JP6314904B2 - Method for producing indium hydroxide powder, method for producing indium oxide powder, and method for producing sputtering target - Google Patents

Description

The present invention relates to a method for producing indium hydroxide powder capable of obtaining indium hydroxide powder having a narrow particle size distribution, a method for producing indium oxide powder using the indium hydroxide powder, and an oxidation method. The present invention relates to a method for producing a sputtering target produced using indium powder.

  In recent years, 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. As the transparent conductive film forming material, an indium oxide-based sintered material is mainly used, and indium oxide powder is used as the main raw material. The indium oxide powder used for the sputtering target desirably has a narrow particle size distribution as much as possible in order to obtain a high-density target.

  As one of the methods for that purpose, as described in Patent Document 1, the present inventors adjusted the pH of the electrolytic solution to 2.5 to 4.0 to adjust the indium hydroxide powder into the electrolytic solution. We have proposed an indium hydroxide powder having a narrow particle size distribution with controlled solubility, and a method for producing indium oxide powder using the same. By this method, a high-density indium oxide-tin oxide sintered body having a relative density of 99.2 to 99.6% can be obtained.

  However, a sintered body having a higher density than this sintered density has been demanded, and in order to solve this problem, the need for indium oxide powder having a narrower particle size distribution has been increased. It was. According to the results of the present inventors' previous studies, the particle size distribution of indium oxide powder is almost equal to the particle size distribution of indium hydroxide powder. It is possible to control the width of the particle size distribution.

Further, in Patent Document 2, as a method of narrowing the particle size distribution of indium hydroxide powder, an aqueous solution of indium salt and a basic aqueous solution are mixed by neutralization to bring the pH to 7 or higher, and then ripened and filtered. By calcining acicular indium hydroxide obtained by a drying treatment, the BET specific surface area is 15 to 30 m ² / g, the ratio of the BET diameter to the crystallite diameter is 2 or less, and the primary obtained by particle size distribution measurement It is described that an indium oxide powder having an average particle diameter of 0.1 μm or less is obtained. However, by using this indium oxide powder, only a target having an ITO target density of 6.0 g / cm ³ and a relative density of 84% or more has been obtained. For this reason, the manufacturing method of the indium oxide powder from which a further high-density sintered compact is obtained is desired.

In Patent Document 3, a method of hydrothermally treating an acidic solution or an alkaline solution having a pH of 2 or more and 6 or less mixed with indium hydroxide under conditions of a pressure of ^{2 to} 150 kgf / cm ² and a temperature of 80 to 300 ° C. Has been proposed. However, this method increases costs due to the necessity of dedicated equipment such as an autoclave. Furthermore, in Patent Document 3, there is a problem that the processing amount per batch is limited due to problems such as container size.

JP 2014-74224 A JP-A-5-193939 Japanese Patent Laid-Open No. 10-17324

Therefore, the present invention has been proposed in view of such circumstances, and indium hydroxide powder that is difficult to agglomerate, has excellent particle size uniformity, and can provide indium hydroxide powder with a narrow particle size distribution width. the method of manufacturing, and the resulting superior to the uniformity of using the indium hydroxide powder, method for producing an indium oxide powder width of the particle size distribution to obtain a narrow indium oxide powder and the manufacture of sputtering targets with indium oxide powder It aims to provide a method .

A method for producing indium hydroxide powder according to one embodiment of the present invention that achieves the above-described object is a method for producing indium hydroxide powder by electrolytic reaction using an anode containing indium in an aqueous ammonium nitrate solution as an electrolytic solution. A production method for producing an electrolytic slurry containing indium hydroxide powder by electrolysis for a predetermined time in a pH range of 2.5 to 4.0 and a liquid temperature of 20 ° C. to 60 ° C. The electrolytic slurry has a pH of 2.5 to 4.0, a liquid temperature of 20 ° C. to 60 ° C., and a holding time in the range of 3 hours to 24 hours to dissolve and recrystallize the electrolytic slurry. And a crystallization process, wherein the solid content concentration of the electrolytic slurry in the production process is controlled to 5 wt% or more and 20 wt% or less .

  At this time, according to one embodiment of the present invention, in the generation step, it is preferable to perform electrolysis in a predetermined time of at least 3 hours or more.

  At this time, according to one embodiment of the present invention, it is preferable that the electrolytic slurry is changed from the saturated state to the supersaturated state a plurality of times within the holding time in the dissolution and recrystallization step.

