JPH0679966B2 - Method for producing magnetoplumbite-type fine ferrite powder - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a magnetoplumbite type ferrite particle powder, and more specifically, to a magnetic recording medium suitable for recording and reproducing high density magnetic recording. The present invention relates to a method for producing a magnetoplumbite-type ferrite fine particle powder capable of obtaining a magnetoplumbite-type ferrite fine particle powder having a force (Hc), a particle size, and a narrow particle size distribution.

[Prior art]

In recent years, ferromagnetic non-acicular particles having a suitable coercive force (Hc) and a large saturation magnetization and good dispersibility have been demanded as a magnetic material for recording, particularly as a magnetic material for perpendicular magnetic recording.

In general, barium ferrite particles are well known as ferromagnetic non-acicular particles.

Conventionally, barium ferrite particle powder has been used as a magnetic material for magnetic recording. The barium ferrite particle powder is obtained by a manufacturing method in which a metal compound of barium and iron oxide are mixed and blended in a predetermined molar ratio, followed by firing and crushing. It has been used as a permanent magnet material such as a field magnet material, but recently, it has been used as a magnetic material for a read-only magnetic card after adjusting the grain size by focusing on its high coercive force.

[Problems to be solved by the invention]

However, the barium ferrite particle powder obtained by the above production method is at least 900 ° C or higher, and usually 1100 ° C.
Since it is fired at the above high temperature and the particle size is adjusted by a pulverizer, there is a limit to the miniaturization, and BE at a maximum of 1-2 m ² / g
The particle size distribution is wide with T method specific surface area, and the particles have strain due to mechanical impact, so the S / N ratio is poor as a magnetic recording material, and the coercive force Hc is too high at 2000 to 3000 Oe or more. It was not suitable as a magnetic material for read / write magnetic recording.

Therefore, as a magnetic material for recording / reproducing magnetic recording, fine particles having an appropriate coercive force and a reduced noise level are required.

It is said that the decrease in noise level is affected by the particle size and particle size distribution of the magnetic material powder used, and in detail, the value of the specific surface area of the particle powder is often used as a method of expressing the particle size of the magnetic particle powder. Although used, it is said that the noise level due to the magnetic recording medium tends to decrease as the specific surface area of the magnetic particle powder increases.

This phenomenon is caused by, for example, IEICE Technical Report MR 81-1.
1 See “Fig. 3” on page 27, 23-9. `` Fig 3
Is a diagram showing the relationship between the specific surface area of particles and the noise level in Co-coated acicular crystal maghemite particle powder, and the noise level decreases linearly as the specific surface area of particles increases.

The same applies to the magnetoplumbite type ferrite particle powder.

The present inventor has conducted extensive studies on a method of making magnetoplumbite-type ferrite particles into fine particles and controlling the coercive force as a magnetic material for recording and reproduction capable of high-density magnetic recording.

[Means for solving problems]

The present inventor, when using the magnetoplumbite ferrite particle powder as a magnetic material for recording and reproducing magnetic recording, in order to obtain an appropriate coercive force, for example, a coercive force in the range of 500 Oe to 1800 Oe, Magnetopranbite type ferrite particle powder in which a part of Fe in the bite type ferrite is replaced with M (II) and M (IV). Furthermore, in order to reduce the noise level, the specific surface area is larger and more In search of magnetoplumbite type ferrite particle powders with narrow particle size distribution, over many years, many experimental studies were carried out on the control method of coercive force, the method of refining particle size and the effect of various additives. I came. And as a result, barium, strontium,
At least one selected from the group consisting of calcium and lead
The sum of M (II) and M (IV) with respect to the compound of a certain kind of metal element and the Fel atom as the iron oxide raw material (where M (II) is a divalent metal ion and M (IV) is a tetravalent metal ion. , And M
(II) and M (IV) are equivalent) 0.017 to 0.22 doped α-FeO (OH) particles, and the α-FeO (OH) particles are used as a starting material for heat dehydration, reduction or reduction and reoxidation. Α-containing M (II) and M (IV) obtained by heat treatment of
Fe ₂ O ₃ particles, Fe ₃ O ₄ particles, γ-Fe ₂ O ₃ particles and α obtained by heating and oxidizing Fe ₃ O ₄ particles or γ-Fe ₂ O ₃ particles obtained by heat treatment of these -When mixing and blending any one iron raw material of Fe ₂ O ₃ particles so as to have a predetermined molar ratio, simultaneously add a mixture of water glass and NaCl, or a mixture of water glass, NaCl and Na ₂ CO _3. If this is done, even if the firing temperature is lowered to a temperature of 900 ° C. or lower, the ferritization reaction occurs, and grain growth of the particles themselves in the firing process and mutual sintering of the particles are suppressed,
The obtained particle powder was confirmed to be a magnetoplumbite type ferrite particle powder having a large specific surface area and a narrow particle size distribution and an appropriate coercive force, and the present invention was reached.

