JP5434665B2 - Method for producing metal oxide nanoparticles - Google Patents

Description

  The present invention relates to a method for producing metal oxide nanoparticles, and in particular, a catalyst, a conductive material, a dielectric material, a ceramic raw material, a pigment, a high refractive index material, a magnetic material, various resins, a plastic film, a plastic plate, and the like. It is preferably used as a filler for improving the thermal properties such as thermal expansion coefficient and glass transition point, or as a filler for improving these mechanical properties, especially with low particle fusibility and dispersibility. It is related with the manufacturing method which can manufacture the metal oxide nanoparticle which is excellent in average particle diameter 10 nm or less in large quantities and cheaply.

Conventionally, several methods for synthesizing ultrafine particles (nanoparticles) with a diameter of several tens of nanometers or less, such as metal nanoparticles and metal oxide nanoparticles, have been proposed. There is a sinking method.
The neutralization / coprecipitation method is a method of neutralizing a metal salt by adding an alkali solution to various metal salt solutions to form a metal oxide precursor such as a metal hydroxide, and then containing the precursor. Is heated to a temperature equal to or higher than the temperature at which the metal oxide is formed to obtain a metal oxide fine particle powder.
However, in this method, when the metal oxide precursor is dehydrated and condensed by heating to form metal oxide fine particles, aggregation and fusion of the metal oxide fine particles occur, so that a relatively coarse metal There is a problem that it becomes oxide fine particles, and this method is unsuitable for producing nanometer-sized metal oxide fine particles.

Therefore, flame methods, spray pyrolysis methods, and the like have been proposed as methods for obtaining metal oxide nanoparticle powders having a relatively small average particle diameter and excellent crystallinity.
The flame method is a method of obtaining metal oxide fine particles by spraying a metal salt solution into a high-temperature flame and oxidizing metal salt droplets at high speed.
The spray pyrolysis method, like the flame method, sprays the metal salt solution as fine droplets in a high-temperature air stream, and oxidizes the metal salt droplets at high speed, thereby oxidizing the metal oxide obtained by the flame method. This is a method for obtaining metal oxide fine particles having a particle size smaller than that of physical particles (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 06-199502

By the way, although the conventional flame method and spray pyrolysis method can obtain metal oxide fine particles having a size of several tens of nanometers, generation of coarse particles due to collision of particles in a high temperature flame or in an air stream. There is a problem that it is difficult to suppress the metal oxide nanoparticles, and uniform metal oxide nanoparticles with single-digit nanometer size cannot be obtained.
Further, in these methods, in order to reduce the particle size of the metal oxide fine particles, it is necessary to use an extremely dilute metal salt solution with a high concentration. Therefore, the productivity is remarkably lowered, and the manufacturing cost is very high. There was a problem of becoming high.

  The present invention has been made in order to solve the above-described problems, and there is no fusion between particles, the average particle diameter is 10 nm or less, and a large amount of metal oxide nanoparticles having high crystallinity and It aims at providing the manufacturing method of the metal oxide nanoparticle which can be manufactured cheaply.

As a result of intensive studies, the present inventor determined that the valence of the metal ion or metal oxide ion in the metal salt solution is m, the metal ion or the metal ion when neutralizing the metal salt solution with the basic solution. When the molar ratio of the hydroxyl group in the basic solution to the metal oxide ion is n, these m and n are represented by the following formula:
0.5 <n <m (1)
The basic solution is added to the metal salt solution so that the metal salt solution is partially neutralized, and then the alkali metal, alkaline earth metal, alkali metal, and alkali are added to the partially neutralized solution. By adding a carbonate containing any one of the earth metals and heating, the metal oxide nanoparticle having no fusion between particles, an average particle diameter of 10 nm or less, and excellent crystallinity The present inventors have found that particles can be easily obtained and have completed the present invention.

