JPS61117117A - Synthesis of m3o4 type compound and solid solution - Google Patents

Abstract

PURPOSE:To provide a method for prepg. an M3O4 type compd. having high purity consisting of fine paticles having a molecular dimension wherein the prepn. is possible by a reaction at a low temp. in the liquid phase without requiring any large apparatus for the reaction. CONSTITUTION:Alkoxide(s) of at least one kind of divalent metal M is (are) formed in an atmosphere contg. no oxygen. Then, a hydroxide of one kind of the metal or a solid soln. of hydroxides of >= two kinds of the metals is prepd. by hydrolyzing the alkoxid(s) in the oxygenfree atmosphere. An M3O4 type compd. of one kind of the metal, or a solid soln. comprising >= two kinds of M3O4 type compd. is obtd. by oxidizing the hydrolyzate. Suitable metals for said M3O4 type compds. are di- or tervalent metals such as Fe, Mn, Co, etc. Suitable alcohols for said alkoxides are methanol, ethanol, butanol, etc. The synthetic process is illustrated by an appendant figure.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a compound consisting of a kind of metal represented by M2O3 (where M is a metal), and a compound consisting of a metal and another metal having the same composition. This invention relates to a method for synthesizing a solid solution (especially ferrite).

(Prior Art) A conventional method for producing ferrite involves mixing an oxide of a divalent metal and an oxide of trivalent iron in a powder state, for example, 13O
This was done by heating the reaction to 0°C to 1500°C. However, in this method, ferrite is obtained by reacting a mixture of solid particles, so the wood composition is non-uniform, and the high temperature reaction results in large ferrite particles and a wide particle size distribution. Therefore, it has not been possible to produce materials with high dimensional accuracy that allow for high-performance, high-reliability microfabrication. In addition, according to the conventional method, when the raw material oxides are mixed and reacted at high temperature,
A ferrite layer is formed only by reaction and diffusion between the surfaces where particles are in contact with each other, and the deep part of the particles remains intact, so heating reaction and pulverization are necessary to obtain highly uniform ferrite. Must be repeated. Therefore, it takes a long time to manufacture, requires a large-scale crushing device, and requires a large furnace to maintain high temperatures.

Furthermore, since pulverization and heating are repeated, contamination with foreign matter is inevitable, making it difficult to obtain a product of high purity.

(Problems to be Solved by the Invention) In view of these drawbacks, the present invention aims to produce high-purity particles of molecular size, which can be produced by low-temperature reaction in a liquid phase, and does not require large-scale equipment for the reaction. The present invention aims to provide a method for obtaining the N3O4 compound and its solid solution.

(Means for Solving the Problems) The synthesis method of N3O4 according to the present invention is to produce an alkoxide of one or more divalent metals M (n) in an oxygen-free atmosphere, and then to create an alkoxide in an oxygen-free atmosphere. A solid solution of one type of metal hydroxide or two types of metal hydroxides is created by hydrolysis, and a solid solution of one type of metal N3O4 is obtained by oxidizing the hydrolysis product. It is characterized by

The metals targeted by the method of the present invention include, for example, Fe, Mn
．． It is a metal that can be divalent or trivalent like Co. Also,
Alcohols for making alkoxides include methanol,
Ethanol (Et), butanol, etc. are used.

(Example 1): As a starting material for the synthesis of Fe3O4(7), FeCl2.nH20 was vacuum-dried at 200°C for 2 hours to form anhydrous chloride FeC2. As shown in the process diagram of Figure 1, first, 0.04% of this anhydrous chloride
Mol in Et for 1 hour, N2 gas at 0, 2 1 /w
Metallic Na at the zero-order stoichiometric ratio is dissolved while flowing at a flow rate of in (Na0Et may be used instead)
was added and refluxed (processing to cool and liquefy the solvent vapor generated by heating and return it to the solution) to generate Fe(OEt)2 by the following reaction.