Moreover, in the manufacturing method of the indium oxide powder which concerns on the other aspect of this invention, manufacture of the indium oxide powder which calcines the indium hydroxide powder obtained by the manufacturing method of the indium hydroxide powder mentioned above, and obtains an indium oxide powder The method is characterized in that the difference between the maximum value and the minimum value of the particle size distribution of the indium hydroxide powder is 0.7 μm or less, and the calcination is performed at 600 ° C. to 800 ° C. for 1 hour to 10 hours .

Furthermore, the sputtering target manufacturing method according to another aspect of the present invention is a sputtering target manufacturing method, wherein the indium oxide powder obtained by the above-described indium oxide powder manufacturing method and tin oxide powder are in a predetermined ratio. The granulated powder obtained by mixing is molded by a cold press method, and the molded body obtained by molding is sintered at 1300 ° C. to 1600 ° C. under atmospheric pressure. Sintering obtained by sintering It is characterized by polishing the plane and side surfaces of the body .

  In the present invention, it is possible to produce indium hydroxide powder having a narrow particle size distribution.

  In the present invention, it is also possible to produce indium oxide powder with good dispersibility in which the width of the particle size distribution is narrow and the specific surface area is controlled by using the indium hydroxide powder having a narrow particle size distribution.

  Furthermore, in this invention, if such an indium oxide powder is used, it becomes possible to produce a sputtering target with a high relative density of the sintered body.

It is a flowchart which shows the manufacturing method of the indium oxide powder to which this invention is applied.

Below, the manufacturing method of the indium hydroxide powder and indium oxide powder to which this invention is applied, and the sputtering target using the indium oxide powder obtained by this manufacturing method are demonstrated. Note that the present invention is not limited to the following detailed description unless otherwise specified. An embodiment of a method for producing indium hydroxide powder and indium oxide powder to which the present invention is applied and a method for producing a sputtering target 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. Dissolution and recrystallization process of indium hydroxide powder 1-3. Recovery process of indium hydroxide powder 1-4. Indium hydroxide powder drying step 1-5. 1. Production process of indium oxide powder Manufacturing method of sputtering target

1. Indium Oxide Powder Manufacturing Method As shown in FIG. 1, the indium oxide powder manufacturing method according to the present embodiment includes an indium hydroxide powder generating step S1 (hereinafter referred to as “generation”). And the indium hydroxide powder dissolution and recrystallization step S2 (hereinafter also referred to as “dissolution and recrystallization step”) for dissolving and recrystallizing the produced indium hydroxide powder. Indium hydroxide powder recovery step S3 for recovering dissolved and recrystallized indium hydroxide powder (hereinafter also referred to as “recovery step”), and indium hydroxide powder for drying the recovered indium hydroxide powder A drying step S4 (hereinafter also referred to as a “drying step”) and an indium oxide powder generating step S5 for calcining the dried indium hydroxide powder to obtain indium oxide powder.

(1-1) Production process of indium hydroxide powder In the production process S1, an anode containing indium and a cathode are immersed in an electrolytic solution, and indium hydroxide powder is produced by an electrolytic reaction.

  Metal indium is used for the anode. The metal indium to be used is not particularly limited, but it is desirable that the metal indium has a high purity in order to suppress the mixing of impurities into the indium hydroxide powder and the indium oxide powder obtained by firing the indium hydroxide powder. As metal indium, a purity of 99.999% (commonly called 5N product) or more can be mentioned as a suitable product.

  For the cathode, a conductive metal, stainless steel, carbon electrode, or the like is used. For example, insoluble titanium or platinum can be used, and titanium may be coated with platinum. Alternatively, the same material as the anode may be used.

  The distance between the anode and the cathode is not particularly specified, but is preferably 10 mm to 50 mm. If the distance between the anode and the cathode is greater than 50 mm, a voltage drop due to the liquid resistance occurs, which increases the liquid temperature, which is not preferable. Further, when the distance between the electrodes between the anode (hereinafter also referred to as “anode”) and the cathode (hereinafter also referred to as “cathode”) becomes narrower than 10 mm, contact / short circuit between the electrodes is likely to occur. It is not preferable.

  Indium hydroxide powder is obtained using an electrolytic reaction. In the production method of indium hydroxide powder, first, a production step of obtaining an electrolytic solution containing indium hydroxide powder (hereinafter also referred to as “electrolytic slurry”) is performed. In the production process, indium metal is used as an anode, a conductive metal or carbon electrode is used for the cathode of the counter electrode, the anode and cathode are immersed in an electrolytic solution, and an electric current is passed between both electrodes to dissolve the anode metal, Indium oxide powder crystallizes to obtain an electrolytic slurry made of an electrolytic solution containing indium hydroxide powder.

