JPS6325224A - Production of ferrite powder - Google Patents

Abstract

PURPOSE:To produce ferrite powder having excellent magnetic properties, by mixing two or more kinds of metal acetylacetones, hydrolyzing the mixture and calcining the produced precipitate. CONSTITUTION:The objective ferrite powder can be produced by mixing two or more kinds of metal acetylacetones, hydrolyzing the mixture and calcining the hydrolyzate. The process is suitable especially for the production of a hexagonal so-called M-phase ferrite (MFe12O19) or hexagonal so-called W-phase ferrite (MFe16O27) wherein M is 1-5-valent metal such as Sr, Ba, Pb, Zn, Ca, Cu, Ni, Co, etc.

Description

[Detailed Description of the Invention] ■ Background Technical Field of the Invention The present invention involves mixing two or more types of metal acetylacetones,
The present invention relates to a manufacturing method for obtaining ferrite powder made of uniform fine powder by hydrolysis.

Prior Art and its Problems Conventionally, methods for producing fine ferrite particles include a solid phase reaction method, a wet coprecipitation method, and a glass ceramic method.

Furthermore, in addition to these methods, the hydrolysis method of organometallic compounds is known to have many excellent features as a method for synthesizing amorphous materials.

This method is said to be especially useful for the synthesis of microparticle crystals because it allows a homogenization reaction at the micro level in a liquid state and facilitates the formation of an amorphous state and the production of microparticles. Under these current circumstances, various proposals have been made regarding methods for producing ferrite fine particles by hydrolysis of organometallic compounds.

That is, the method is based on the so-called metal alkoxide method in which ferrite fine particles are produced by hydrolysis using two or more metal alkoxides (Japanese Patent Application Laid-open No. 140721-1989).
No. 55-140722, No. 56-26726,
No. 58-45118, No. 58-45119, No. 58
-199724 publication, production of barium ferrite from metal alkoxide, "Powder and powder metallurgy", Vol. 29, No. 5, July 1982), mixing metal alkoxide and metal acetylacetonate, and hydrolyzing (Japanese Patent Application Laid-Open No. 56-2672)
No. 7, No. 58-45120, No. 58-45121, etc.) have been proposed.

According to these proposals, the obtained fine particles will be highly active and have good sinterability, so the sintered body produced using these particles will have a sintered density that is lower than that obtained by the ordinary powder method. It is said to be larger than that using fine particles.

However, the magnetic properties of these materials, particularly values such as coercive force and residual magnetization, are still not sufficient, and further improvements in these points are required.

1. Purpose of the Invention An object of the present invention is to improve the magnetic properties of ferrite powder obtained in a method for producing ferrite powder by hydrolyzing an organometallic compound.

■Disclosure of invention Such objects are achieved by the invention described below.

That is, the present invention is a method for producing ferrite powder, which is characterized by mixing two or more kinds of metal acetylacetones, hydrolyzing the mixture, and then calcining the mixture.

■Specific structure of the invention Hereinafter, a specific configuration of the present invention will be explained in detail.

The present invention mixes two or more metal acetylacetones,
This is a manufacturing method in which a specified ferrite powder is obtained by hydrolysis. Among ferrites, especially those called hexagonal M-phase ferrites (M Fe
12019) and hexagonal W-phase ferrite (MFe1a027).

Here, M is 1 to 5 metals, specifically, the following M
Among the metals listed as ', those excluding Fe can be mentioned.

The manufacturing method of the present invention will be described in detail below.

The metal acetylacetone used as a starting material in the present invention is usually M' (C5H702). It is indicated by. Here, n is 1-5. In this case, the metal acetylacetone that does not have coordinated water-like H2O is usually used, but the metal acetylacetone that does not have coordinated water, such as S r (C3H7
02) 2.2H20 etc. may be used.

M' is 1 to 5 metals, specifically Fe, Sr
, Ba, All, Li, Be, B.

Na, Mg, Si, Ca, Sc, Ti, V, Cr,
Mn, Co, Ni, Cu, Zn.

Ga, Ge, As, Se, Rb, Y, Zr, Nb, Mo
, Cd, In, Sn, Sb, Te.

Examples include Cs, La, Pb, Bi, and the like.

In the present invention, two different metal acetylacetones are used for each of M. A preferable combination of starting materials includes, for example, Fe ((,,11
7(h) 3 and Sr (Cr, It, O□)2, Fe
((:511702) 3 and Ba(C, l, It, 0
2) 2, Fe ((:511702)3 and Pb (C
611702) 2, etc., to obtain the final product as shown below, and use it as a starting material.

(a) M-phase ferrite i) MA-F e 2oO, n+.

n: 4.0 to 6.0 MA: one or more of Ba, Sr, Pb and Ca, starting materials B a (C5H702)2, S r (C2
H502)2 etc. ii) Substituted ferrite (1) MA"tl-x) -M8", ・F e 2n
O,n,.