FeCJL2 +2NaOEt 1F e (OEt)2 +2NaC! ;L・-
(1) This reaction is carried out in an N2 gas atmosphere because Fe(OEt)2 and Fe(OH)2 are very easily oxidized, and Fe(OEt)2 is insoluble in general solvents (EtOH and benzene). )2 is oxidized to dark brown Fe (OE
t) becomes 3 and changes into a substance soluble in the general solvent,
Obata et al.'s study revealed that the final product cannot be obtained from a mixture of solid and solution alkoxides, so it is necessary to avoid contact with air as much as possible until the hydrolysis procedure described below. It is from. Therefore, inert gases other than N2 gas can be used as long as an oxygen-free atmosphere can be formed. In addition, Na is used to speed up the reaction that produces alkoxides,
Li or K can also be used instead.

Next, 100ml of Niura water was added and refluxed for 1 hour to perform hydrolysis. The injection of N2 was stopped, and air was instead injected into the suspension of the hydrolysis product at a flow rate of 0.21 to 2 Jl/win to perform air oxidation. We also examined the effects of varying the oxidation time while keeping the air injection amount per hour constant. In these operations, the reflux temperature was maintained at 65 to 70°C, and the temperature during oxidation was 70 to 80°C. The obtained precipitate was vacuum dried at room temperature and then examined by thermal analysis, X-ray analysis and electron microscopy.

The results are as follows. Hydrolysis of the alkoxide Fe(OEt)2 of Fe(n) produces Fe(OH
) 2 was obtained as a dark green solid in ethanol solvent.
After filtering this, immediately remove the
It was placed on an X-ray glass holder, covered with cellophane tape, and subjected to X-ray diffraction. X-ray diffraction was also performed by varying the oxidation time with air. The results are shown in FIG. Second
As shown in the figure, when Fe(OH)2 is oxidized for 1 hour, a sharp diffraction peak of magnetite (FezOa) appears, and a slight peak of oxide hydrate (FeOOH) is also observed. In oxidation, the mono-
phase, and the peak becomes larger. However, the peak shifts to higher angles with increasing oxidation time. Since magnetite is a cubic crystal system, the lattice constant plane was determined and the change corresponding to the oxidation time was determined. The results are shown in FIG. Oxidation 1~
After 4 hours, a value almost equal to the lattice constant of magnetite, 8.3967, was obtained, but after oxidation for 5 hours or more, the lattice constant gradually decreased. It is said that if the oxidation continues, the magnetite progresses to the point where γ-Fe3O4 is oxidized, so it is thought that the lattice constant plane decreases due to the solid solution of γ-Fe2O3 in magnetite.

Figure 4 shows the thermal analysis results of the product after 5 hours of air oxidation.
There is an increase in the weight of the exothermic peak due to the formation of y-Fe203 due to the oxidation of e3O4, and at 510°C there is an increase in the weight of α-Fe203.
An exothermic peak due to phase transition is observed. Fe (O
Theoretically, the weight increase when changing from H)2 to Fe3O4 is 3.46%, but in this case, the oxidation time 2
．． 3, 5. 2.0%, 2°4%, 1 at 20 hours, respectively
．． They were 8% and 1.5%. Therefore, it contains more trivalent iron than the Fe3O4 composition, but as mentioned above,
Since the lattice constant is close to the theoretical value, it is considered that the excess trivalent iron at this point is due to oxidized aqueducts such as α-FeOOH.

Figure 5 shows the air oxidation products at 200'0.4
In Figure 5, which shows the X-ray diffraction results of samples calcined for 2 hours at 00°C, 600°C, aOO°C and 1000°C,
During calcination at 200℃ and 400℃, the peak of Fe3O4 shifts to the high angle side, and the lattice constant of each is 8.36.
4-. It became 8.352. The results show that Fe3O4 was oxidized to y-Fe203 (8,350). In addition, a-Fe203 is also seen from 400℃, and from y-Fe203 (X-F e203 to 17
) Metastasis is observed.

In addition, when each sample (dried material, calcined product at 200°C, 400°C, and 600°C) was observed using an electron microscope after oxidation for 20 hours, cubic-shaped fine particles with a side of about 0.14 m were observed. , no endothermic grain growth occurred.

