KR20160012134A - Method for producing indium hydroxide powder, method for producing indium oxide powder, and sputtering target - Google Patents

Abstract

Thereby producing an indium hydroxide powder having a uniform particle diameter and a narrow particle size distribution width. A method for producing an indium hydroxide powder by electrolysis using metal indium in an anode, characterized in that the electrolytic solution has an electrolyte concentration of 0.1 to 2.0 mol / L, a pH of 2.5 to 5.0 and a liquid temperature of 20 to 60 캜, The electrolysis is performed so that the density is ⁴ to 20 A / dm ² and the concentration of the electrolytic slurry containing precipitated indium hydroxide powder is in the range of 2 to 15%.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a method for producing indium hydroxide, a method for producing indium oxide powder, a method for producing indium oxide powder, and a sputtering target,

The present invention relates to a process for producing an indium hydroxide powder which can obtain an indium hydroxide powder having a uniform particle size and a narrow particle size distribution width, a process for producing an indium oxide powder, and a sputtering target using the obtained indium oxide powder . The present application claims priority based on Japanese Patent Application No. 2013-111289 filed on May 27, 2013, the entirety of which is incorporated herein by reference.

2. Description of the Related Art In recent years, use of a transparent conductive film as a solar cell application or a touch panel application has been increasing, and a demand for a material for forming a transparent conductive film such as a sputtering target has increased. An indium oxide-based sintered material is mainly used as a material for forming a transparent conductive film. Indium oxide powder is used as the main material of the transparent conductive film forming material. It is preferable that the particle size distribution of the indium oxide powder used for the sputtering target is as small as possible in order to obtain a high density target.

As a production method of the indium oxide powder, it is mainly produced by a so-called neutralization method in which the precipitation of indium hydroxide which is generated by neutralizing an acid aqueous solution such as an aqueous solution of indium nitrate or an aqueous solution of indium chloride with an aqueous alkaline solution such as ammonia water is dried and calcined.

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

However, the indium oxide powder produced by the neutralization method tends to be uneven in particle diameter and particle size distribution, and there is a problem that particles of relatively large size coexist. For this reason, when such a sputtering target is produced by using such indium oxide, there arises a problem that voids between particles due to large particles are generated, making it difficult to improve the density.

In addition, in the neutralization method, since a large amount of nitrogen wastewater is generated after the production of the indium oxide powder, there is a problem that the wastewater treatment cost becomes large.

As a method for improving this, there has been proposed a method of producing indium oxide powder by causing precipitation of indium hydroxide powder by electrolytic treatment of metal indium, and calcining the indium hydroxide powder, so-called electrolytic solution (for example, see Patent Document 2). In this method, the amount of nitrogen discharged after the production of the indium oxide powder can be remarkably reduced as compared with the neutralization method, and the particle size of the obtained indium oxide powder can be made uniform.

However, since the pH of the electrolytic solution is close to neutrality, the indium hydroxide powder obtained by the electrolytic method has a problem that it is very fine and easily aggregated. The indium oxide powder obtained by calcining this is relatively uniform in primary particle size, but agglomerated powder in which these particles are agglomerated strongly is likely to be obtained. There is a problem that the increase in the particle size distribution due to agglomeration leads to a reduction in the density of the target.

Accordingly, there is a need for a method for producing an indium hydroxide powder having a uniform particle size and a narrow particle size distribution, by using an electrolysis method with a small amount of nitrogen discharge after production, in a method for producing indium hydroxide powder.

Patent Document 1: Japanese Patent No. 3314388 Patent Document 2: Japanese Patent No. 2829556

DISCLOSURE OF THE INVENTION It is therefore an object of the present invention to provide a process for producing an indium hydroxide powder which has been proposed in view of the above circumstances and which is difficult to agglomerate and has a uniform particle size and a narrow particle size distribution width can be obtained, An object of the present invention is to provide a method for producing an indium oxide powder to obtain an indium oxide powder and a sputtering target produced using the obtained indium oxide powder.

