Nonstoichiometric oxide particle, and manufacturing method thereof

The present invention relates to non-stoichiometric oxide particles and a method for producing the same, and more particularly to nano-sized non-stoichiometric oxide particles and a method for producing non-stoichiometric oxide particles using thermal plasma.

Currently, fine particles such as oxide fine particles, nitride fine particles, and carbide fine particles are used as electrical insulating materials such as semiconductor substrates, printed circuit boards, and various electrical insulating parts, and high-hardness and high-precision machining materials such as cutting tools, dies, and bearings. Manufacture of functional materials such as grain boundary capacitors and humidity sensors, sintered bodies such as precision sintered molding materials, thermal spray parts manufacturing of materials that require high temperature wear resistance such as engine valves, and electrodes for fuel cells. , Electrode materials and various catalysts.

Recently, among the above-mentioned fine particles, the reduced titanium oxide disclosed in Patent Document 1 has attracted attention. What is reduced titanium oxide?_２It is different from (titanium dioxide) and Ti_nO_2n-1Ti, a substoichiometric oxide phase with n = 4 to , called the magneti phase of_３O_５Phase, Ti_２O_３Refers to the phase, TiO phase, etc. Reduced titanium oxide is TIO_２It is disclosed in Patent Document 1 that it is expected to be sufficiently applied as an electrode and a conductive filler because it is excellent not only in terms of absorption of visible light but also in electron conductivity.

In Patent Document 1, rutile-type TiO_２Nanoparticles are used as the main raw material, and CaH is used as the reducing agent._２Using powder, reduce at 350 ° C. for about 4 to 10 days to obtain corundum-type Ti as a reduced titanium oxide._２O_３I am getting nanoparticles. As a reducing agent, CaH_２Besides, LiH, NaH, MgH_２, LiAlH_４And NaBH_４Is listed.

<p><patcit num="1"><text>Japanese Unexamined Patent Publication No. 2012-214348</text></patcit></p>

<p num="0006"> In Patent Document 1 described above, CaH is used as the reducing agent._２Is used, and substances other than titanium are included. Therefore, there is a problem that a reduced titanium oxide having high purity cannot be obtained. Further, Patent Document 1 has a problem that it takes a long time to produce a reduced titanium oxide having a nanostructure by reducing it at 350 ° C. for about 4 to 10 days. Further, in Patent Document 1, rutile-type TiO is used as a main raw material._２Since nanoparticles are used, there is also a problem that the nanoparticles are easily aggregated, the handling becomes complicated, and the productivity is lowered.</p><p num="0007"> An object of the present invention is to solve the problems based on the prior art and to produce nano-sized non-stoichiometric oxide particles in a short time by using high-purity nano-sized non-stoichiometric oxide particles and thermal plasma. Is to provide a manufacturing method that can be used.</p>

<p num="0008"> In order to achieve the above object, the present invention relates to a metal oxide powder, a metal powder of a metal element constituting the metal oxide powder, a powder of a compound of an element other than oxygen and the metal element, and the metal element. It is characterized by having a step of preparing at least one powder of an indefinite ratio oxide powder and a step of supplying the metal oxide powder and the at least one powder into a thermal plasma flame. It provides a method for producing an indefinite ratio oxide particle. Further, the metal oxide powder and the at least one powder are supplied to the thermal plasma flame in a premixed state.</p><p num="0009"> For example, the combination of the composition of the metal oxide powder and the composition of the at least one powder is TiO._２And Ti, Titanium Hydrogenated, Ti_２O_３Or TiO, SiO_２And Si, Co_３O_４And Co, Cr_２O_３And Cr, Fe_２O_３And Fe, MnO_２And Mn, MoO_３And Mo, Nb_２O_５And Nb, PbO_３And Pb, SnO_２And Sn, or V_２O_５And V or vanadium hydride. Further, for example, the thermal plasma flame is derived from at least one gas among hydrogen gas, nitrogen gas, helium gas and argon gas.</p><p num="0010"> The present invention also provides non-stoichiometric oxide particles which are composed of non-stoichiometric oxides and have a particle size of less than 200 nm. In this case, the particle size is preferably 5 to 100 nm. Further, the non-stoichiometric oxide particles are produced by, for example, a thermal plasma method.</p>

