JPS63274627A - Powdery fine particle of plate magnetoplumbite type ferrite to be used for magnetic recording - Google Patents

Abstract

PURPOSE:The title powdery fine ferrite particles having appropriate coercive force and high thermal stability consisting of plate magnetoplumbite type ferrite particles having a specified compsn. contg. Ba wherein the change of coercive force of said Ba is regulated within a specified range. CONSTITUTION:The powdery plate magnetoplumbite type fine ferrite particles to be used for magnetic recording of this invention have a compsn. expressed by the formula and consist of plate magnetoplumbite type fine ferrite particles contg. Ba having a coercive force changeable within a range from -2.0-+2.0Oe/ deg.C at 20-120 deg.C. For the prepn. of said fine particles, a Ba material such as BaCO3, an Fe material such as hematite, a Zn (as substituting element) material such as ZnO, a Ti material such as TiO2, and a Co material, are mixed in a specified proportion. Then, the mixture is calcined at 750-950 deg.C in the presence of a flux, crushed coarsely thereafter, and washed by the conventional process with water or an acid, etc.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides BaO.n ((FeI-JW)gOzl
(However, A is Ba or Ba and Srs M is Zn and Ti or Zn, 'Co and Ti, n=6.5-11.
0, X=0.05 to 0.25), and 2
The change in coercive force in the temperature range of 0 to 120℃ is -2,
The present invention is made of plate-like magnetoblanbite-type ferrite fine particles containing Ba within the range of 00e/°C to ÷2.00e/'C (this relates to plate-like magnetobrambite-type ferrite fine particles powder for n-air recording).

[Conventional technology]

In recent years, for example, as described in Japanese Patent Application Laid-Open No. 55-86103, it has a suitable coercive force and a large magnetization value,
In addition, ferromagnetic non-acicular particles having a suitable average particle size are increasingly desired as magnetic materials for recording, particularly magnetic materials for perpendicular magnetic recording.

-M, magnetobrambite-type ferrite particles containing Ha are well known as ferromagnetic non-acicular particles.

First, regarding magnetic properties, the coercive force of the plate-shaped magnetoblanbite type ferrite fine particle powder for magnetic recording is generally required to be about 300 to 20,000e; In order to reduce the
It has also been proposed to substitute with a divalent metal ion M(1) such as MnsZn.

In addition, (Rization 1.α needs to be as large as possible, and this fact can be seen, for example, in Japanese Patent Application Laid-Open Publication No. 149328/1983, “... Magnetobrambite ferrite used in magnetic recording media materials. As described above, "the largest possible saturation magnetization... is required for this purpose."

Next, regarding the particle size of the plate-shaped magnetobrambite type ferrite W particles for magnetic recording, it is required that the particles be as fine as possible, especially 0.3 μm or less.

This fact can be seen, for example, in Japanese Patent Application Laid-Open No. 56-125219, which states, However, in order to perform sufficient recording and reproduction in this wavelength range, the crystal grain size of the ferrite must be approximately 0.3μ.
-The following is desirable, but when it comes to about 0.01 μm,
Since it does not exhibit desired ferromagnetism, an appropriate crystal grain size is required to be approximately 0.01 to 0.3 μ-. It is as described in J.

In recent years, there has been an unstoppable demand for improving the properties of plate-shaped magnetoblanbite-type ferrite m particles ↑5) containing Ba, which have the above-mentioned appropriate coercive force and large magnetization value, and have an appropriate average In addition to having a particle size, furthermore,
Magnetic (especially coercive force) stability against temperature (hereinafter simply referred to as temperature stability).

) is strongly required.

The reason for this is that magnetic recording is performed by converting the magnetic 15) end in the magnetic recording medium into Eii using a magnetic field generated by a magnetic field. Even if you adjust the magnetic field of the magnetic field and the coercive force value, which is the magnetization component of the magnetic powder, if the coercive force value of the magnetic powder fluctuates due to temperature rise due to environmental changes, optimal recording will not be possible. be.

[Problem that the invention seeks to solve]

Ba has an appropriate coercive force, a large magnetization value, an appropriate average particle size, and excellent temperature stability.
There is currently a demand for plate-shaped magnetobrambite-type ferrite fine-particle powder containing Ba. Temperature stability was poor.

This phenomenon can be seen, for example, in
CTIONS ON MAGNETrC5) MAG-
18 No. 6, page 1123, rFig, 4 J.

