JP6090442B2 - Method for producing indium hydroxide powder and method for producing indium oxide powder - Google Patents

Description

The present invention is excellent in uniformity of the particle size, a manufacturing how preparation and indium oxide powder indium hydroxide powder can be obtained narrow indium hydroxide powder particle size distribution width. This application claims priority on the basis of Japanese Patent Application No. 2013-111289 filed on May 27, 2013 in Japan. This application is incorporated herein by reference. Incorporated.

  Recently, the use of transparent conductive films has increased for solar cell applications and touch panel applications, and accordingly, the demand for transparent conductive film forming materials such as sputtering targets has increased. For these transparent conductive film forming materials, indium oxide-based sintered materials are mainly used. Indium oxide powder is used as the main raw material for the transparent conductive film forming material. It is desirable that the indium oxide powder used for the sputtering target has the smallest possible particle size distribution in order to obtain a high-density target.

  As a method for producing indium oxide powder, mainly, a so-called medium-indium hydroxide precipitate formed by neutralizing an acidic aqueous solution such as an indium nitrate aqueous solution or an indium chloride aqueous solution with an alkaline aqueous solution such as ammonia water is dried and calcined. Manufactured by the sum method.

  In the neutralization method, in order to suppress aggregation of the obtained indium oxide powder, a method of obtaining needle-like indium hydroxide by adding an alkali to a high-temperature indium nitrate aqueous solution at 70 to 95 ° C. has been proposed ( For example, see Patent Document 1.) It is disclosed that indium oxide powder with less aggregation can be obtained by calcining acicular indium hydroxide.

  However, the indium oxide powder produced by the neutralization method has a problem that the particle size and particle size distribution are likely to be non-uniform, and relatively large particles coexist. For this reason, when a sputtering target is produced using such indium oxide, voids between particles due to large particles are generated, resulting in problems such as difficulty in improving the density.

  In addition, the neutralization method has a problem that wastewater treatment costs increase because a large amount of nitrogen wastewater is generated after the production of indium oxide powder.

  As a method for improving this, there has been proposed a method of producing indium oxide powder by precipitating indium hydroxide powder by electrolytic treatment of metal indium, and so-called electrolytic method (for example, , See Patent Document 2). In this method, the amount of nitrogen drainage after the production of indium oxide powder can be remarkably reduced as compared with the neutralization method, and the particle diameter of the resulting indium oxide powder can be made uniform.

  However, the indium hydroxide powder obtained by the electrolytic method has a problem that it is very fine and easily aggregates because the pH of the electrolytic solution is close to neutral. Although the indium oxide powder obtained by calcining this has a relatively uniform primary particle size, it becomes easy to obtain an agglomerated powder in which these particles are strongly aggregated. Due to the aggregation, the width of the particle size distribution is widened, so that there is a problem that densification of the target is inhibited.

  Therefore, in the method for producing indium hydroxide powder, there is a demand for a method for obtaining indium hydroxide powder having a uniform particle size and a narrow particle size distribution by using an electrolytic method with a small amount of nitrogen drainage after production.

Japanese Patent No. 3314388 Japanese Patent No. 2829556

  Therefore, the present invention has been proposed in view of such circumstances, and is an indium hydroxide powder that is difficult to agglomerate, has a uniform particle size, and can obtain an indium hydroxide powder with a narrow particle size distribution width. An object of the present invention is to provide a production method, a production method of indium oxide powder obtained by calcining the obtained indium hydroxide powder to obtain indium oxide powder, and a sputtering target produced using the obtained indium oxide powder.

The method for producing indium hydroxide powder according to the present invention that achieves the above-described object is a method for producing indium hydroxide powder by electrolysis using metal indium for the anode, and the concentration of the electrolytic solution Is 0.1 to 2.0 mol / L, pH is 2.5 to 5.0, liquid temperature is 20 to 60 ° C., electrode current density is 4 to 20 A / dm ² , and the distance between the electrodes is It is 1 to 4 cm, and electrolysis is performed so that the concentration of the electrolytic slurry containing the precipitated indium hydroxide powder is in the range of 2 to 15%.

  The method for producing indium oxide powder according to the present invention that achieves the above-described object is characterized by being obtained by calcining the above-mentioned indium hydroxide powder.

  In the present invention, the electrolytic solution concentration, pH, liquid temperature, electrode current density are controlled, and electrolysis is performed so that the concentration of the electrolytic slurry containing the deposited indium hydroxide powder is within a specific range. Indium hydroxide powder is hard to agglomerate, has a uniform particle size, and can produce indium hydroxide powder with a narrow particle size distribution width. Accordingly, in the present invention, by using the obtained indium hydroxide powder, indium oxide powder having a uniform particle size and a narrow particle size distribution width can be obtained, and a high-density sputtering target can be obtained.