According to the present invention, there is provided a process for producing an indium hydroxide powder by electrolytic electrolysis using metal indium on an anode, wherein the concentration of the electrolytic solution is 0.1 to 2.0 mol / L, the pH is 2.5 to 5.0, the liquid temperature is 20 to 60 ° C, the electrode current density is 4 to 20 A / dm ² , the concentration of the electrolytic slurry containing precipitated indium hydroxide powder is in the range of 2 to 15% So that electrolysis is performed.

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

The sputtering target according to the present invention for achieving the above-mentioned object is characterized by being manufactured using the indium oxide powder obtained by the above-mentioned production method of indium oxide.

In the present invention, by controlling the concentration, the pH, the liquid temperature and the electrode current density of the electrolytic solution and electrolyzing the electrolytic slurry so that the concentration of the electrolytic slurry containing the precipitated indium hydroxide powder is within a specific range, the produced indium hydroxide powder is difficult to aggregate, It is possible to produce an indium hydroxide powder having a uniform particle diameter and 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 narrow particle size distribution width can be obtained, and a high-density sputtering target can be obtained.

1 is a schematic view of an electrolytic apparatus used in Examples and Comparative Examples.
2 is a schematic view showing the arrangement of a cathode and an anode in the electrolytic apparatus.

Hereinafter, a method for producing indium oxide powder to which the present invention is applied and a sputtering target using indium oxide powder obtained by the manufacturing method will be described. Further, the present invention is not limited to the following detailed description unless otherwise specified. The method for producing the indium oxide powder to which the present invention is applied and the embodiment of the sputtering target will be described in detail in the following procedure.

1. Manufacturing method of indium oxide powder

1-1. Manufacturing process of indium hydroxide powder

1-2. Recovery process of indium hydroxide powder

1-3. Drying process of indium hydroxide powder

1-4. Production process of indium oxide powder

2. Sputtering target

1. Manufacturing method of indium oxide powder

(1-1. Production process of indium hydroxide powder)

The production method of the indium hydroxide powder uses an electrolytic reaction to produce an indium hydroxide powder.

A method of producing indium hydroxide powder is a method in which indium is used as an anode (anode), a conductive metal or a carbon electrode is used for a cathode (cathode) of a counter electrode, a positive potential is generated between the anode and the cathode by immersing the anode and the cathode in an electrolytic solution, Thereby dissolving the anode metal. In the electrolysis, the pH of the electrolytic solution is controlled to be lower than the solubility of the indium hydroxide, whereby indium hydroxide powder is precipitated to obtain indium hydroxide powder.

As the anode, for example, metal indium or the like is used. The metal indium to be used is not particularly limited, but it is preferable that the metal indium is of high purity in order to suppress the incorporation of impurities into the indium oxide powder. As a suitable metal indium, a purity of 99.9999% (commonly referred to as 6N) is used as a suitable product.

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

As the electrolytic solution, an aqueous solution of a common electrolytic salt such as a water-soluble nitrate salt, a sulfate salt, and a chloride salt can be used. Among them, an aqueous solution of ammonium nitrate using ammonium nitrate in which no 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. When the concentration is lower than 0.1 mol / L, the electric conductivity of the electrolytic solution is too low to cause no current, or the required voltage exceeds the practical range, which is not preferable. On the other hand, when the concentration of the electrolytic solution is 2.0 mol / L, a sufficient electric conductivity is secured. Therefore, if it is higher than 2.0 mol / L, it is not economical.

The pH of the electrolytic solution is set in the range of 2.5 to 5.0. When the pH is less than 2.5, precipitation of hydroxide does not occur. When the pH is more than 5.0, precipitation rate of hydroxide is excessively high and precipitation is formed with concentration unevenness, which is not preferable because the particle size distribution width widens. The pH at which the hydroxide precipitates is also influenced by the coexisting ions, so it is necessary to adjust the pH within the range of 2.5 to 5.0 within the respective pH ranges. Also, since the dissolution stability of hydroxides is improved by the coexistence of oxygen-containing chelate compounds such as citric acid, tartaric acid and glycolic acid, and nitrogen-containing chelates such as ethylenediamine acetic acid (EDTA), the hydroxides It is necessary to adjust the pH to be settled.