(Example-2): Synthesis of Mn3O4 Using MnCl2 instead of FeCl2, using Et as the solvent and Na as the alkali metal in the same manner as above, refluxing and air oxidation in the same N2 gas atmosphere as above. Mn3O4 was obtained by this operation.

Figure 6 shows the X-ray diffraction results of the air oxidation product of Mn(OH)z. In the oxidation of Mn(OH)2, a diffraction peak of hausmannite (Mn3O+) was observed after 1 hour, indicating that the oxidation The diffraction peak becomes larger as time increases.

It was observed that M n (OH) 2 remained for about 3 hours after oxidation. Figure 7 shows the DTA-TG curve of the air oxidation product of Mn(OH)2, and in the case of Mn3O4, two exothermic peaks are also seen, but β-M n 00 H
This is thought to be due to the decomposition of oxidized hydrates such as Also, 60
At 0°C, there is an exothermic peak and weight increase of Mn3O4 to a-Mn203, and at 1000°C, α Mn3O4 to Mn3O
An endothermic peak and weight loss due to reduction to 4 are observed. 1
The endothermic peak at 200°C is the M n O of M n 3O4
This is probably due to the reduction reaction to .

FIG. 8 is an X-ray diffraction pattern of the calcined product of Mn(OH)2 air oxide at various temperatures, which agrees well with the case of Fe.

(Example-3): Synthesis of Co3O4 Using CoCl2 instead of FeC12(7) in Example-1, CO flucoxide (G
O(OE t) 2 was obtained as a bluish-white solid insoluble in solvents such as ethanol and benzene, and the product obtained by hydrolyzing this was Co00H. The results of this thermal analysis are shown in FIG. In Figure 9, there are endothermic peaks due to dehydration near 110°C and 160°C, an exothermic peak due to decomposition of Co0OH at 220°C, and an endothermic peak accompanied by weight loss due to reduction of Co2O3 to Co3O4 near 400°C. Admitted. It is known that Co2O3 does not exist as a stable phase, but as an interstitial solid solution of COO1+X and CO3O44, and in this experiment, the
As a result of calcination at 00°C, a spinel structure similar to Co3O4 was obtained.

(Example-4): Synthesis of Feelo4-c03 o4 Instead of FeC9,2 in Example 1, FeCl2
and CoCJL2, and the mixing ratio was set to Co/F
e=1/3.1/2.1/], changed to 3/1,
The same operations as in the example were performed up to air oxidation and filtration.

Note that the air oxidation time was 15 hours. Figure 10 is F
The figure shows the change in the crystal phase of the e3O4-Co3O4 system due to heating. According to this, in the composition region with a high iron content, a spinel phase was present at the time of vacuum drying. When the cobalt content increases, Co00H,! =FeOOHcr+solid solution was obtained.

Co/Fe=I/3 was separated into two phases, a spinel phase and a hematite phase, by calcination at 600°C. Co/F e =
In 3/1, two spinel phases precipitated during calcination at 600°C.

FIG. 11 shows X-ray diffraction patterns when calcined at 1000° C. at various mixing ratios, and FIG. 12 shows changes in the lattice constant with respect to changes in the mixing ratio.

The lattice constant of spinel T does not change when Co/Fe=O~1/2, decreases gradually when Co/Fe=1/2~1/1, and remains constant when Co/Fe=1/1~I10. became. As a result, Co/Fe=1/2~l/1
It is thought that Co3O4 is dissolved in CoFe2O4. Spinel II with Co/Fe=3/l is
Fe3O4 (ao=8.3967) and Co3O4 (
Since there are two existing on the straight line connecting ao=8.084),
It is thought that Fe3O4 is dissolved in Co3O4.

(Example-5) i Fe3O4-Mnz o, (7) Instead of FeCl2 in Synthesis Example 1, FeCfL
2 and M n Ci2, the mixing ratio M
The same operations as in the example were carried out, including air oxidation and filtration, while varying n/Fe. here.