It is the schematic of the electrolysis apparatus used by the Example and the comparative example. It is the schematic which shows arrangement | positioning of the cathode and anode in the same electrolysis apparatus.

Below, the manufacturing method of the indium oxide powder to which this invention is applied and the sputtering target using the indium oxide powder obtained by the manufacturing method are demonstrated. Note that the present invention is not limited to the following detailed description unless otherwise specified. Embodiments of a method for producing indium oxide powder and a sputtering target to which the present invention is applied will be described in detail in the following order.
1. 1. Method for producing indium oxide powder 1-1. Production process of indium hydroxide powder 1-2. Recovery process of indium hydroxide powder 1-3. Indium hydroxide powder drying process 1-4. 1. Production process of indium oxide powder Sputtering target

1. Manufacturing method of indium oxide powder (1-1. Manufacturing process of indium hydroxide powder)
The manufacturing method of indium hydroxide powder manufactures indium hydroxide powder using an electrolytic reaction.

  Indium hydroxide powder is produced by using indium as an anode (anode), using a conductive metal or carbon electrode for the cathode (cathode) of the counter electrode, and immersing the anode and cathode in the electrolyte to create a potential difference between the two electrodes. The anode metal is dissolved by generating and generating an electric current. In electrolysis, the pH of the electrolytic solution is controlled to a region that is lower than the solubility of indium hydroxide, thereby causing precipitation of indium hydroxide powder and obtaining indium hydroxide powder.

  For the anode, for example, metal indium or the like is used. The metal indium to be used is not particularly limited, but a high-purity metal indium is desirable in order to suppress the mixing of impurities into the indium oxide powder. As a suitable metal indium, a purity of 99.9999% (commonly called 6N product) is preferably used.

  As the cathode, a conductive metal, a carbon electrode, or the like is used, and for example, insoluble titanium or the like can be used.

  As the electrolytic solution, an aqueous solution of a general electrolyte salt such as a water-soluble nitrate, sulfate, or chloride salt can be used. Among them, an aqueous ammonium nitrate solution using ammonium nitrate in which impurities remain after drying and calcining after precipitation of indium hydroxide powder is preferable.

  The concentration of the electrolytic solution is 0.1 to 2.0 mol / L. The lower the concentration of the electrolytic solution, the lower the cost. However, when the concentration is lower than 0.1 mol / L, the electrical conductivity of the electrolytic solution is too low and no current is generated, or the necessary voltage exceeds the practical range. Therefore, it is not preferable. On the other hand, if the concentration of the electrolytic solution is 2.0 mol / L, sufficient electric conductivity is secured. Therefore, if it is higher than 2.0 mol / L, it becomes uneconomical and it is not necessary to increase it further.

  The pH of the electrolytic solution is in the range of 2.5 to 5.0. When the pH is less than 2.5, hydroxide precipitation does not occur. When the pH is greater than 5.0, the precipitation rate is too high and the precipitate is formed with non-uniform concentration. The distribution width becomes wide, which is not preferable. The pH at which the hydroxide precipitates is also affected by the coexisting ions, so it is necessary to adjust the pH within the range of 2.5 to 5.0. In addition, coexistence of oxygen-containing chelate compounds such as citric acid, tartaric acid and glycolic acid and nitrogen-containing chelates such as ethylenediaminetetraacetic acid (EDTA) improves the dissolution stability of hydroxides. Therefore, it is necessary to adjust the pH appropriately so that the hydroxide precipitates.

  The liquid temperature of the electrolytic solution is 20 to 60 ° C. When the temperature is lower than 20 ° C., the precipitation rate of the hydroxide is too slow, and when it is higher than 60 ° C., the precipitation rate is too high, and the precipitate is formed with non-uniform concentration. Is unfavorable since the particle size distribution width cannot be controlled to be small.

The current density is in the range of 4 to ²⁰ A / dm2. When the current density is lower than 4 A / dm ² , the production rate of indium hydroxide powder decreases. If the current density increases too much, the reaction in which indium precipitates on the negative electrode begins to prevail over the occurrence of hydroxide precipitation, and as a result, the precipitated indium metal mixes with indium hydroxide metal and coarsens the particle size. Therefore, it is not preferable. When it is higher than 20 A / dm ^2, the tendency becomes remarkable, which is not preferable. Further, since the electrolysis voltage is increased, the liquid temperature is likely to increase, and the surface of the metal indium at the anode is passivated, which makes it difficult to perform electrolysis.