That is, the present invention provides a magnetoplumbite-type ferrite particle powder comprising a step of firing and crushing a mixture of iron oxide and a compound of at least one metal element selected from the group consisting of barium, strontium, calcium and lead. In the manufacturing method, M for Fel atom as iron oxide raw material
The sum of (II) and M (IV) (where M (II) is a divalent metal ion, M (IV) is a tetravalent metal ion, and M (II) and M (IV) are equal amounts) is 0.017. Α doped to a ratio of ~ 0.22
-FeO (OH) particles, α-FeO (OH) particles containing M (II) and M (IV) obtained by subjecting the α-FeO (OH) particles as a starting material to a heat treatment of heat dehydration, reduction or reduction and reoxidation Fe ₂ O ₃ particles, Fe ₃ O ₄ particles, γ-Fe ₂ O ₃ particles and α obtained by heating and oxidizing Fe ₃ O ₄ particles or γ-Fe ₂ O ₃ particles obtained by heat treatment of these At least one selected from the group consisting of barium, strontium, calcium and lead in the presence of water glass and NaCl or water glass, NaCl and Na ₂ CO ₃ using any one of —Fe ₂ O ₃ particles; A method for producing a magnetoplumbite-type ferrite fine particle powder, which is characterized by mixing a compound of a metal element of a seed and firing the mixture in a temperature range of 750 to 900 ° C.

[Action]

 Next, the present invention will be described in detail.

First, the composition of the magnetoplumbite-type ferrite particle powder of the present invention will be described. The general formula A · M (II) _x M (I
V) _x Fe _12-2x O ₁₉ (where 0.1 ≦ x ≦ 1.1), A is one or more of Ba, Sr, Ca and Pb, and the composition ratio is Fe and M ( II) and M (IV) are contained in a ratio of about 1 atom to 12 atoms of all metal ions, and when the x value in the general formula is 0.1 or less, the Hc control effect of M (II) and M (IV) Is not remarkable, and when it is 1.1 or more, the saturation magnetization is greatly reduced, which is not preferable in practical use.

The iron raw material in the present invention includes M (I
The sum of I) and M (IV) is 0.017 to 0.22 doped α-
FeO (OH) particles, α-Fe ₂ O ₃ particles containing M (II) and M (IV) obtained by heat treatment such as heat dehydration, reduction or reduction and reoxidation, Fe ₃ O ₄ , Γ-Fe ₂ O ₃ and these were heat-treated. Α-Fe ₂ O ₃ particles obtained by heating and oxidizing Fe ₃ O ₄ or γ-Fe ₂ O ₃ and having a BET specific surface area of 20 to 200 m.
^{The 2} / g one is used.

Doped M (II) is Co, Zn, Mn, Ni, Cu, M
(IV) is each metal atom of Ti, Ge, and Zr.

The doping amount of M (II) and M (IV) is such that the sum of M (II) and M (IV) is 0.017 to 0.22 with respect to the Fel atom in the range of M (II) and M (IV). ) Is equivalent. If it is 0.017 or less and 0.22 or more, the above general formula A · M (II) _x M (IV) _x Fe _12-2x O ₁₉
In, the composition in the range of 0.1 ≦ x ≦ 1.1 cannot be obtained.

In addition, M (II) and M (IV) -doped α-FeO (OH)
The wet synthesis method of particles is exemplified below.