<p num="0011"> According to the present invention, a metal oxide powder, a metal powder of a metal element constituting the metal oxide powder, a powder of a compound of an element other than oxygen and a metal element, and a powder of an indefinite ratio oxide of the metal element. Of these, at least one powder is used, and the metal element contained in the at least one powder used together with the metal oxide powder functions as a reducing agent, and high-purity indefinite ratio oxide particles can be obtained. Further, by using thermal plasma, nano-sized indefinite specific oxide particles can be produced without using nano-sized particles in the metal oxide powder as a raw material and the above-mentioned metal powder, compound powder and indefinite ratio oxide powder. It can be obtained, and it does not take several days to manufacture. Furthermore, it is possible to obtain nano-sized non-stoichiometric oxide particles having a high purity and less than 200 nm. Since nano-sized particles are not used as a raw material, productivity does not decrease.</p>

<figref num="1">It is a graph which shows the analysis result of the crystal structure by the X-ray diffraction method of the particle produced by the reduction treatment using hydrogen plasma.</figref><figref num="2">It is a flowchart which shows the manufacturing method of the non-stoichiometric oxide particle of the embodiment of this invention.</figref><figref num="3">It is a schematic diagram which shows the fine particle manufacturing apparatus for manufacturing the non-stoichiometric oxide particle of the embodiment of this invention.</figref><figref num="4">(A) and (b) are graphs showing the results of analysis of the crystal structure of the non-stoichiometric oxide particles obtained in the first embodiment by the X-ray diffraction method.</figref><figref num="5">(A) and (b) are graphs showing the results of analysis of the crystal structure of the non-stoichiometric oxide particles obtained in the first embodiment by the X-ray diffraction method.</figref><figref num="6">(A) and (b) are graphs showing the results of analysis of the crystal structure of the non-stoichiometric oxide particles obtained in the second example by the X-ray diffraction method.</figref><figref num="7">(A) and (b) are graphs showing the results of analysis of the crystal structure of the non-stoichiometric oxide particles obtained in the second example by the X-ray diffraction method.</figref><figref num="8">It is a graph which shows the analysis result of the crystal structure of the non-stoichiometric oxide particles obtained by the 3rd Example by the X-ray diffraction method.</figref>

Hereinafter, the non-stoichiometric oxide particles of the present invention and a method for producing the same will be described in detail based on the preferred embodiments shown in the accompanying drawings. As a result of diligent experimental research by the present inventors, the metal oxide powder and the metal powder of the metal element constituting the metal oxide are supplied into a thermal plasma flame and treated by using thermal plasma. It has been found that non-stoichiometric oxide particles are produced. Here, the non-stoichiometric oxide is generally a metal oxide such as a non-stoichiometric compound. The non-stoichiometric compound is a compound showing a deviation from the non-stoichiometric composition (non-stoichiometricity). The non-stoichiometric oxide is also referred to as a suboxide.

In the present invention, the metal element of the metal powder of the metal element constituting the metal oxide acts as a reducing agent with respect to the metal oxide powder, and the metal oxide powder is partially reduced by the thermal plasma flame, resulting in an indefinite ratio. It becomes an oxide. Oxygen generated by the reduction of the metal oxide powder combines with the metal element of the metal powder to form a metal oxide, but there is no external oxygen supply and sufficient oxygen is obtained to generate a constant ratio oxide. Since it is not possible, it becomes an oxide with an indefinite ratio. In this way, it is considered that the non-stoichiometric oxide particles are generated from both the metal oxide powder and the metal powder. Furthermore, the present inventors have stated that non-stoichiometric oxide particles are produced even when a powder of a compound of a metal element constituting a metal oxide and an element other than oxygen is used instead of the metal powder. I'm checking. As described above, if the amount of oxygen generated by the reduction of the metal oxide powder is an amount that does not become a constant ratio oxide even if it is bonded to the metal element bonded to oxygen, the non-stoichiometric oxide particles Is thought to be generated. Therefore, it is considered that the non-stoichiometric oxide particles can be produced even when the non-stoichiometric oxide of the metal element constituting the metal oxide is used instead of the metal powder.