Conventionally, as a method for improving the temperature stability of plate-shaped magnetoblanbite type ferrite a particle powder containing Ba, there is a method described in, for example, Japanese Patent Application Laid-Open No. 152003/1983.

The method described in JP-A No. 61-152003 uses Co
(1) - Plate-shaped Ba ferrite 1 particle powder containing elements for reducing coercive force such as Ti @300~7
Although the heat treatment is performed at 00° C., the coercive force increases by more than double the value before the heat treatment, and it has the disadvantage that it is difficult to control the coercive force to an appropriate value.

Therefore, there is a strong demand for establishing a method for obtaining Ba-containing plate-shaped magnetoblanbite-type ferrite fine particles having appropriate coercive force and excellent temperature stability.

(Means for solving the problem) The present inventor has conducted various studies in order to obtain a Ba-containing plate-shaped magnetobrambite-type ferrite fine particle powder that has an appropriate coercive force and excellent temperature stability. As a result, we have arrived at the present invention.

That is, the present invention provides 80 ・n ((Pe+−J,)z
Os) (However, A is Ha or Ba and Sr, M is Zn
and Ti or Zn, Co and Ti, n=6.5-1
1.0,
Ba within the range of 2,00e/l to +2.00e/l
This is a plate-shaped magnetoblanbite-type ferrite fine particle powder for magnetic recording, which is made of plate-shaped magnetoblanbite-type ferrite fine particles containing.

[For production]

First, the most important point in the present invention is that AO-nr(F
e+--M-)xOzl (However, A is Ba or Ha
and Sr, bamboo is Zn and Ti or Zn, Co and Ti,
n=6.5-11. It is a fact that the Ha-containing plate-like magnetoblanbite type ferrite fine particle powder having a composition of 0.05 to 0.25) has excellent temperature stability.

Particularly, the plate-shaped magnetobrambite type ferrite fine particle powder containing Ba in the present invention has a change in coercive force in the temperature range of 20 to 120°C from -2, OOe/'C to +
It is within the range of 2.00e/''C.

In particular, when the Ra-containing plate-shaped magnetoblumbite-type ferrite fine particle powder of the present invention further contains Co in addition to Zn and Ti, the change in coercive force in the temperature range of 20-120°C is 00e/'. C~÷2,00e/
'C is within the range.

In the present invention, it is not yet clear why the plate-like magnetoblanbite type ferrite fine particle powder containing Ba with excellent temperature stability is obtained, but the present inventor has determined that ^0. n ((Fe.

-yr+*) In the case of a Ba-containing plate-like magnetobrambite type ferrite fine particle powder having a composition outside the range of n=6.5 to 11.0 in zozl, a part of Fe@ in the ferrite is composed of Zn or Ti. 6 replaced with either
In either case, a plate-like magnetobrambite-type ferrite fine particle powder containing Ba with an excellent temperature stability can be obtained. Since there is no such difference, it is thought that this is due to a synergistic effect between Zn and Ti that replaced a part of Pe@ in the ferrite and the magnetobrambite type ferrite H8k particle powder having a specific composition.

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

The plate-shaped magnetoblanbite type ferrite fine particle powder containing Ba in the present invention has the following characteristics: ^0·n ((Fe, -.

Mw) n=6 at t(:h). s ~11.0,
x=0.05 to 0.25.

If n is 6.5 or less, the change in coercive force in the temperature range of 20 to 120°C will be +2.00e/°C or more, making it impossible to achieve the object of the present invention.

When n is 11.0 or more, a nonmagnetic phase or a spinel ferrite phase is mixed, and the magnetization value decreases.

If the summer temperature is less than 0.05, the change in coercive force in the temperature range of 20 to 120°C will be more than +2-00e/'C, making it impossible to achieve the object of the present invention.

is greater than or equal to 0.25, then non-vAtl! phase or spinel ferrite phase coexist, and the magnetization value decreases.

The plate-like magnetobrambite-type ferrite fine particle powder containing Ba in the present invention is a Ba raw material such as barium carbonate (
If necessary, a part of the Ba raw material may be replaced with an Sr raw material such as strontium carbonate), and l+e raw materials such as hematite, magnetophyte, maghemite, goethite, etc. and substitute elements zinc oxide, zinc carbonate, and zinc hydroxide. Zn raw materials such as, Ti raw materials such as titanium oxide, and cobalt carbonate,
Cobalt hydroxide, basic cobalt carbonate (2CoCOz
・Co raw materials such as 3Co(OR)t' HzO) are mixed at a specific blending ratio, then heated and calcined in the presence of a flux in a temperature range of 750 to 950°C, pulverized, and mixed with water, It can be obtained by washing in a conventional manner using an acid or the like.

