JP2003073125A - Method for producing yttrium - aluminum - iron oxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new method for producing a polycrystal of yttrium - aluminum - iron oxide useful for an optical material, in large amount at a low cost. SOLUTION: This method comprises the steps of treating powder of compounds of yttrium, aluminum and iron as raw materials by a ball mill to effect solid reaction, and crystallizing the obtained non-equilibrated substance to form polycrystalline powder of yttrium - aluminum - iron perovskite-type oxide.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The invention of this application relates to a method for producing a yttrium-aluminum-iron composite oxide. More specifically, the invention of this application uses a polycrystalline yttrium / aluminum / iron composite oxide powder as a powder, which is useful for manufacturing laser optical technology, various cathode ray tubes, display devices, sensors, catalysts, etc. as an optical material. The present invention relates to a new method that enables mass production at a cost.

[0002]

2. Description of the Related Art Yttrium-aluminum-iron perovskite complex oxide (YAl _1-X Fe
_{X O 3, 0 <X <} 1) is a new material that has attracted attention optical materials and sensors, as a catalyst or the like. There are not many reports on its manufacturing method, but (1)
Starting from iron oxide, yttria, and alumina 150
A high temperature process of 0 ° C. or higher, (2) a sol-gel process or a synthesis method by other solution reaction is known as a general manufacturing method.

However, the high-temperature process (1) requires a special high-temperature device, and it is necessary to perform synthesis in consideration of decomposition reactions and various side reactions that proceed at the same time, which leads to efficient industrial production. It wasn't an advantage.

The method (2) is a reaction which proceeds at a low temperature and has been actively developed in recent years, but it is difficult to use it in a wide range of chemical compositions and the reaction requires a long time. However, there are disadvantages that there are many by-products and the yield is not so high. It is also a costly method overall.

Therefore, there has been a demand for realization of a new manufacturing method which is low in cost and highly efficient without requiring special equipment or special conditions. Therefore, the invention of this application has been made in view of the circumstances as described above, and solves the problems of the prior art and improves the yttrium-aluminum-iron composite oxide (YAl _1-X Fe _X O ₃ , 0 An object of the present invention is to provide a new method capable of mass-producing the polycrystalline powder of <X <1) at a low cost without requiring special equipment or special conditions.

[0006]

Therefore, the invention of this application provides the following invention in order to solve the above problems.

That is, first of all, the invention of this application is a method for producing a yttrium-aluminum-iron perovskite type complex oxide, in which a powder of a compound of yttrium, aluminum and iron as a raw material is treated by a ball mill. A solid-state reaction is carried out to crystallize the non-equilibrium substance produced, and a method for producing a yttrium-aluminum-iron perovskite complex oxide is provided.

The invention of this application is, in the method for producing the yttrium-aluminum-iron composite oxide of the above-mentioned invention, secondly, as a raw material, a powder of yttrium, aluminum, iron oxide or hydroxide. Thirdly, a manufacturing method characterized by using
A method for producing an yttrium-aluminum-iron composite oxide in which a yttrium site is substituted with a rare earth compound containing at least one kind of lanthanoid rare earth element having an atomic number of 58 to 71. I will provide a.

On the other hand, a fourth aspect of the invention of the present application is a method for producing the yttrium-aluminum-iron composite oxide according to any one of the above methods, characterized in that crystallization is performed in a ball mill. Fifth, a manufacturing method characterized by crystallization in a temperature range of 5 ° C to 35 ° C, and sixthly, 600 ° C to 1200 with respect to a substance containing a non-equilibrium phase obtained in a ball mill. A manufacturing method characterized by performing a heat treatment in a temperature range of ℃, a seventh, a manufacturing method characterized by performing a heat treatment after adding a sintering aid substance, an eighth, the Also provided is a method for producing a compact yttrium-aluminum-iron composite oxide, which is characterized in that molding is performed prior to heat treatment.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The invention of this application has the characteristics as described above, and the embodiments thereof will be described below.

First, in the method for producing the yttrium-aluminum-iron perovskite type complex oxide provided by the invention of this application, a powder of a compound of yttrium, aluminum and iron as a raw material is treated by a ball mill to cause a solid phase reaction, The non-equilibrium substance formed is crystallized.

Ball mills are generally the means used to mix and grind powders by milling. However, in the invention of this application, the ball mill is
It is characterized in that it is used as a place for solid-phase reaction, as a place for producing a non-equilibrium substance having a controlled composition, and as a place for crystallization of the non-equilibrium substance. It is not common to use a ball mill for the purpose of synthesizing an oxide, and there has been no application for yttrium-aluminum-iron oxides in the past, and it is first presented by the inventors of this application. It is a thing.

