KR102068832B1 - Indium hydroxide powder and indium oxide powder - Google Patents

Abstract

A high density sintered compact is obtained. The orientation index of the (200) plane and the (400) plane obtained from the Wilson equation is 2.0 or more, and the orientation index of the (442) plane is 0.5 or less, respectively, and the (400) plane's orientation index with respect to the (200) plane's orientation index. The indium oxide powder obtained by calcining the indium hydroxide powder whose ratio is 1.5 or more and the diffraction peaks of the (220) plane and the (420) plane is not shown is used.

Description

Indium hydroxide powder and indium oxide powder {INDIUM HYDROXIDE POWDER AND INDIUM OXIDE POWDER}

The present invention relates to an indium hydroxide powder and an indium oxide powder capable of producing a high density indium tin oxide sputtering target (ITO sputtering target). In addition, this application claims the priority based on Japanese Patent Application No. 2014-47507 for which it applied on March 11, 2014 in Japan, This application is referred to, and it uses for this application.

In recent years, the use of a transparent conductive film is increasing as a solar cell use and a touch panel use, and the demand of transparent conductive film formation materials, such as a sputtering target, has increased accordingly. Indium oxide type sintered materials are mainly used for these transparent conductive film formation materials, and indium oxide powder is used as the main raw material. It is preferable that the indium oxide powder used for the sputtering target has a specific surface area controlled as much as possible in order to obtain a high density target and have good dispersibility.

As a manufacturing method of an indium oxide powder, it manufactures mainly by the so-called neutralization method which dries and calcines the precipitate of indium hydroxide produced by neutralizing acidic aqueous solutions, such as aqueous solution of indium nitrate and aqueous solution of indium chloride, with alkaline aqueous solutions, such as aqueous ammonia.

In the neutralization method, in order to suppress aggregation of indium oxide powder, a method of obtaining acicular indium hydroxide powder by adding alkali to a high temperature indium nitrate aqueous solution at 70 to 95 ° C (for example, a patent) is proposed. See Document 1). In this method, the indium oxide powder with little aggregation can be obtained by calcining the acicular indium hydroxide powder.

However, the indium oxide powder produced by the neutralization method tends to be uneven in particle diameter and particle size distribution, and when the sputtering target is produced, the density of the target does not increase, and the problem of unevenness in density or abnormality during sputtering The problem that discharge is easy to occur arises. Moreover, in the neutralization method, since a large amount of nitrogen drainage occurs after the production of indium oxide powder, there is a problem that the drainage treatment cost increases.

As a method of improving such a problem, a method of producing a precipitate of indium hydroxide by electrolytically treating metal indium and calcining it to produce an indium oxide powder, a so-called electrolytic method, has been proposed (see Patent Document 2, for example). In the electrolytic method, compared with the neutralization method, the amount of nitrogen drainage after the production of the indium oxide powder can be significantly reduced, and the particle diameter of the indium oxide powder obtained can be made uniform.

However, the indium hydroxide powder obtained by the electrolytic method has a problem that the pH of the electrolytic solution is close to neutral and very fine and easily aggregated. The indium oxide powder obtained by calcining this has a relatively uniform primary particle diameter, but tends to be a cohesive powder in which these particles are strongly aggregated. Such indium oxide powder has a problem that the density of the target is inhibited because the width of the particle size distribution becomes wider by aggregation.

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

Then, this invention is proposed in view of such a situation, and an object of this invention is to provide the indium hydroxide powder which can obtain a high density sintered compact, and the indium oxide powder obtained by calcining it.

The indium hydroxide powder according to the present invention which achieves the above-mentioned object has an orientation index of (200) plane and (400) plane of 2.0 or more, and an orientation index of (442) plane of 0.5 or less, respectively, obtained from the Wilson equation. The ratio of the orientation index of the (400) plane to the orientation index of the (200) plane is 1.5 or more, and has no diffraction peaks of the (220) plane and the (420) plane.