An M (II) compound such as CoCl ₂ and an M (IV) compound such as TiCl ₄ which are soluble in an aqueous ferrous salt solution such as ferrous sulfate are adjusted to a predetermined amount and mixed, and an alkali is added to add Co and Ti. Aqueous Fe (OH) ₂ colloidal solution containing pH 10 or more is aerated at a heating temperature of 50 ° C or more with an oxygen-containing gas such as air
Α-FeO (OH) particles containing Ti are obtained.

In the other well-known method for producing α-FeO (OH) particles, when preparing the raw Fe aqueous solution, M
The water-soluble compounds of (II) and M (IV) are adjusted to a predetermined amount and mixed, and an aqueous Fe salt solution containing M (II) and M (IV) is used as a starting material to obtain M (II) and M (IV). It is possible to obtain α-FeO (OH) particles doped with (IV).

As raw materials for barium, strontium, calcium and lead, BaCO ₃ , SrCO ₃ , CaCO ₃ , PbCO _3, etc. can be used.
A Ba compound, Sr compound, Ca compound, or Pb compound which becomes BaO, SrO, CaO, or PbO when heated can also be used.

Next, the additives in the present invention will be described.

As the water glass in the present invention, water-soluble silicates such as sodium silicate, sodium orthosilicate, potassium silicate and the like can be used.

The added amount (the amount to be present) is iron oxide (Fe ₂ O ₃
It is effective between 10.0 to 30.0% by weight in terms of SiO ₂ relative terms). When it is added in an amount of 30.0% by weight or more, the saturation magnetization of the product ferrite decreases, which is not preferable as a magnetic material. Also
If it is less than 1.0% by weight, the desired effect of the present invention cannot be obtained.

The amount of NaCl added in the present invention is iron oxide (Fe ₂ O ₃
It is effective in the range of 2.0 to 40.0% by weight. 2.0
If it is less than 5% by weight, its effect is small, while
If it is 0.0% by weight or more, the specific surface area of the ferrite particles tends to be small, and it is not economical. Considering the particle size and particle size distribution of the target ferrite particles, 2.0 to 40.0% by weight is preferable.

The amount of Na ₂ CO ₃ added in the present invention is iron oxide (Fe ₂ O 3
It is effective in the range of 3.0 to 20.0% by weight relative to ₃ ). 3.
If it is less than 0% by weight, the effect of addition is small. On the other hand, when the content is 20.0% by weight or more, it is possible to obtain ferrite particle powder having desired fine particles and a narrow particle size distribution, but if it is added excessively, the specific surface area of the ferrite particles tends to be small, which is not desirable.

Incidentally, it is appropriate to add each additive in the present invention immediately before the firing step. That is, in each of the raw material blending step, the firing step, and the crushing step, it can be added at the time of raw material blending, which is the step immediately before the firing step.

The firing temperature range in the present invention may be between 750 and 900 ° C. If the temperature is 750 ° C or lower, it is insufficient to carry out the ferrite formation reaction, and if the temperature is 900 ° C or higher, the grain growth of the particles themselves in the firing process of the ferrite particles and the mutual sintering of the particles are caused. It is not desirable because it occurs.

In the case of the above-mentioned firing temperature, the pulverization after firing can be carried out under a relatively mild condition by using an ordinary pulverizer such as an atomizer or an attritor. Is not necessary.

〔Example〕

 Next, the present invention will be described with reference to Examples and Comparative Examples.

The water glass used in Examples and Comparative Examples was sodium metasilicate (Japanese Industrial Standard 1). The specific surface area of the particles in Examples and Comparative Examples was measured by the BET method, and X-ray was used for the structural analysis of the products.
For the magnetic measurement, a sample vibrating magnetometer (manufactured by Toei Industry Co., Ltd.) was used, and the measurement magnetic field was 10 Koe.

