least two kinds of alkaline earth metals represented by formula II.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is directed to an inorganic titanate perovskite containing at least two types of alkaline earth metals, which is a type of dielectric material used in a wide range of fields. Regarding the composition.

<Prior art> In general, an inorganic composition having a perovskite structure is
A composition having a crystal structure similar to calcium titanate ore (perovskite), and by molding and sintering such a composition, it has properties such as dielectric, piezoelectric, semiconducting, insulating, and pyroelectric properties. Electronic ceramics with electrical functions can be obtained.

In recent years, they have been used in large quantities in electronic devices, such as capacitors and thermistors.

Conventionally, inorganic compositions having a perovskite structure are made by mixing carbonates or oxides such as -1CaSSrsBa5Pb and oxides such as '1SZr and Sn in the film;
It is manufactured by calcining at a temperature of about 1000°C, followed by wet pulverization, filtration, and drying.

<Problems to be Solved by the Invention> When producing an inorganic composition having a perovskite structure by a calcination method, powder raw materials of carbonates or oxides of the above several types of alkaline earth metals and powders of oxides such as Ti are used. The raw materials are mixed using a dry or wet method. However, it is difficult to obtain raw material powder with a uniform composition.

[δ] In order to complete the chemical reaction of the mixture, it is necessary to set the firing temperature during calcination high, which causes the problem that the particle size of the calcined product becomes coarse.

In order to solve the above-mentioned problems when producing an inorganic composition having a perovskite structure by a calcination method, the present inventors have developed a method using Ba SSr among alkaline earth metals.
Concerning carbonates containing at least two selected from s Ca, a novel alkaline earth metal carbonate compound different from the mixture of two or three types of alkaline earth metal carbonate compounds disclosed in Japanese Patent Application No. 1131841/1984 etc. When perovskite is produced by mixing and firing a similar metal carbonate compound and a titanium compound, the chemical reaction during calcination is approximately 50°C compared to when firing a mixture using the corresponding powder raw materials. We obtained the knowledge that the process can be completed at a relatively low temperature.

The present invention has been made based on the above findings, and an object of the present invention is to create an inorganic composition having a fine particle size suitable for use as a ceramic dielectric material because it can be calcined at a low temperature. It is about providing.

Means for Solving the Problems> The inorganic composition according to the present invention for achieving the above objects includes:
It has a perovskite structure represented by the following general formula (2) obtained by calcining a compound represented by the following general formula (1) and a titanium compound.

Ba M CO3・''(1) 1-x Ba M Tie3=42) l-x However, in the above general formulas (1) and (2), M is strontium (Sr) and/or calcium (Ca), and X is 0 or more and less than 1.

In addition to titanium oxide, the above titanium compounds include various titanic acids that produce titanium oxide when heated, titanium tetrachloride, titanium sulfate, and titanyl sulfate (TLOS O&
) etc.

The present invention also relates to titanium oxide obtained by adding aqueous ammonia, caustic alkali, alkali carbonate, etc. to an aqueous solution of titanium tetrachloride, titanium sulfate, etc. to neutralize it to form a precipitate, and then thermally decomposing the precipitate. It can be suitably used in the production of inorganic compositions.

<Example> Hereinafter, the present invention will be explained in more detail based on examples.

It should be noted that the present invention is not limited to the same extent by the following examples.

(Example 1) High purity barium strontium carbonate, Ba Sr CO30, as referred to in Japanese Patent Application No. 161841/1984, etc.
,500,50 17,25g' (Ignition loss equivalent weight, same applies below), High purity titanium oxide (manufactured by Sakai Chemical Industry Co., Ltd.) 7
．． 99 g and 15,011 g of pure water were wet mixed in a polyethylene ball mill equipped with zirconium oxide balls. Thereafter, this mixture slurry was filtered, dried, and then calcined at a temperature of 1030° C. for 2 hours. This calcined product was wet-pulverized again in the ball mill, filtered, and dried to obtain a fine powder.

The results of analyzing the fine particle powder obtained by the above operation by X-ray diffraction (copper target, nickel filter) are
As shown in the figure. In Figure 1, the vertical axis shows CPS (Count P
er 5econd), and 2θ (degrees) is plotted on the horizontal axis (the same applies to FIGS. 2 to 6 below). From the X-ray diffraction pattern shown in the same figure, this fine particle is a single-phase Ba of the cubic perovskite phase.
It was confirmed that it was SrTcOx (X-0,50 is based on the chemical analysis results).

In addition, a transmission electron micrograph of the above-mentioned fine particles (magnification: 1
000 times) is shown in FIG. From the micrograph shown in the same figure, it was found that the fine powder was composed of fairly uniform fine particles with a particle size of around 0.7 μm.

Furthermore, the relationship between weight loss and temperature was determined using the mixed powder before calcination, and is shown as a solid line in FIG.

(Example 2) High purity strontium carbonate was prepared in the same manner as in Example 1.
Calcium Sr Ca CO314,050,
850.15 g, high purity titanium oxide 7.99 g and pure water 15011
A calcined fine particle powder was obtained using the following method.

Calcining was performed at a temperature of 900° C. for 2 hours.

The fine particle powder obtained by the above operation is
From the results of line diffraction analysis, a single phase S of cubic perovskite phase was detected.
Confirmed that it is r Ca TL 03 011
5 0.15 I was able to do it. The particle size was approximately 0.5 μm.

Furthermore, the relationship between weight loss and temperature was determined using the mixed powder before calcination, and is shown as a solid line in FIG.

(Example 3) In the same manner as in Example 1, 16,80 g of high-purity barium/strontium/calcium carbonate Ba Sr Ca CO, 7.99 g of high-purity titanium chloride, and 150 g of pure water were added. A calcined fine particle powder was obtained using II.