  The distance between the anode and the cathode is preferably in the range of 1 cm to 4 cm. When it is narrower than 1 cm, it is not preferable because a physical contact easily occurs and a short circuit easily occurs. If it is wider than 4 cm, no current is generated or the necessary voltage exceeds the practical range, which is not preferable.

  The electrolysis is performed within a range of 2 to 15% of the concentration of the electrolytic solution (hereinafter also referred to as electrolytic slurry) on which the indium hydroxide powder is deposited. The precipitation amount of indium hydroxide powder increases with the progress of electrolysis. However, when the concentration is lower than 2%, the concentration is too low, and the efficiency of solid-liquid separation is lowered, which is not preferable. On the other hand, if it is higher than 15%, the viscosity of the electrolytic solution is increased too much and the uniform diffusion in the electrolytic solution is hindered, so that a precipitate is formed with a non-uniform concentration and the particle size distribution width is not reduced. It is not preferable.

(1-2. Indium hydroxide powder recovery process)
The indium hydroxide powder obtained by electrolysis is solid-liquid separated from the electrolytic solution, and the separated indium hydroxide powder is washed with pure water, solid-liquid separated again, and recovered.

  The solid-liquid separation method is not particularly limited, and examples thereof include a rotary filter, centrifugal separation, filter press, pressure filtration, and vacuum filtration.

(1-3. Indium hydroxide powder drying step)
Next, the recovered indium hydroxide powder is dried.

  The drying method is performed by a dryer such as a spray dryer, an air convection type drying furnace, an infrared drying furnace or the like.

  The drying conditions are not particularly limited as long as the moisture of the indium hydroxide powder can be removed. For example, the drying temperature is preferably in the range of 80 ° C to 150 ° C. When the drying temperature is lower than 80 ° C., the drying is insufficient. When the drying temperature is higher than 150 ° C., the indium hydroxide changes to indium oxide. The drying time varies depending on the temperature, but is about 10 hours to 24 hours.

In the method for producing indium hydroxide powder as described above, in the electrolysis, the concentration of the electrolyte is 0.1 to 2.0 mol / L, the pH is 2.5 to 5.0, and the temperature of the solution is 20 to 60 ° C. such an anode and a cathode immersed in the electrolyte, in the range electrode current density of ^{4A / dm 2 ~20A / dm 2} , the concentration of the electrolyte slurry perform electrolysis in a range of a 2-15% As a result, it is possible to obtain an indium hydroxide powder that is difficult to aggregate, has a uniform particle size, and has a narrow particle size distribution width.

  Moreover, the shape of the primary particle of the obtained indium hydroxide powder is a columnar shape. When the primary particles of the indium hydroxide powder are columnar, aggregation is moderately suppressed, and spherical secondary particles having a narrow particle size distribution with a particle size of submicron or several microns are obtained.

(1-4. Production process of indium oxide powder)
In the indium oxide powder production step, the indium hydroxide powder after drying is calcined to produce indium oxide powder. The calcination conditions are preferably, for example, a calcination temperature of 600 ° C to 800 ° C and a calcination time of 1 hour to 10 hours. In addition, in the production | generation process of an indium oxide powder, in order to make an indium hydroxide powder into a more desirable particle size, you may crush or grind | pulverize as needed. Moreover, in the production | generation process of indium oxide powder, when ammonium nitrate is used for electrolyte solution, decomposition | disassembly of ammonium nitrate arises by calcination and it can prevent mixing in indium oxide powder.

  In the method for producing indium oxide powder as described above, when indium hydroxide powder is produced by electrolysis, the concentration, pH, liquid temperature, and electrode current density of the electrolyte are controlled as described above, and the precipitated hydroxide By performing electrolysis so that the concentration of the electrolytic slurry containing indium powder is within a specific range, the produced indium hydroxide powder has a uniform particle size and produces indium hydroxide powder with a narrow particle size distribution width. Can do. As a result, in the method for producing indium oxide powder, indium hydroxide powder having a uniform particle size and a narrow particle size distribution width is obtained by calcining indium hydroxide powder having a uniform particle size and a narrow particle size distribution width. Can be obtained.

  Moreover, in the manufacturing method of indium oxide powder, the nitrogen waste_water | drain amount after manufacture of indium oxide powder can be suppressed compared with the neutralization method.

2. Sputtering target The indium oxide powder obtained by calcining the indium hydroxide powder obtained by the above-described method for producing indium hydroxide powder is used as a raw material for a sputtering target used for forming a transparent conductive film, for example.