The liquid temperature of the electrolytic solution is 20 to 60 캜. When the temperature is lower than 20 ° C, the precipitation rate of hydroxide is excessively slow. When the temperature is higher than 60 ° C, the precipitation rate becomes excessively high and the precipitate is formed with unevenness of concentration. It is not preferable.

The current density is in the range of 4 to ²⁰ A / dm ² . When the current density is lower than 4 A / dm ² , the generation rate of the indium hydroxide powder is lowered. If the current density becomes too high, the reaction in which indium precipitates on the negative electrode starts to take precedence over the occurrence of hydroxide precipitation. As a result, the precipitated indium metal is mixed with the indium hydroxide and the particle size becomes rough. When it is higher than 20 A / dm ² , the tendency becomes remarkable, which is not preferable. Further, since the rise of the electrolytic voltage is liable to cause rise of the liquid temperature, the surface of the metal indium of the anode becomes passivated and becomes difficult to be electrolyzed, and so on.

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

The electrolysis is carried out at a concentration of 2 to 15% of the electrolytic solution in which the hydroxide hydroxide precipitates (hereinafter also referred to as electrolytic slurry). The precipitation amount of the indium hydroxide powder increases with the progress of the electrolysis, but when the concentration is lower than 2%, the concentration is too low and the efficiency of the solid-liquid separation lowers, which is not preferable. If it is higher than 15%, the viscosity of the electrolytic solution becomes excessively high, and uniform diffusion in the electrolyte is inhibited. Therefore, precipitation occurs with unevenness in concentration and the particle size distribution width is not reduced.

(1-2. Recovery process of indium hydroxide powder)

The indium hydroxide powder obtained by electrolysis is subjected to solid-liquid separation from the electrolytic solution, and the separated indium hydroxide powder is washed with pure water and separated again by solid-liquid separation.

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

(1-3. Drying process of indium hydroxide powder)

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, or an infrared drying furnace.

The drying condition is not particularly limited as long as it can remove the moisture of the indium hydroxide powder. For example, the drying temperature is preferably in the range of 80 to 150 캜. When the drying temperature is lower than 80 캜, drying becomes insufficient, and when the drying temperature is higher than 150 캜, indium hydroxide is changed to indium oxide. The drying time varies depending on the temperature, but is about 10 hours to 24 hours.

In the process for producing the indium hydroxide powder as described above, the electrolytic solution has a concentration of 0.1 to 2.0 mol / L, a pH of 2.5 to 5.0, and a liquid temperature of 20 to 60 캜 in electrolysis, and the positive electrode and the negative electrode are immersed The electrolytic solution is carried out within a range in which the electrode current density is in the range of 4 A / dm ² to 20 A / dm ² and the concentration of the electrolytic slurry is in the range of ² to 15%, whereby the aggregation is difficult, A narrow indium hydroxide powder can be obtained.

In addition, the shape of primary particles of the obtained indium hydroxide powder becomes a main phase. As the primary particles of the indium hydroxide powder are the main phase, aggregation is appropriately suppressed, and spherical secondary particles having a particle size of submicron or a narrow particle size distribution of several microns are obtained.

(1-4. Production process of indium oxide powder)

In the production process of the indium oxide powder, the dried indium hydroxide powder is calcined to produce indium oxide powder. The firing conditions are preferably, for example, a firing temperature of 600 ° C to 800 ° C and a firing time of 1 hour to 10 hours. In the production process of the indium oxide powder, it is also possible to carry out the crushing or crushing as necessary in order to make the indium hydroxide powder have a desired particle diameter. In addition, in the step of producing the indium oxide powder, when ammonium nitrate is used for the electrolytic solution, the ammonium nitrate is decomposed by the preliminary firing, so that the incorporation into the indium oxide powder can be prevented.

In the above-mentioned production method of the indium oxide powder, when the indium hydroxide powder is produced by the electrolytic method, the concentration, the pH, the liquid temperature and the electrode current density of the electrolytic solution are controlled as described above and the electrolytic solution containing the precipitated indium hydroxide powder By conducting electrolysis so that the concentration of the slurry is within a specific range, the produced indium hydroxide powder can produce an indium hydroxide powder having a uniform particle size and a narrow particle size distribution width. Thus, in the method for producing indium oxide powder, indium hydroxide powder having a uniform particle size and a narrow particle size distribution can be obtained by preheating indium hydroxide powder having a uniform particle size and narrow particle size distribution width.

