JPS60246225A - Ferric oxide particle powder and its production - Google Patents

Abstract

PURPOSE:To obtain a novel ferric oxide powder having cubic shape and bixbyite crystal structure, by heating a mixture of anhydrous ferric sulfate and an alkali metal chloride at a temperature within a specific range. CONSTITUTION:1mol of anhydrous ferric sulfate prepared by heating hydrated ferric sulfate at 200-600 deg.C is mixed with preferably about 1.5-3mol of an alkali metal chloride (e.g. NaCl, KCl, etc.), and the mixture is heated at 500-600 deg.C. The ferric oxide obtained by this process is relatively coarse powder having an average particle diameter of >=1mu, and its X-ray diffraction pattern has peaks having the same indices and nearly the same intensities as those of bixbyite. However, the powder is a ferric oxide having bixbyite crystal structure which is absolutely different from the crystal structure of known alpha-type ferric oxide powder or gamma-type ferric oxide powder.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel ferric oxide particle powder having a cubic shape and a binoxheite crystal structure, and a method for producing the same.

The shape of the η parallelepiped obtained by the present invention is (1), (1)
Ferrous oxide particles having a binoxheite crystal structure are
For pigments, magnetic toners, carriers, sintered ferrite 1
- (Can be used as a 651-ki recording material.)

Ferric oxide particles are widely used for face coatings, carriers, sintered ferrites, and magnetic recording materials. Various ferrous oxide particles with different average particle diameters are required.

First of all, as ferrous oxides with different crystal structures, α-type ferric oxide and γ-type ferric oxide are well known, and α-type ferric oxide is mainly used as a material for Ceramics 4. Since γ-type ferric oxide has magnetism, it is used as a magnetic recording material.

In addition to α-type ferric oxide and T-type ferric oxide, the existence of ferric oxide, which is called β-type ferric oxide and ζ-type ferric oxide, has been reported.

It has been reported that β-type ferric oxide can be obtained by hydrolyzing iron chloride (l[I) in steam. The β-type ferric oxide obtained in this way is sometimes called binoxheite type ferric oxide because its lattice constant and diffraction intensity are similar to β-Mn203 and MnFe0:+ (binoxheite). It is different from the binoxheit type crystal structure, and its actual state has not yet been clarified.

ζ-type ferric oxide is F e , OJ・2SO,・1(2
It is produced during the thermal decomposition process of 0, and there are reports on its X-ray diffraction position and intensity.

Judging from X-ray diffraction, this ζ-type ferric oxide is considered to be the same as the β-type ferric oxide described above, and therefore,
It is different from the binox height type crystal structure,
The actual situation is still not clear.

On the other hand, FeO generated during the thermal decomposition process of β-Fe0011
+, <5 (Off) o, + or Fetut, tz
There is also a report that clo, + b is β-type ferric oxide, but this is also different from the binoxite-type crystal structure.

As mentioned above, the actual state of the crystal structure of ferric oxides other than α-type ferric oxide and β-type ferric oxide is unknown. Currently, iron is still unknown.

Next, regarding the particle morphology of ferrous oxide, ゛(, -λ(tt1
Ferrous oxide, which has particle shapes such as horn-shaped, powdery, and spherical, is used for pigments that require uniform dispersion and for magnetic applications. As a carrier material, ferric oxide in the form of acicular particles is used as a magnetic recording material by dispersing the particles in a symmetrical arrangement.

Furthermore, according to the conventionally known method, the average particle size of ferric oxide is 0.5 μm, especially 1 μm.
Only a modest amount has been obtained.

That is, the most representative force for obtaining ferric oxide? Fe as L
There is a horn method in which Fenot particles obtained by oxidizing an upper layer solution consisting of 1 volume of water and 7 volumes of alkaline water are heated in air by passing an oxygen-containing gas through it to oxidize it.