X: 0 to 0.25 M,: One or more divalent and vine metals such as Fe, Zn, Cu, Ni, Co, etc. (2) M A' Fe (2n-yl
'Mc"fy/21・""(y/21・of3
n+11 MA −F e (2n-yl HM,”,・O
(:ln+IIM A ” F e f2n-y
l ” M C'Z2y/31・Mr”tyy3+・
of3n+11, etc. y: 0 to 20/3 Mc, Mo, ME, MP: One or more of the above-mentioned metals with respective ionic valences (3) Two or more of (1) and (2) at the same time Substituted substance intended to be combined (b) W-phase ferrite i) MA" °M B"2F e ", 602゜ii)
Substituted ferrite MA”+・(MB”11-0M C”□)2・Fe3+
+6027 MA": B a ", Sr", Pb2◆ and C
A2+ 1 persimmon or more MB", M(": Fe", Zn", Cu", Ni
One or more divalent metals such as ", Co" Z: 0 to 1 Starting material Ba (Cs Ht 02) 2, Fe
(CB, Ht 02)3, Z n
(Cs Ht 02)2 , Cu (Cs
The mixing ratio of these starting materials, such as Ht 02) 2, is adjusted so as to provide the desired final stoichiometric composition of the above-mentioned M-phase ferrite, W-phase ferrite, etc.

After mixing a predetermined amount of raw materials in this manner, alcohol, particularly ethanol, is added as a solvent so that the total amount of metal acetylacetone is about 0.01 to 0.04 mol/ffi. Thereafter, heating and refluxing is performed at the boiling point of ethanol for about 1 hour. After that, it was naturally cooled and left to stand for about one night, and aqueous ammonia and 1 mol of the above metal acetylacetone were added.
Add at room temperature so that the amount is about 1.5 Il.

Then, after aging for about 2 days, that is, about 40 to 48 hours, a heating reaction is carried out at 80 to 100° C. for about 3 hours to complete the hydrolysis.

Thereafter, the precipitate precipitated in the solvent by hydrolysis is separated by suction, filtration, and dried. The material that hardens during drying is loosened into powder and used as a fired sample. Usually, the hydrolysis product is amorphous and needs to be crystallized by heat treatment (calcination) or the like.

Firing is usually carried out in the atmosphere or in an atmosphere in which the oxygen partial pressure of N2+02 mixed gas is adjusted.

When adjusting the oxygen partial pressure, the partial pressure is P02/(P o
2+P N2) is preferably about 10-5 to the value in the atmosphere.

Such a firing atmosphere should be appropriately selected depending on the desired ferrite composition to be obtained.
In the case of R-ferrite, it is preferable to carry out the process in the atmosphere, and in the case of W-phase Sr ferrite, it is usually necessary to carry out the process in an atmosphere in which the oxygen partial pressure of the N2+02 mixed gas is adjusted.
In particular, it is preferable to perform firing in the range of PO2/(PO2+PN2)=10-' to atmospheric air. However, because
When divalent iron is replaced with Cu-Zn, Mn-Zn, etc., a W phase can be formed stably even in the atmosphere. This also applies to W-phase ferrites such as Ba and Pb, for example.

The firing temperature and time are also appropriately selected depending on the desired ferrite composition. For example, in the case of M phase Sr ferrite, 800
-1300°C, preferably 900-1050°C, 1-2
approximately 1200 to 14 hours for W-phase Sr ferrite
00°C, preferably 1200-1300°C, for 3-5 hours. The suitability of this firing temperature affects magnetic properties, particularly saturation magnetization, residual magnetization, coercive force, and the like. In addition, in the case of W phase, 800 to 1200℃ in the atmosphere, 1 to 2
It is preferable to perform calcination for a period of time on the firing surface.

The particle size of the obtained powder is about 500 to several F.
For example, in the case of M-phase Sr ferrite, 500 to 100
Approximately 0 people.

The ferrite powder obtained by the manufacturing method of the present invention, which has been described in detail above, has excellent magnetic properties compared to that obtained by conventional manufacturing methods.

In this case, in the M phase, MO(FC203) 9 (M has the same meaning as above, 9 is 4 to 6), and in the W phase, MO
(F C203) p (M has the same meaning as above, P is 9) as confirmed by X-ray diffraction.

In addition, in the present invention, a part of the metal M of the ferrite is Fe, Sr, Ba, Al1, Li, Be, B, Na, M
g, Si, Ca, Sc, Ti, ■, C", Mn%
Co, Ni.

Cu, Zn, Ga, Ge, As, Se, Rb.

Y, Zr, Nb, Mo, Cd, In, Sn, Sb, Te
, Cs, La, Pb, Bi, etc. as described above, or may be added as an excess amount of additives.

As described above, the substituted product may be prepared by mixing a metal acetylacetone compound containing these elements in a predetermined amount as a starting material. Alternatively, a predetermined amount of an oxide, carbonate compound, halogen compound, etc. containing these elements may be added and mixed during firing.