That is, in the method for producing metal oxide nanoparticles of the present invention, a metal salt solution is neutralized with a basic solution to generate a metal oxide precursor, and the metal oxide nanoparticles are produced from the metal oxide precursor. A method of manufacturing comprising:
The metal salt solution is one selected from the group consisting of zirconium (Zr), indium (In), tin (Sn), aluminum (Al), cerium (Ce), yttrium (Y), and titanium (Ti). And the ionic valence is one selected from the group of m-valent metal ions or zirconia, ceria, yttria, titania, and the ionic valence contains m-valent metal oxide ions,
When the molar ratio of the hydroxyl group in the basic solution to the metal ion or the metal oxide ion is n, this n is represented by the following formula:
0.5 <n <m (1)
So that the metal salt solution is partially neutralized by adding the basic solution to the metal salt solution,
Next, a carbonate containing any one of alkali metal, alkaline earth metal, alkali metal and alkaline earth metal is added to the partially neutralized solution to form a mixed solution, and the mixed solution is heated. It is characterized by that.

The carbonate is preferably potassium carbonate.
The amount of the carbonate added is preferably 20% by weight or more based on the metal oxide equivalent value of metal ions or metal oxide ions in the metal salt solution.
It is preferable to heat the mixed solution after drying.

According to the method for producing metal oxide nanoparticles of the present invention, a metal salt solution is made of zirconium (Zr), indium (In), tin (Sn), aluminum (Al), cerium (Ce), yttrium (Y), It is one selected from the group of titanium (Ti) and its ion valence is m-valent metal ion or one selected from the group of zirconia, ceria, yttria, titania and its ionic valence is When it is assumed that the m-valent metal oxide ion is contained and the molar ratio of the hydroxyl group in the basic solution to the metal ion or metal oxide ion is n, this n is represented by the following formula:
0.5 <n <m (1)
The basic solution is added to the metal salt solution so that the metal salt solution is partially neutralized, and then the alkali metal, alkaline earth metal, alkali metal and alkaline earth metal are added to the partially neutralized solution. , A carbonate containing any one of them is added to form a mixed solution, and this mixed solution is heated, so that there is no fusion between particles, high crystallinity, and an average particle diameter of 10 nm or less. Particles can be produced in large quantities and inexpensively.

  Furthermore, by making the addition amount of carbonate 20% by weight or more with respect to the metal oxide equivalent value of the metal ion or metal oxide ion in the metal salt solution, the average particle diameter is 10 nm or less and the particle diameter Uniform (monodisperse) metal oxide nanoparticles can be produced in large quantities and at low cost.

The form for implementing the manufacturing method of the metal oxide nanoparticle of this invention is demonstrated.
This embodiment is specifically described for better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

The method for producing metal oxide nanoparticles according to the present embodiment includes producing a metal oxide precursor by neutralizing a metal salt solution with a basic solution, and producing metal oxide nanoparticles from the metal oxide precursor. And how to
When the valence of the metal ion or metal oxide ion in the metal salt solution is m, and the molar ratio of the hydroxyl group in the basic solution to the metal ion or metal oxide ion is n, these m and n are Next formula
0.5 <n <m (1)
The basic solution is added to the metal salt solution so that the metal salt solution is partially neutralized, and then the alkali metal, alkaline earth metal, alkali metal and alkali are added to the partially neutralized solution. In this method, a carbonate containing any one of the earth metals is added to form a mixed solution, and the mixed solution is heated.

  The type of metal salt solution is not limited, but, for example, any one or two or more metal ions or metal oxide ions having a valence of 2, 3, 4, 5, or 6. And a solution composed of inorganic acid ions such as chlorine ions, nitrate ions and sulfate ions, or organic acid ions such as acetate ions, oxalate ions, tartaric acid ions, citrate ions, and lactic acid ions.

Examples of the metal ion include ions such as zirconium (Zr), indium (In), tin (Sn), aluminum (Al), cerium (Ce), yttrium (Y), and titanium (Ti).
Examples of the metal oxide ion include metal oxide ions such as zirconia, ceria, and yttria titania.
The solvent is not limited to water. For example, a water-soluble organic solvent such as a monohydric alcohol such as ethanol, methanol, 2-propanol, or a dihydric alcohol (glycol) such as ethylene glycol is also preferably used. It is done.