  In the production step S1, an aqueous solution of a general electrolyte salt such as a water-soluble nitrate, sulfate, or chloride salt can be used as the electrolyte. Among them, an ammonium nitrate aqueous solution is used in the generation process. Ammonium nitrate aqueous solution, after drying indium hydroxide powder, drying and calcining, nitrate ions and ammonium ions are removed as nitrogen compounds and do not remain as impurities, increase the purity of the indium hydroxide powder produced and Can be reduced.

  In the production method of indium hydroxide powder according to the present embodiment, in the production step S1, the electrolytic solution is electrolyzed for a predetermined time in the range of pH of 2.5 to 4.0 and liquid temperature of 20 ° C to 60 ° C. An electrolytic slurry is prepared.

In the production step S1, the pH of the electrolytic solution is controlled in the range of 2.5 to 4.0. When the pH of the electrolytic solution is smaller than 2.5, the solubility of the indium hydroxide powder in the electrolytic solution is 10 ⁻³ mol / L or more, and the precipitation of hydroxide is difficult to occur. In addition, when the pH of the electrolytic solution is greater than 4.0, the solubility of the indium hydroxide powder in the electrolytic solution is 10 ⁻⁶ mol / L or less, so the width of the particle size distribution of the indium hydroxide powder is It spreads.

In production | generation process S1, the liquid temperature of electrolyte solution is controlled by the range of 20 to 60 degreeC. When the temperature of the electrolytic solution is lower than 20 ° C., the solubility of indium hydroxide powder in the electrolytic solution becomes 10 ⁻⁶ mol / L or less, which is not preferable. On the other hand, when the liquid temperature of the electrolytic solution is higher than 60 ° C., the solubility of the indium hydroxide powder in the electrolytic solution becomes 10 ⁻³ mol / L or more, thereby widening the width of the particle size distribution.

  In the production step S1, a predetermined time for electrolysis (hereinafter also referred to as “electrolytic energization time”) is preferably at least 3 hours. Specifically, the electrolysis energization time is 3 hours to 24 hours, and the particle size of the indium hydroxide powder can be made uniform. When the electrolysis energization time is shorter than 3 hours, the primary particle size is not sufficiently grown due to the lack of electrolysis energization time, and in the dissolution and recrystallization step S2, which is the next step, the indium hydroxide powder into the electrolyte solution Dissolution increases and particle size becomes smaller and non-uniform. On the other hand, when the electrolysis energization time is longer than 24 hours, it is not preferable from the viewpoint of production cost.

In production | generation process S1, it is preferable to adjust electrolyte solution so that the solubility of the produced | generated indium hydroxide powder may be 10 < ^-6 > mol / L-10 < ^-3 > mol / L. In the production step S1, the growth of primary particles of the indium hydroxide powder is moderately promoted by setting the solubility of the produced indium hydroxide powder within the range of 10 ⁻⁶ mol / L to 10 ⁻³ mol / L. The Thereby, in production | generation process S1, since aggregation of a primary particle is suppressed, the width | variety of a particle size distribution does not become wide, but the width | variety of a particle size distribution is narrow and the indium hydroxide powder with a uniform particle size can be obtained.

When the solubility of the indium hydroxide powder is less than 10 ⁻⁶ mol / L, the metal ions dissolved from the anode are easily nucleated, so that the primary particle diameter becomes too fine. In that case, it becomes difficult to separate and recover the indium hydroxide powder later.

On the other hand, when the solubility of the indium hydroxide powder exceeds 10 ⁻³ mol / L, the primary particle diameter increases due to the promotion of particle growth. The difference in particle size increases. Since the difference in particle diameter affects the degree of aggregation, as a result, the width of the particle size distribution of the indium hydroxide powder becomes wide. When the width of the particle size distribution of the indium hydroxide powder is widened, the width of the particle size distribution of the indium oxide powder obtained by calcining these is also widened. Absent.

  In production | generation process S1, it is preferable that the density | concentration of ammonium nitrate aqueous solution which is electrolyte solution is controlled by 0.1 mol / L-2.0 mol / L. If the concentration of the ammonium nitrate aqueous solution is less than 0.1 mol / L, the voltage rise during electrolysis is increased, and problems such as heating of the energizing part and an increase in power cost are undesirable. When the concentration of the ammonium nitrate aqueous solution is higher than 2.0 mol / L, the solubility of indium hydroxide in the electrolytic solution is increased, so that the indium hydroxide particles are coarsened and the variation in particle size is increased.

In the production step S1, the current density during electrolysis is preferably 4 A / dm ^{2 to} 20 A / dm ^{2, and} can be a wide range of current densities. When the current density during electrolysis is lower than 4 A / dm ² , the production efficiency of indium hydroxide powder is lowered. On the other hand, when the current density during electrolysis exceeds 20 A / dm ² , problems such as an increase in the electrolytic solution and passivation on the surface of the anode (metal indium), which makes electrolysis difficult, are not preferable.