If the content of Mn is X mol%, then the solid solution is.

(Mnx Fe+<) 3O< Te is expressed, xt-
0;0.084.0.16.0.275;0.333;
0.40; 0.50; 0.667; and 1°0, but x=0 and 1. The case of OO was described in the previous embodiment. Samples were taken several times over an air oxidation period of up to 20 hours and subjected to X-ray diffraction.

Figure fiSl 3 shows the results of oxidation products for x=0.333, ie MnFe2O4, as a representative example. 1st
As shown in Figure 3, the hydroxides are Mn(OH)2 and Fe
Obtained as a solid solution of (OH)2. M in air oxidation for 1 hour
The diffraction line peak of nFe204 and a small amount of (Fe,
A diffraction line peak of Mn)OOH is observed, and after oxidation for 3 hours or more, only the peak of M n Fe 204 becomes visible. Furthermore, as in the case of magnetite, the peak of MnFe2O4 shifted to the higher angle side with the passage of oxidation time. X=0
The diffraction lines from x=0.333 are almost the same, and clear spinel diffraction patterns are obtained in all cases,
= 0.40, the diffraction peak of spinel decreases, and even if the oxidation time becomes long, (Fe.

Mn)OOH remains. When x=o, 50; 0.667, the spinel phase is no longer clear, and when x=1.0, it becomes Mn3O4 as described above. Moreover, the peak of the obtained spinel phase shifted to the lower angle side as the Mn content increased. 1st
Figure 4 summarizes one or more results for the case of oxidation time of 5 hours.

FIG. 15 shows the change in lattice constant with respect to oxidation time for various Mn mixing amounts.

The change in lattice constant with respect to oxidation time is that of magnetite (x=
Almost the same as in case O), the highest value is obtained in 2 to 3 hours, and then it gradually decreases. This is thought to be a change due to excessive oxidation, as in the case of magnetite, and Mn(II) and Fe(II), which should be divalent, are oxidized and become Mn(In) and Fe(DI), respectively. This is because

Figure 16 shows the thermal analysis results for each composition.
Figure 17 shows temperatures of 200℃, 400'O, and 600℃, respectively.
, 800°C, and 1000°C.
An increase in weight due to heat generation is observed in the vicinity. Furthermore, when Mn is contained, the spinel phase remains even after calcination at 400°C, but when X=0.084.0.16, α is already present at 200°C
-Fe203 is now recognized. As with magnetite, although there is heat generated by the decomposition of oxide hydrates at around 200°C, this is thought to be mainly due to the oxidation reaction of Fe(II) to Fe([).

Furthermore, a sharp exothermic peak and weight increase are observed from 600°C to 700°C, which is due to the Mn(II) of Mn(H).
This is thought to be due to the oxidation reaction to f). The calcination results show that α-Fe203 is heated at 600°C, and a-M is heated at 800°C.
nzO3 becomes clearly visible. Fe, Mn
It can be said that the crystallization temperature was considerably higher than that of each alone.

When X≧0.40, the thermal analysis results begin to change differently than before. The exothermic peak near 230°C is (Mn, F
e) Weight loss accompanied by an endothermic peak at 620°C is observed, probably due to the decomposition reaction of OOH. This seems to be due to the reduction reaction known as M n O2→a −M n 203 . The changes at temperatures higher than this are the same as in the previous case, but x=o, 4
At 0:0.50, the spinel phase was observed quite stably.

FIG. 18 shows the lattice constants of spinel obtained for each composition of Fe3O4 and Mn3O+(7). As can be seen from Fig. 18, when X≦0.40, the lattice constant of air oxide changes linearly as the Mn content decreases, and Fe104
It is thought that Mn2O3 is mutually dissolved in solid solution. In addition, the lattice constant of the spinel phase remaining after calcination at 200℃ and 400℃ is also described, but the lattice constant decreases uniformly and finally settles on 8.350 of 7-Fe3O4. it is conceivable that.

According to an electron microscope observation of a sample of the Mn3O4-Fe3O4 solid solution system, the particle size was considerably smaller than that of Fe3O4, and was about 0.01 to 0.02 lm.