  The basic solution may be any solution that can neutralize the metal salt solution. For example, an aqueous solution of sodium hydroxide, potassium hydroxide, ammonia, etc., ammonium carbonate, ammonium bicarbonate, sodium carbonate, sodium bicarbonate In addition, an aqueous solution of an alkali carbonate such as potassium carbonate or potassium hydrogen carbonate or an alkali hydrogen carbonate, or a solution containing a basic organic compound such as ethanolamine, diethanolamine, or formamide can be used.

In this embodiment, the neutralization reaction is performed by adding the above basic solution to the above metal salt solution, and conditions are provided when this neutralization reaction is performed.
That is, when the valence of the metal ion or metal oxide ion in the metal salt solution is m and the molar ratio of the hydroxyl group in the basic solution to the metal ion or metal oxide ion is n, these m and n Is
0.5 <n <m (1)
The basic solution is added to the metal salt solution so that the partial neutralization reaction is performed.

Here, the reason for performing the partial neutralization reaction will be described.
In a normal neutralization reaction, n ≧ m is set in order to complete the neutralization reaction. The neutralization reaction product of the metal oxide obtained by performing the neutralization reaction under these conditions always passes the isoelectric point of the metal oxide precursor (pH at which the precursor particle surface charge becomes zero) during the neutralization reaction. Therefore, the metal oxide precursor has a network structure in which fine particles are aggregated and bonded in a three-dimensional network.
When such a network structure is heated, fusion of the particles occurs due to dehydration condensation of the metal oxide precursor, and eventually, coarse metal oxide particles are generated, and the average particle size is increased. Metal oxide fine particles having a uniform particle diameter of 10 nm or less cannot be produced.

On the other hand, the valence m of the metal ion or metal oxide ion in the metal salt solution and the molar ratio n of the hydroxyl group in the basic solution to the metal ion or metal oxide ion are:
0.5 <n <m (1)
When m is equal to n (n = m) and the neutralization rate is 1, if the neutralization rate is less than 1, the neutralization reaction is terminated before the isoelectric point of the metal oxide precursor. Therefore, aggregation of the metal oxide precursor does not occur, and metal oxide precursor particles having a cluster size (nm size) exist in the solution in a sol state.

When the neutralization rate is 1 or more, n ≧ m is satisfied as described above, so that the metal oxide precursor becomes a network-like aggregate. Therefore, nanometer-sized metal oxide fine particles cannot be obtained.
On the other hand, when the neutralization rate is 0.5 or less, the production rate of the metal oxide precursor is extremely lowered, and as a result, the yield of the metal oxide nanoparticles is deteriorated, which is not practical.

Carbonate is added to the solution subjected to the partial neutralization reaction in this way to obtain a mixed solution.
The carbonate must not react with the metal oxide at the heating temperature necessary to form the metal oxide and must not decompose at the heating temperature. The alkali metal, alkaline earth metal, alkali A carbonate containing any one of a metal and an alkaline earth metal is preferably used.

  As the carbonate containing any one of alkali metal, alkaline earth metal, alkali metal and alkaline earth metal, for example, lithium carbonate, sodium carbonate, sodium hydrogen carbonate, potassium carbonate and the like are preferably used. .

By adding this carbonate, it is possible to prevent fusion of cluster-sized metal oxide precursor particles present in the solution after the partial neutralization reaction.
The amount of carbonate added must be 20% by weight or more based on the metal oxide equivalent value of the metal ions or metal oxide ions in the metal salt solution.
If the addition amount is less than 20% by weight, the effect of preventing fusion between the metal oxide precursor particles is reduced, and as a result, there is a possibility that coarse particles are generated, which is not preferable.
Since this carbonate can be recovered and reused, there is no upper limit to the amount of the carbonate added, but it is generally 400% by weight or less.