  In production | generation process S1, it is preferable that the solid content concentration of the electrolysis slurry after electrolysis is 5 to 20 weight%. When the solid content concentration of the electrolytic slurry is less than 5% by weight, dissolution is promoted and the particle size becomes minute. On the other hand, when the solid content concentration of the electrolytic slurry is larger than 20% by weight, crystal growth does not proceed, and as a result, the width of the particle size distribution is widened. The solid content concentration of the electrolytic slurry can be adjusted by the total amount of the electrolytic solution and the electrolysis energization time.

  In addition, solid content concentration (weight%) of the electrolysis slurry after electrolysis means the ratio of the weight of the indium hydroxide powder obtained by drying the electrolysis slurry with respect to the weight of electrolyte solution slurry.

  In the production step S1, an electrolytic slurry is obtained after the electrolysis is completed.

(1-2) Indium hydroxide powder dissolution and recrystallization step In the dissolution and recrystallization step S2, the indium hydroxide powder produced in the indium hydroxide powder production step S1 is not subjected to solid-liquid separation, but after electrolysis. The electrolytic slurry is dissolved and recrystallized under predetermined conditions.

  In the method for producing indium hydroxide powder according to the present embodiment, the pH of the electrolytic slurry is 2.5 to 4.0, the liquid temperature is 20 ° C. to 60 ° C., and the holding time is 3 in the dissolution and recrystallization step S2. The electrolytic slurry is dissolved and recrystallized by stirring in the range of time to 24 hours. Thereby, the width | variety of the particle size distribution of the indium hydroxide powder obtained by drying process S4 mentioned later becomes narrow because the indium hydroxide powder produced | generated by production | generation process S1 raise | generates and recrystallizes.

  In the dissolution and recrystallization step S2, the pH of the electrolytic slurry is controlled to 2.5 to 4.0. When the pH of the electrolytic slurry is less than 2.5, the amount of dissolved indium hydroxide powder increases, and the yield decreases. On the contrary, when the pH of the electrolytic slurry is higher than 4.0, the amount of indium hydroxide dissolved is lowered, and the uniformity of the particle size distribution is not improved.

  In the dissolution and recrystallization step S2, the liquid temperature of the electrolytic slurry is controlled to 20 ° C to 60 ° C. When the liquid temperature of the electrolytic slurry is lower than 20 ° C., not only the solubility of the indium hydroxide powder is lowered and the uniformity of the particle size distribution is not improved, but also the cost for controlling the liquid temperature is increased. On the other hand, when the temperature of the electrolytic slurry is higher than 60 ° C., not only does the amount of indium hydroxide powder dissolve and the yield decreases, but the crystal state of indium hydroxide grown by recrystallization changes. The width of the particle size distribution becomes wide due to the aggregation of the crystals of indium hydroxide.

  Next, the mechanism of dissolution and recrystallization in the dissolution and recrystallization step S2 will be described. In the dissolution and recrystallization step S2, the electrolytic slurry is stirred under the above-described conditions of pH and liquid temperature, so that the indium hydroxide powder is dissolved in the saturated electrolytic slurry, thereby obtaining a supersaturated electrolytic slurry. . In the dissolution and recrystallization step S2, indium hydroxide crystals are precipitated because the supersaturated electrolytic slurry returns to the saturated electrolytic slurry. Thereafter, in the dissolution and recrystallization step S2, the change of the electrolytic slurry from the saturated state to the supersaturated state is repeated a plurality of times within the holding time.

  Thereby, dissolution and precipitation of indium hydroxide crystals are repeated a plurality of times. As a result, in the method for producing indium hydroxide powder according to the present embodiment, indium hydroxide powder having a narrow particle size distribution can be produced.

  In the dissolution and recrystallization step S2, the holding time is agitated in the range of 3 hours to 24 hours. Here, the holding time refers to the time for maintaining the above-described pH and liquid temperature while stirring the electrolytic slurry in the dissolution and recrystallization step S2.

  This holding time can be arbitrarily set according to the width of the required particle size distribution of the indium hydroxide powder. In the dissolution and recrystallization step S2, the width of the particle size distribution of the indium hydroxide powder becomes narrower as the dissolution and recrystallization time becomes longer.

  However, when the holding time is less than 3 hours, the holding time for dissolution and recrystallization is too short, so the width of the particle size distribution of the indium hydroxide powder does not change. On the other hand, when the holding time is longer than 24 hours, no further effect can be obtained even if dissolution and recrystallization are performed, and costs are wasted.