Indium oxide powder according to the present invention for achieving the above object has a BET value of 10 to 15 m 2 / g, the cumulative particle size 10% diameter (D10) of the particle size distribution is 0.2 ㎛ or more, the cumulative particle size 90% diameter (D90) It is characterized by being 2.7 micrometers or less.

In the present invention, it is obtained by calcining certain specific crystal planes, i.e., (200) planes, (400) planes and (442) planes, and calcining the highly crystalline indium hydroxide powder having a specific orientation index, and the specific surface area is controlled. It is an indium oxide powder with good dispersibility. Thereby, in this invention, the sintered compact with a high relative density can be obtained by using this indium oxide powder.

1 is a flowchart showing a method for producing an indium oxide powder to which the present invention is applied.

Below, the indium hydroxide powder and indium oxide powder to which this invention is applied are demonstrated. In addition, this invention is not limited to the following detailed description unless there is particular limitation. Embodiments of the indium hydroxide powder and the indium oxide powder to which the present invention is applied will be described in detail in the following order.

1. Manufacturing method of indium oxide powder

 1-1. Production Process of Indium Hydroxide Powder

 1-2. Recovery Process of Indium Hydroxide Powder

 1-3. Drying Process of Indium Hydroxide Powder

 1-4. Indium hydroxide powder

 1-5. Production Process of Indium Oxide Powder

 1-6. Indium oxide powder

2. Manufacturing method of sputtering target

1. Manufacturing method of indium oxide powder

As shown in FIG. 1, the production method of the indium oxide powder includes the production step S1 of the indium hydroxide powder which produces the indium hydroxide powder by the electrolytic method, the recovery step S2 of recovering the generated indium hydroxide powder, and the recovered It has drying process S3 which dries an indium hydroxide powder, and production process S4 of the indium oxide powder which calcinates dry indium hydroxide powder and obtains an indium oxide powder.

Indium hydroxide powder is produced by using an anode containing indium and an aqueous solution of ammonium nitrate in an electrolyte solution as described later, controlling the pH of the electrolyte solution to 2.5 to 4.0 and the liquid temperature so as to be in a range of 20 to 60 ° C. The crystal plane orientation obtained by the crystal is high in crystallinity oriented on the (200) plane, the (400) plane, and the (442) plane. The indium hydroxide powder has an orientation index of the (200) plane and the (400) plane, respectively, obtained from the Wilson formula being at least 2.0, orientated to the (400) plane first, and the (400) plane with respect to the orientation index of the (200) plane. The ratio of the orientation index of is 1.5 or more, the orientation index of the (442) plane is 0.5 or less, and it does not have the diffraction peaks of the (220) plane and the (420) plane. The indium oxide powder obtained by calcining such indium hydroxide powder has a specific surface area controlled and has good dispersibility.

(1-1) Formation Process of Indium Hydroxide Powder

In the production step S1 of the indium hydroxide powder, the positive electrode and the negative electrode containing indium are immersed in the electrolytic solution, and the indium hydroxide powder is produced by electrolytic reaction.

For example, metal indium or the like can be used for the anode, and in order to suppress the incorporation of impurities into the indium oxide powder, it is preferable that the purity is as high as possible. As the cathode, a conductive metal, a carbon electrode, or the like is used. For example, a coating of insoluble titanium with platinum can be used.

As electrolyte solution, the aqueous solution of general electrolyte salts, such as water-soluble nitrate, sulfate, chloride salt, can be used. Especially, when an ammonium nitrate aqueous solution is used, since nitrate ion and ammonium ion are removed as a nitrogen compound by calcination in the production process S4 of an indium oxide powder, mixing of an impurity component can be prevented. On the other hand, when ammonium chloride or ammonium sulfate is used as the electrolyte, impurity components such as chloride ions and sulfate ions are mixed. Therefore, it is preferable to use an ammonium nitrate aqueous solution for electrolyte solution.