  A granulated powder is prepared by mixing the above-mentioned indium oxide powder with other raw materials of the target such as tin oxide powder at a predetermined ratio. Next, a molded body is produced by using, for example, a cold press method using the granulated powder. Next, the molded body is sintered in the temperature range of 1300 ° C. to 1600 ° C., for example, under atmospheric pressure. Next, processing such as polishing the flat surface and side surfaces of the sintered body is performed as necessary. Then, an indium tin oxide sputtering target (ITO sputtering target) can be obtained by bonding the sintered body to a Cu backing plate.

  In the sputtering target manufacturing method, since the indium oxide powder used as a raw material has a uniform particle size and a narrow particle size distribution width, a high-density sintered body can be obtained and the target density is increased. Can do. As a result, cracks are not generated during processing of the target, and abnormal discharge can be prevented from occurring during sputtering.

  Moreover, indium oxide powder is added not only to the raw material of the sputtering target but also to conductive paste and transparent conductive film paint. Since indium oxide powder has a uniform particle size, it exhibits high dispersion when added to conductive paste, transparent conductive film paint, and the like.

  Specific examples to which the present invention is applied will be described below, but the present invention is not limited to these examples.

  In the following Examples and Comparative Examples, indium hydroxide powder was generated using the electrolysis apparatus 1 shown in FIG. A specific configuration of the electrolyzer will be described in Example 1.

Example 1
The electrolysis apparatus 1 includes a 36 L electrolytic cell 2 having a length of 30 cm, a width of 40 cm, and a depth of 30 cm, and an 80 L adjustment tank 3 having a length of 40 cm, a width of 40 cm, and a depth of 50 cm, and the electrolytic cell 2 and the adjustment tank 3 are adjacent to each other. Yes. The electrolytic bath 2 and the adjustment bath 3 are connected by a circulation pump 4.

  The electrolytic cell 2 is provided with a punch plate 6 for dispersing the liquid flow of the electrolytic solution 5 in parallel with the bottom at a height of 2 cm from the bottom. That is, the punch plate 6 has a total of 25 holes of 3 mm in diameter, 5 rows in a row and 5 rows in a 10 cm square. As a result, in the electrolytic cell 2, the electrolytic solution 5 injected into the lower part of the electrolytic cell 2 by the circulation pump 4 passes through the punch plate 6, and each liquid flow can ensure a substantially uniform liquid flow with no drift.

  In addition, a cathode 7 and an anode 8 were disposed in the electrolytic cell 2 as shown in FIG. For the cathode (cathode) 7, five titanium metal plates having a thickness of 1 mm, a width of 30 cm, and a height of 25 cm were prepared. Four anodes (anodes) 8 were prepared by molding indium metal having a purity of 99.9999% into a plate shape having a width of 30 cm, a height of 25 cm, and a thickness of 5 mm. As shown in FIG. 2, these five cathodes 7 and four anodes 8 were alternately arranged vertically on the punch plate 6 in the electrolytic cell 2 so that both electrodes were parallel to each other. The distance between the cathode 7 and the anode 8 was adjusted to 3.0 cm. The five cathodes 7 are electrically connected by a conductive wire 9.

  The adjustment tank 3 includes a temperature control heater 11 and a cooler 12 for controlling and maintaining the temperature of the electrolytic solution. Moreover, the adjustment tank 3 is equipped with the stirring rod 13 which stirs the electrolyte solution 5 in a tank.

  In the electrolysis apparatus 1, 60 L of 2.0 mol / L ammonium nitrate aqueous solution is contained in the adjustment tank 3. In the adjustment tank 3, 1N nitric acid was added to the ammonium nitrate aqueous solution of the electrolytic solution 5 to adjust the hydrogen ion concentration index pH to 4.0. The pH was measured using the pH electrode 10 attached to the adjustment tank 3. While maintaining this state, the temperature of the electrolytic solution 5 was maintained at 25 ° C. using the temperature control heater 11 and the cooler 12. In the adjustment tank 3, the electrolytic solution 5 was adjusted by stirring the electrolytic solution 5 in the tank with the stirring rod 13.

  During the electrolysis, the electrolytic solution 5 in the adjustment tank 3 was sent to the electrolytic tank 2 by the circulation pump 4 at a speed of 20 L / min. The electrolytic solution 5 in the electrolytic tank 2 is returned to the adjustment tank 3 due to overflow.

The electrode current density was adjusted to 15 A / dm ² and electrolysis was continued for 6 hours. The indium hydroxide powder deposited by electrolysis was collected by filtration under reduced pressure in a Nutsche filter bottle.

  Table 1 shows the results of measuring the particle size distribution of the recovered indium hydroxide powder by the laser beam Doppler method. The particle size distribution of the indium hydroxide powder had a minimum diameter of 0.3 μm and a maximum diameter of 1.2 μm, and had a particle size distribution in a very limited range.