Further, in the production method of the indium oxide powder, the amount of nitrogen discharge after the production of the indium oxide powder can be suppressed as compared with the neutralization method.

2. Sputtering target

The indium oxide powder obtained by calcining the indium hydroxide powder obtained by the above-mentioned production method of the indium hydroxide powder is used for a raw material of a sputtering target used for forming a transparent conductive film, for example.

The granulated powder obtained by mixing the above-mentioned indium oxide powder with other raw materials of the target such as tin oxide powder at a predetermined ratio is produced. Next, a molded body is manufactured by, for example, a cold press method using a granulated powder. Next, sintering is performed in a temperature range of, for example, 1300 DEG C to 1600 DEG C at atmospheric pressure. Next, as necessary, the sintered body is subjected to processing such as grinding the plane or the side face. Then, the indium tin oxide sputtering target (ITO sputtering target) can be obtained by bonding the sintered body to a backing plate made of Cu.

In the method for producing a sputtering target, since the particle size of the indium oxide powder as a raw material is uniform and the particle size distribution width is narrow, a high-density sintered body can be obtained and the density of the target can be increased. As a result, it is possible to suppress occurrence of an anomalous discharge during sputtering without causing cracks during processing of the target.

Further, the indium oxide powder is added not only to the raw material of the sputtering target but also to the conductive paste or the transparent conductive film paint. The indium oxide powder exhibits high dispersion when added to a conductive paste, a transparent conductive film coating or the like because the particle diameter is uniform.

Example

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

In the following Examples and Comparative Examples, indium hydroxide powder was produced by using the electrolytic apparatus 1 shown in Fig. The specific configuration of the electrolytic apparatus will be described in the first embodiment.

(Example 1)

The electrolytic apparatus 1 is provided with 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 adjusting tank 3 having a length of 40 cm, a width of 40 cm and a depth of 50 cm, (2) and the adjustment tank (3) are adjacent to each other. The electrolytic bath 2 and the conditioning tank 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 5 rows, 5 rows, and 25 holes each having a diameter of 3 mm per 10 cm square, which are arranged at regular intervals in a checkered pattern. Thus, 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 flows in a substantially homogeneous liquid flow .

Further, in the electrolytic cell 2, the cathode 7 and the anode 8 were arranged as shown in Fig. The cathode (cathode) 7 was provided with five titanium metal plates each having a thickness of 1 mm, a width of 30 cm and a height of 25 cm. Four pieces of indium metal having a purity of 99.9999% and having a plate shape of 30 cm in width, 25 cm in height, and 5 mm in thickness were prepared as the anode (anode) 8. The five cathodes 7 and the four cathodes 8 were arranged vertically on the punch plate 6 in the electrolytic bath 2 as shown in Fig. 2 so that the anodes were parallel to each other. And the distance between the cathode 7 and the anode 8 was adjusted to 3.0 cm. The five cathodes (7) are electrically connected to the lead wire (9).

The adjusting tank 3 is provided with a temperature adjusting heater 11 and a cooler 12 for controlling and maintaining the temperature of the electrolytic solution. Further, the adjustment tank 3 is provided with a stirring rod 13 for stirring the electrolyte solution 5 in the tank.

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

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

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

Table 1 shows the results of measurement of the particle size distribution of the recovered indium hydroxide powder by the laser light Doppler method. The particle size distribution of the indium hydroxide powder has a minimum diameter of 0.3 μm and a maximum diameter of 1.2 μm and a well-defined range of particle size distribution.

Next, the obtained indium hydroxide powder was dried under atmospheric conditions at 120 DEG C for 12 hours, and then calcined at 700 DEG C in the atmosphere. The obtained indium oxide particle size distribution had a minimum diameter of 0.5 占 퐉 and a maximum diameter of 1.2 占 퐉 and had a particle size distribution in the same well-defined range. From the results of the investigation of the weight of solid content, the concentration of the electrolytic slurry in the electrolytic solution 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% of a high density relative to a true specific gravity of 7.18 g / cm ³ of indium oxide.