  In the dissolution and recrystallization step S2, after completion of the dissolution and recrystallization, a slurry containing indium hydroxide powder having a narrow particle size distribution (hereinafter also referred to as “dissolution and recrystallization slurry”) is obtained. .

(1-3) Recovery process of indium hydroxide powder The recovery process S3 solid-liquid separates the indium hydroxide powder contained in the dissolution and recrystallization slurry generated in the dissolution and recrystallization process S2 from the electrolytic solution, The separated indium hydroxide powder is washed with pure water, and again solid-liquid separated and recovered.

  In the recovery step S3, solid-liquid separation is performed in a state where the pH of the dissolved and recrystallized slurry is in the range of 5.0 to 9.0. When the pH of the dissolution and recrystallization slurry before solid-liquid separation is not within the range of 5.0 to 9.0, the pH is adjusted.

  When the pH of the dissolved and recrystallized slurry is lower than 5.0 during solid-liquid separation, the generated precipitated particles are positively charged and repelled and dispersed, and the particle size is too small. Filtration is difficult and not preferred. Moreover, since remelting of indium may occur, it is not preferable. If the pH of the dissolved and recrystallized slurry is higher than 9.0, it is not preferable because repulsion due to negative charge occurs on the contrary and the repulsion occurs and the particle size becomes too small and filtration becomes difficult. Therefore, in the solid-liquid separation, the indium hydroxide powder is aggregated to some extent by setting the pH of the dissolved and recrystallized slurry within the range of 5.0 to 9.0. Thereby, the fine indium hydroxide powder does not pass through the filter medium and can be easily filtered.

  Ammonia water is preferably used for adjusting the pH of the electrolytic solution, and a primary alkylamine aqueous solution such as methylamine or ethylamine can also be used. The time until the filtration after adding these alkaline aqueous solutions may be arbitrary, and if stirring is sufficient, the filtration may be started immediately.

  Then, solid-liquid separation is performed in a state where the pH of the dissolved and recrystallized slurry is in the range of 5.0 to 9.0. Examples of the solid-liquid separation method include filtration by a rotary filter, centrifugation, filter press, pressure filtration, vacuum filtration, crossflow filtration, and the like, and among these, crossflow filtration is preferable.

  For the filtration, there is a method of finely pulverizing cake filtration. In this cake filtration, filtration progresses with a filtration deposit as an appropriate filter medium. However, when the cake layer is thick, there is a disadvantage that the filtration time of the slurry is increased in inverse proportion to the thickness of the cake layer. On the other hand, in the cross flow method, the cake layer is scraped at a constant thickness, so that the cake layer can be kept at a thin constant thickness by this scavenging effect. Thereby, the filtration resistance becomes substantially constant, and a constant filtration time can be maintained over a long time.

  Since the indium hydroxide powder after filtration is accompanied by ammonium nitrate, which is an impurity, in proportion to the amount of water, washing is necessary.

  As the cleaning method, for example, there are circulating cleaning by continuous pressure cross flow and water redispersion filtration method. Circulating washing is a method of gradually washing by returning the filtrate to the electrolytic slurry and adding the filtered water. The water redispersion filtration method is a method in which a filtered cake is once redispersed with water and filtered.

  Circulating washing has the advantage that the operation is simple, but has the disadvantage that the amount of waste water is large. The water redispersion filtration method has the merit of requiring a relatively small amount of waste liquid, although it takes time for redispersion. You can choose according to the situation.

  An example of the cross-flow filtration device is a rotary filter (manufactured by Kotobuki Industries Co., Ltd.).

  In the recovery step S3, indium hydroxide powder is recovered after solid-liquid separation.

(1-4) Indium hydroxide powder drying step In the drying step S4, the indium hydroxide powder recovered in the recovery step S3 is dried under predetermined conditions.

  In drying process S4, although it does not specifically limit as a drying method, For example, it performs with drying machines, such as a spray dryer, an air convection type drying furnace, an infrared drying furnace.

  In drying process S4, it will not specifically limit if the water | moisture content of indium hydroxide powder can be removed as drying conditions, For example, the range of 80 to 150 degreeC is preferable for drying temperature. When the drying temperature is lower than 80 ° C., drying becomes insufficient. On the other hand, when the drying temperature is higher than 150 ° C., the indium hydroxide changes to indium oxide, which is inconvenient in adjusting the particle size distribution of the indium oxide powder in the next step, the indium oxide powder generation step S5.

  Moreover, in drying process S4, although drying time changes with the drying temperature mentioned above, it is about 10 hours-24 hours.