It is preferable to make concentration of electrolyte solution into the range of 0.1-2.0 mol / L. If the concentration of the electrolyte solution is lower than 0.1 mol / L, the electrical conductivity of the electrolyte solution is lowered and the electrolytic voltage is increased, which is not preferable because problems such as heat generation of the current-carrying part and power cost increase. On the other hand, when the concentration of the electrolyte solution is higher than 2.0 mol / L, it is not preferable because the indium hydroxide powder produced by electrolysis becomes coarsened and the variation in the particle diameter becomes large. Therefore, it is preferable to make concentration of electrolyte solution into the range of 0.1-2.0 mol / L.

It is preferable to make pH of electrolyte solution into the range of pH2.5-4.0. When the electrolyte solution is higher than pH 4.0, the resulting indium hydroxide powder causes diffraction peaks on the (220) plane and the (420) plane other than the desired (200) plane, (400) plane and (442) plane. Such indium hydroxide powder is disturbed in crystallinity, the primary particle diameter becomes fine, becomes a powder having cohesiveness, and as a result, the width of the particle size distribution becomes wider. Moreover, when electrolyte solution is lower than pH2.5, indium of a metal will precipitate on a negative electrode, and the production efficiency of an indium hydroxide powder will fall. Therefore, it is preferable to make pH of electrolyte solution into the range of pH2.5-4.0.

As for the liquid temperature of electrolyte solution, the range of 20-60 degreeC is preferable. When the temperature of the electrolyte solution is lower than 20 ° C or higher than 60 ° C, diffraction peaks on the (220) plane and the (420) plane other than the desired (200) plane, (400) plane and (442) plane will appear. In addition, when the temperature of the electrolyte solution is lower than 20 ° C, the crystallinity of the indium hydroxide powder is disturbed, the primary particle diameter becomes fine, and the powder becomes cohesive, and as a result, the width of the particle size distribution becomes wider. Or when the temperature of electrolyte solution is higher than 60 degreeC, since particle growth is promoted, a primary particle diameter becomes large. Since the difference in particle diameter affects the degree of aggregation, as a result, the width of the particle size distribution becomes wider when indium hydroxide powders having different particle diameters are included. Therefore, it is preferable to make the liquid temperature of electrolyte solution into the range of 20-60 degreeC.

Although electrolytic conditions are not specifically limited, It is preferable to carry out current density at 3-15 A / dm <^2> . When the current density is lower than 3 A / dm ² , the production efficiency of the indium hydroxide powder is reduced. If the current density is higher than 15 A / dm ² , problems such as increase in liquid temperature tend to occur due to an increase in the electrolytic voltage, passivation of the surface of the metal indium, and difficulty in electrolysis occur. Therefore, it is preferable to make current density into 3-15 A / dm <^2> .

(1-2) Recovery Process of Indium Hydroxide Powder

The recovery step S2 of the indium hydroxide powder is solid-liquid separated from the indium hydroxide powder produced in the production step S1 of the indium hydroxide powder from the electrolytic solution, and the separated indium hydroxide powder is washed with pure water, and then solid-liquid separated and recovered. Examples of the solid-liquid separation method include filtration by rotary filters, centrifugal separation, filter presses, pressure filtration, reduced pressure filtration, and the like. In addition, the frequency | count of washing | cleaning is not specifically limited, It carries out in multiple times as needed.

(1-3) Drying Process of Indium Hydroxide Powder

In the drying step S3 of the indium hydroxide powder, the recovered indium hydroxide powder is dried. Although a drying method is not specifically limited, For example, it performs with dryers, such as a spray dryer, an air convection drying furnace, and an infrared drying furnace. The drying conditions are not particularly limited as long as the moisture of the indium hydroxide powder can be removed, but the drying temperature is preferably in the range of 80 to 150 ° C. If the drying temperature is lower than 80 ° C., drying becomes insufficient. When drying temperature is higher than 150 degreeC, it will change from indium hydroxide to indium oxide, and it becomes unsuitable in adjustment of the particle size distribution of the indium oxide powder in a next process. Moreover, although drying time changes with temperature, it is about 10 to 24 hours.