  Next, the obtained indium hydroxide powder was dried at 120 ° C. for 12 hours in the air, and baked at 700 ° C. in the air. The particle size distribution of the obtained indium oxide had a minimum diameter of 0.5 μm and a maximum diameter of 1.2 μm, and similarly had a particle size distribution in a very limited range. From the result of examining the weight of the amount of solid matter, the concentration of the electrolytic slurry in electrolysis was 3.2 wt%.

Thereafter, a sintered body of indium oxide alone was produced by a cold press atmospheric pressure sintering method. As a result, the density of the sintered body was 99.5% higher than the true specific gravity of indium oxide of 7.18 g / cm ³ .

(Example 2)
In Example 2, electrolysis was performed in the same manner as in Example 1 except that the ammonium nitrate aqueous solution of the electrolytic solution was changed to 0.5 mol / L under the conditions of Example 1. And the indium oxide sintered compact was produced by the same method as Example 1 from the obtained indium hydroxide powder.

  In Example 2, the concentration of indium hydroxide powder in the electrolytic solution was 3.2 wt%. Further, the particle size distribution of the indium hydroxide powder measured in the same manner as in Example 1 had a minimum diameter of 0.3 μm and a maximum diameter of 1.0 μm, and had a well-defined range of particle size distribution. Similarly, the particle size distribution of the indium oxide powder was a minimum particle size of 0.5 μm and a maximum particle size of 1.2 μm. The density of the indium oxide sintered body was 99.6% of the true specific gravity.

(Example 3)
In Example 3, electrolysis was performed in the same manner as in Example 1 except that the electrolysis temperature was set to 50 ° C. under the conditions of Example 1. And the indium oxide sintered compact was produced by the same method as Example 1 from the obtained indium hydroxide powder.

  In Example 3, the concentration of indium hydroxide powder in the electrolytic solution was 3.2 wt%. In addition, the particle size distribution of the indium hydroxide powder measured in the same manner as in Example 1 had a minimum diameter of 0.3 μm and a maximum diameter of 1.2 μm, and had a well-defined range of particle size distribution. Similarly, the particle size distribution of the indium oxide powder was a minimum particle size of 0.5 μm and a maximum particle size of 1.2 μm. The density of the indium oxide sintered body was 99.5% of the true specific gravity.

Example 4
In Example 4, electrolysis was performed in the same manner as in Example 1 except that the electrode current density was 8 A / dm ^{2 under} the conditions of Example 1. And the indium oxide sintered compact was produced by the same method as Example 1 from the obtained indium hydroxide powder.

  In Example 4, the concentration of indium hydroxide powder in the electrolytic solution was 2.0 wt%. In addition, the particle size distribution of the indium hydroxide powder measured in the same manner as in Example 1 had a minimum diameter of 0.3 μm and a maximum diameter of 1.2 μm, and had a well-defined range of particle size distribution. Similarly, the particle size distribution of the indium oxide powder was a minimum particle size of 0.5 μm and a maximum particle size of 1.2 μm. The density of the indium oxide sintered body was 99.5% of the true specific gravity.

(Example 5)
In Example 5, electrolysis was performed in the same manner as in Example 1 except that the electrode current density was 17 A / dm ^{2 under} the conditions of Example 1. And the indium oxide sintered compact was produced by the same method as Example 1 from the obtained indium hydroxide powder.

  In Example 5, the concentration of the electrolytic slurry was 3.2 wt%. In addition, the particle size distribution of the indium hydroxide powder measured in the same manner as in Example 1 had a minimum diameter of 0.3 μm and a maximum diameter of 1.2 μm, and had a limited range of particle size distribution. Similarly, the particle size distribution of the indium oxide powder was a minimum particle size of 0.5 μm and a maximum particle size of 1.2 μm. The density of the indium oxide sintered body was 99.3% of the true specific gravity.

(Example 6)
In Example 6, electrolysis was performed in the same manner as in Example 1 except that the current density was 19 A / dm ² and the electrolysis time was 15 hours under the conditions of Example 1. And the indium oxide sintered compact was produced by the same method as Example 1 from the obtained indium hydroxide powder.

  In Example 6, the concentration of the electrolytic slurry was 12.0 wt%. The particle size distribution of indium hydroxide measured in the same manner as in Example 1 had a minimum diameter of 0.2 μm and a maximum diameter of 1.4 μm, and had a limited range of particle size distribution. Similarly, the particle size distribution of indium oxide was a minimum diameter of 0.6 μm and a maximum diameter of 1.4 μm, and the particle size distribution was limited in the same manner. The density of the indium oxide sintered body was 99.2% with respect to the true specific gravity.