Example 1 BE in which Co and Ti are doped by 0.056 with respect to Fel atoms
When mixing 1000 g of α-FeO (OH) particle powder having a T specific surface area of 145 m ² / g with 195 g of barium carbonate, 700 g of sodium metasilicate (equivalent to 17.9 wt% in terms of SiO _{2 with} respect to Fe ₂ O ₃ ) And 150 g of NaCl (corresponding to 14.3 wt% with respect to Fe ₂ O ₃ ) were added and mixed well, then the mixture was calcined at 800 ° C. for 2 hours, then the calcined product was crushed with an atomizer and washed with water. Soluble salts were removed. As a result of X-ray analysis, the obtained dry product powder particles were magnetoplumbite-type barium ferrite particles, and as a result of composition analysis, BaCo ₀ . ₆ T
i ₀ . ₆ Fe ₁₀ . It was ₈ O ₁₉ .

The specific surface area of the obtained magnetoplumbite-type barium ferrite fine particle powder was measured by the BET method. 40 m ² / g
As a result of measuring the magnetic properties of this material, the saturation magnetization was σs: 57.5emu / g, and the coercive force was Hc: 830Oe.

Example 2 BE in which Fe1 atoms are doped with Co and Ti by 0.031 respectively
When mixing 1000 g of α-FeO (OH) particle powder having a T specific surface area of 80 m ² / g and 195 g of barium carbonate, 1050 g of sodium metasilicate (equivalent to 24.6 wt% in terms of SiO _{2 with} respect to Fe ₂ O ₃ ) And 160 g of Na ₂ Cl (corresponding to 15.1% by weight with respect to Fe ₂ O ₃ ) were added and mixed well, then the mixture was calcined at 850 ° C. for 1.5 hours, and then the calcined product was crushed with an atomizer and washed with water. To remove water-soluble salts. Resulting dried product powder particles results of X-ray analysis, a magnetoplumbite type barium ferrite particles, the result of the composition analysis BaCo _{0. 35} Ti _0.
Was ₃₅ Fe _{11. 3} O _19.

The specific surface area of the obtained magnetoplumbite-type barium ferrite fine particle powder was measured by the BET method. 30 m ² / g
As a result of measuring the magnetic characteristics of this material, the saturation magnetization was s: 60.4emu / g, and the coercive force was Hc: 1750Oe.

Example 3 BET in which Co and Ti are doped with 0.10 each of Fel atoms
When mixing 1000 g of α-FeO (OH) particle powder having a specific surface area of 180 m ² / g and 195 g of barium carbonate, 600 g of sodium metasilicate (corresponding to 15.7 wt% in terms of SiO _{2 with} respect to Fe ₂ O ₃ ) After adding 300 g of NaCl (corresponding to 25.0% by weight with respect to Fe ₂ O ₃ ) and 120 g of Na ₂ CO ₃ (corresponding to 11.8% by weight with respect to Fe ₂ O ₃ ) and thoroughly mixing, the mixture was mixed with 800 The mixture was calcined at 0 ° C. for 2 hours, then the calcined product was pulverized with an atomizer and washed with water to remove water-soluble salts. As a result of X-ray analysis, the obtained dry product powder particles were magnetoplumbite-type strontium ferrite particles, and as a result of composition analysis, SrCO ₁ . ₀
Ti ₁ . _{It was 0} Fe ₁₀ O ₁₉ .

The specific surface area of the obtained magnetoplumbite-type strontium ferrite fine particle powder measured by the BET method 5
It was 5 m ² / g, and the magnetic characteristics of this product were measured. As a result, the saturation magnetization σs was 54.7 emu / g and the coercive force Hc was 650 Oe.

Example 4 BE in which Co and Ti are each doped with 0.071 with respect to Fel atom
When mixing 1000 g of α-FeO (OH) atomic powder having a T specific surface area of 110 m ² / g and 195 g of barium carbonate, 200 g of sodium metasilicate (corresponding to 5.9 wt% in terms of SiO _{2 with} respect to Fe ₂ O ₃ ) And 60 g of NaCl (equivalent to 6.3% by weight in terms of SiO _{2 with} respect to Fe ₂ O ₃ ) and 160 g of Na ₂ CO ₃ (equivalent to 15.1% by weight with respect to Fe ₂ O ₃ ) were added and sufficiently mixed, 850 ℃ the mixture
The product was calcined for 1 hour, then the calcined product was pulverized with an atomizer and washed with water to remove water-soluble salts.