In the formation of non-stoichiometric oxide particles, as described above, the amount of oxygen generated in the formation process may be an amount that does not form a constant ratio oxide even if it is bonded to a metal element that binds to oxygen. Just do it. Therefore, even if the thermal plasma flame contains oxygen, even if the amount of oxygen caused by the thermal plasma flame is added and the total amount of oxygen generated in the generation process is combined with the above, it is a constant ratio oxide. The thermal plasma flame may contain oxygen as long as it does not. Of course, the thermal plasma flame may not contain oxygen. Here, the term "thermal plasma flame containing oxygen" means a thermal plasma flame in which a gas containing oxygen such as oxygen gas or air is used in part or all of the plasma gas, while the thermal plasma flame contains oxygen. "Not contained" means a thermal plasma flame in which a gas containing oxygen such as oxygen gas or air is not used in part or all of the plasma gas.

In the present invention, as the non-stoichiometric oxide particles, for example, TIO having less oxygen than the constant ratio composition_2-x(0 &lt;x &lt;2) particles can be mentioned. In this case, the raw material is, for example, metal oxide powder and TiO._２Ti powder can be used as the powder and the metal powder. TiO_２Has excellent corrosion resistance and insulating properties. On the other hand, TiO_2-x(0 &lt;x &lt;2) is excellent in corrosion resistance, has conductivity, and absorbs visible light. In this way, an indefinite ratio oxide having properties different from those of the metal oxide can be obtained.

On the other hand, the present inventors have not mixed Ti particles and have TiO._２By reducing the particles alone using thermal plasma using hydrogen gas and argon gas as plasma gas, TiO_2-xAn attempt was made to generate (0 &lt;x &lt;2) particles. However, as shown in FIG. 1, the raw material, TiO._２It has been confirmed that only particles can be obtained, and that the non-stoichiometric oxide is not produced in the reduction treatment using the above-mentioned thermal plasma containing hydrogen. The present invention has been made based on the above findings.

Next, a method for producing non-stoichiometric oxide particles will be described. FIG. 2 is a flowchart showing a method for producing non-stoichiometric oxide particles according to the embodiment of the present invention. In the present invention, a metal oxide and a metal element constituting the metal oxide are selected according to the composition of the non-stoichiometric oxide to be produced. Then, the metal oxide powder of the selected metal oxide, the metal powder of the metal element constituting the selected metal oxide powder, the powder of the element other than oxygen and the compound of this metal element (hereinafter referred to as compound powder), and At least one powder of the indefinite ratio oxide powder of the metal element (hereinafter referred to as indefinite ratio oxide powder) is prepared and mixed to obtain a mixed powder as a raw material of the indefinite ratio oxide particles. (Step S10). The composition of the indefinite ratio oxide, the metal oxide as a raw material, the metal element, and the combination of an element other than oxygen and a compound of the metal element will be described in detail later.

Next, the mixed powder is supplied to the thermal plasma flame and subjected to thermal plasma treatment (step S12). The thermal plasma treatment evaporates the mixed powder into a gas phase mixture. In this mixture, the metal oxide powder is partially reduced and the oxygen generated by the reduction of the metal oxide powder combines with the metal element of the powder. Since there is no oxygen supply from the outside, the metal oxide powder becomes oxygen-deficient. Further, the metal element of the powder becomes a metal oxide, but the oxygen generated by the reduction of the metal oxide powder does not exist in a sufficient amount to become a constant ratio oxide. Then, the mixture in the gas phase state is cooled by the cooling gas. As a result, nano-sized non-stoichiometric oxide particles are generated (step S14). If the mixture can be taken out from the thermal plasma flame to obtain non-stoichiometric oxide particles, cooling is not always necessary.