That is, the inventors of the present application have found that in the yttrium / aluminum / iron system, a non-equilibrium phase is generated at around room temperature due to a solid-phase reaction due to milling by a ball mill, and depending on the composition and other conditions, the non-equilibrium phase is generated. Crystallization of the equilibrium phase also occurs in the ball mill at the same time, paying attention to the fact that crystals with a size of several nanometers to several tens of nanometers, that is, nanocrystals can be generated, and the general formula YAl _1-X Fe _X O ₃ (0 < The present invention was found based on the finding that a perovskite type complex oxide represented by X <1) can be obtained. This YAl _1-X Fe _X O ₃
Is obtained by substituting Fe for Al sites of YAlO ₃ perovskite type composite oxides used as various optical materials.

According to the method of the invention of this application, the solid-phase reaction by milling in a ball mill proceeds even at a temperature near room temperature. This solid state reaction produces a non-equilibrium phase,
Nanocrystals are first generated by the crystallization, but depending on the composition and other conditions, the crystallization further proceeds in the ball mill, and a polycrystalline powder can be obtained as it is. The inside of the ball mill in this case includes the inside of the ball mill during milling and the inside of the ball mill after milling. Various factors may be considered for the conditions under which crystallization progresses in the ball mill, so it cannot be unequivocally shown, but it seems that the conditions largely depend on the raw materials. In the invention of this application, the temperature around room temperature is, specifically,
For example, about 5 ° C to 50 ° C, more realistically 5 ° C to 3 ° C.
It can be in the range of about 5 ° C.

The raw material for the ball mill treatment is basically a compound powder of yttrium, aluminum and iron. Specifically, for example, powders of oxides, hydroxides, carbonates and nitrates can be used.
More preferably, powder of yttrium, aluminum, iron oxide or hydroxide can be used. Such a raw material may be, for example, one that substantially becomes an oxide or hydroxide in the process of ball mill treatment.

Further, these raw materials may be used in combination with a material of a lanthanoid rare earth element having an atomic number of 58 to 71 for substituting the yttrium site and one or more kinds of sintering aid materials. These can be used by adding various materials such as oxides, complex oxides, nitrates, carbonates, and complexes to raw material powders of yttrium, aluminum and iron.

Regarding the particle size of the raw material powder,
It is considered that the average particle diameter is usually 10 μm or less, more preferably 1 μm or less. Regarding the purity, it is possible to use a powder having such a particle size, which has a general value of 99.9% or more.
These are blended so as to have a desired composition and then subjected to a ball mill. However, 100 derived from the ball mill process, etc.
Incorporation of unavoidable impurities in the order of ppm is naturally allowed.

As the ball mill, one that gives sufficient energy to cause a solid phase reaction of these powders can be used. Specifically, for example, a planetary ball mill capable of achieving a rotation speed of 250 rpm or more, a ball mill provided with balls and a container made of a hard material such as tungsten carbide (WC), and the like are considered.

When the substance produced by the solid phase reaction near room temperature contains a non-equilibrium phase, it can be heat-treated at 600 to 1200 ° C. to crystallize the non-equilibrium phase. . The powder that has already been crystallized and contains nanocrystals can be subjected to the same heat treatment in order to improve the crystallinity. Further, there is no particular limitation on the means of heat treatment of these powders, for example, the substance produced by the solid phase reaction is taken out from the ball mill,
The heat treatment is performed by an electric furnace or the like as a general example, but it is also possible to perform the heat treatment during or after milling using a ball mill having a heating function. Further, these powders may be subjected to heat treatment after being molded into a molded body. Regarding the heat treatment temperature of the non-equilibrium substance, for example, the crystallization temperature can be accurately grasped by performing differential thermal analysis or the like in advance on the polycrystalline powder after the ball mill or the molded product thereof. The heat treatment time varies depending on whether it is a powder or a molded product, and further depending on the shape of the molded product, etc., but is generally several minutes to several hours, more preferably, for example, 10 minutes. It is preferably within a range of about 2 hours. Further, when the heat treatment is performed, it is possible to add the above lanthanoid rare earth element and the sintering aid substance to the powder after the ball mill, and then to perform the heat treatment instead of the raw material powder. As a mixing means, a ball mill may be continuously used, or manual mixing using a mortar or the like may be used for careful mixing.

The technique for obtaining a polycrystalline powder of yttrium-aluminum-iron perovskite-type complex oxide by the method of the invention of the present application as described above is a new method, and at the same time, is extremely applicable and practical. In other words, it does not require special equipment or special conditions, and is a method that is lower in cost and more efficient than any conventional method. For example, on a laboratory scale, a high-energy ball mill for 24 hours and a general-purpose inexpensive electric furnace for about 2 hours are enough to produce 10 to several tens of grams of yttrium-aluminum-iron perovskite-type composite oxide. A polycrystalline powder can be obtained. It is also considered promising to take out the nanocrystals obtained by crystallization of the non-equilibrium phase in a ball mill as they are and apply them to a material such as a catalyst that pays attention to their small size. This method can be easily scaled up and is also suitable for industrial mass production.

Yttrium-aluminum-iron perovskite type complex oxide is an important optical material, and if the method of the invention of this application enables mass production with low cost and high efficiency, laser engineering technology, various cathode ray tubes, It is thought that this will spread to the manufacturing technology of display devices, sensors, catalysts, etc., and promote the progress of those manufacturing technologies.

