JPS61261217A - Production of magnetoplumbite-type ferrite powder - Google Patents

Abstract

PURPOSE:To obtain the titled ferrite powder having fine particle size, uniform composition and high purity, by hydrolyzing a ferrous alkoxide and other bivalent metal alkoxide, oxidizing the product, and calcining the produced oxide. CONSTITUTION:A mixture of a ferrous alkoxide and alkoxide of one or more kinds of bivalent metals selected from Ba, Sr and Pb is hydrolyzed in nitrogen stream at 0-100 deg.C by dripping water to the mixture. The obtained hydrolysis product is oxidized by passing oxygen or an oxygen-containing gas through the suspension of the product. The oxidized product is separated and calcined at 700-1,000 deg.C to obtain the objective magnetoplumbite-type ferrite powder having an impurity content of <=0.1% and particle diameter of 0.06-0.3mum.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides magnetoplumbite (l
The present invention relates to a method for producing agnetaplu layer (bite) type ferrite powder. More specifically, the present invention relates to a method for producing magnetoplumbite-type ferrite powder suitable as a magnetic material.

[Prior Art] It has been known that ferrite powder having an acute pyramidal hexagonal system, such as magnetoplumbite ferrite, has excellent magnetic properties and can therefore be used as a magnetic material.

Conventionally, the method for producing magnetoplumbite-type ferrite powder used for this type of material is to uniformly mix divalent metal carbonate and iron oxide, and then process the mixture to 130%
There is a method of calcining at a high temperature of 0° C. or higher to cause a solid phase reaction, and then pulverizing.

[Problems to be solved by the invention] In recent years, electronic parts have been required to be smaller and have more advanced characteristics, and therefore the raw material powder used for them has also become smaller.
More than ever before, it has become necessary to have fine particles with uniform composition and high purity.

However, when the magnetoplumbite-type ferrite powder obtained by the above conventional method is observed microscopically,
The particle size increases due to high-temperature calcination, and the composition becomes inhomogeneous due to the solid phase reaction, making it difficult to stabilize its properties.

Further, there is a problem that impurities are easily mixed in during manufacturing, and the properties as a magnetic material are deteriorated.

An object of the present invention is to provide a method for producing magnetoplumbite-type ferrite powder with a uniform composition, high purity, and fine particles at a relatively low temperature.

[Means for solving the problems] The present invention involves hydrolyzing a ferrous alkoxide and an alkoxide of a divalent metal other than ferrous, oxidizing the hydrolyzed product, and then calcining the product. This is a method for obtaining magnetoplumbite type ferrite powder.

The divalent metal is preferably one or more metals selected from Ba, Sr, and Pb because they form magnetoplumbite, and the hydrolysis of the alkoxide is performed so that the alkoxide does not decompose and It is preferable to carry out the treatment in a temperature range of 0 to 100°C, which is easy to handle. Further, the oxidation of the hydrolyzed product is preferably carried out at a temperature range of 0 to 200°C at which the hydrolyzed product does not decompose.

In this specification, "alkoxide" refers to a compound in which the hydrogen atom of the OH group of an alcohol is replaced with a metal atom.

The starting materials of the present invention are ferrous alkoxides and divalent metal alkoxides. This divalent metal alkoxide is
It is an alkoxide of a divalent metal other than ferrous iron. F
Other divalent metals other than e are preferably l or two or more metals selected from Ba, Sr, and Pb that form magnetoplumbite, ferrous alkoxide and other divalent metals other than ferrous iron. The hydrolysis of the alkoxide simultaneously hydrolyzes ferrous alkoxide and alkoxides of divalent metals other than ferrous.

This hydrolysis is preferably carried out in a nitrogen stream to prevent oxidation of ferrous iron, and it can also be carried out by directly adding water to the solution (water vapor blown out from a pressurized container). The reaction temperature for hydrolysis is preferably 0 to 100°C, and particularly preferably 25 to 100°C, since the alkoxide does not decompose in the absence of pressure and is easy to handle. 1
It is 00℃. In the case of applying pressure or contacting with a steam stream, a temperature of 100 to 200°C is appropriate.

The above-mentioned oxidation of the hydrolysis product is carried out by passing oxygen or a gas containing oxygen and another gas, such as air, through the suspension of the hydrolysis product.

Oxidation conditions vary depending on the type and combination of starting materials or the type of target substance.

After completing the specified oxidation, the hydrolyzed product is separated from the hydrolyzed liquid by centrifugation or filtration, dried by vacuum drying if necessary, and calcined at 700°C to 1000°C to form fine powder. is obtained.

When the structure of the hydrolyzed product obtained by the above reaction and the powder calcined at around 700°C was examined by X-ray diffraction, it was found that the hydrolyzed product was amorphous, and the calcined powder was crystalline magnetopran. Indicated by bite-type ferrite powder. According to electron microscopy, the particle size of this magnetoplumbite-type ferrite powder was 0.08 pm when calcined at 700°C.
, 1000''C(7) calcined to produce fine particles of 0.1 to 0.3 gm.The higher the calcining temperature, the more interaction occurs between particles due to grain growth, and the composition tends to vary.