(2) Specific effects of the invention According to the invention, ferrite powder is produced by hydrolysis using two or more metal acetylacetones as starting materials.

The ferrite powder thus obtained has extremely superior magnetic properties.

(2) Specific Examples of the Invention Hereinafter, specific examples of the present invention will be shown and the present invention will be explained in more detail.

[Example 1] S r (Cs H702)2 and Fe(C5H70
2) :ll is the final composition of M phase S "S which is ferrite"
ro (F C203) Blend to become C4,
700 cc of ethanol was added to the mixture, and the mixture was heated to reflux at the boiling point of ethanol. After heating under reflux for 1 hour, it was cooled as it was, and after about 24 hours, 200 cc of ammonia water was added.
was added at room temperature.

After aging for 2 days, a heating reaction was carried out at 80° C. for 3 hours to complete the hydrolysis. Thereafter, the precipitate precipitated in the solvent by hydrolysis was filtered off by suction filtration and dried.

Then, what solidified during drying was loosened into powder and fired in the air to make a fired sample. The firing temperature was 900°C. The firing time was 1 hour.

The crystallization of the ferrite powder was confirmed by X-ray diffraction. The results of X-ray diffraction are shown in FIG. From the results shown in FIG. 1, it can be seen that it is a single M phase. The magnetic properties of the sample of the present invention thus obtained are as=6
2.7 emu/g, or=35.1 emu/g, 1
Hc==67000e.

For a rough comparison of magnetic properties, the following comparison samples 1~
3 was produced.

(Preparation of comparative sample 1) S r (OC2H5)2 and Fe(C5-HyO2)3
were blended to give a final composition of 1201 g of S r Fe, ethanol was added to the mixture, and the mixture was heated to about 70 g in a nitrogen stream.
After refluxing at ℃ for 1 hour, ammonia water was added and aged for 1 hour to form a precipitate. After obtaining a fine powder, this was heated to 900℃.
Comparative sample 1 was prepared by heat treatment at ℃. Regarding this product, when the above magnetic properties were determined by ff111, σ5 = 62.2 emu/g, or = 33~34e
mu/g, 1Hc=5500 Oe.

(Preparation of comparative sample 2) S r (OC2H5) 2 and Fe (C3HyO)3
were blended to have a final composition of S r Fe 12019, and Comparative Sample 2 was produced according to the manufacturing method of Comparative Sample 1 above.

The magnetic PL of this item is a s = 57emu 7g
, or=30emu 7g, 1Hc=50000e.

(Production of Comparative Sample 3) Comparative Sample 2 was produced according to the method for producing Comparative Sample 1 above using S r (OC2H5) and Fe (OC2Hs )3.

The magnetic properties of this material are σs = 63, Oemu/
k, or=31emu 7g, 1Hc=48000e.

[Example 2] In Example 1, an experiment was conducted by changing the firing temperature to 900 to 1250°C.

The ratio of the S r Fe 1201g phase (M phase) and the αFe2O3 phase was measured by X-ray diffraction. The results are shown in Figure 2.

In addition, the relationship between iHc, O5, σr and firing temperature T is
Shown in the figure.

From this result, it can be seen that an M phase with good magnetic properties is generated at a temperature of 900 to 1-050°C.

[Example 3] In Example 1, the firing temperature and compounding ratio n were changed.
The formation of M phase was investigated by line diffraction.

The results are shown in Figure 4.

From this result, it can be seen that the M phase is generated at 850 to 1200°C.

[Actual example 4 M-phase barium ferrite B a Fe 120
Regarding No. 19, a comparative sample was prepared with that of the present invention using the same method as in Example 1, and a comparative experiment was conducted, and it was confirmed that the coercive force was improved in the same way as in the case of the M-phase strontium ferrite.

[Example 5] In Example 1, a sample was prepared by firing at a firing temperature of 1300° C. for 5 hours at an atmospheric pressure of PO2/(PO2+PN2)=10-3.

When this material was subjected to X-ray diffraction as shown in FIG. 5, the formation of a single W phase was confirmed. The magnetic properties of this sample are σS=70emu/g, i Hc
= 2000 e.

[Brief explanation of drawings]

FIG. 1 and FIG. 5 respectively show x and x of the present invention sample.
vI! This is a diffraction chart graph. Figure 2 shows the S r Fe 17019 phase and αFe2O3
It is a graph showing the relationship between phase ratio and temperature. FIG. 3 is a graph showing the relationship between iHc, σS, σr and firing temperature T. FIG. 4 is a graph showing the relationship between the firing temperature and the blending ratio of the M phase. Applicant DK Co., Ltd. Agent Attorney: Yo Ishii - FIG, l 5rQ5.4FezO3 900°Cx1HIN AIR 2e(') 5r05.4FezO3 7'(C) FIG, 4 M5aSrOn FerO3

Claims (1)

[Claims] (1) A method for producing ferrite powder, which comprises mixing two or more metal acetylacetones, hydrolyzing the mixture, and then calcining the mixture.