(Example 2)

In Example 2, electrolysis was carried out in the same manner as in Example 1, except that the aqueous ammonium nitrate solution of the electrolytic solution was changed to 0.5 mol / L under the conditions of Example 1. An indium oxide sintered body was produced from the obtained indium hydroxide powder in the same manner as in Example 1.

In Example 2, the concentration of the indium hydroxide powder in the electrolytic solution was 3.2 wt%. 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 mu m and a maximum diameter of 1.0 mu m and a particle size distribution in a finite range. In the same manner, 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 and a particle size distribution in the same limited range. The density of the indium oxide sintered body was 99.6% of the true specific gravity.

(Example 3)

In Example 3, electrolysis was carried out in the same manner as in Example 1, except that the electrolytic temperature was changed to 50 캜 under the conditions of Example 1. An indium oxide sintered body was produced from the obtained indium hydroxide powder in the same manner as in Example 1.

In Example 3, the concentration of the indium hydroxide powder in the electrolytic solution was 3.2 wt%. 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 mu m and a maximum diameter of 1.2 mu m and a particle size distribution in a finite range. In the same manner, 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 and a particle size distribution in the same limited range. The density of the indium oxide sintered body was as high as 99.5% of the true specific gravity.

(Example 4)

In Example 4, electrolysis was carried out 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. An indium oxide sintered body was produced from the obtained indium hydroxide powder in the same manner as in Example 1.

In Example 4, the concentration of the indium hydroxide powder in the electrolytic solution was 2.0 wt%. 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 mu m and a maximum diameter of 1.2 mu m and a particle size distribution in a finite range. In the same manner, 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 and a particle size distribution in the same limited range. The density of the indium oxide sintered body was as high as 99.5% of the true specific gravity.

(Example 5)

Example 5 was electrolytic 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. An indium oxide sintered body was produced from the obtained indium hydroxide powder in the same manner as in Example 1.

In 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 had a minimum diameter of 0.3 mu m and a maximum diameter of 1.2 mu m and had a limited particle size distribution. In the same manner, 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 and a particle size distribution in the same limited range. The density of the indium oxide sintered body was 99.3% of the true specific gravity.

(Example 6)

In Example 6, electrolysis was carried out 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. An indium oxide sintered body was produced from the obtained indium hydroxide powder in the same manner as in Example 1.

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

(Example 7)

In Example 7, electrolysis was carried out in the same manner as in Example 1 except that the electrolytic solution concentration was 1.0 mol / L and the inter-electrode distance was 1.5 cm under the conditions of Example 1. An indium oxide sintered body was produced from the obtained indium hydroxide powder in the same manner as in Example 1.

In Example 7, 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 had a minimum diameter of 0.3 mu m and a maximum diameter of 1.2 mu m and a particle size distribution in the same limited range. In the same manner, the particle size distribution of the indium oxide powder was a minimum diameter of 0.5 μm, a maximum diameter of 1.2 μm and a uniformly limited particle size distribution. 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 carried out in the same manner as in Example 1, except that the concentration of the electrolytic solution 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 meet the predetermined current density largely deviates from the commercial range and the stable voltage value could not be maintained.

(Comparative Example 2)

In Comparative Example 2, electrolysis was carried out in the same manner as in Example 1, except that the concentration of the electrolytic solution 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 was a minimum diameter of 0.3 mu m and a maximum diameter of 3.0 mu m. The particle size distribution of the indium oxide powder was 0.3 mu m minimum and 3.0 mu m maximum, Compared to the results in Examples 1 to 7, it was broad distribution. The relative density of the indium oxide-sintered body was 89.7%, which was clearly lower than those of Examples 1 to 7.

(Comparative Example 3)

In Comparative Example 3, electrolysis was carried out in the same manner as in Example 1 except that the electrolytic pH was 2.3, the electrolytic temperature was 30 ° C, and the electrolytic time was 4 hours under the conditions of Example 1.

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

(Comparative Example 4)

In Comparative Example 4, electrolysis was carried out in the same manner as in Example 1, except that the electrolytic pH was changed to 6.5 under the conditions of Example 1. An indium oxide sintered body was produced from the obtained indium hydroxide powder in the same manner as in Example 1.