The mixed solution thus obtained is dried and then heated at a predetermined temperature.
Any drying method may be used as long as the solvent in the mixed solution can be dissipated, and a normal method such as heating drying with a heater, vacuum drying, vacuum drying, drying by energy irradiation such as infrared rays or microwaves can be used. . These drying methods may be performed alone or in combination of a plurality of methods.

As a heating method, a normal method such as heating by a heater, reduced pressure heating, vacuum heating, heating by energy irradiation such as infrared rays or microwaves can be used.
As heating by a heater or the like, for example, there are a method of heating by standing in an electric furnace (batch type electric furnace) of a predetermined temperature, a method of heating by a fluidized bed type electric furnace (tunnel type electric furnace), and the like.

The heating temperature range is preferably equal to or higher than the generation temperature of the metal oxide generated from the metal ions or metal oxide ions contained in the metal salt solution.
As the atmosphere at the time of heating, in addition to the air atmosphere, if necessary, an oxidizing atmosphere having a high partial pressure of oxygen gas, a reducing atmosphere such as 5 v / v% H ₂ -N _2, or a non-reducing atmosphere such as Ar or N ₂ An active gas atmosphere may be used.
Moreover, you may perform these drying processes and a heating process simultaneously. Furthermore, you may heat as it is, without drying said mixed solution.

In this mixed solution, the cluster-sized metal oxide precursor is contained in a carbonate containing any one of alkali metal, alkaline earth metal, alkali metal and alkaline earth metal that acts as an anti-fusing agent. Since heating is performed in a dispersed state, nanometer-sized metal oxide fine particles having no particle fusion and high crystallinity can be easily produced in large quantities.
After the heat treatment, the carbonate containing any one of alkali metal, alkaline earth metal, alkali metal, and alkaline earth metal is removed by washing.

As described above, according to the method for producing metal oxide nanoparticles of this embodiment, the valence of the metal ion or metal oxide ion in the metal salt solution is m, and the base for this metal ion or metal oxide ion When the molar ratio of hydroxyl groups in the aqueous solution is n, these m and n are
0.5 <n <m (1)
So that the metal salt solution is partially neutralized by adding a basic solution to the metal salt solution, and then the alkali metal, alkaline earth metal, alkali metal and alkaline earth metal are added to the partially neutralized solution. , A carbonate containing any one of them is added to form a mixed solution, and this mixed solution is heated, so that there is no fusion between particles, high crystallinity, and an average particle diameter of 10 nm or less. Particles can be easily obtained.

EXAMPLES Hereinafter, although this invention is demonstrated concretely with Examples 1, 2, Reference Examples 1-3 and Comparative Examples 1 and 2, this invention is not limited by these Examples.

(Reference Example 1)
“Preparation of zirconia nanoparticles (OH / ZrO ²⁺ = 0.7)”
To a zirconium salt solution in which 2615 g of zirconium oxychloride octahydrate is dissolved in 40 L (liter) of pure water, dilute ammonia water in which 344 g of 28% ammonia water is dissolved in 20 L of pure water is added with stirring, and the zirconia precursor slurry is added. It was adjusted.
Next, an aqueous sodium sulfate solution in which 300 g of sodium sulfate was dissolved in 5 L of pure water was added to this slurry with stirring. The amount of sodium sulfate added at this time was 30% by weight with respect to the zirconia converted value of zirconium ions in the zirconium salt solution.

Next, this mixture was dried in the air at 130 ° C. for 24 hours using a dryer to obtain a solid.
Next, the solid was pulverized with an automatic mortar or the like and then baked at 500 ° C. for 1 hour in the air using an electric furnace.
Next, the fired product is put into pure water, stirred to form a slurry, washed using a centrifuge, and after sufficiently removing the added sodium sulfate, dried in a dryer, Zirconia powder was produced.
The yield of this zirconia powder was 85%.