In the present invention, the mixed powder is prepared in advance in step S10, but the present invention is not limited to this. The metal oxide powder and at least one of the metal powder, the compound powder and the indefinite ratio oxide powder are separately supplied to the thermal plasma flame without preparing a mixed powder in advance, and this thermal plasma is provided. Of course, the metal oxide powder and at least one of the above selected powders may be mixed in the flame.

In the present invention, the metal oxide powder and at least one of the above powders are used, and no metal element other than those constituting the non-stoichiometric oxide particles is used. Therefore, high-purity non-stoichiometric oxide particles can be obtained. it can. It is generally known that in the thermal plasma method using a thermal plasma flame, nano-sized particles having a particle size of less than 200 nm can be obtained even if the particle size of the powder supplied to the thermal plasma flame is about 100 μm. ing. Therefore, also in the present invention, indefinite ratio oxide particles having a particle size of less than 200 nm can be obtained even when a metal oxide powder having a particle size of about 100 μm and a metal powder, a compound powder, and an indefinite ratio oxide powder are used. The particle size of the non-stoichiometric oxide particles of the present invention is less than 200 nm, but the particle size of the non-stoichiometric oxide particles is more preferably 5 to 100 nm. As described above, in the present invention, nano-sized indefinite specific oxide particles can be obtained from the raw materials of metal oxide powder and metal powder, compound powder and indefinite ratio oxide powder without using nano size particles as raw materials. Therefore, productivity does not decrease by using nano-sized particles that are difficult to handle.

The particle size of the metal oxide powder is preferably 1 to 100 μm, and the particle size of the metal powder, the compound powder and the indefinite ratio oxide powder is preferably 1 to 100 μm. The metal oxide powder and the metal powder, the compound powder, and the indefinite ratio oxide powder are all difficult to handle when the particle size is less than 1 μm. On the other hand, when the particle size of the metal oxide powder, the metal powder, the compound powder and the indefinite ratio oxide powder exceeds 100 μm, the amount of the metal oxide powder that does not evaporate during the thermal plasma treatment increases. Here, in the present invention, the particle size is a value obtained by converting from the specific surface area measurement. As described above, if the amount of oxygen generated by the reduction of the metal oxide powder is an amount that does not form a constant ratio oxide with respect to the metal element bonded to oxygen, the non-stoichiometric ratio is indefinite. It is considered that oxide particles are produced. Therefore, the mixing ratio of the metal oxide powder as a raw material and at least one selected powder among the metal powder, the compound powder, and the indefinite ratio oxide powder is determined by, for example, an indefinite specific oxidation in advance by an experiment or the like. The ratio at which physical particles are produced can be appropriately determined.

As the non-stoichiometric oxide particles, TIO_2-xIt is not limited to (0 &lt;x &lt;2) particles, and various non-stoichiometric oxide particles can be produced by combining the metal oxide powder with the metal powder, the compound powder and the non-stoichiometric oxide powder. it can. For example, examples of the combination of the non-stoichiometric oxide particles, the metal oxide powder, the metal powder, and the compound powder include those shown in Table 1 below. In addition, TiO_2-xFor (0 &lt;x &lt;2) particles, TiH shown in Table 1 below_２Titanium hydride other than that can be used, and Ti as an indefinite ratio oxide._２O_３, TiO can be used. In addition, VH in Table 1 below_xRepresents vanadium hydride.

<tables num="1"></tables>

As a characteristic developed by making the particle size nano-sized, the transparency is improved when the particles are dispersed in a resin, glass, or the like. In addition to this, the characteristics developed by nanosizing include a decrease in thermal conductivity and an increase in specific surface area. Applications of non-stoichiometric oxide particles having a particle size of less than 200 nm include, for example, heat ray shielding materials, thermoelectric elements, and catalysts and supporting materials.