  As described above, in the method for producing indium hydroxide powder having the indium hydroxide powder production step S1, the dissolution and recrystallization step S2, the recovery step S3, and the drying step S4, the pH of the electrolytic solution is 2.5-4. 0.0. Electrolysis slurry was prepared by electrolysis for a predetermined time in a liquid temperature range of 20 ° C to 60 ° C, and then the pH of the electrolytic slurry was 2.5 to 4.0, and the liquid temperature was maintained at 20 ° C to 60 ° C. The electrolytic slurry is dissolved and recrystallized by stirring for a time ranging from 3 hours to 24 hours. Thereby, in the method for producing indium hydroxide powder according to the present embodiment, indium hydroxide powder having a narrow particle size distribution can be produced.

  Moreover, in the manufacturing method of the indium hydroxide powder which concerns on this Embodiment, an electrolysis slurry after electrolysis is melt | dissolved and recrystallized on predetermined conditions, and a special installation is not required.

  Furthermore, in the method for producing indium hydroxide powder according to the present embodiment, since the particle diameter of indium hydroxide powder is uniform, after calcination, high dispersion is expressed in the conductive paste, transparent conductive film paint, etc. An indium hydroxide powder exhibiting high density can be obtained as a target material for producing a transparent conductive thin film.

(1-5) Production process of indium oxide powder In the production process S5 of indium oxide powder, the indium hydroxide powder after drying in the drying process S4 is calcined to produce indium oxide powder. The calcination conditions are appropriately determined. For example, the calcination temperature is preferably 600 to 800 ° C., and the calcination time is preferably 1 to 10 hours.

When the calcining temperature is lower than 600 ° C., the BET value of the indium oxide powder exceeds 15 m ² / g, and the primary particles are too small, so that the powder has cohesive properties. Thereby, with the obtained indium oxide powder, a high-density sintered material, for example, indium tin oxide (ITO) sintered material cannot be obtained. When the calcination temperature is higher than 800 ° C., the BET value of the indium oxide powder is less than 10 m ² / g, the primary particle diameter is increased, and the voids generated between the particles are increased, so that the sinterability is lowered. Thereby, with the obtained indium oxide powder, a high-density sintered material cannot be obtained. Therefore, in order to obtain a high-density sintered material, it is preferable to set the calcining temperature in the range of 600 ° C to 800 ° C.

The obtained indium oxide powder has a BET value of specific surface area is controlled within a range of ^{10m 2} / ^g~15m 2 / g, cumulative particle size of 10% the diameter of the particle size distribution (D10) is 0.3μm or more, cumulative The 90% particle size (D90) is 1.1 μm or less. The difference between the absolute values of the 90% cumulative particle size (D90) and the 10% cumulative particle size (D10) is 0.4 μm or more and 0.7 μm or less. Such indium oxide powder has a controlled specific surface area, good dispersibility, and little aggregation, so that a high-density sintered material can be produced.

  In addition, in the production | generation process S5 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 this indium oxide powder production | generation process S5, when ammonium nitrate aqueous solution is used for electrolyte solution in the case of electrolysis of indium hydroxide powder, decomposition | disassembly of ammonium nitrate arises and it can prevent mixing in indium oxide powder.

  As described above, in the method for producing indium oxide powder, in which an indium hydroxide powder is obtained by an electrolytic reaction using an anode containing indium, the pH of the electrolyte is 2.5 to 4.0, and the temperature of the solution is 20 ° C. to 60 ° C. In this range, after electrolysis for a predetermined time to prepare an electrolytic slurry, the electrolytic slurry has a pH of 2.5 to 4.0, a liquid temperature of 20 ° C. to 60 ° C., and a holding time of 3 hours to 24 hours. Then, the electrolytic slurry is dissolved and recrystallized. Thereby, in the manufacturing method of the indium oxide powder which concerns on this Embodiment, the dispersible indium oxide powder with which the specific surface area was controlled can be produced.

2. Sputtering target manufacturing method The sputtering target manufacturing method is as follows. First, indium oxide powder obtained by the above-described indium oxide powder manufacturing method is mixed with other raw materials of the target such as tin oxide powder in a predetermined ratio, and granulated powder. Is made. Next, a molded body is produced by using, for example, a code 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, the 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, the specific surface area of the indium oxide powder as a raw material is controlled and the dispersibility is good, so that a high-density sintered body can be obtained and the density of the sputtering target is increased. I can. Thereby, a crack target does not arise in a sputtering target during a process, but it can also suppress that abnormal discharge generate | occur | produces in the case of sputtering.

  As described above, in the sputtering target manufacturing method, a high-density sintered body can be obtained by using the above-described indium oxide powder.