Examples will be shown below to describe the embodiments of the present invention in more detail.

[0023]

Example 1 A commercially available raw material powder shown in Table 1 was used.
Y: Al: Fe = 1: 0.7: 0.3 are mixed,
Ball milling was performed under the conditions shown in Table 2. In this example, a tungsten carbide (WC) container and a ball mill were used.

[0024]

[Table 1]

[0025]

[Table 2]

As shown in the X-ray diffraction pattern of FIG. 1, (a)
The peak corresponding to the crystal structure of the starting material of
After 4 hours of milling, almost disappeared, and YAl _1-X Fe _X
A crystal peak of O ₃ (X = 0.3) was obtained. That is, it was shown that YAl _0.7 Fe _0.3 O ₃ polycrystalline powder was synthesized.

Since a part of the non-equilibrium phase substance that had not been crystallized was mixed in this powder, the powder was placed in an alumina crucible and subjected to heat treatment by heating. Using a commercially available electric furnace, the temperature is raised at 100 to several hundreds of degrees Celsius per hour in the atmosphere, and 115
By holding at 0 ° C. for 2 hours, the powder could be completely crystallized as shown in (C). The holding temperature (1150 ° C.) at this time was determined by performing a differential thermal analysis of the polycrystalline powder in advance as shown in FIG. 2 and using the exothermic peak position corresponding to crystallization as an index.

The X of the material obtained after the heat treatment of FIG. 1 (c)
The line diffraction pattern was in good agreement with the YAP diffraction pattern in the database, and it was confirmed that the target substance was synthesized. The results of observing this powder with a scanning electron microscope (SEM) are shown in FIG. In FIG. 3, particles having a round shape and a smooth surface with a diameter of 0.1 to 1 micron are recognized, and the yttrium-aluminum-iron composite oxide particles obtained by the method of the invention of this application are produced by another method. It was confirmed that it was comparable to the powder. (Example 2) CeO ₂ powder was added to the powder of the Y-Al-Fe-O polycrystal after the ball mill obtained in Example 1 above, and then milled for 10 minutes with the ball mill. This was molded into pellets with a diameter of 13 mm, and then heated in an electric furnace at 200 ° C./hr.
By keeping it at 0 ° C for 2 hours, it was possible to completely crystallize. As a result, a (Y, Ce) -Al-Fe-O polycrystalline bulk body in which Ce was substituted at the Y site could be obtained.

Of course, the present invention is not limited to the above examples, and it goes without saying that various details can be made.

[0030]

As described in detail above, according to the present invention, a polycrystal of yttrium-aluminum-iron composite oxide useful as an optical material for producing laser optical technology, various cathode ray tubes, display devices, sensors, catalysts and the like. The present invention relates to a new method that enables mass production of a body at low cost.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of yttrium aluminum.
It is a figure which illustrated the result of the X-ray diffraction measurement corresponding to the synthetic | combination process of an iron complex oxide, Comprising: (a) raw material powder, (b) after ball mill, (c) after heat processing is shown.

FIG. 2 is a diagram illustrating the results of differential thermal analysis of polycrystalline powder obtained by a ball mill in the examples.

FIG. 3 is a view exemplifying a SEM image of the yttrium-aluminum-iron composite oxide powder obtained in the example.

Claims (8)

[Claims] 1. A method for producing a yttrium-aluminum-iron perovskite-type composite oxide, comprising a non-equilibrium substance produced by treating a powder of a compound of yttrium, aluminum and iron as a raw material with a ball mill to cause a solid phase reaction. A method for producing a yttrium-aluminum-iron perovskite-type composite oxide, which comprises crystallization of 2. The method for producing the yttrium-aluminum-iron composite oxide according to claim 1, wherein a powder of yttrium, aluminum, iron oxide or hydroxide is used as a raw material. 3. A yttrium-aluminum-iron composite oxide in which a yttrium site is substituted with a rare earth compound containing at least one lanthanoid rare earth element having atomic numbers 58 to 71 as a raw material is produced. The method for producing the yttrium-aluminum-iron composite oxide according to claim 1 or 2, wherein 4. The method for producing the yttrium-aluminum-iron composite oxide according to claim 1, wherein the crystallization is performed in a ball mill. 5. The yttrium according to claim 4, which is crystallized in a temperature range of 5 ° C. to 35 ° C.
Method for producing aluminum-iron composite oxide. 6. The yttrium according to claim 5, wherein the substance containing the non-equilibrium phase obtained in the ball mill is subjected to heat treatment in a temperature range of 600 ° C. to 1200 ° C.
Method for producing aluminum-iron composite oxide. 7. The method for producing an yttrium-aluminum-iron composite oxide according to claim 6, wherein the sintering aid material is added and then heat treatment is performed. 8. The method for producing a compact yttrium-aluminum-iron composite oxide according to claim 6 or 7, wherein the forming is performed prior to the heat treatment.