(Example 7)
In Example 7, electrolysis was performed in the same manner as in Example 1 except that the electrolyte concentration was 1.0 mol / L and the distance between the electrodes was 1.5 cm under the conditions of Example 1. And the indium oxide sintered compact was produced by the same method as Example 1 from the obtained indium hydroxide powder.

  In Example 7, the concentration of the electrolytic slurry was 3.2 wt%. Further, the particle size distribution of the indium hydroxide powder measured in the same manner as in Example 1 had a minimum diameter of 0.3 μm and a maximum diameter of 1.2 μm, and had a particle size distribution in a limited range. Similarly, the particle size distribution of the indium oxide powder has a minimum diameter of 0.5 μm and a maximum diameter of 1.2 μm. The density of the indium oxide sintered body was 99.5% of the true specific gravity.

(Comparative Example 1)
In Comparative Example 1, electrolysis was performed in the same manner as in Example 1 except that the electrolytic solution concentration was 0.04 mol / L and the electrode current density was 6 A / dm ² under the conditions of Example 1.

  As a result, the voltage applied to match the predetermined current density greatly deviated from the normal range, and a stable voltage value could not be maintained.

(Comparative Example 2)
In Comparative Example 2, electrolysis was performed in the same manner as in Example 1 except that the electrolytic solution concentration was 3.0 mol / L under the conditions of Example 1.

  In Comparative Example 2, the concentration of the electrolytic slurry was 3.2 wt%. The particle size distribution of the indium hydroxide powder measured in the same manner as in Example 1 has a minimum diameter of 0.3 μm and a maximum diameter of 3.0 μm. Similarly, the particle size distribution of indium oxide powder has a minimum diameter of 0.3 μm and a maximum diameter. The distribution was 3.0 μm, both of which were wider than the results in Examples 1-7. The relative density of the indium oxide sintered body was 89.7%, which was clearly lower than those of Examples 1-7.

(Comparative Example 3)
In Comparative Example 3, electrolysis was performed in the same manner as in Example 1, except that the electrolysis pH was 2.3, the electrolysis temperature was 30 ° C., and the electrolysis time was 4 hours.

  As a result, electrolysis of anodic indium did not proceed, and precipitation of indium hydroxide did not proceed at all.

(Comparative Example 4)
In Comparative Example 4, electrolysis was performed in the same manner as in Example 1 except that the electrolysis pH was set to 6.5 under the conditions of Example 1. And the indium oxide sintered compact was produced by the same method as Example 1 from the obtained indium hydroxide powder.

  As a result, the concentration of the electrolytic slurry was 3.2 wt%. The particle size distribution of the indium hydroxide powder measured in the same manner as in Example 1 has a minimum diameter of 0.1 μm and a maximum diameter of 9.0 μm. Similarly, the particle size distribution of indium oxide powder has a minimum diameter of 0.2 μm and a maximum diameter. The distribution was 8.8 μm, both of which were wider than the results in Examples 1 to 7. The relative density of the indium oxide sintered body was 87.0%, which was clearly lower than those of Examples 1-7.

(Comparative Example 5)
In Comparative Example 5, electrolysis was performed in the same manner as in Example 1 except that the electrolysis temperature was 18 ° C. under the conditions of Example 1. And the indium oxide sintered compact was produced by the same method as Example 1 from the obtained indium hydroxide powder.

  In Comparative Example 5, the concentration of the electrolytic slurry was 3.2 wt%. The particle size distribution of the indium hydroxide powder measured in the same manner as in Example 1 has a minimum diameter of 0.8 μm and a maximum diameter of 2.8 μm. Similarly, the particle size distribution of indium oxide powder has a minimum diameter of 0.9 μm and a maximum diameter. The distribution was 3.0 μm, both of which were wider than the results in Examples 1-7. The relative density of the indium oxide sintered body was 91.0%, which was clearly lower than those of Examples 1-7.

(Comparative Example 6)
In Comparative Example 6, electrolysis was performed in the same manner as in Example 1 except that the electrolysis temperature was set to 65 ° C. under the conditions of Example 1. And the indium oxide sintered compact was produced by the same method as Example 1 from the obtained indium hydroxide powder.

  In Comparative Example 6, the electrolytic slurry concentration was 3.2 wt%. The particle size distribution of the indium hydroxide powder measured in the same manner as in Example 1 has a minimum diameter of 0.2 μm and a maximum diameter of 8.0 μm. Similarly, the particle size distribution of indium oxide powder has a minimum diameter of 0.2 μm and a maximum diameter. It was 8.2 μm, and both were broader than the results in Examples 1 to 7. The relative density of the indium oxide sintered body was 88.0%, which was clearly lower than those of Examples 1-7.