Example 1
“Preparation of zirconia nanoparticles (OH / ZrO ²⁺ = 1.2)”
To a zirconium salt solution in which 2615 g of zirconium oxychloride octahydrate was dissolved in 40 L of pure water, dilute ammonia water in which 591 g of 28% ammonia water was dissolved in 20 L of pure water was added with stirring to prepare a zirconia precursor slurry.
Next, an aqueous sodium carbonate solution in which 300 g of sodium carbonate was dissolved in 5 L of pure water was added to this slurry with stirring. The amount of sodium carbonate added at this time was 30% by weight with respect to the zirconia-converted value of zirconium ions in the zirconium salt solution.

Next, this mixture was dried in the air at 130 ° C. for 24 hours using a dryer to obtain a solid.
Next, the solid was pulverized with an automatic mortar or the like and then baked at 500 ° C. for 1 hour in the air using an electric furnace.
Next, the fired product is put into pure water, stirred to form a slurry, washed using a centrifuge, and after sufficiently removing the added sodium carbonate, dried in a dryer, Zirconia powder was produced.
The yield of this zirconia powder was 95%.

(Example 2)
“Preparation of zirconia nanoparticles (OH / ZrO ²⁺ = 1.8)”
To a zirconium salt solution in which 2615 g of zirconium oxychloride octahydrate was dissolved in 40 L of pure water, dilute ammonia water in which 886 g of 28% ammonia water was dissolved in 20 L of pure water was added with stirring to prepare a zirconia precursor slurry.
Next, an aqueous potassium carbonate solution in which 300 g of potassium carbonate was dissolved in 5 L of pure water was added to this slurry with stirring. The amount of potassium carbonate added at this time was 30% by weight with respect to the zirconia-converted value of zirconium ions in the zirconium salt solution.

Next, this mixture was dried in the air at 130 ° C. for 24 hours using a dryer to obtain a solid.
Next, the solid was pulverized with an automatic mortar or the like and then baked at 500 ° C. for 1 hour in the air using an electric furnace.
Next, the fired product is put into pure water, stirred to form a slurry, washed using a centrifugal separator, and after sufficiently removing the added potassium carbonate, dried in a dryer, Zirconia powder was produced.
The yield of this zirconia powder was 98%.

( Reference Example 2 )
“Preparation of ceria-zirconia nanoparticles (OH / (ZrO ²⁺ + Ce ³⁺ ) = 1.2)”
While stirring 1289 g of zirconium oxychloride octahydrate and 1737 g of cerium nitrate hexahydrate in 40 L of pure water, dilute ammonia water in which 729 g of 28% ammonia water was dissolved in 20 L of pure water was stirred. In addition, a ceria-zirconia precursor slurry was prepared.
Next, an aqueous potassium carbonate solution in which 1000 g of potassium carbonate was dissolved in 5 L of pure water was added to this slurry with stirring. At this time, the amount of potassium carbonate added was 85% by weight based on the ceria-zirconia equivalent value of cerium ions and zirconium ions in the cerium salt-zirconium salt solution.

Next, this mixture was dried in the air at 130 ° C. for 24 hours using a dryer to obtain a solid.
Next, the solid was pulverized with an automatic mortar or the like and then baked at 700 ° C. for 1 hour in the air using an electric furnace.
Next, the fired product is put into pure water, stirred to form a slurry, washed using a centrifugal separator, and after sufficiently removing the added potassium carbonate, dried in a dryer, Ceria-zirconia powder was produced.
The yield of this ceria-zirconia powder was 96%.

( Reference Example 3 )
“Preparation of yttria nanoparticles (OH / Y ³⁺ = 1.2)”
To a yttrium salt solution in which 2605 g of yttrium nitrate hexahydrate was dissolved in 40 L of pure water, dilute ammonia water in which 496 g of 28% ammonia water was dissolved in 20 L of pure water was added with stirring to prepare an yttria precursor slurry.
Next, an aqueous sodium sulfate solution in which 500 g of sodium sulfate was dissolved in 5 L of pure water was added to this slurry with stirring. The amount of sodium sulfate added at this time was 65% by weight with respect to the yttria-converted value of yttrium ions in the yttrium salt solution.