The obtained dry product powder particles were magnetoplumbite-type barium ferrite particles as a result of X-ray analysis, and the composition analysis results of BrCo ₀ . ₇₅ Ti ₉ . ₇₅ Fe ₁₀ . It was ₅ O ₁₉ .

The specific surface area of the obtained magnetoplumbite-type barium ferrite fine particle powder was measured by the BET method. 43 m ² / g
As a result of measuring the magnetic characteristics of this material, the saturation magnetization was s: 53.8emu / g, and the coercive force was Hc: 780Oe.

Example 5 As the iron oxide raw material, Co and Ti used in Example 1 were each 0.
[056] Doped α-FeO (OH) particle powder was heated in air at 300 ° C to obtain α containing Bet specific surface area of 174 m ² / g containing Co and Ti.
-When mixing 900 g of Fe ₂ O ₃ particle powder and 146 g of strontium carbonate, 400 g of sodium metasilicate (corresponding to 11.2% by weight in terms of SiO _{2 of} Fe ₂ O ₃ ) and 170 g of NaCl (Fe ₂ O 3
(Corresponding to 15.9% by weight with respect to ₃ ) and 50 g of Na ₂ CO ₃ (corresponding to 5.3% by weight with respect to Fe ₂ O ₃ ) were mixed well, and then the mixture was calcined at 780 ° C. for 2 hours. Example 1 except
Under the same conditions as above, strontium ferrite particle powder was obtained.

As a result of X-ray analysis, the obtained particles were magnetoplumbite-type strontium ferrite particles, and as a result of composition analysis, SrCo ₀ . ₆ Ti ₀ . ₆ Fe ₁₀ . It was ₈ O ₁₉ .

The specific surface area of the obtained magnetoplumbite-type strontium ferrite fine particle powder measured by the BET method 2
It was 4 m ² / g, and the magnetic characteristics of this product were measured. As a result, the saturation magnetization σs was 58.2 emu / g and the coercive force Hc was 950 Oe.

Example 6 Co and Ti used in Example 2 were respectively used as iron oxide raw materials.
0.031 Doped α-FeO (OH) particle powder in H ₂ stream 350
BET specific surface area containing Co and Ti after reduction at ℃ 150m ² / g
When 870 g of black iron oxide (magnetite) powder having a Fe (II) / Fe (III) composition ratio of 0.35 was mixed with 195 g of barium carbonate, 700 g of sodium metasilicate (for Fe ₂ O ₃ was mixed with S
17.9% by weight in terms of iO ₂ ) and 200 g of NaCl (based on Fe ₂ O ₃ )
(Corresponding to 18.2% by weight) was added and mixed well, and barium ferrite particle powder was obtained under the same conditions as in Example 1 except that the mixture was calcined at 880 ° C. for 1.5 hours.

The obtained particles were magnetoplumbite-type barium ferrite particles as a result of X-ray analysis, and the results of composition analysis as BaCo
₀ . ₃₅ Ti ₀ . ₃₅ Fe ₁₁ ． It was ₃ O ₁₉ .

The specific surface area of the obtained magnetoplumbite-type barium ferrite fine particle powder was measured by the BET method. 26 m ² / g
As a result of measuring the magnetic characteristics of this material, the saturation magnetization was s: 61.2emu / g, and the coercive force was Hc: 1780Oe.

Example 7 As the iron oxide raw material, Co and Ti used in Example 3 were each 0.10.
After reducing α-FeO (OH) particle powder doped with H ₂ at 350 ° C. in H ₂ stream, it is oxidized at 300 ° C. in air, and BET specific surface area containing Co and Ti is 160 m ² / g γ-Fe. _When mixing 900 g of ₂ O ₃ particle powder and 195 g of barium carbonate, 500 g of sodium metasilicate (equivalent to 13.5 wt% in terms of SiO _{2 with} respect to Fe ₂ O ₃ ) and 550 g of NaCl (37.9 wt% with respect to Fe ₂ O ₃ ). (Corresponding to) and were mixed thoroughly, and barium ferrite particle powder was obtained under the same conditions as in Example 1 except that the mixture was calcined at 800 ° C. for 2 hours.