Hereinafter, the fine particle manufacturing apparatus 10 (hereinafter, simply referred to as the manufacturing apparatus 10) used for producing the non-stoichiometric oxide particles of the present invention will be described in detail with reference to FIG. The non-stoichiometric oxide particles of the present invention are not limited to being produced by the production apparatus 10 shown in FIG. The manufacturing apparatus 10 generates a plasma torch 12 that generates a thermal plasma flame 24 and performs thermal plasma treatment to generate indefinite ratio oxide particles, and a material supply unit 14 that supplies the above-mentioned mixed powder into the plasma torch 12. It has a chamber 16 that functions as a cooling tank for cooling the indefinite ratio oxide particles. Further, the manufacturing apparatus 10 has a cyclone 18 for removing coarse particles having a particle size equal to or larger than an arbitrarily specified particle size from the non-stoichiometric oxide particles 30, and an indefinite specific oxidation having a predetermined particle size classified by the cyclone 18. It has a recovery unit 20 for recovering the object particles 32.

The plasma torch 12 has a quartz tube 12a and a high-frequency oscillation coil 12b surrounding the outside of the quartz tube 12a. A material supply unit 14 is provided above the plasma torch 12 via a supply pipe 14a. A ring-shaped plasma gas supply port 12c is formed in the peripheral portion of the supply pipe 14a.

The plasma gas supply unit 22 is connected to the plasma gas supply port 12c via a pipe 22a. The plasma gas is supplied from the plasma gas supply unit 22 into the plasma torch 12 via the plasma gas supply port 12c. A power supply unit 28 for applying a high frequency voltage is connected to the high frequency oscillation coil 12b. As the power supply unit 28, a known one for generating plasma can be used. When a predetermined high-frequency voltage is applied to the high-frequency oscillation coil 12b by the power supply unit 28, a thermal plasma flame 24 is generated in the plasma torch 12.

The plasma gas supply unit 22 stores various gases corresponding to the plasma gas. In the present embodiment, the plasma gas is not particularly limited. For example, as the plasma gas, hydrogen gas, nitrogen gas, helium gas, argon gas and the like can be used. The plasma gas is not limited to one type, and these plasma gases may be used in combination, such as hydrogen gas and argon gas, and nitrogen gas and argon gas. Further, a gas containing oxygen in part can be used.

The temperature of the thermal plasma flame 24 is preferably a temperature exceeding the boiling points of the metal oxide powder and the metal powder, the compound powder and the non-stoichiometric oxide powder, and is, for example, about 2000 ° C. to 3000 ° C. The temperature of the thermal plasma flame 24 can be 6000 ° C, and is theoretically considered to reach about 10000 ° C. Further, the pressure atmosphere in the plasma torch 12 is preferably atmospheric pressure or less. Here, the atmosphere below the atmospheric pressure is not particularly limited, but is, for example, 0.5 to 100 kPa.

The material supply unit 14 supplies the mixed powder that is the raw material of the non-stoichiometric oxide particles to the thermal plasma, and for example, the material supply device disclosed in Japanese Patent Application Laid-Open No. 2007-138287 can be used. The material supply unit 14 includes, for example, a storage tank (not shown) for storing the metal oxide powder, at least one of the metal powder, the compound powder, and the indefinite ratio oxide powder, and the metal oxide powder. A mixed powder is prepared by mixing at least one of a metal powder, a compound powder, and an indefinite oxide powder, and the mixed powder is conveyed by a screw feeder (not shown) and a screw feeder. It has a dispersion part (not shown) and a carrier gas supply source (not shown) to disperse the mixed powder before it is finally sprayed.

Extrusion pressure is applied to the mixed powder by the carrier gas from the carrier gas supply source, and the mixed powder is supplied into the thermal plasma flame 24 in the plasma torch 12 via the supply pipe 14a. As the carrier gas, an inert gas such as argon gas is used. The material supply unit 14 is not limited to the above configuration. For example, the material supply unit 14 does not have to have a screw feeder for producing the mixed powder. In this case, the metal oxide powder and at least one powder of the metal powder, the compound powder and the indefinite ratio oxide powder are provided. From each storage tank for storage, the metal oxide powder and at least one powder of the metal powder, the compound powder and the indefinite ratio oxide powder are separately supplied into the thermal plasma flame 24 by a carrier gas.