Examples of the flux in the present invention include alkali metals,
One or more of alkaline earth total pressure halides, g-acid salts and silicates can be used.

The amount of flux present is 15 to 100% by weight based on the iron raw material.

If it is less than 15% by weight, the object of the present invention cannot be achieved.

, 100% by weight or more, the object of the present invention can be achieved, but there is no point in having it present in an amount greater than necessary.

When the firing temperature in the present invention is 750° C. or lower, the ferrite formation reaction is insufficient and unreacted substances remain.

If the temperature is 950° C. or higher, sintering occurs between the particles and between the particles, which is not preferable as a magnetic particle powder for magnetic recording.

(Example) Next, the present invention will be explained with reference to Examples and Comparative Examples.

In addition, the average diameter of particles in the following Examples and Comparative Examples is a value measured using an electronic Sgi micro-otoscope photograph.

Further, the magnetization value and coercive force were measured in a powder state in a magnetic field of 10 Oe.

Temperature stability is calculated by calculating the difference between the coercive force value at 20°C and the coercive force value at 120°C as the temperature difference between 20°C and 120°C (1
00°C) is expressed as Oe/'C.

Example 1 Barium carbonate 195 g, magnetite 1070 g%
131.8g of zinc oxide and 116.2g of titanium oxide,!
: 1250 g of NaC and NagSi (1 m
250g was mixed and placed in an alumina crucible, and heated and calcined at 800°C for 1.5 hours using an electric furnace.
The heated and calcined product was pulverized and washed in a conventional manner to remove the flux, and then filtered and dried to obtain a brown particle powder.

As is clear from the electron micrograph (XIOo, 000) shown in FIG. 1, the obtained ferromagnetic brown powder has an average diameter of 0.
．． 07μ-, and as a result of fluorescent X-ray analysis and X-ray diffraction,
Ba0 ・8.19 ((Fee, +5Zno, *q
It was a magnetobrambite type ferrite fine particle powder having the composition of iTio, 5eas)to,).

This BaO・8.19 ((Pea, *+5Zns,
mqhTis, **ie)gos) The magnetic properties of the fine particle powder are coercive force Hc 5300e, magnetization value 53.4
ergu/g, temperature stability is -1,30e/℃
Met.

Examples 2 to 7, Comparative Examples 1 to 2 Type and amount of Fe raw material, type and amount of Ba or Ba and Sr raw material, type and amount of Zn raw material, type and amount of Ti raw material, type and amount of flux B was prepared in the same manner as in Example 1 except that the heating and firing temperature and time were varied.
A plate-shaped magnetoblanbite type ferrite fine particle powder containing a was obtained.

The main manufacturing conditions at this time are shown in Table 1, and the characteristics are shown in Table 2.

〔Effect of the invention〕

The plate-shaped magnetoblanbite-type ferrite fine particle powder containing Ba according to the present invention has an AO
-n ((Fe+-JjJs) (However, A is Ba or Ba and Sr, M is Zn and Ti or Zns Co
and Ti, n=6.5-11.0, X・0.05-0.
Due to the composition of 25), it has an appropriate coercive force and excellent temperature stability, especially 20 to 120
The change in coercive force in the temperature range of ℃ is -2,00e/℃
Since the particle powder is within the range of ~+2.00e/'C, it is most suitable as the plate-shaped magnetoblanbite type ferrite fine particle powder for magnetic recording, which is currently most in demand.

[Brief explanation of the drawing]

Figure 1 shows an electron micrograph (X
100.000).

Claims (1)

[Claims] (1) AO・n{(Fe_1_−_xM_x)_2O_
3} (However, A is Ba or Ba and Sr, M is Zn and Ti or Zn, Co and Ti, n = 6.5 to 11.0,
x=0.05~0.25), and 20~
The change in coercive force in the temperature range of 120℃ is -2.00
Powder of plate-shaped magnetoplumbite-type ferrite fine particles for magnetic recording, comprising plate-shaped magnetoplumbite-type ferrite fine particles containing Ba within the range of e/°C to +2.00e/°C.