Fe50. obtained by wet method. The particles have a +7-shaped, octahedral, or granular particle morphology, and the average tLf diameter is 0. O is a fine particle of 1 to 0.5 μm, therefore, the F
The average particle diameter of ferric oxide particles obtained by heating eJ04 particles is also about 0.5 μm at most.

Therefore, ferric oxide single crystal particles having a particle size larger than IIIm are not yet known.

In view of the above, the present invention has been developed as a result of various studies on the method for producing ferric oxide and the crystal structure, particle morphology, and average particle size of the produced ferric oxide particles, which have a cubic shape. , and found that novel ferric oxide particles having a pinocyhide crystal structure can be obtained.

That is, the present invention mixes ferric oxide particle powder consisting of ferric oxide particles having a cubic shape and a binoxheite crystal structure, anhydrous iron sulfate (■), and an alkali metal chloride. and by heating the mixture in a temperature range of 550 ° C to 600 ° C, it has a cubic shape,
The present invention also provides a method for producing ferric oxide particles, which comprises obtaining ferric oxide particles having a bixpite crystal structure.

Next, the configuration of the present invention will be described.

The present inventor has repeatedly conducted various tests on the method for producing ferric oxide and the crystal structure, particle morphology, and average particle diameter of the produced ferric oxide, and has determined that anhydrous iron sulfate (II+) and alkali metal When mixed with chloride and heated at a temperature range of 550 to 600°C, ferrous oxide particles having a sword-like shape and a binox high] type crystal structure are formed. I have found that it is possible to obtain

The ferrous oxide powder-F obtained by the present invention has a 1"1L body shape and has a hinoxite crystal structure.

In addition, the average particle diameter of the obtained ferrous oxide particles is 1μ
It is relatively large, about 100 m or more.

The following is an explanation of some of the many experimental examples conducted by the inventor.

Figure 1 shows the x
It is a vA diffraction diagram.

As is clear from FIG. 1, the same index peak as Binox High 1- appears, and its intensity is almost the same.

Note that the numbers shown at the peak positions indicate indexes.

In the figure, no diffraction peak of α-type ferric oxide particles is found.

The lattice constant a was 0.9398 nm.

FIG. 2 is a Mössbauer spectrum at room temperature and 4.2 K of ferric oxide particles obtained in Example 1, which will be described later.

In FIG. 2, (A) is the case at room temperature, and (B) is the case at 4.2.

As is clear from Figure 2(A), the isomer shift δ is 0.3
8 mm/sec, the four-layer splitting Q, S was 0.75 mIn/sec, and as is clear from FIG. 2(B), the values of the internal magnetic field were 506 KOe and 486 KOe. Considering the crystal structure of the binoxite MnFeOs, there are two types of iron positions, and two internal magnetic fields appear correspondingly to the positions t,+. It is clear from these Mössbauer data that iron is only trivalent and the composition is Feze3.

The Neel point was found to be 119 from the Mössbauer spectrum and temperature changes in magnetization. Further, as a result of thermal analysis of this iron oxide, an exothermic peak was observed around 720°C. This is α
-Fe20. This was due to a phase transition to .

From FIG. 1 and FIG. 2, the particle powder obtained by the present invention is
It can be confirmed that this is a ferrous oxide having a bi-kussheite type crystal structure, which is completely different from the conventionally known α-type ferric oxide particles and γ-type ferric oxide.

FIG. 3 is an electron micrograph (X7,500) of the ferrous oxide tM powder obtained in Example 1, which will be described later.

All of them have a cubic grain shape, and the grain size is larger than lttm.

As a result of electron beam diffraction, it was confirmed that it is a 1γ force field surrounded by [+003]. This is thought to be due to the fact that the crystal structure is a 1'1 cubic system.

Next, various conditions for implementing the present invention will be described.

The anhydrous iron sulfate (III) in the present invention is iron sulfate (In
) can be obtained by adding and heating the hydrate at 200°C to 600°C. In the case of 200℃ or higher 1.; 31,
Anhydrous iron (III) sulfate cannot be obtained, and if the temperature is 600° C. or higher, it changes to α-type ferric oxide particles.