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

<Example 1>
In the electrolytic cell (length 50 cm × width 40 cm × height 50 cm), four cathodes made of a titanium metal plate having a width of 26 cm, a height of 40 cm and a thickness of 4 mm, and indium metal having a purity of 99.999%, a height of 26 cm, Three anodes molded into a plate shape having a thickness of 40 cm and a thickness of 8 mm were alternately arranged, and a solution containing 90 L of 1.0 mol / L ammonium nitrate aqueous solution prepared at a liquid temperature of 40 ° C. adjusted to pH 3.5 was prepared. The distance between the cathode and the anode was adjusted to 2.0 cm. In the production step, the anode current density was adjusted to 15 A / dm ² (battery current 936 A), and was carried out for 6 hours.

  In Example 1, after completion of electrolysis in the production step, an electrolytic slurry was collected from the electrolytic cell, and the solid content concentration of the indium hydroxide powder was measured.

  In the dissolution and recrystallization step, after completion of electrolysis in the production step, the electrolyte solution in which the indium hydroxide powder was deposited was dissolved and recrystallized with stirring at pH 2.5 and a liquid temperature of 20 ° C. for 16 hours. Thereafter, in the recovery step, filtration and washing were performed twice. In the drying step, indium hydroxide powder was obtained by drying at 110 ° C. for 15 hours. In the production process of indium oxide powder, the obtained indium hydroxide powder was calcined at 750 ° C. for 4 hours to obtain indium oxide powder. In Example 1, the particle size distribution of the obtained indium hydroxide powder and indium oxide powder was measured using a laser diffraction particle size distribution analyzer (SALD-2200, manufactured by Shimadzu Corporation).

  Moreover, in Example 1, the specific surface area of the indium oxide powder was measured as a BET value (gas adsorption method) using a specific surface area measurement device (product name: macsorb 1210, manufactured by Mountec Co., Ltd.).

  In Example 1, 967 g of the obtained indium oxide powder was mixed with 33 g of tin oxide powder, and then a molded body was obtained by a cold press method and sintered at 1400 ° C. for 30 hours under atmospheric pressure. A ligature was prepared. The relative density of the sintered body was measured by the Archimedes method.

<Examples 2 to 8>
In Examples 2 to 8, electrolytic slurry was produced in the same manner as in Example 1 for electrolysis conditions. In Examples 2 to 8, the conditions of the electrolytic slurry dissolution and recrystallization steps obtained in each Example were adjusted as shown in Table 1 to produce indium hydroxide powder and indium oxide powder. Further, in Examples 2 to 8, sintered bodies were produced in the same manner as in Example 1 except that the indium oxide powder obtained in each Example was used.

<Examples 9 and 10>
In Examples 9 and 10, the electrolysis slurry was produced by adjusting the electrolysis time in the production process so that the solid content concentration of the electrolysis slurry after electrolysis was a value shown in Table 1. In Examples 9 and 10, the conditions of the dissolution and recrystallization process of the electrolytic slurry obtained in each Example were adjusted as shown in Table 1 to produce indium hydroxide powder and indium oxide powder. Further, in Examples 9 and 10, sintered bodies were produced in the same manner as in Example 1 except that the indium oxide powder obtained in each Example was used.

  Hereinafter, for Examples 1 to 10, the particle size distribution of indium hydroxide powder and the ratio based on Comparative Example 1 are shown in Table 1. Here, the ratio (%) based on Comparative Example 1 is the ratio of the indium hydroxide powder after electrolysis in Comparative Example 1 to the recovery rate of indium hydroxide powder after electrolysis in each of Examples 1 to 10. The percentage calculated when the recovery rate is used as a reference. Moreover, about Example 1 thru | or 10, the particle size distribution and BET value of indium oxide powder, and the relative density of the sintered compact were shown in Table 1.

<Comparative Examples 1 to 7>
In Comparative Examples 1 to 7, electrolytic slurry was produced in the same electrolytic conditions as in Example 1. In Comparative Example 1, as shown in Table 1, indium hydroxide powder and indium oxide powder were prepared in the same manner as in Example 1 except that the dissolution and recrystallization steps were not performed. In Comparative Examples 2 to 7, the conditions of the electrolytic slurry dissolution and recrystallization process obtained in each Comparative Example were adjusted as shown in Table 1 to produce indium hydroxide powder and indium oxide powder. Further, in Comparative Examples 1 to 7, sintered bodies were produced in the same manner as in Example 1 except that the indium oxide powder obtained in each Comparative Example was used.