(1-4) Indium Hydroxide Powder

Indium hydroxide powder is produced by the electrolytic conditions mentioned above, and is high in crystallinity whose crystal surface orientation is oriented to the (200) plane, the (400) plane, and the (442) plane. The indium hydroxide powder has an orientation index of (200) plane and a (400) plane of 2.0 or more, and an orientation index of (442) plane of 0.5 or less, respectively, obtained from the Wilson equation, and (400) to an orientation index of (200) plane. The ratio of the index of orientation of the plane) is 1.5 or more. The obtained indium hydroxide powder does not have diffraction peaks on the (220) plane and the (420) plane. Such indium hydroxide powder has suppressed aggregation and has a narrow particle size distribution. The crystal phase was measured using an X-ray diffraction apparatus. The orientation index was computed by Wilson formula using the diffraction intensity of each surface index calculated | required from the X-ray diffraction.

(1-5) Formation Process of Indium Oxide Powder

In the production step S4 of the indium oxide powder, the indium hydroxide powder after drying in the drying step S3 of the indium hydroxide powder is calcined to produce an indium oxide powder. Although calcination conditions are determined suitably, it is preferable to carry out by calcination temperature of 600-800 degreeC and calcination time 1 to 10 hours, for example.

If the calcination temperature is lower than 600 ° C., the BET value of the indium oxide powder will exceed 15 m 2 / g, and the primary particles are too small, resulting in a powder having cohesiveness. As a result, in the obtained indium oxide powder, a high-density sintered material such as indium tin oxide (ITO) sintered material cannot be obtained. If 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 becomes large, and the voids generated between the particles also become large, so that the sinterability is lowered. Thereby, in 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 make the calcination temperature into the range of 600 to 800 degreeC.

(1-6) indium oxide powder

The obtained indium oxide powder was controlled in the range of 10-15 m <2> / g of BET of a specific surface area, the cumulative particle size 10% diameter (D10) of a particle size distribution is 0.2 micrometer or more, and the cumulative particle size 90% diameter (D90) is 2.7 micrometers or less. Such indium oxide powder can produce a high density sintered material because the specific surface area is controlled, the dispersibility is good, and there is little aggregation.

In addition, in the production step S4 of the indium oxide powder, in order to make the indium hydroxide powder into a more desired particle diameter, you may disintegrate or grind as needed. In addition, in the production step S4 of the indium oxide powder, when ammonium nitrate is used as the electrolyte during the electrolysis of the indium hydroxide powder, decomposition of ammonium nitrate occurs, and it is possible to prevent mixing into the indium oxide powder.

As mentioned above, in the manufacturing method of an indium oxide powder, when obtaining an indium hydroxide powder by the electrolytic reaction using the anode containing indium, aqueous solution of ammonium nitrate is used as electrolyte solution, for example, pH of electrolyte solution is 2.5-4.0, and liquid temperature is used. By controlling it to the range of 20-60 degreeC, the indium hydroxide powder with high crystallinity which orientates to the (200) plane, the (400) plane, and the (442) plane can be obtained. The obtained indium hydroxide powder has suppressed aggregation and has a narrow particle size distribution. In the method for producing the indium oxide powder, by calcining the obtained indium hydroxide powder, the specific surface area is in the range of 10 to 15 m 2 / g, and the dispersibility is good, the particle size distribution having a D10 of 0.2 µm or more and D90 of 2.7 µm or less is narrow Indium oxide powder can be prepared. Therefore, when a sputtering target is manufactured using the obtained indium oxide powder, a high density sintered compact can be obtained.

Moreover, in the manufacturing method of this indium oxide powder, the nitrogen drainage amount after manufacture of an indium oxide powder can be suppressed compared with the neutralization method.

2. Manufacturing method of sputtering target

The manufacturing method of a sputtering target first mixes the indium oxide powder obtained by the manufacturing method of the above-mentioned indium oxide powder with other raw materials, such as a tin oxide powder, in a predetermined ratio, and produces granulated powder. Next, a molded article is produced by, for example, a cold press method using the granulated powder. Next, the molded body is sintered at atmospheric pressure, for example, in a temperature range of 1300 to 1600 ° C. Next, if necessary, processing such as polishing the plane or side surface of the sintered compact is performed. And an indium tin oxide sputtering target (ITO sputtering target) can be obtained by bonding a sintered compact to the backing plate made from Cu.