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 was a minimum diameter of 0.1 탆 and a maximum diameter of 9.0 탆, and the particle size distribution of the indium oxide powder was 0.2 탆 minimum and 8.8 탆 maximum, Compared to the results from 1 to 7, the distribution was wide. The relative density of the indium oxide-sintered body was 87.0%, which was obviously lower than those of Examples 1 to 7.

(Comparative Example 5)

In Comparative Example 5, electrolysis was carried out in the same manner as in Example 1, except that the electrolytic temperature was 18 ° C under the conditions of Example 1. An indium oxide sintered body was produced from the obtained indium hydroxide powder in the same manner as in Example 1.

In Comparative 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 0.8 탆 and a maximum diameter of 2.8 탆, and the particle size distribution of the indium oxide powder was 0.9 탆 minimum and 3.0 탆 maximum, Compared to the results from 1 to 7, the distribution was wide. The relative density of the indium oxide-sintered body was 91.0%, which was clearly lower than those of Examples 1 to 7.

(Comparative Example 6)

In Comparative Example 6, electrolysis was carried out in the same manner as in Example 1, except that the electrolytic temperature was changed to 65 캜 under the conditions of Example 1. An indium oxide sintered body was produced from the obtained indium hydroxide powder in the same manner as in Example 1.

In Comparative Example 6, 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 was a minimum diameter of 0.2 탆 and a maximum diameter of 8.0 탆, and the particle size distribution of the indium oxide powder was 0.2 탆 minimum and 8.2 탆 maximum in the same manner Compared to the results in Examples 1 to 7, it was broad distribution. The relative density of the indium oxide-sintered body was 88.0%, which was clearly lower than that of Examples 1 to 7.

(Comparative Example 7)

In Comparative Example 7, electrolysis was carried out 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. An indium oxide sintered body was produced from the obtained indium hydroxide powder in the same manner as in Example 1.

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

(Comparative Example 8)

In Comparative Example 8, electrolysis was carried out in the same manner as in Example 1 except that the temperature of the electrolytic solution was 28 ° C and the electrode current density was 28 A / dm ² under the conditions of Example 1. An indium oxide sintered body was produced from the obtained indium hydroxide powder in the same manner as in Example 1.

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 had a minimum diameter of 0.2 탆 and a maximum diameter of 8.1 탆, and the particle size distribution of the indium oxide powder was 0.3 탆 minimum and 8.3 탆 maximum diameters in the same manner Compared to the results in Examples 1 to 7, it was broad distribution. The relative density of the indium oxide-sintered body was 89.0%, which was clearly lower than those of Examples 1 to 7.

(Comparative Example 9)

In Comparative Example 9, electrolysis was carried out in the same manner as in Example 1, except that the electrolysis time was changed to 34 hours under the conditions of Example 1. An indium oxide sintered body was produced from the obtained indium hydroxide powder in the same manner as in Example 1.

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 was a minimum diameter of 0.3 탆 and a maximum diameter of 2.0 탆 and the particle size distribution of the indium oxide powder was 0.5 탆 minimum and 2.0 탆 maximum in the same manner Compared to the results in Examples 1 to 7, it was broad distribution. The relative density of the indium oxide-sintered body was 96.2%, which was clearly lower than those of Examples 1 to 7.

(Comparative Example 10)

In Comparative Example 10, electrolysis was carried out in the same manner as in Example 1, except that the electrolysis time was changed to 42 hours under the conditions of Example 1. An indium oxide sintered body was produced from the obtained indium hydroxide powder in the same manner as in Example 1.

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 was a minimum diameter of 0.7 μm and a maximum diameter of 2.8 μm, and the particle size distribution of the indium oxide powder was 0.8 μm minimum and 3.0 μm maximum, Compared to the results in Examples 1 to 7, it was broad distribution. The relative density of the indium oxide-sintered body was 91.0%, which was clearly lower than those of Examples 1 to 7.