As the alkali metal chloride in the present invention, NaC
l, MCI can be used.

The amount of alkali metal chloride is not particularly limited, but from the standpoint of equipment and economy, it is preferably about 1.5 to 3 moles per mole of anhydrous iron sulfate (■).

The heating temperature of the mixture of anhydrous iron (III) sulfate and alkali metal chloride in the present invention is 550 to 600°C.

When the temperature is below 550'C, it is difficult to generate vinox high (-type ferric oxide particles).When the temperature is above 600°C, α-type ferric oxide particles are formed and mixed.

The present invention configured as described above has the following effects.

That is, according to the present invention, it is possible to obtain ferric oxide particles having a cubic shape and having a binoxheite crystal structure. Further, according to the present invention, only ferric oxide having a binoxheite crystal fM structure can be produced without α-type ferrous oxide mixed therein, and the average particle size is relatively large from 1 μm to 2 μm. The ferric oxide that has the cubic shape obtained in this way and has a binoxheite crystal structure is
By increasing the temperature in the air over 670°C,
It was possible to obtain single crystal α-type ferric oxide particles that retained the particle morphology and size of the starting source.
By each hydrogen reduction at a temperature of C or higher, magnetite particles or metallic iron which retain and inherit the grain-f morphology and size of the starting material can be obtained.

The 0.5μ chains thus obtained are particularly lμn~2
α-type ferrous oxide particles, magnetite particles, or metal iron particles having a cube size of μI are excellent in filling and fluidity, so they can be used for pigments, magnetic toners, carriers, sintered ferrites, etc. It can be used as a widely useful material for magnetic recording.

Further, when the ferric oxide having a cubic shape and bisoxhite crystal structure obtained by the present invention is mixed with other oxides or carbonates and heated, the temperature reaches 800°C.
Almost 100% ferrite was produced by heating up to 100%.

That is, when bixheite type ferric oxide and manganese carbonate are mixed to form MnFezO1 and heated to 800°C in a nitrogen stream, MnFezOa is formed, and the particles have a cubic or nearly spherical shape. was.

This is because the spinel reaction is promoted during the transition from binoxheite-type ferric oxide to α-type ferric oxide, and because the reaction is carried out at a low temperature, the particle morphology of the binoxheite-type ferric oxide is retained and inherited. Depends on the situation.

In this way, the binoxite type ferric oxide can be used to produce α-Fe208, F, which has a particle morphology and particle size that have not been previously available.
eJ, , many uses can be considered as a material for synthesizing ferrite.

Next, Example Jf! The present invention will be explained with reference to Examples and Comparative Examples.

Example 1 Hydrate of iron(III) sulfate ()f! z(SOa):+
・N1lz(1) was heated at 400° (゛) for 1 hour in air.

The obtained crystals were analyzed by X-ray diffraction as 11 sulfuric anhydride iJ, (
■) (To e2 (504) 3)” (I L2
．． 'C/-2 1 mol of this iron(III) anhydride and N
aC12-E and the mixture was heated at 580°C:
After heating for 1 hour, the mixture was washed with water and treated to obtain a ferric oxide cat.

The obtained ferric oxide had no α-type ferric oxide peak at all, as shown in Figure 1t, which is clear from the 4X-ray diffraction, and it was a complete bi-, Kushai I-type crystal lateral crystal. It was showing.

Moreover, as is clear from the small electron microscope (X 7.500) shown in FIG. 3, it had a q-cuboidal shape, and its 1' average particle diameter was 1.45 μm.

Example 2 Hydrate of iron(III) sulfate (Fe2(SO4) 3 n
Ferric oxide particles were obtained in the same manner as in Example 1, except that 1lzO) was heated at 300°C.

As a result of observation using an X-ray diffraction pattern, the obtained ferric oxide
No α-type ferric oxide peak was observed, indicating a complete binoxite crystal structure.