The chamber 16 is provided adjacent to the lower side of the plasma torch 12 and is connected to the cooling gas supply unit 26 via the pipe 26a. The cooling gas supply unit 26 supplies cooling gas into the chamber 16 to cool the generated non-stoichiometric oxide particles. As a result, nano-sized non-stoichiometric oxide particles 30 are obtained. More specifically, the cooling gas supply unit 26 supplies the cooling gas toward the terminal portion of the thermal plasma flame 24, for example, in the direction of arrow Q, and further, from above along the side wall of the chamber 16. The cooling gas is supplied downward, that is, in the direction of the arrow R shown in FIG. The cooling gas supplied in the direction of the arrow R prevents the non-stoichiometric oxide particles 30 from adhering to the inner wall of the chamber 16.

The cooling gas supply unit 26 is a pressure applying means (not shown) such as a compressor or a blower that applies an extrusion pressure to the cooling gas, a cylinder for storing the cooling gas (not shown), and a pressure for controlling the gas supply amount of the cylinder. It has a control valve (not shown) and the like. As the cooling gas, for example, argon gas or a mixed gas of argon gas and helium gas is used. As the cooling gas, various gases other than the above can be used as long as they do not affect the composition of the non-stoichiometric oxide particles. For example, nitrogen gas, hydrogen gas, and a mixed gas thereof can be used as the cooling gas.

As shown in FIG. 3, the manufacturing apparatus 10 is provided with a cyclone 18 at the lower side of the chamber 16. The cyclone 18 is for classifying the non-stoichiometric oxide particles 30 into a desired particle size. As the cyclone 18, for example, those disclosed in Japanese Patent Application Laid-Open No. 2007-138287 can be used. In addition, since the non-stoichiometric oxide particles can be produced in this manufacturing apparatus 10 without the cyclone 18, the cyclone 18 may not be present. In this case, the non-stoichiometric oxide particles 30 accumulated in the bottom 16a of the chamber 16 are collected and the like. The cooling gas supplied from the cooling gas supply unit 26 has an additional action such as contributing to the classification of the non-stoichiometric oxide particles 30 in the cyclone 18.

The cyclone 18 has an inlet pipe 18a that is sucked from the chamber 16 in the T direction and to which the indefinite ratio oxide particles 30 are supplied, and a cylindrical outer cylinder 18b that is connected to the inlet pipe 18a and is located above the cyclone 18. A truncated cone 18c that is continuous from the lower part of the outer cylinder 18b toward the lower side and whose diameter gradually decreases, and a coarse particle that is connected to the lower side of the truncated cone 18c and has a particle size equal to or larger than the above-mentioned desired particle size. It includes a coarse particle collection chamber 18d for collecting particles, and an inner tube 18e connected to a collection unit 20 to be described in detail later and projecting from an outer cylinder 18b.

On the extension of the inner tube 18e in the cyclone 18, a recovery unit 20 is provided for recovering the non-stoichiometric oxide particles 32 that are classified and have a predetermined nano-sized particle size. The collection unit 20 includes a collection chamber 20a, a filter 20b provided in the collection chamber 20a, and a vacuum pump (not shown) connected via a pipe provided in the lower part of the collection chamber 20a. There is. The non-stoichiometric oxide particles 32 sucked in the U direction and sent from the cyclone 18 are drawn into the recovery chamber 20a by being sucked by a vacuum pump (not shown) and stay on the surface of the filter 20b. Will be collected at.