(Comparative Example 7)
In Comparative Example 7, electrolysis was performed in the same manner as in Example 1 except that the electrode current density was 2 A / dm ² and the electrolysis time was 12 hours under the conditions of Example 1. And the indium oxide sintered compact was produced by the same method as Example 1 from the obtained indium hydroxide powder.

  In Comparative Example 7, the concentration of the electrolytic slurry was small and less than 1.0 wt%. The particle size distribution of the indium hydroxide powder measured in the same manner as in Example 1 has a minimum diameter of 0.2 μm and a maximum diameter of 2.8 μm. Similarly, the particle size distribution of indium oxide powder has a minimum diameter of 0.8 μm and a maximum diameter. The distribution was 3.1 μm, both of which were wider than the results in Examples 1 to 7. The relative density of the indium oxide sintered body was 90.0%, which was clearly lower than those of Examples 1-7.

(Comparative Example 8)
In Comparative Example 8, electrolysis was performed in the same manner as in Example 1 except that the temperature of the electrolyte was 28 ° C. and the electrode current density was 28 A / dm ² under the conditions of Example 1. And the indium oxide sintered compact was produced by the same method as Example 1 from the obtained indium hydroxide powder.

  In Comparative Example 8, the concentration of the electrolytic slurry was 6.0 wt%. The particle size distribution of the indium hydroxide powder measured in the same manner as in Example 1 has a minimum diameter of 0.2 μm and a maximum diameter of 8.1 μm. Similarly, the particle size distribution of indium oxide powder has a minimum diameter of 0.3 μm and a maximum diameter. The distribution was 8.3 μm, both of which were wider than the results in Examples 1-7. The relative density of the indium oxide sintered body was 89.0%, which was clearly lower than those of Examples 1-7.

(Comparative Example 9)
In Comparative Example 9, electrolysis was performed in the same manner as in Example 1 except that the electrolysis time was 34 hours under the conditions of Example 1. And the indium oxide sintered compact was produced by the same method as Example 1 from the obtained indium hydroxide powder.

  In Comparative Example 9, the concentration of the electrolytic slurry was 18.0 wt%. The particle size distribution of the indium hydroxide powder measured in the same manner as in Example 1 has a minimum diameter of 0.3 μm and a maximum diameter of 2.0 μm. Similarly, the particle size distribution of indium oxide powder has a minimum diameter of 0.5 μm and a maximum diameter. The distribution was 2.0 μm, both of which were wider than the results in Examples 1 to 7. The relative density of the indium oxide sintered body was 96.2%, which was clearly lower than those of Examples 1-7.

(Comparative Example 10)
In Comparative Example 10, electrolysis was performed in the same manner as in Example 1 except that the electrolysis time was 42 hours under the conditions of Example 1. And the indium oxide sintered compact was produced by the same method as Example 1 from the obtained indium hydroxide powder.

  In Comparative Example 10, the concentration of the electrolytic slurry was 22.0 wt%. The particle size distribution of the indium hydroxide powder measured in the same manner as in Example 1 has a minimum diameter of 0.7 μm and a maximum diameter of 2.8 μm. Similarly, the particle size distribution of indium oxide powder has a minimum diameter of 0.8 μm and a maximum diameter. The distribution was 3.0 μm, both of which were wider than the results in Examples 1-7. The relative density of the indium oxide sintered body was 91.0%, which was clearly lower than those of Examples 1-7.

(Comparative Example 11)
In Comparative Example 11, electrolysis was performed in the same manner as in Example 1 except that the distance between the electrodes was set to 0.5 cm under the conditions of Example 1.

  As a result, a short circuit occurred due to contact between the electrodes, the current value was not stable, and stable electrolysis was not possible.

(Comparative Example 12)
In Comparative Example 12, electrolysis was performed in the same manner as in Example 1 except that the distance between the electrodes was set to 5.0 cm under the conditions of Example 1. However, if the distance between the electrodes is 5.0 cm, the same number of electrode plates as in Example 1 cannot be arranged in the electrolytic cell, so three cathodes and two positive electrodes are prepared and alternately arranged in the electrolytic cell. Arranged. And the indium oxide sintered compact was produced by the same method as Example 1 from the obtained indium hydroxide powder.

