JPS6021925B2 - Method for producing gamma type ferric oxide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides Fe304 and y-AI2Q and La, Ce, P
It is characterized in that the transition temperature to a-Fe203 is significantly improved by pulverizing 10G or more of mixed powder containing at least one of r, Nd, heat treatment, and oxidizing it.
-This invention relates to a method for producing Fe2Q.

-Fe2Q is a ferromagnetic powder and is widely used mainly in magnetic storage materials and electronic materials. Usually, to obtain this y-Fe203, Fe304 is
Examples include a method of oxidizing by heating at about 0 to 0, and a method of heating and dehydrating y-Fe00 days. The y-Fe203 obtained by these methods is affected by its particle size, impurities contained, lattice defects, etc., but approximately 30
Transforms into a-Fe203 at 0 to 500q○. For this reason, when y-Fe203 is used as an electronic material, the temperature at which it can be used is limited to a very limited range.
The present invention combines Fe304, Y-mount 203 and La, Ce.
The purpose of the present invention is to provide a method for producing y-Fe203 in which the transition temperature of y-Fe203 to a-Fe203 can be significantly increased by mixing and pulverizing 10 cm or more of Pr, Nd or more.

Examples thereof will be described below.

Example 1 Ferric chloride (FeC13/mother LO) and ferrous sulfate (Fe
S04 and 7 mountains 0) were collected at composition ratios of 667 mol% and 33.3 mol%, respectively, and dissolved in water.

This aqueous solution was heated and maintained at 50°C, and ammour water (NH40H) was added until the pH reached 9. Suction filter this,
It was dried at 9000 °C. The powder obtained by this is F
It is e304. Commercially available y-A for this Fe304
I2Q Toji 203 was blended to have the composition ratio shown in Table 1, and ground for 10 to 1 minute using a mustard grinder. Grinding conditions and sample ship at that time. The relationship is shown in Table 2. Then, each of the obtained powders was heat treated in vacuum at 50 to 1200 pm for 1 hour. Heat treatment conditions and sample M.
The relationship is shown in Table 3. Then, each of the obtained powders was heated in air at a heating rate of 100 powders per hour.
Heat to 0x0 and hold at 40p○ for 1 hour to form y-Fe2
03 powder was obtained. Differential thermal analysis was performed on each of these powders, and the transition temperature was determined from the exothermic peak when y-Fe203 transitions to a-Fe203. The results of determining the transition temperature from the exothermic peak of each sample are shown in Tables 4-1 to 4-5 and FIGS. 1 to 6. Table 1 * is a comparative example Table 2 * is a comparative example Table 3 * is a comparative example Table 4-1 * is a comparative example Table 4-2 * is above l Table 4-3 * is above l 4- Table 4 * is Comparative Example Table 4-5 * is l Figure A-1 to M-1 show the characteristics when the blending amounts of y-AI2Q and La203 were varied and the grinding time was also varied.

A-D to M-0' are the characteristics when the blending composition and heat treatment temperature are changed. From the above results, y-AI203 is 10-6
A mixture containing Fe304 in a proportion of 0 mol%, 89.95 to 25 mol% and La203 in a proportion of 0.05 to 1 mol% was ground for 1 to 1 minute, then heat treated in vacuum at 600 to 1200 pm, and further a of y-Fe203 obtained by oxidation
-The maximum transition temperature to Fe203 is 204℃ (A-3 and M
-3 comparison) can also be shifted to the high temperature side.

Also, compared to before mixing La203, it is 50 to 620 (B-
3 and E-3, F-3 and 1-3, and J-3 and M-3) can also be shifted to the high temperature side. Also, from Tables 4-1 to 4-5 and Figures 1 to 6, it is clear that simply Fe30
It can be seen that this effect does not appear even if only 4 is crushed, and that it must be crushed together with the Y-mount 203. Furthermore, it can be seen that the mixture of Aku 203 is extremely effective in making the effect more noticeable. Claims 4-1 to 4-5 set the crushing time to 100 minutes or more.
This is because, as shown in the table and FIGS. 1 to 3, when the grinding time is less than 100 minutes, the effect of the method of the present invention is not significant.
Furthermore, the heat treatment temperature was set at 600 to 1200 oo because as shown in Tables 4-1 to 4-5 and Figures 4 to 6, the effect of the method of the present invention is not significant when the heat treatment temperature is less than 600 oo. It's for a reason.

Next, in addition to Aku 203, Ce203, Pr203 and N40
An example in which one or more types of 3 are mixed will be described.

Example 2 Commercially available N203, La203, Ce2Q, Pr203, and Nq03 were blended to Fe304 prepared in the same manner as in Example 1 at a composition ratio shown in Table 5,
The mustard was crushed in a machine for 1 to 1 minute.

Grinding conditions and sample M. The relationship is shown in Table 6.
Then, each of the obtained powders was heat treated in vacuum at 60 mm for 1 hour. Then, it was oxidized in the same manner as in Example 1, and the transition temperature was determined in the same manner. The results are shown in Tables 7-1 to 7-2. Table 5, Table 6, Table 7-1, Table 7-2 From the above results, in addition to Fe304 and y-N203, at least one selected from Ce203, Pr203 and Nd203 was added in a total amount of 0.05 By pulverizing a mixture containing ~15 mol% for over 100 minutes, heat-treating it in a non-oxidizing atmosphere, and then oxidizing it, y-Fe203
It can be seen that the transition temperature of a-Fe203 to a-Fe203 can be shifted to a high temperature side.

Here, the mixing ratio of Ce, Pr and Nd is 0.05
The reason for limiting the amount to 1 flow ol% is that the effect of the method of the present invention is not significant below 0.08 hol%. Also 18
This is because if it exceeds hol%, there will be large variations and poor reproducibility, making it impossible to put it to practical use. In Example 2, as in Example 1, there was no effect unless the mixture was mixed together with the Y-mount 203, and the grinding time was significantly longer than 100 minutes.

In the examples, a pulverizing means is used as a pulverizing means, but the method is not limited to these, and any means capable of pulverizing, such as a ball mill, can be used.

As described above, according to the method of the present invention, a-F of y-Fe203
The transition temperature to e2Q can be greatly increased.

As a result, the temperature range in which y-Fe203 can be used as an electronic material will be greatly expanded, and its stability and reliability will be improved by several steps, and its application fields will also expand. be.

[Brief explanation of the drawing]

Figures 1 to 3 are diagrams showing the relationship between the grinding time of the powder obtained by the method of the present invention and the transition temperature from y-Fe203 to a-Fe203, and Figures 4 to 6 are similar diagrams. The heat treatment temperature of the powder obtained by the method and the change from y-Fe2Q to a-Fe2
FIG. 3 is a diagram showing the relationship with the transition temperature to 03. Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1 Triiron tetroxide (Fe_3O_4) 89.95-25 mol%, gamma type aluminum oxide (γ-Al_2O_3
), and lanthanum (La), cerium (Ce), praseodymium (Pr) and neodymium (
L) at least one selected from the four types of Nd)
a_2O_3, Ce_2O_3, Pr_2O_3, Nd
In terms of _2O_3 form, this total amount added is 0.05~
A method for producing gamma-type ferric oxide, which comprises pulverizing a mixed powder containing 15 mol% for 100 minutes or more, heat-treating it at 600 to 1200°C in a non-oxidizing atmosphere, and then oxidizing it.