(Comparative Example 11)

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

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

(Comparative Example 12)

In Comparative Example 12, electrolysis was carried out in the same manner as in Example 1, except that the distance between the electrodes was 5.0 cm under the conditions of Example 1. However, when the distance between the electrodes was set to 5.0 cm, since the same number of electrode plates as in Example 1 could not be arranged in the electrolytic cell, three cathodes and two cathodes were prepared and placed alternately in the electrolytic cell. An indium oxide sintered body was produced from the obtained indium hydroxide powder in the same manner as in Example 1.

In Comparative Example 12, the concentration of the electrolytic slurry was 3.2 wt%. The particle size distribution of the 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. The particle size distribution of the indium oxide powder was 0.8 μm minimum and 3.0 μm maximum, Compared to the results in Examples 1 to 7, it was broad distribution. The relative density of the indium oxide-sintered body was 93.0%, which was clearly lower than those of Examples 1 to 7.

(Comparative Example 13)

Comparative Example 13 was prepared in the same manner as in Example 1 except that the electrolyte concentration was 0.5 mol / L, the pH of the electrolytic solution was 8.0, the electrolytic temperature was 10 ° C, and the electrode current density was 12 A / dm ² , Electrolysis was carried out in the same manner as in Example 1. An indium oxide sintered body was produced from the obtained indium hydroxide powder in the same manner as in Example 1.

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 was a minimum diameter of 0.1 mu m and a maximum diameter of 8.5 mu m and a particle size distribution of indium oxide was 0.2 mu m and a maximum diameter of 8.8 mu m, Compared to the results from 1 to 7, the distribution was wide. The relative density of the indium oxide-sintered body was 87.0%, which was obviously lower than those of Examples 1 to 7.

(Comparative Example 14)

In Comparative Example 14, except that the electrolytic solution concentration was set to 1.0 mol / L, the pH of the electrolytic solution was set to 6.0, the electrolytic temperature was set to 50 ° C, and the electrode current density was set to 12 A / dm ² under the conditions of Example 1 Electrolysis was carried out in the same manner as in Example 1. An indium oxide sintered body was produced from the obtained indium hydroxide powder in the same manner as in Example 1.

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 in the same manner as in Example 1, and the minimum diameter was 0.1 탆 and the maximum diameter was 8.0 탆. The particle size distribution of the indium oxide powder was 0.1 탆 minimum and 8.0 탆 maximum, Which was broader than the results in Examples 1 to 7. The relative density of the indium oxide-sintered body was 87.0%, which was obviously lower than those of Examples 1 to 7.

From the results of Examples and Comparative Examples as described above, it was found that the concentration of the electrolytic solution was 0.1 to 2.0 mol / L, the pH was 2.5 to 5.0, the liquid temperature was 20 to 60 캜, the electrode current density was 4 A / dm ² to 20 A / dm ² , and the concentration of the indium hydroxide powder in the electrolytic solution is ² to 15%, the particle size distribution of the indium hydroxide powder and the indium oxide powder is narrow and the particle diameter is uniform, The density of the sintered body is high.

Claims (7)

A process for producing indium hydroxide powder by electrolytic precipitation using metal indium in an anode,
The concentration of the electrolytic solution is 0.1 to 2.0 mol / L, the pH is 2.5 to 5.0, the liquid temperature is 20 to 60 캜,
The electrode current density is 4 to 20 A / dm ² ,
And electrolysis is conducted 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 an indium hydroxide powder according to claim 1, wherein the electrolytic solution is ammonium nitrate. The method for producing an indium hydroxide powder according to claim 1 or 2, wherein the primary particles of the indium hydroxide powder have a columnar shape. A process for producing indium oxide powder which is obtained by calcining an indium hydroxide powder obtained by electrolysis using metal indium on an anode to obtain indium oxide powder,
The concentration of the electrolytic solution is 0.1 to 2.0 mol / L, the pH is 2.5 to 5.0, the liquid temperature is 20 to 60 캜,
The electrode current density is 4 to 20 A / dm ² ,
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 an indium oxide powder according to claim 4, wherein the electrolytic solution is ammonium nitrate. The method for producing an indium oxide powder according to claim 4 or 5, wherein the primary particles of the indium hydroxide powder have a columnar shape. A sputtering target produced using the indium oxide powder obtained by the method for producing an indium oxide powder according to any one of claims 4 to 6.

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