In the manufacturing method of a sputtering target, since the specific surface area of the indium oxide powder used as a raw material is controlled and dispersibility is good, a high density sintered compact can be obtained and the density of a sputtering target can be made high. Thereby, a sputtering target does not generate | occur | produce crushing during processing, and can also suppress that abnormal discharge generate | occur | produces at the time of sputtering.

Example

Hereinafter, although the specific Example which applied this invention is described, this invention is not limited to these Examples.

<Example 1>

In Example 1, first, the concentration of the aqueous ammonium nitrate solution used as the electrolyte solution was adjusted to 0.5 mol / L, pH to 3.5, and liquid temperature to 40 ° C. pH was adjusted by the amount of nitric acid added to electrolyte solution. The liquid amount of the electrolyte solution was 100L.

Next, indium hydroxide was electrolyzed using the adjusted electrolyte solution. A 99.9% purity metal indium plate was used for the positive electrode, and an insoluble Ti / Pt electrode was used for the negative electrode. The current density was 10 A / dm ² . Next, after repeating filtration and washing | cleaning about the obtained indium hydroxide slurry, it dried at 100 degreeC and 15 hours, and obtained 3.6 kg of indium hydroxide powders. The crystallization efficiency of the indium hydroxide powder by electrolysis was 100%.

Next, X-ray diffraction measurement (X'Pert-PRO, manufactured by PANalytical) was performed on the obtained indium hydroxide powder, and the orientation index was evaluated from the diffraction peak intensity of each crystal plane. The orientation index was calculated from the Wilson equation.

Next, the obtained indium hydroxide powder was calcined at 700 ° C. for 5 hours to obtain an indium oxide powder.

The specific surface area of the indium oxide powder was measured as a BET value (gas adsorption method) using a specific surface area measuring device (macsorb1210 manufactured by Mountain Tech, Inc.).

Thereafter, 33 g of tin oxide powder was mixed with 967 g of the obtained indium oxide powder. Then, a molded product was obtained by a cold press method and sintered at 1400 ° C. for 30 hours under atmospheric pressure to produce a sintered body of indium tin oxide. The relative density of the sintered compact was measured by the Archimedes method.

<Examples 2-7 and Comparative Examples 1-9>

In Examples 2 and 3 and Comparative Examples 5 and 6, an indium hydroxide powder was produced in the same manner as in Example 1, and the calcination temperature of the indium hydroxide powder was adjusted as shown in Table 2 to produce an indium oxide powder and a sintered body. .

In Examples 4 to 7 and Comparative Examples 1 to 4 and 7 to 9, the calcination temperature of the indium hydroxide powder was adjusted as shown in Table 2 as shown in Table 1 for the ammonium nitrate concentration, pH, and liquid temperature of the electrolyte solution. In the same manner as in Example 1 except for the indium hydroxide powder, the indium oxide powder, and the sintered compact.

In Table 1 below, the orientation index and crystallization efficiency of the indium hydroxide powder are shown, and in Table 2, the BET value of the indium oxide powder and the relative density of the sintered compact are shown.

From the results shown in Tables 1 and 2, in Examples 1 to 7, the orientation indexes of the (200) plane and the (400) plane obtained from the Wilson equation are 2.0 or more, and the orientation index of the (442) plane is 0.5 or less, respectively. Indium hydroxide powder having a high crystallinity having a ratio of the orientation index of the (400) plane to the orientation index of the (200) plane of 1.5 or more was obtained. In addition, in Examples 1-7, the diffraction peak of the (220) plane and the (420) plane did not appear.

Moreover, in Examples 1-7, BET value is the range of 10-15 m <2> / g by calcining in the temperature range of 600 degreeC-800 degreeC using the produced indium hydroxide powder, D10 is 0.2 micrometer or more, D90 An indium oxide powder having a narrow particle size distribution of 2.7 µm or less was obtained. In Examples 1-7, the relative density of the sintered compact became very high compared with the comparative example.