Next, this mixture was dried in the air at 130 ° C. for 24 hours using a dryer to obtain a solid.
Next, the solid was pulverized with an automatic mortar or the like and then baked at 550 ° C. for 1 hour in the air using an electric furnace.
Next, the fired product is put into pure water, stirred to form a slurry, washed using a centrifuge, and after sufficiently removing the added sodium sulfate, dried in a dryer, Yttria powder was prepared.
The yield of this yttria powder was 95%.

(Comparative Example 1)
“Preparation of zirconia nanoparticles (OH / ZrO ²⁺ = 0.5)”
To a zirconium salt solution in which 2615 g of zirconium oxychloride octahydrate was dissolved in 40 L of pure water, dilute ammonia water in which 246 g of 28% ammonia water was dissolved in 20 L of pure water was added with stirring to prepare a zirconia precursor slurry.
Next, an aqueous sodium sulfate solution in which 300 g of sodium sulfate was dissolved in 5 L of pure water was added to this slurry with stirring. The amount of sodium sulfate added at this time was 30% by weight with respect to the zirconia converted value of zirconium ions in the zirconium salt solution.

Next, this mixture was dried in the air at 130 ° C. for 24 hours using a dryer to obtain a solid.
Next, the solid was pulverized with an automatic mortar or the like and then baked at 500 ° C. for 1 hour in the air using an electric furnace.
Next, the fired product is put into pure water, stirred to form a slurry, washed using a centrifuge, and after sufficiently removing the added sodium sulfate, dried in a dryer, Zirconia powder was produced.
The yield of this zirconia powder was 34%, which was a very small yield.

(Comparative Example 2)
“Preparation of zirconia nanoparticles (OH / ZrO ²⁺ = 2.0)”
To a zirconium salt solution in which 2615 g of zirconium oxychloride octahydrate was dissolved in 40 L of pure water, dilute ammonia water in which 986 g of 28% ammonia water was dissolved in 20 L of pure water was added with stirring to prepare a zirconia precursor slurry.
Next, an aqueous potassium carbonate solution in which 300 g of potassium carbonate was dissolved in 5 L of pure water was added to this slurry with stirring. The amount of potassium carbonate added at this time was 30% by weight with respect to the zirconia-converted value of zirconium ions in the zirconium salt solution.

Next, this mixture was dried in the air at 130 ° C. for 24 hours using a dryer to obtain a solid.
Next, the solid was pulverized with an automatic mortar or the like and then baked at 500 ° C. for 1 hour in the air using an electric furnace.
Next, the fired product is put into pure water, stirred to form a slurry, washed using a centrifugal separator, and after sufficiently removing the added potassium carbonate, dried in a dryer, Zirconia powder was produced.
The yield of this zirconia powder was 98%.

(Comparative Example 3)
“Preparation of zirconia nanoparticles (OH / ZrO ²⁺ = 0.7 and the amount of sodium sulfate added is 15% by weight)”
To a zirconium salt solution in which 2615 g of zirconium oxychloride octahydrate was dissolved in 40 L of pure water, dilute ammonia water in which 344 g of 28% ammonia water was dissolved in 20 L of pure water was added with stirring to prepare a zirconia precursor slurry.
Next, an aqueous sodium sulfate solution in which 150 g of sodium sulfate was dissolved in 5 L of pure water was added to this slurry with stirring. The amount of sodium sulfate added at this time was 15% by weight with respect to the zirconia-converted value of zirconium ions in the zirconium salt solution.

Next, this mixture was dried in the air at 130 ° C. for 24 hours using a dryer to obtain a solid.
Next, the solid was pulverized with an automatic mortar or the like and then baked at 500 ° C. for 1 hour in the air using an electric furnace.
Next, the fired product is put into pure water, stirred to form a slurry, washed using a centrifuge, and after sufficiently removing the added sodium sulfate, dried in a dryer, Zirconia powder was produced.
The yield of this zirconia powder was 85%.

