JPS58199724A - Manufacture of ferrite - Google Patents

Abstract

PURPOSE:To manufacture fine-grained ferrite of high purity by a liq. phase reaction by reacting a composite alkoxide of an alkali metal with a metallic alkoxide or chloride to substitute the ferrite forming metal of the metallic alkoxide or chloride for the alkali metal and by hydrolyzing the reaction product. CONSTITUTION:A composite alkoxide of an alkali metal represented by formula I (where Mx is an alkali metal, My' is a bivalent metal or tervalent iron, and R is an alkyl) is mixed with a metallic alkoxide represented by formula II(where Mz''is a bivalent metal or tervalent iron) and/or the chloride of the metal Mz'', and the mixture is reacted under reflux to form a metallic alkoxide represented by formula III. Ferrite is formed by hydrolyzing the metallic alkoxide, and the ferrite is separated from the solvent to manufacture fine ferrite powder. Ferrite obtd. by a conventional method by which the oxide of a bivalent metal is mixed with the oxide of tervalent iron in a powdered state and reacted by heating at a high temp. is large in grain size and has a wide grain size distribution, so a material with high performance and high reliability is not obtd. By this method fine-grained ferrite of high purity is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to ferrite used as a magnetic material and to a method for producing fine powder thereof.

The conventional method for producing ferrite is to mix a divalent metal oxide and a trivalent iron oxide in powder form, for example, 130
This was done by heating the reaction to 0°C to 1500°C. However, such methods suffer from inherent compositional heterogeneity due to reacting mixtures of solid particles;
Because high-temperature reactions are required, the resulting ferrite has a large particle size and a large particle size distribution, making it impossible to produce a material with high dimensional accuracy that can be microfabricated with high performance and reliability. In addition, according to the conventional method, when the raw material oxides are mixed and reacted at high temperature, the ferrite layer is only formed by reaction and diffusion between the surfaces where the particles are in contact with each other, and the deep part of the particles is Therefore, in order to obtain highly uniform ferrite, the heating reaction and crushing operations must be repeated. Therefore, it takes a long time to manufacture, requires a large-scale crushing device, and requires a large furnace to maintain high temperatures. Furthermore, since pulverization and heating are repeated, contamination with foreign substances is inevitable, making it difficult to obtain highly pure products.

In view of these problems, the present invention has been developed to reduce the temperature (low temperature) in the liquid phase.
It is produced by a reaction (approximately 100℃ or less), and was developed with the aim of providing a method for producing high-purity ferrite using molecular-sized fine particles without requiring large-scale equipment for the reaction. be.

The present invention is a method using a metal alkoxide, Mx
``y (OR), (where Machi is an alkali metal, sen is a divalent metal or trivalent iron, R is an alkyl group), and M
% (OR), L (where M″z is a divalent metal or trivalent iron) or one or more chlorides of the metal M−, and the mixture is heated at a temperature of about 100°C or less, e.g. 60′c. ~80
By refluxing and reacting at about 'c, M'yM
It is characterized in that a metal alkoxide of τ(OR)n is produced, this is hydrolyzed to produce ferrite, and the ferrite is separated from a solvent to obtain a fine powder with the molecular size of ferrite.

Hereinafter, the present invention will be described as Zn ferrite, Cu ferrite Ni
Example 1 will be used to synthesize ferrite, and an experimental example will be described.

(Synthesis of Zn ferrite) (1) 0.1 mol of synthetic metal Na of NaZn (OE t) 5 was added to 100 m of ethanol (EtoH).
1 and refluxed at about 70'C for about 1 hour (a process in which ethanol is heated, the ethanol vapor generated by heating is cooled and liquefied, and returned to the ethanol liquid).
produced Et. To this ethanol solution containing Na0Et, a solution of 0.04 mol of ZnC42 dissolved in 100 m (l) of ethanol was added and refluxed at about 70°C for about 20 hours to proceed with the reaction of the following formula (note that the above ZnCj ?,, before dissolving in ethanol,
In order to remove the adhering water, it was heat-treated at 200°C for 3 hours to make it anhydrous.)

2 Z n Cl 2 + 5 N a OE t→N
aZn2(OEt) 5+4NaCj? Next, ethanol was removed by evaporation under reduced pressure, and 200 ml of benzene was added as a solvent in its place, and N a Cl!, which is insoluble in benzene, was added. going door to door, NaI! : A benzene solution in which complex ethoxide NaZn2(OEt)5 with Zn was dissolved was obtained.

(2) Synthesis of Fe (OEt) 3 Anhydrous FeCj
? 315 g to 150 mjl of ethanol! and benzene (100 ml), and dry ammonia gas was passed through the mixture at about 70° C. for about 1 hour until the reaction described below was completed. Note that in this step, benzene does not necessarily need to be mixed.