Next, TiO by the manufacturing apparatus 10_2-xA method for producing (0 &lt;x &lt;2) particles will be described. TIO as a raw material in the material supply unit 14._２The powder and Ti powder are stored in the storage tank, and TIO_２The powder and Ti powder are mixed at a predetermined ratio to prepare a mixed powder. Then, for example, hydrogen gas and argon gas are supplied into the plasma torch 12 as plasma gas, and a predetermined high frequency voltage is applied to the high frequency oscillation coil 12b to generate a thermal plasma flame 24 in the plasma torch 12. Then, the mixed powder is supplied to the thermal plasma flame 24 from the material supply unit 14 via the carrier gas. As a result, from the mixed powder as an indefinite ratio oxide, TIO_2-x(0 &lt;x &lt;2) is generated, and a cooling gas such as argon gas is supplied from the cooling gas supply unit 26 to cool the particles, and the TiO is used as the non-stoichiometric oxide particles 30._2-x(0 &lt;x &lt;2) particles are obtained. When the thermal plasma flame 24 is used in this way, as described above, the nano-sized TiO_2-x(0 &lt;x &lt;2) particles are obtained. Therefore, classification by cyclone 18 is not always necessary.

Further, TiO by the manufacturing apparatus 10_2-xAlso in the method for producing (0 &lt;x &lt;2) particles, as described above, TiO_２A mixed powder of powder and Ti powder was prepared, but the present invention is not limited to this, and TIO is not limited to this._２The powder and Ti powder are separately supplied to the thermal plasma flame 24, and TIO is supplied in the thermal plasma flame 24._２Of course, the powder and Ti powder may be mixed.

The present invention is basically configured as described above. Although the non-stoichiometric oxide particles of the present invention and the method for producing the same have been described in detail above, the present invention is not limited to the above-mentioned embodiments, and various improvements or modifications have been made without departing from the gist of the present invention. Of course, it is also good.

<p> Hereinafter, the non-stoichiometric oxide particles of the present invention will be described in more detail. In the first embodiment, the above-mentioned manufacturing apparatus 10 is used as the non-stoichiometric oxide particles of TiO._2-xAn attempt was made to produce (0 &lt;x &lt;2) particles. The raw material powder is TiO_２A mixed powder of powder (particle size 2 μm) and Ti powder (particle size 22 μm) was used. In this example, TiO_２The ratio of powder to Ti powder was set to 20:80, 50:50, 60:40, 80:20 by mass ratio, and TIO was used._2-xAn attempt was made to produce (0 &lt;x &lt;2) particles. The particle size of the obtained particles was measured, and the crystal structure was analyzed using the X-ray diffraction method. The results are shown in FIGS. 4 (a) and 4 (b) and 5 (a) and 5 (b). The particle size was obtained by measuring the specific surface area of the obtained particles and converting it from this specific surface area.</p><p> In the production, hydrogen gas and argon gas were used as the plasma gas to generate a thermal plasma flame, and argon gas was used as the carrier gas, and the mixed powder was supplied to the thermal plasma flame.</p><p> As shown in FIG. 4 (a), TiO_２When the ratio of powder is 20% by mass, TiO, Ti_２O_３Non-stoichiometric oxide particles were obtained. The particle size of the obtained non-stoichiometric oxide particles is 60 nm. As shown in FIG. 4 (b), TiO_２When the ratio of powder is 50% by mass, TiO, Ti_２O_３, TIO_2-xNon-stoichiometric oxide particles of (0 &lt;x &lt;2) were obtained. The particle size of the obtained non-stoichiometric oxide particles is 57 nm. As shown in FIG. 5 (a), TiO_２When the ratio of powder is 60% by mass, Ti_２O_３, TIO_2-xNon-stoichiometric oxide particles of (0 &lt;x &lt;2) were obtained. The particle size of the obtained non-stoichiometric oxide particles is 41 nm. Further, as shown in FIG. 5 (b), TiO_２When the ratio of powder is 80% by mass, TiO_２Although a little remains, it is almost Ti_２O_３, TIO_2-xNon-stoichiometric oxide particles of (0 &lt;x &lt;2) were obtained. The particle size of the obtained non-stoichiometric oxide particles is 55 nm. As described above, non-stoichiometric oxide particles having high purity were obtained.</p>