The specific surface area and particle diameter of each of the powders of Examples 1 and 2, Reference Examples 1 to 3, and Comparative Examples 1 to 3 thus obtained were measured.
(1) Specific surface area The specific surface area of the powder was measured by the BET method.
(2) Particle diameter by BET method The particle diameter was calculated from the measured value of the specific surface area.
(3) Particle diameter by X-ray diffraction The profile of a specific diffraction line of the powder was measured by a powder X-ray diffraction method, and the crystallite size (crystallite diameter) was determined from the spread of the profile.
(4) Particle diameter by TEM A transmission electron microscope (TEM) image of the powder was taken, and the particle diameter of the powder was measured from this TEM image.

These results are shown in Tables 1 and 2.
In Table 1, “metal” is the type of metal ion in the metal salt solution, and is represented by an element symbol.
“ OH / M ^{m +} ” is a molar ratio n of the hydroxyl group (OH) in the basic solution to the metal ion in the metal salt solution.
“Inorganic salt / metal oxide” is the ratio between the amount of inorganic salt added and the metal oxide equivalent value of the metal ion in the metal salt solution. It is expressed in weight% with respect to the value.

According to these results, the measured values of the BET method, X-ray diffraction, and TEM for the particle diameters of Examples 1 and 2 are almost the same, and the primary particles are independent without fusion. Furthermore, it was found that single nanometer-sized particles with good crystallinity can be obtained because each particle is made of a single crystal.
Moreover, the yield of these powders was 85% or more, and it was found that the mass productivity was excellent.

  On the other hand, with respect to the particle size of Comparative Example 1, as in Examples 1 and 2, the measured values of the BET method, X-ray diffraction, and TEM are almost the same, and the primary particles are independent without fusion. In addition, the individual particles consisted of single crystals and were single nanometer-sized zirconia particles with good crystallinity, but the yield of this powder was extremely low at 34%, which is inferior in mass production. I understood that.

Moreover, about the particle diameter of the comparative example 2, the measured value of BET method, X-ray diffraction, and TEM did not correspond, but it was a zirconia particle with a large particle diameter which the primary particle fuse | melted.
Also, the particle diameter of Comparative Example 3 was a zirconia particle having a large particle diameter in which the measured values of the BET method, X-ray diffraction, and TEM did not match and primary particles were fused.

  The method for producing metal oxide nanoparticles of the present invention can produce metal oxide nanoparticles in a large amount and at low cost without fusion between particles, an average particle diameter of 10 nm or less, and high crystallinity. It can be used for the production of nanoparticles such as catalysts, conductive materials, dielectric materials, ceramic raw materials, pigments, high refractive index materials, magnetic materials, various resins, plastic films, fillers for plastic plates, etc. Needless to say, it is extremely useful for producing composite particles in which the dispersibility of nanoparticles is ensured by compositing with ceramics, polymers and the like.

Claims (4)

A method of producing a metal oxide nanoparticle from a metal oxide precursor by neutralizing a metal salt solution with a basic solution,
The metal salt solution is one selected from the group consisting of zirconium (Zr), indium (In), tin (Sn), aluminum (Al), cerium (Ce), yttrium (Y), and titanium (Ti). And the ionic valence is one selected from the group of m-valent metal ions or zirconia, ceria, yttria, titania, and the ionic valence contains m-valent metal oxide ions,
When the molar ratio of the hydroxyl group in the basic solution to the metal ion or the metal oxide ion is n, this n is represented by the following formula:
0.5 <n <m (1)
So that the metal salt solution is partially neutralized by adding the basic solution to the metal salt solution,
Next, a carbonate containing any one of alkali metal, alkaline earth metal, alkali metal and alkaline earth metal is added to the partially neutralized solution to form a mixed solution, and the mixed solution is heated. A method for producing metal oxide nanoparticles.   The method for producing metal oxide nanoparticles according to claim 1, wherein the carbonate is potassium carbonate.   3. The metal oxidation according to claim 1, wherein the addition amount of the carbonate is 20 wt% or more based on a metal oxide equivalent value of metal ions or metal oxide ions in the metal salt solution. Method of manufacturing nanoparticles.   The method for producing metal oxide nanoparticles according to claim 1, wherein the mixed solution is heated after being dried.