  In Comparative Example 12, the concentration of the electrolytic slurry was 3.2 wt%. The particle size distribution of this indium hydroxide was measured by the same method as in Example 1, and the minimum diameter was 0.6 μm and the maximum diameter was 3.0 μm. Similarly, the particle size distribution of indium oxide powder was the minimum diameter of 0.8 μm and the maximum The diameter was 3.0 μm, both of which were wider than the results in Examples 1-7. The relative density of the indium oxide sintered body was 93.0%, which was clearly lower than those of Examples 1-7.

(Comparative Example 13)
In Comparative Example 13, the electrolytic solution concentration was 0.5 mol / L, the electrolytic solution pH was 8.0, the electrolytic temperature was 10 ° C., and the electrode current density was 12 A / dm ^{2 under} the conditions of Example 1. The others were electrolyzed in the same manner as in Example 1. And the indium oxide sintered compact was produced by the same method as Example 1 from the obtained indium hydroxide powder.

  In Comparative Example 13, the concentration of the electrolytic slurry was 2.6 wt%. The particle size distribution of the indium hydroxide powder measured in the same manner as in Example 1 has a minimum diameter of 0.1 μm and a maximum diameter of 8.5 μm. Similarly, the particle size distribution of indium oxide has a minimum diameter of 0.2 μm and a maximum diameter of 8. μm. 8 μm, both of which were wider than the results in Examples 1-7. The relative density of the indium oxide sintered body was 87.0%, which was clearly lower than those of Examples 1-7.

(Comparative Example 14)
In Comparative Example 14, the electrolytic solution concentration was 1.0 mol / L, the electrolytic solution pH was 6.0, the electrolytic temperature was 50 ° C., and the electrode current density was 12 A / dm ^{2 under} the conditions of Example 1. The others were electrolyzed in the same manner as in Example 1. And the indium oxide sintered compact was produced by the same method as Example 1 from the obtained indium hydroxide powder.

  In Comparative Example 14, the concentration of the electrolytic slurry was 2.6 wt%. The particle size distribution of the indium hydroxide powder was measured by the same method as in Example 1, and the minimum diameter was 0.1 μm and the maximum diameter was 8.0 μm. Similarly, the particle size distribution of the indium oxide powder was the minimum diameter of 0.1 μm, The maximum diameter was 8.0 μm, and both had a wider distribution than the results in Examples 1-7. The relative density of the indium oxide sintered body was 87.0%, which was clearly lower than those of Examples 1-7.

As described above, from the results of Examples and Comparative Examples, as in Examples 1 to 7, the concentration of the electrolytic solution was 0.1 to 2.0 mol / L, the pH was 2.5 to 5.0, and the liquid temperature was Electrolysis is performed so that the concentration of indium hydroxide powder in the electrolytic solution is 20 to 60 ° C., the electrode current density is 4 A / dm ^{2 to} 20 A / dm ² , and the concentration of indium hydroxide powder in the electrolytic solution is 2 to 15%. It can be seen that the particle size distribution width of the indium powder is narrow, the particle size is uniform, and the density of the indium oxide sintered body is high.

Claims (6)

In the method for producing indium hydroxide powder, which produces indium hydroxide powder by electrolysis using metal indium for the anode,
The concentration of the electrolytic solution is 0.1 to 2.0 mol / L, the pH is 2.5 to 5.0, and the liquid temperature is 20 to 60 ° C.
The electrode current density is 4-20 A / dm ² ;
The distance between the electrodes is 1 to 4 cm,
Electrolyzing so that the density | concentration of the electrolysis slurry containing the said indium hydroxide powder deposited may be 2 to 15% of range, The manufacturing method of the indium hydroxide powder characterized by the above-mentioned.   2. The method for producing indium hydroxide powder according to claim 1, wherein the electrolytic solution is ammonium nitrate.   The method for producing indium hydroxide powder according to claim 1 or 2, wherein the primary particles of the indium hydroxide powder have a columnar shape. In the method for producing indium oxide powder, indium oxide powder obtained by calcining indium hydroxide powder obtained by electrolysis using metal indium for the anode,
The concentration of the electrolytic solution is 0.1 to 2.0 mol / L, the pH is 2.5 to 5.0, and the liquid temperature is 20 to 60 ° C.
The electrode current density is 4-20 A / dm ² ;
The distance between the electrodes is 1 to 4 cm,
Electrolyzing so that the density | concentration of the electrolysis slurry containing the said indium hydroxide powder which precipitated may become the range of 2-15%, The manufacturing method of the indium oxide powder characterized by the above-mentioned.   5. The method for producing indium oxide powder according to claim 4, wherein the electrolytic solution is ammonium nitrate.   6. The method for producing indium oxide powder according to claim 4, wherein the primary particles of the indium hydroxide powder have a columnar shape.

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