The obtained particles were magnetoplumbite type barium ferrite particles as a result of X-ray analysis, and the results of composition analysis were SrCo.
₁ . ₀ Ti ₁ . _{It was 0} Fe ₁₀ O ₁₉ .

The specific surface area of the obtained magnetoplumbite-type ribalium ferrite fine particles was measured by the BET method, and the result was 39 m ² /
As a result of measuring the magnetic properties of this material, the saturation magnetization was s: 55.3 emu / g, and the coercive force was Hc: 680 Oe.

Comparative Example 1 1000 g of the α-FeO (OH) particle powder used in Example 1 and 195 g of barium carbonate were thoroughly mixed, the mixture was fired at 1200 ° C. for 2 hours, and then the fired product was oscillated with a vibrating ball mill for 60 minutes. The particles obtained by the pulverization treatment were magnetoplumbite type barium ferrite particles as a result of X-ray analysis. As a result of measuring the magnetic properties of this product, the saturation magnetization s: 65.1emu /
g, coercive force Hc: 1430 Oe, but the specific surface area measured by the BET method was 4.2 m ² / g, the particles were coarse, and the noise level was high and unsuitable as a magnetic material for magnetic recording. It was

Comparative Example 2 As an iron oxide raw material, α-FeO (O with a BET specific surface area of 145 m ² / g
H) When mixing 1000 g of particle powder and 195 g of barium carbonate, 650 g of sodium metasilicate (16.8% relative to Fe ₂ O ₃₎
(Corresponding to the weight) and 170 g of NaCl (corresponding to 15.9 weight with respect to Fe ₂ O ₃ ) were added under the same conditions as in Example 1 to obtain a barium ferrite particle powder. BE of the obtained particle powder
Although the T specific surface area was 26.0 m ² / g and the particles had a low noise level, they had a high coercive force of 3250 Oe and were not suitable for read / write magnetic recording.

Comparative Example 3 α-F used in Example 1 and 0.056 doped with Co and Ti, respectively
When mixing 1000 g of eO (OH) particle powder and 195 g of barium carbonate, 200 g of NaCl (corresponding to 18.2% by weight with respect to Fe ₂ O ₃ ) was added and thoroughly mixed, and then the mixture was heated at 850 ° C. for 2 hours. After firing, the fired product was pulverized with an atomizer and washed with water to remove water-soluble salts. As a result of X-ray analysis, the obtained dried product powder particles were magnetoplumbite type barium ferrite particle powders.

As a result of measuring the magnetic characteristics of this product, the saturation magnetization σs: 56.4
Although it was emu / g and coercive force Hc: 920 Oe, it was 8.5 m ² / g as a result of measuring the specific surface area by the BET method. there were.

Comparative Example 4 α-F used in Example 1 and doped with Co and Ti by 0.056 respectively
When mixing 1000 g of eO (OH) powder and 195 g of barium carbonate, 200 g of NaCl (equivalent to 18.2 wt% for Fe ₂ O ₃ ) and 150 g of NaCO ₃ (equivalent to 14.3 wt% for Fe ₂ O ₃ ) After adding and mixing well, the mixture was calcined at 850 ° C. for 2 hours, and then the calcined product was pulverized with an atomizer and washed with water to remove water-soluble salts. As a result of X-ray analysis, the obtained dried product powder particles were magnetoplumbite type barium ferrite particle powders. As a result of measuring the magnetic properties of this product, saturated oxidation σs: 54.3emu / g, coercive force Hc: 1050Oe
However, the result of measuring the specific surface area by the BET method was 4.3 m ² / g
The particles were coarse, and the noise level was high and unsuitable as a magnetic material for magnetic recording.

〔effect〕

According to the method for producing the magnetoplumbite-type ferrite fine particle powder according to the present invention, the specific surface area of the particles is large, the particle size distribution is narrow, and the desired coercive force is controlled, as shown in the above-mentioned Examples. Since a fine particle powder of magnetoplumbite ferrite can be obtained, it can be suitably used as a magnetic material for recording / reproducing magnetic recording having a high recording density which is currently most required.