(Example-6): Fezo, -Ni3Oa (7)
Instead of coC12 in Synthesis Example 4, N1Cf
Using Lz, the mixing ratio of FeCJL2 and N1CfL2 is
Ni/Fe=1/3. 1/2. 1/l, 3/1
The same operation was performed up to air oxidation and filtration.

FIG. 19 shows the X-ray diffraction pattern of the powder calcined at 100°C, and as a result of compositional analysis, it was found that the end components were dispersed similarly to the Co-Fe system of Example 4, and were similar in other respects. The results were obtained.

(Effects of the Invention) As described above, the method of the present invention is a method for obtaining oxides by hydrolysis and oxidation at a lower temperature than conventional methods, and it is possible to obtain fine particles with a uniform composition as described above. I can do it. Furthermore, according to the present invention, there is no need for pulverization or high-temperature heating, so these large-scale devices are no longer necessary.
Moreover, since there is no need to repeat operations, manufacturing time is shortened. Further, according to the present invention, since the particle size of the product is small, it is possible to produce a material with high dimensional accuracy that allows for high performance and reliable microfabrication, and furthermore, it is possible to produce a material with high dimensional accuracy that can be processed into a crystalline material without using a sintering process. Since it is also possible to obtain oxides of , it is also possible to obtain products without using a firing process (furnace) by combining with polymeric materials.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing an example of the operation flow according to the present invention, and FIG. 2 shows
Line diffraction diagram, Figure 3 is a diagram showing the change in lattice constant with respect to oxidation time of Fe3O4, Figure 4 is a DTA-TG curve diagram of air oxidation product of Fe(OH)2, Figure 5 is Fe(OH)
Figure 6 is the X-ray diffraction diagram of the air oxidation product of Mn(OH)2 at various temperatures, Figure 7 is the X-ray diffraction diagram of the air oxidation product of Mn(OH)2. 2. Air oxidation product (7) DTA-TG curve diagram, Figure 8 is an X-ray diffraction diagram of the calcined product at each temperature of the air oxidation product of Fe(OH)2,
Figure 9 is a DTA-TG curve diagram of the product obtained by hydrolysis of Go(OEt)2, and Figure 1O is a diagram of the product obtained by hydrolysis of Go(OEt)2.
A diagram showing the phase change with respect to temperature of the -Mn3O4-based product.
X-ray diffraction diagram of sample heated to 0℃, Figure 12 shows Fe3O4-M
A diagram showing the change in lattice constant with respect to the composition of n3 o4 type products. Figure 13 is an X-ray diffraction diagram of the air oxidizer of (Mn, Fe) (OH)2. Figure 14 is an X-ray diffraction diagram of (Mnx F). e 1-X) 3O4 species h c7
) Figure 15 shows the X-ray diffraction diagram of the M
Figure 14 is a diagram showing the lattice constants at various Mn contents of (Mnx F e I-X) 3O4.
e +−x) D at various Mn contents of 3O4
TA-TG curve diagram, Figure 17 is (Mn):FeH)3O
4 at various temperatures at various Mn contents, FIG. 18 is a diagram showing changes in lattice constant at various temperatures for the composition of the Fe3O4-Mn3O4 system, and FIG. It is an X-ray diffraction diagram at the Ni content of seed #.

Claims (1)

[Claims] The alkoxide of one or more mono- or divalent metals M(II) is produced in an oxygen-free atmosphere, and then hydrolyzed in an oxygen-free atmosphere to produce one kind of metal water. By making a solid solution of oxide or hydroxide of two or more metals and oxidizing the hydrolysis product, M of one metal can be
_3O_4 compound or 2 consisting of the composition of M_3O_4
M_3O characterized by obtaining a solid solution of more than one metal
_4 Synthesis method of compound and its solid solution. 2. The method for synthesizing M_3O_4 compounds and solid solutions thereof according to claim 1, wherein the oxidation is carried out by blowing into a suspension of the hydrolysis product a gas that oxidizes the product.