Further, as a result of electron microscopic observation, it was found that the particles had a cubic shape and the average particle diameter was 1.60 μm.

Example 3 Hydrate of iron(III) sulfate (Few(SO4)3·nH
Ferric oxide particles were obtained in the same manner as in Example 1 except that J) was heated at 200°C.

As a result of observation using an X-ray diffraction pattern, the obtained ferric oxide
No α-type ferric oxide peak was observed, indicating a complete bixpite crystal structure.

Further, as a result of electron microscopic observation, it was found that the particles had a cubic shape and the average particle diameter was 1.75 μm.

Example 4 Ferric oxide particles were obtained in the same manner as in Example 1, except that 11.5 mol of NaC was used for 1 mol of anhydrous iron sulfate (■).

The obtained ferric oxide has 3E1jIl in the X-ray diffraction diagram.
As a result of the investigation, no peak of α-type ferric oxide was observed, indicating that a complete binox-type crystal was present.

Further, as a result of electron microscopic observation, it was found that the particles had a η-cuboid shape, and the average particle diameter was 1.50 μm.

Example 5 Ferrous oxide particles were obtained in the same manner as in Example 1, except that 1 mol of anhydrous iron sulfate (■) was replaced with 3 mol of NaCl.

As a result of observation using an X-ray diffraction pattern, the obtained ferric oxide
No α-type ferric oxide peak was observed, indicating a complete binoxite crystal structure.

Further, as a result of electron microscopic observation, it was found that the particles had a q-cuboid shape, and the average particle diameter was 1.30 μm.

Example 6 Ferric oxide particles were obtained in the same manner as in Example 1 except that the heating temperature was 550°C.

As a result of observation using an X-ray diffraction pattern, the obtained ferric oxide
No α-type ferric oxide peak was observed, indicating a complete binoxite crystal structure.

Further, as a result of electron microscopic observation, it was found that the particles had a cubic shape and the average particle diameter was 1.5 μm.

Comparative Example 1 Ferrous sulfate (III) hydrate (Fez (SO4) z -1011,0) was used in place of anhydrous iron sulfate ([[l]. Got iron.

As a result of observation using an X-ray diffraction pattern, the obtained ferric oxide
Binoxheite type ferric oxide and α type ferric oxide were mixed.

Usage Example 1 When the ferric oxide having the bisoxubi I type crystal structure obtained in Example 1 is heated at 670°C for 1 hour, the phase changes to α-type ferric oxide, but the particle morphology is different from that observed by electron microscopy. As a result, it retained its cubic shape.

This particle was determined to be a single crystal of α-type ferric oxide by an electron beam diffraction pattern (6'&L'2). This shows that even relatively large particles of 1.5 μm or more undergo a phase change from single crystal to single crystal.

[Brief explanation of the drawing]

FIG. 1 is an X-ray diffraction diagram of a ferric oxide t,'Ir151 powder having a tl-7kuscheite crystal structure obtained in Example 1. FIG. 2 shows the Mösshauer spectrum of the ferrous oxide particles O obtained in Example 1 at room temperature and 4.2K. In FIG. 2, (A) is the case at room temperature, and (8) is the case at 4.2. FIG. 3 is an electron micrograph (X7,500) of the ferrous oxide powder f obtained in Example 1. Patent Applicant 1 Anti-East Inner Round 2 (△) 1 Rising Sun) Conicity (mm7 seconds) Figure 3 (X7500) --142--

Claims (1)

[Scope of Claims] fll A ferric oxide particle powder comprising ferric oxide particles having a cubic shape and a binoxite crystal structure. (2) By mixing anhydrous iron sulfate ([[I] and an alkali metal chloride and heating the mixture in a temperature range of 550°C to 600°C, it has a cubic shape and a binoxheit type. A method for producing ferric oxide particles, the method comprising obtaining ferric oxide particles having a crystalline structure. (3) The amount of alkali metal chloride is
I) The method for producing ferric oxide particles according to claim 2, wherein the amount is 1.5 to 3 moles per mole.