Claims (9)

[Claims] 1. A method for producing a magnetoplumbite ferrite particle powder, which comprises a step of firing and pulverizing a mixture of iron oxide and a compound of at least one metal element selected from the group consisting of barium, strontium, calcium and lead. In the method, M (I
The sum of I) and M (IV) (provided that M (II) is a divalent metal ion, M (IV) is a tetravalent metal ion, and M (II) and M (IV) are the same amount) is 0.017 to 0.22 doped α
-FeO (OH) particles, α-FeO (OH) particles containing M (II) and M (IV) obtained by subjecting the α-FeO (OH) particles as a starting material to a heat treatment of heat dehydration, reduction or reduction and reoxidation Fe ₂ O ₃ particles, Fe ₃ O ₄ particles, γ-Fe ₂ O ₃ particles and α-obtained by heating and oxidizing Fe ₃ O ₄ particles or γ-Fe ₂ O ₃ particles obtained by heat treatment of these After using any one of Fe ₂ O ₃ particles and mixing with a compound of at least one metal element selected from the group consisting of barium, strontium, calcium and lead in the presence of water glass and NaCl, A method for producing a magnetoplumbite-type ferrite fine particle powder, which comprises firing in a temperature range of 750 to 900 ° C. 2. A method for producing a magnetoplumbite-type ferrite fine particle powder according to claim 1, wherein M (II) is cobalt, nickel, manganese, copper, zinc, and M (IV) is titanium, germanium, or zirconium. Law. 3. The amount of water glass present is an iron raw material (calculated as Fe ₂ O ₃ ).
The method for producing a magnetoplumbite-type ferrite fine particle powder according to claim 1 or 2, wherein the amount is 1.0 to 30.0% by weight in terms of SiO ₂ . 4. The magnetoplumbite type according to claim 1, wherein the amount of NaCl present is 2.0 to 40.0% by weight based on the iron raw material (calculated as Fe ₂ O ₃ ). Manufacturing method of ferrite fine particle powder. 5. Production of magnetoplumbite-type ferrite particle powder, which comprises a step of firing and pulverizing a mixture of iron oxide and a compound of at least one metal element selected from the group consisting of barium, strontium, calcium and lead. In the method, M (I
The sum of I) and M (IV) (provided that M (II) is a divalent metal ion, M (IV) is a tetravalent metal ion, and M (II) and M (IV) are the same amount) is 0.017 to 0.22 doped α
-FeO (OH) particles, α-FeO (OH) particles containing M (II) and M (IV) obtained by subjecting the α-FeO (OH) particles as a starting material to a heat treatment of heat dehydration, reduction or reduction and reoxidation Fe ₂ O ₃ particles, Fe ₃ O ₄ particles, γ-Fe ₂ O ₃ particles and α obtained by heating and oxidizing Fe ₃ O ₄ particles or γ-Fe ₂ O ₃ particles obtained by heat treatment of these A compound of at least one metal element selected from the group consisting of barium, strontium, calcium and lead in the presence of water glass, NaCl and Na ₂ CO ₃ , using any one of Fe ₂ O ₃ particles After mixing with, 750 ~ 900 ℃
A method for producing a magnetoplumbite-type ferrite fine particle powder, which is characterized by firing in the temperature range of. 6. The method of claim 5, wherein M (II) is cobalt, nickel, manganese, copper, zinc and M (IV) is titanium, germanium, zirconium. Law. 7. The amount of water glass present is an iron raw material (calculated as Fe ₂ O ₃ ).
The method for producing a magnetoplumbite-type ferrite fine particle powder according to claim 5 or 6, wherein the amount is 1.0 to 30.0% by weight in terms of SiO ₂ . 8. The magnetoplumbite ferrite according to claim 5, wherein the amount of NaCl present is 2.0 to 40.0% by weight based on the iron raw material (calculated as Fe ₂ O ₃ ). Method for producing fine particle powder. 9. The magnetoplan according to any one of claims 5 to 8, wherein the amount of Na ₂ CO ₃ present is 3.0 to 20.0% by weight with respect to the iron raw material (calculated as Fe ₂ O ₃ ). Bite-type ferrite fine particle powder manufacturing method.