Furthermore, chemical analysis of the obtained magnetoplumbite-type ferrite powder revealed that each particle was extremely uniform, with almost the same composition as the prepared one, and contained no impurities.
．． It is a highly pure substance of 1% or less.

[Effects of the Invention] As described above, according to the present invention, after hydrolyzing a ferrous alkoxide and an alkoxide of a divalent metal other than ferrous and oxidizing the hydrolyzed product, By calcining to obtain magnetoplumbite-type ferrite powder, there is an excellent effect that magnetoplumbite-type ferrite powder with fine particles and extremely uniform composition can be manufactured with high purity.

[Examples] Next, in order to show specific embodiments of the present invention, the present invention will be explained in more detail using Examples, but the examples shown below are merely examples, and do not limit the technical scope of the present invention. It's not something you do.

<Example 1> Anhydrous FeCIt 1. OOg and BaC1z 0.14g
was dissolved in 100 mJl of dehydrated ethanol, and 0.39 g of stoichiometric sodium metal was added to this solution, followed by reaction at 70° C. for 1 hour under reflux. A substitution reaction was carried out to obtain ferrous ethoxide Fe(OEt)2 and barium ethoxide Ba(OEt)2.

100 ml of decarboxylated distilled water was added dropwise to the thus obtained Fe(OEt)2 and Ba(OEt)z,
Hydrolysis in a nitrogen stream produced a precipitate.

While the temperature of the suspended solution containing the precipitate was kept at 70° C., air was passed through the suspended solution at a flow rate of 200 m JL/win for 2 hours to perform air oxidation of the precipitate. After separating and washing this air-oxidized precipitate from the hydrolyzate by filtration,
It was dried at 70°C for 1 hour to obtain a powder.

When the structure of the obtained powder was examined by X-ray diffraction, it was found that the dried powder was amorphous, and B
It was a magnetoplumbite type ferrite powder designated as aFetz OII.

<Example 2> 1.00 g of anhydrous FeCl and 10 g of 5rCh O were dissolved in 100 m i of dehydrated ethanol, and 0.39 g of metallic sodium in a stoichiometric ratio was added to this solution, and the mixture was refluxed at 70°C for 1 hour. I reacted while doing so. A substitution reaction was carried out to yield ferrous ethoxide Fe(OEt) 2 and strontium ethoxide 5r(OEt) 2 .

When the thus obtained Fe(OEt)2 and 5r(OEth) were hydrolyzed in the same manner as in Example 1, a precipitate was generated.This precipitate was air oxidized in the same manner as in Example 1.This air oxidized precipitate It was separated and washed from the hydrolyzate by filtration, and then dried at 70°C for 1 hour to obtain a powder.

When the structure of the obtained powder was investigated by X-ray diffraction, it was found that the dried powder was amorphous, and that it was
It was a magnetoplumbite type ferrite powder indicated by Fet*Ots.

<Example 3> Anhydrous FeC1z 1.00g and Pb(CHsCOO)z
In addition, a stoichiometric ratio of metallic sodium was dissolved in 100 ml of dehydrated ethanol.
．． 39 g was added, and the mixture was reacted under reflux at 70° C. for 1 hour. A substitution reaction is carried out to form ferrous ethoxide Fe (OE
t)z and lead ethoxide Pb(OEt)2 were obtained.

When Fe(OEt)z and Pb(OEt)t thus obtained were hydrolyzed in the same manner as in Example 1, a precipitate was generated. This precipitate was air oxidized in the same manner as in Example 1. This air-oxidized precipitate was separated and washed from the hydrolyzate by filtration, and then dried at 70° C. for 1 hour to obtain a powder.

When the structure of the obtained powder was investigated by X-ray diffraction, it was found that the dried powder was amorphous and that Pb
It was a magnetoplumbite type ferrite powder shown by Fetz Ots.

When the particle size of each of the powders obtained in Examples 1 to 3 was measured using an electron microscope, the hydrolyzed product was 0.005 to 0.011 L, and the particle diameter was 0.005 to 0.011 when calcined at 700°C. It is a hexagonal plate-shaped fine particle of 0B to 0.08 #Lm, and has a particle size of 0.1 to 0.3 when calcined at 1000°C. It was observed that the particles were hexagonal plate-shaped particles. Further chemical analysis revealed that the composition of each fine particle matched the prepared composition and was a highly pure substance with impurities of 0.1% or less.

Patent applicant Mitsubishi Mining Cement Co., Ltd. Representative Patent attorney Su 1) Masayoshi.

(2 others)'

Claims (2)

[Claims] (1) Hydrolyzing ferrous alkoxide and alkoxides of divalent metals other than ferrous, oxidizing the hydrolysis product, and then calcining to obtain magnetoplumbite-type ferrite powder. Method for manufacturing type ferrite powder. (2) The method for producing magnetoplumbite-type ferrite powder according to claim 1, wherein the divalent metal alkoxide is one or more metals selected from Ba, Sr, and Pb.