F e C(13+ 3 E t OH+ 3 NH3
→Fe (OEt) 3°+3NH4(j! Then, in the same manner as in (1) above, the solvent was replaced with 250 m4 of benzene, the insoluble NH4Cl"if was separated, and pure Fe(O
A benzene solution containing Et)3 was prepared.

(3) Synthesis of Zn ferrite The benzene solution of NaZn2(OEt) 5 obtained in the above (1) and the benzene solution of Fe (OEt) 3 obtained in the above (2) were mixed at a Zn:Fe molar ratio of 1:2. The mixture is mixed so that It was formed as a precipitate. Then, the benzene solution containing the precipitate was filtered, and the precipitate was separated from the benzene solution containing NaoH produced by the reaction, thoroughly rinsed with distilled water, and then dried at 70°C.

The results of X-ray diffraction analysis of the sample obtained in this way indicate that Zn
It was Fe2O4. Also, 200℃, 400℃, 60℃
The material calcined at 0° C. and 800°C (in an oxidizing atmosphere, the same applies hereinafter) was confirmed to be ZnFe,.04 by similar analysis, and no infertile phase was found at any temperature.

[Synthesis of Cu ferrite] (1) Synthesis of Cu (OMe) 2 The above ZnC6□
Similarly, 20.005 mol of CuCA' from which attached water was removed was dissolved in 100 m (l) of methanol (MeOH), 0.014 mol of metal Li (approximately three times the theoretical amount) was added, and 60'c Reflux and react at ~70'C,
As a result, a lick was formed with Cu (OMe) 2. In this case, Li was dissolved in methanol and refluxed (70t
, lh) and Li alkoxide (Li OMe
), and adding CuC62 to the solution,
Although Cu(OMe) 2 may be produced by refluxing, Cu(OMe) 2 is solid at room temperature and insoluble in organic solvents such as benzene, toluene, and 3-pentanone. Although this solution contains residual -〇(LiOMe), the Cu alkoxide is insoluble as mentioned above, so it can be separated into sand from door to door, etc., but LiCj? will be mixed therein.

(2) Synthesis of Fe (OEt) A Nohensen solution containing Fe (OE) was obtained in the same manner as in the case of Zn ferrite.

(3) Synthesis of Cu ferrite Cu (OMe) containing the Lice obtained in (1) above
was mixed with the benzene solution of Fe (OEt) 3 obtained in (2) above so that Cu:Fe was 1=2 and refluxed at about 70'C to 80'C for about 3 hours, then hot water was added. The mixture was refluxed again at about 80'C to 90'C for 1 hour, LiCl and the solvent were removed by filtration, thoroughly washed with distilled water, and dried at 7oC.

This dried material was dried at 200'c, 400'c, 600'c.
'c, 800'c, and X-ray diffraction analysis after calcination at 1000°C revealed that it became amorphous when calcined up to 400°C.
It was confirmed that it was crystalline CuFe2O4 by calcining at a temperature of 00'c or higher. In addition, the presence of CuO was confirmed at the same time in the calcining of 1ooo'C. The crystal system was tetragonal. Further, as a result of differential thermal analysis, a final peak appeared at 490°C.

In addition, when the Li amount was increased to 0.04 mol in the above operation, calcination up to 400°C resulted in an amorphous state as in the previous case, and calcination at 600°C or above resulted in a cubic system instead of a tetragonal system. CuO appeared after calcination at 600'C or higher, and the final peak of differential thermal analysis was 520C.

[Synthesis of Ni ferrite] Sodium ethoxide (Na
0Et) was prepared, and to 1 mole of this Na0Et, % mole of a benzene solution of Fe(OEt)3 prepared by the method explained in the experimental example for the synthesis of Zu ferrite was added, and the mixture was refluxed at about 70°C for about 1 hour. was carried out to synthesize sodium iron composite ethoxide (NaFe (OEt)4).

l; Add hemol of this composite ethoxide NiC62 to 1 mole of iron and reflux at about 70 to 80°C for about 4 hours to dissolve Na
By performing a substitution reaction between and Ni, N1(Fe(O
Et)4']2 was synthesized. After the reaction, the Na(J?) produced as a precipitate was removed by p-filtration, refluxed again, and then a large excess of water was added to perform hydrolysis.
After continuing to reflux for about 1 hour at 'C', the precipitate was separated, washed with distilled water in the same manner as above, and dried at 70°C.

This hydrolysis product was found to be amorphous by X-ray diffraction. This product was mixed at 200°C, 400°C, 600'c, 80°C.
Calcined at 0'C, amorphous at 200''C, 400℃
With the above, NiFe2O4d has been subdued.

The results of differential thermal analysis of this hydrolysis product showed an endothermic peak at 100°C, an exothermic peak at 280'C, and an exothermic peak accompanied by weight loss at 330°C.