Calcining was performed at a temperature of 1000° C. for 2 hours.

The fine particle powder obtained by the above operation is
Based on the results of line diffraction analysis, BaS with perovskite structure
It can be confirmed that r Ca Ti 03 is 0
．． 60 0.20 0.20. The particle size was approximately 0.7 μm.

Furthermore, the relationship between weight loss and temperature was determined using the mixed powder before calcination, and is shown as a solid line in FIG.

(Comparative Example 1) Ba Sr CXJs used in Example 1
0.50 0.50 A single carbonate compound, namely high purity barium carbonate (
(manufactured by Sakai Chemical Industry Co., Ltd.) 9.87 g, high purity strontium carbonate (manufactured by Sakai Chemical Industry Co., Ltd.) 7.38 g, and high purity titanium oxide 7
．． A comparative test was conducted in the same manner as in Example 1 using 99 g and 15,011 g of pure water. Calcination was performed at a temperature of 1100° C. for 2 hours, based on the heating loss measurement results shown by the broken line in FIG. 9.

Further, from the X-ray diffraction analysis results shown in FIG. 2, it was confirmed that the sample had a cubic perovskite phase as in Example 1.

Furthermore, an electron micrograph (magnification: 100
It was found that the particle size was approximately 1.1 μl, which was slightly larger than that of Example 1.

(Comparative Example 2) In the same manner as Comparative Example 1, a comparative test for Example 2 was conducted.

As a raw material, 12.55g of high-purity strontium carbonate,
High purity calcium carbonate (manufactured by Nippon Lime Kogyo Co., Ltd.) 1.50
g, 7.99 g of high purity titanium oxide and 150 x pure water
l was used.

Based on the heating loss measurement results shown by the broken line in Figure 10, calcination is as follows.
The test was carried out at a temperature of 950° C. for 2 hours.

It was confirmed that the X-ray diffraction analysis results shown in FIG. 4 were the same as the results shown in FIG. 3 obtained in Example 2. Moreover, the particle size was about 1.0 μm.

(Comparative Example 3) A comparative test for Example 3 was conducted in the same manner as Comparative Example 1.

As a raw material, BaCO311, 84g 5SrCO32
,95g5CaCO32,00g1 piece,827.99g
and pure water 15011 were used.

Calcination was performed at a temperature of 1070° C. for 2 hours based on the heating area ff1i9J results shown in FIG. 11.

It was confirmed that the X-ray diffraction analysis results shown in FIG. 6 were the same as the results shown in FIG. 5 obtained in Example 3. Moreover, the particle size was about 1.5 μm.

From the above Examples 1 to 3 and Comparative Examples 1 to 3, it is clear that the perovskite structure which is a titanate containing two or three types of alkaline earth metals according to the above patent application No. 82-1 [11B41 etc. The inorganic compositions unexpectedly calcinate at about 50° C. lower than similarly prepared inorganic compositions using mixtures of two or three single carbonate compounds of the corresponding alkaline earth metals. It was found that a dense sintered body with small grain size could be obtained by this method.

Therefore, by using the inorganic composition according to the present invention, excellent electrical properties are expected in the production of ceramic halt bodies, and it is possible to reduce production costs by saving thermal energy.

Further, other components may be added to the inorganic composition according to the present invention. For example, it can be made into a semiconductor by doping with positive, Y, etc. Also, a so-called mineralizing agent such as 101St 02 may be added.

Furthermore, 1-x M in the above general formula (Ba M TLOx) can be replaced with an element of 21 ali such as 11 yen, and all or part of T can be replaced with 4 such as Zr s ST1.
It is well known that it can be replaced with a valent element.

<Effects of the Invention> As detailed above, the inorganic composition according to the present invention can be obtained by calcining at a lower temperature than conventional inorganic compositions, so it can be used as a fine material suitable for use as a ceramic dielectric material, for example. The present invention exhibits excellent and unique effects such as having a particle size of

[Brief explanation of the drawing]

Figures 1, 3 and 5 are X-ray diffraction diagrams of inorganic compositions according to the present invention, and Figures 2, 4 and 6 are X-ray diffraction diagrams of corresponding comparative test compositions, respectively. 7 is a transmission electron micrograph of an inorganic composition according to the present invention, FIG. 8 is a transmission electron micrograph of a corresponding comparative test product composition, and FIGS. 9 to 11 are transmission electron micrographs of an inorganic composition according to the present invention. 1 is a graph showing the relationship between temperature and weight loss for an inorganic composition and a corresponding comparative test product composition. Patent applicant: Sakai Chemical Industry Co., Ltd. Fig. Each column 2 of the brief explanation, title of the invention, No. 10354, 1999, 7゜ Contents of amendment (1) "The above-mentioned fine particles
......1000x)" was replaced with "Transmission electron micrograph showing the particle structure of the above-mentioned fine particles (magnification: 1
000 times),” he corrected. (2 Ibid., page 8, lines 10-11, “Show...
...from an electron micrograph (magnification: 1000 times)" is corrected to "From an electron micrograph (magnification: 1000 times) of the particle structure shown." (3) The relationship between the same book, page 11, lines 10 to 12 of the [Inorganic composition...... Electron microscopy 36 correction person case]

Claims (1)

[Claims] 1. An inorganic composition having a perovskite structure represented by the following general formula (2) obtained by calcining a compound represented by the following general formula (1) and a titanium compound. Ba_XM_1_-_XCO_3...(1) Ba_X
M_1_-_XTiO_3...(2) However, in the above general formulas (1) and (2), M is strontium (Sr) and/or calcium (Ca), and X is 0 or more and less than 1.