On the other hand, in Comparative Example 1, an indium hydroxide powder was produced in the same manner as in Example 1 except that the pH of the electrolyte solution was set to 2.0. As a result, in Comparative Example 1, metal indium precipitated on the anode in the electrolytic step, and indium hydroxide powder could not be obtained, and crystallization efficiency was 0%.

On the other hand, in Comparative Examples 2 to 4, in the indium hydroxide powder, diffraction peaks on the (420) planes other than the desired (200) plane, (400) plane and (442) plane appear, resulting in disturbance in crystallinity, It became the powder which has cohesion. In Comparative Examples 2-4, the BET value of the indium oxide powder produced at the calcination temperature of 700 degreeC was in the range of 10-15 m <2> / g, but D10 is 0.4 micrometer or more, D90 is 4.2 micrometer or more, and particle size distribution is wide lost. Therefore, in Comparative Examples 2-4, sinterability fell and the relative density of the sintered compact became low.

Moreover, as shown in the comparative example 5, in the case of the calcination temperature of 500 degreeC of indium hydroxide powder, the BET value of the indium oxide powder increased and it became the powder which has cohesiveness. Also in Comparative Example 5, D10 was 0.4 µm, D90 was 6.7 µm, and the particle size distribution was widened. In Comparative Example 6, the BET value of the indium oxide powder produced at the calcination temperature of 930 ° C. was too low, D10 was 0.5 μm, D90 was 9.8 μm, and the particle size distribution was widened. In these comparative examples 5 and 6, sinterability fell and the relative density of the sintered compact fell.

In Comparative Examples 7, 8, in the indium hydroxide powder, diffraction peaks on surfaces other than the desired (200) plane, (400) plane, and (442) plane appear, disturbing crystallinity, and having cohesiveness. It became a powder. In Comparative Examples 7, 8, the BET value of the indium oxide powder produced at the calcination temperature of 1100 ° C was too low, D10 was 0.5 µm and 0.3 µm, D90 was 14.8 µm and 10.2 µm, and the particle size distribution was wide. lost. In these comparative examples 7, 8, sinterability fell and the relative density of the sintered compact became very low.

Moreover, in the comparative example 9, the indium hydroxide powder which was orientated to the (200) plane but not to the (400) plane and (442) plane was obtained, and it became the powder which has cohesiveness. In Comparative Example 9, the BET value of the indium oxide powder produced at the calcination temperature of 700 ° C. was in the range of 10 to 15 m 2 / g, but D10 was 0.4 μm, D90 was 12.6 μm, and the particle size distribution was wide, and the cohesiveness was high. It became the powder which has. In this comparative example 9, sinterability fell and the relative density of the sintered compact became low.

Indium hydroxide powder by the electrolytic reaction which carried out by using the positive electrode containing indium from the above result, using ammonium nitrate aqueous solution as electrolyte solution, controlling pH of electrolyte solution to 2.5-4.0, and liquid temperature so that it might be in the range of 20-60 degreeC. It can be seen that indium hydroxide powder obtained by aligning to the (200) plane, the (400) plane, and the (442) plane, having high crystallinity and narrow particle size distribution is obtained. By using the indium hydroxide powder, an indium oxide powder having good dispersibility in which the specific surface area is controlled can be obtained, and a high density sintered compact can be obtained by using the indium oxide powder.

Claims (2)

The orientation indexes of the (200) plane and the (400) plane obtained from the Wilson equation are 2.0 or more, and the orientation index of the (442) plane is 0.5 or less, respectively. An indium hydroxide powder having an orientation index ratio of 1.5 or more and no diffraction peaks on the (220) plane and the (420) plane. An indium oxide powder having a BET value of 10 to 15 m 2 / g, a cumulative particle size 10% diameter (D10) of a particle size distribution of 0.2 µm or more, and a cumulative particle size of 90% diameter (D90) of 2.7 µm or less.

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