In addition, when we conducted an experiment by changing the amount of Na, we found that when the amount of NaO was in the stoichiometric ratio, the Ni
When Fe204 and Fe2O3 were obtained and the amount of NaO was 15 times the stoichiometric ratio, the diffraction pattern was only for NiFe2O4. This is Ni[Fe (OEt)
4) It is thought that if 2 is in a stoichiometric ratio, the entire amount will not react and chemical equilibrium will not be reached.

Synthesis of C, Co ferrite] NiCe was synthesized using the same procedure as the synthesis of Ni ferrite.
Co ferrite was synthesized using Cock2 instead of Cock2. In this case, the results of differential thermal analysis of the thermal decomposition product show that there is only an endothermic peak at 100°C, an exothermic peak at 260°C, and no exothermic peak at 330°C, and the weight loss is 100°C.
It was found only at the endothermic peak of °C.

In addition, it is amorphous when calcined up to 200'c, and
CoFe2O4 was confirmed by calcination at temperatures above ℃, and Co(
Also in the case of Fe(OEt)n)2, the amount of NaO is 1.5
When the magnification was doubled, a diffraction pattern of only CoFe2O4 was obtained.

This method of manufacturing Ni and Co ferrite is described below.
Since each ethoxide of i and U Co is insoluble in benzene, ethanol, etc., each chloride is used, and the chloride is
The composite ethoxide with the alkali metal was mixed in a dissolving solvent and refluxed to react and replace the alkali metal.
It is clear that Cu C (!2) can be similarly applied to the production of ferrite, since Cu 2 ethoxide is insoluble.

Also, Mg Ferrai) (Mg Fe204)
In the case of production, Mg is added to a mixed solution of methanol and benzene and refluxed to produce Mg ethoxide (Mg (OM
e) t) A dissolving solution was prepared, and this was carried out using Fe ethoxide (Fe (OE
t) It is manufactured by mixing a benzene solution containing s) and subjecting it to a reflux reaction, followed by hydrolysis, furnace separation, drying and calcination, and the dry product and calcination temperature 4
The temperature up to 00℃ was amorphous, but the temperature up to 600℃ and 80℃ was amorphous.
Crystallinity was confirmed in all samples calcined at 0°C.

Note that the diameter of the ferrite powder obtained in each of the above experimental examples was as small as one hundred to several hundred angstroms.

Table 1 shows a comparison of the magnetic properties of conventional products and those according to the present invention for NiFe2O and MgFe2O. The magnetic properties were tested by filling a glass tube with the sample powder. Regarding MgFe, O, as mentioned in the example, this is done by refluxing Mg, MeOH, and benzene for 2 hours to create a solution that generates Mg (OMe) t, and then combining this with Fe (OE t ) and the benzene solution of s were refluxed for 1 hour, water was added to perform hydrolysis, and the precipitate was dried and calcined.

In the present invention, divalent iron that forms a composite oxide with trivalent iron is
The number of valent metals is not limited to one type.゛By mixing and reacting two or more metal alkoxides or chlorides with an alkali metal complex alkoxide at an appropriate composition ratio, a ferrite containing a solid solution of three or more metals excluding the alkali metal can be produced. By changing the mixing amount, the proportion of metals other than iron in the final ferrite can be changed.

The alkali metal used in the present invention includes Na
In addition to and Li, ni, etc. are also used.

In this way, the method of the present invention combines -tan alkali metal and two
By making a composite alkoxide with a valent metal (including iron) or trivalent iron and reacting this with a chloride or alkoxide of trivalent iron or divalent metal, ferrite can be produced as a substitute for an alkali metal. This is a method in which hydrolysis is performed by replacing the metal forming Ultra-fine powder enables uniformity and high purity, which in turn provides high performance and reliability. Further, according to the present invention, since pulverization and high-temperature heating are not necessary, these large-scale devices are not required9, and repeating operations is not required, so that manufacturing time can be shortened. Furthermore, according to the present invention, it is possible to obtain crystalline ferrite without using a firing process, so by combining it with a polymeric material such as magnetic tape, it is possible to produce products and substitutes without using a firing process (furnace). Man
Patent attorney Masaru Wakata - Procedural amendment (method) 1. Indication of the case 1982 Patent Application No. 82758 2. Title of the invention Method for manufacturing ferrite 3. Person making the amendment Relationship with the case Patent applicant 4. Agent Address: Room 6, 612, 1-1-8 Minami, Ichiyo, Chiba Prefecture
, the number of inventions increased by amendment 0

Claims (1)

[Claims] M, r: MIy(OR)t (where M is an alkali metal, MIy is a divalent metal or trivalent iron, R is an alkyl group), and M: (OR)m (wherein M- is a divalent metal or trivalent iron) or M' M
A method for producing ferrite, which comprises producing a metal alkoxide of ``(OR)n, hydrolyzing this to produce ferrite, and obtaining fine ferrite powder by separating the ferrite from a solvent.