<p> Next, the second embodiment will be described. In this embodiment, as in the first embodiment, TiO is used as non-stoichiometric oxide particles._2-xAn attempt was made to produce (0 &lt;x &lt;2) particles. In this embodiment, compared to the first embodiment, TiH is used instead of Ti powder in the mixed powder._２Using powder (particle size 10 μm), TiO_２As the powder, the same powder as in the first example was used. In this example, TiO_２Powder and TiH_２TiO using a mass ratio of 50:50, 60:40, 70:30, 90:10 with the powder._2-xAn attempt was made to produce (0 &lt;x &lt;2) particles. In this example, the particle size of the particles obtained in the same manner as in the first example was measured, and the crystal structure was analyzed by using the X-ray diffraction method. The results are shown in FIGS. 6 (a) and 6 (b) and 7 (a) and 7 (b). The particle size measurement and crystal structure analysis were carried out in the same manner as in the first example. Since the manufacturing conditions are the same as those in the first embodiment, detailed description thereof will be omitted.</p><p> As shown in FIG. 6 (a), TiO_２When the ratio of powder is 50% by mass, TiO, Ti_２O_３, TIO_2-xNon-stoichiometric oxide particles of (0 &lt;x &lt;2) were obtained. The particle size of the obtained non-stoichiometric oxide particles is 42 nm. As shown in FIG. 6 (b), TiO_２When the ratio of powder is 60% by mass, TiO, Ti_２O_３, TIO_2-xNon-stoichiometric oxide particles of (0 &lt;x &lt;2) were obtained. The particle size of the obtained non-stoichiometric oxide particles is 35 nm. As shown in FIG. 7 (a), TiO_２When the ratio of powder is 70% by mass, TiO_2-xNon-stoichiometric oxide particles of (0 &lt;x &lt;2) were obtained. The particle size of the obtained non-stoichiometric oxide particles is 40 nm. Further, as shown in FIG. 7 (b), TIO_２When the ratio of powder is 90% by mass, TiO_２Although a little remains, it is almost Ti_２O_３, TIO_2-xNon-stoichiometric oxide particles of (0 &lt;x &lt;2) were obtained. The particle size of the obtained non-stoichiometric oxide particles is 41 nm. As described above, non-stoichiometric oxide particles having high purity were obtained.</p>

<p> Next, a third embodiment will be described. In this example, we tried to produce SiO particles as non-stoichiometric oxide particles. For raw material powder, SiO_２A mixed powder of powder (particle size 4 μm) and Si powder (particle size 5 μm) was used. The mixed powder SiO_２The ratio of the powder to the Si powder was 20:80 in terms of mass ratio. In this example, the particle size of the particles obtained in the same manner as in the first example was measured, and the crystal structure was analyzed by using the X-ray diffraction method. The result is shown in FIG. The particle size measurement and crystal structure analysis were carried out in the same manner as in the first example. Since the manufacturing conditions are the same as those in the first embodiment, detailed description thereof will be omitted.</p><p> As shown in FIG. 8, no clear peak was obtained by the X-ray diffraction method, and the amount of oxygen was measured. The amount of oxygen was 36.7% by mass. An oxygen / nitrogen analyzer EMGA-920 manufactured by HORIBA, Ltd. was used for measuring the amount of oxygen. Here, SiO_２The theoretical oxygen amount of is 53% by mass, and the theoretical oxygen amount of SiO is 36% by mass. From the measurement result of the amount of oxygen, it is clear that SiO particles could be produced in this example. The particle size was 11.2 nm. In this way, SiO particles could be produced as non-stoichiometric oxide particles.</p>

10 Fine particle manufacturing equipment (manufacturing equipment) 12 Plasma torch 14 Material supply section 16 chamber 18 Cyclone 20 Recovery Department 22 Plasma gas supply unit 24 Thermal plasma flame 26 Cooling gas supply unit 28 Power supply 30, 32 Non-stoichiometric oxide particles