<Comparative Examples 8 and 9>
In Comparative Examples 8 and 9, the electrolytic slurry was prepared by adjusting the electrolysis time in the production step so that the solid content concentration of the electrolytic slurry after electrolysis would be the value shown in Table 1. In Comparative Examples 8 and 9, the conditions of the electrolytic slurry dissolution and recrystallization steps obtained in each Comparative Example were adjusted as shown in Table 1 to produce indium hydroxide powder and indium oxide powder. Further, in Comparative Examples 8 and 9, sintered bodies were produced in the same manner as in Example 1 except that the indium oxide powder obtained in each Comparative Example was used.

  Hereinafter, for Comparative Examples 1 to 9, the particle size distribution of the indium hydroxide powder and the ratio based on Comparative Example 1 are shown in Table 1. The ratio (%) based on Comparative Example 1 is the recovery rate of indium hydroxide powder after electrolysis in Comparative Example 1 with respect to the recovery rate of indium hydroxide powder after electrolysis in Comparative Examples 2 to 9. The percentage calculated when the rate is used as a reference. For Comparative Examples 1 to 9, the particle size distribution and BET value of indium oxide powder and the relative density of the sintered body are shown in Table 1.

In Examples 1 to 10, as shown in Table 1, using the resulting indium hydroxide powder, after calcination, in the range BET value is ^{10m 2} / ^g~15m 2 / g, particle size distribution 0. An indium oxide powder having a width of 3 μm or more and 1.1 μm or less and a narrow particle size distribution was obtained.

On the other hand, in Comparative Examples 1 to 9, in the range BET value is ^{10m 2} / ^g~15m 2 / g, the width of the particle size distribution the particle size distribution is 0.3μm or more 1.1μm or less narrow indium oxide powder obtained I couldn't.

  In Examples 1 to 10, the relative density of the sintered body exceeded 99.0%, and the relative density of the sintered body was extremely high compared to Comparative Examples 1 to 9.

  As mentioned above, it is a manufacturing method of indium hydroxide powder which obtains indium hydroxide powder by electrolytic reaction using an anode containing indium in an ammonium nitrate aqueous solution as an electrolytic solution, and the pH of the electrolytic solution is 2.5 to 4.0, After the electrolytic temperature is electrolyzed for a predetermined time in a liquid temperature range of 20 ° C to 60 ° C, the electrolytic slurry has a pH of 2.5 to 4.0, a liquid temperature of 20 ° C to 60 ° C, and a holding time of 3 It was confirmed that indium hydroxide powder having a narrow particle size distribution width was obtained by stirring and dissolving and recrystallizing in the range of time to 24 hours. It was also confirmed that by using the indium hydroxide powder, the specific surface area was controlled and indium oxide powder with good dispersibility was obtained. It was also confirmed that a high-density sintered body was obtained by using the indium oxide powder.

Claims (5)

A method for producing indium hydroxide powder by obtaining an indium hydroxide powder by an electrolytic reaction using an anode containing indium in an aqueous ammonium nitrate solution as an electrolytic solution,
A production step of producing an electrolytic slurry containing indium hydroxide powder by electrolysis for a predetermined time in a pH range of 2.5 to 4.0 and a liquid temperature of 20 ° C. to 60 ° C.
The electrolytic slurry having a pH of 2.5 to 4.0, a liquid temperature of 20 ° C. to 60 ° C., and a holding time of 3 hours to 24 hours are stirred to dissolve and recrystallize the electrolytic slurry. A recrystallization step ,
The method for producing indium hydroxide powder, wherein the solid content concentration of the electrolytic slurry in the generating step is controlled to 5 wt% or more and 20 wt% or less . In the above generation method of manufacturing an indium hydroxide powder according to claim 1, characterized in that the predetermined time is electrolyzed in at least 3 hours or more. 3. The indium hydroxide according to claim 1, wherein in the dissolution and recrystallization step, the electrolytic slurry is changed from a saturated state to a supersaturated state a plurality of times within the holding time. Powder manufacturing method. A method for producing indium oxide powder, wherein the indium hydroxide powder obtained by the method for producing indium hydroxide powder according to any one of claims 1 to 3 is calcined to obtain indium oxide powder ,
The difference between the maximum value and the minimum value of the particle size distribution of the indium hydroxide powder is 0.7 μm or less,
A method for producing indium oxide powder, wherein the calcining is performed at 600 ° C to 800 ° C for 1 hour to 10 hours . A method for producing a sputtering target, comprising:
Indium oxide powder obtained by the method for producing indium oxide powder according to claim 4 and tin oxide powder are mixed at a predetermined ratio,
The granulated powder obtained by the above mixing is molded by a cold press method,
The molded body obtained by the above molding is sintered at 1300 ° C. to 1600 ° C. under atmospheric pressure,
A method for producing a sputtering target, comprising polishing a flat surface and a side surface of a sintered body obtained by the sintering.

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