KR20160131996A - Indium hydroxide powder and indium oxide powder - Google Patents

Abstract

A high-density sintered body is obtained. The orientation indices of the (200) plane and the (400) plane obtained from the Wilson equation are 2.0 or more, the orientation index of the (442) plane is 0.5 or less and the orientation index of the (400) plane to the orientation index of the Of the indium oxide powder obtained by calcining the indium hydroxide powder not having a diffraction peak on the (220) plane and the (420) plane is used.

Description

[0001] INDIUM HYDROXIDE POWDER AND INDIUM OXIDE POWDER [0002]

The present invention relates to indium hydroxide powder and indium oxide powder capable of producing a high-density indium tin oxide sputtering target (ITO sputtering target). The present application also claims priority to Japanese Patent Application No. 2014-47507, filed on March 11, 2014, which is hereby incorporated by reference in its entirety.

2. Description of the Related Art In recent years, use of a transparent conductive film as a solar cell application and a touch panel application has been increasing, and accordingly, a demand for a material for forming a transparent conductive film such as a sputtering target is increasing. An indium oxide-based sintered material is mainly used as the material for forming a transparent conductive film, and indium oxide powder is used as the main material. The indium oxide powder used in the sputtering target is preferably controlled in its specific surface area as much as possible in order to obtain a high-density target and good in dispersibility.

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

In the neutralization method, there has been proposed a method of obtaining needle-shaped indium hydroxide powder by adding alkali to an aqueous solution of indium nitrate at a high temperature of 70 to 95 캜 in order to suppress aggregation of the indium oxide powder See Document 1). In this method, the indium hydroxide powder of the needle-like phase is calcined to obtain an indium oxide powder having less aggregation.

However, the indium oxide powder produced by the neutralization method tends to be uneven in particle diameter and particle size distribution, and the density of the target is not increased when the sputtering target is produced, There arises a problem that discharge tends to occur. 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 solving this problem, there has been proposed a method for producing indium oxide powder by calcination of indium hydroxide by electrolytic treatment of metal indium, so-called electrolytic solution (for example, refer to Patent Document 2). In the electrolytic solution, 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 diameter 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 the primary particle diameter, but is liable to be a coagulated powder in which these particles are strongly aggregated. This indium oxide powder has a problem that the density of the target is prevented from becoming high because the particle size distribution is broadened by coagulation.

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

DISCLOSURE OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to provide indium hydroxide powder capable of obtaining a high-density sintered body and indium oxide powder obtained by calcining thereof.

The indium hydroxide powder according to the present invention for achieving the above objects has an orientation index of 2.0 or more and an orientation index of the (200) plane and a (400) plane of 0.5 or less, 200) plane is not less than 1.5 and the diffraction peaks of the (220) plane and the (420) plane are not present.

The indium oxide powder according to the present invention for achieving the above object has a BET value of 10 to 15 m 2 / g, a cumulative particle size of 10% diameter (D10) of 0.2 μm or more, a cumulative particle size of 90% diameter (D90) Is 2.7 mu m or less.

In the present invention, it is possible to obtain indium hydroxide powder having a specific crystallinity, which is oriented to a specific crystal plane, i.e., (200) plane, (400) plane and (442) plane and has a specific orientation index, It is an indium oxide powder with good dispersibility. Thus, in the present invention, by using the indium oxide powder, a sintered body having a high relative density can be obtained.

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

Hereinafter, the indium hydroxide powder and the indium oxide powder to which the present invention is applied will be described. Further, the present invention is not limited to the following detailed description unless otherwise specified. 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 method for producing indium oxide powder includes a step S1 of producing indium hydroxide powder to produce indium hydroxide powder by electrolysis, a recovering step S2 for recovering the produced indium hydroxide powder, A drying step S3 for drying the indium hydroxide powder, and a production step S4 of indium oxide powder for calcining the dried indium hydroxide powder to obtain indium oxide powder.

The indium hydroxide powder is produced by controlling the pH of the electrolytic solution to be in the range of 2.5 to 4.0 and the liquid temperature in the range of 20 to 60 캜 by using an anode containing indium and an aqueous solution of ammonium nitrate in the electrolytic solution as described later, (400) plane and the (442) plane, the crystallinity oriented at the (200) plane is high. The indium hydroxide powder has orientation indices of the (200) plane and the (400) plane determined from the Wilson equation of 2.0 or more and preferentially oriented to the (400) plane and the (400) plane Is not less than 1.5 and the orientation index of the (442) plane is not more than 0.5, and the diffraction peaks of the (220) plane and the (420) plane are not present. The indium oxide powder obtained by calcining the indium hydroxide powder has a controlled specific surface area and is excellent in dispersibility.

(1-1) Production process of indium hydroxide powder

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

As the anode, for example, metal indium and the like can be used, and it is preferable that the purity is as high as possible in order to suppress the incorporation of impurities into the indium oxide powder. For the cathode, a conductive metal, a carbon electrode, or the like is used, and for example, insoluble titanium coated with platinum 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 or a chloride salt can be used. Among them, when an ammonium nitrate aqueous solution is used, nitrate ions and ammonium ions are removed as nitrogen compounds by calcination in the production step S4 of the indium oxide powder, so that the incorporation of the impurity components can be prevented. On the other hand, when ammonium chloride or ammonium sulfate is used for the electrolytic solution, impurity components such as chloride ions and sulfate ions are mixed. Therefore, it is preferable to use an ammonium nitrate aqueous solution as the electrolytic solution.

The concentration of the electrolytic solution is preferably in the range of 0.1 to 2.0 mol / L. When the concentration of the electrolytic solution is lower than 0.1 mol / L, the electric conductivity of the electrolytic solution lowers and the electrolytic voltage rises, which causes problems such as heat generation of the current-carrying portion and high power cost. On the other hand, if the concentration of the electrolytic solution is higher than 2.0 mol / L, the indium hydroxide powder produced by electrolysis becomes coarse and the fluctuation of the particle diameter becomes large, which is not preferable. Therefore, the concentration of the electrolytic solution is preferably in the range of 0.1 to 2.0 mol / L.

The pH of the electrolytic solution is preferably in the range of pH 2.5 to 4.0. When the electrolytic solution is higher than pH 4.0, the resulting indium hydroxide powder shows diffraction peaks of (220) plane and (420) plane other than the desired (200) plane, the (400) plane and the (442) plane. Such indium hydroxide powder causes crystallization disturbance, makes the primary particle diameter fine, and has a cohesive property, resulting in a wider range of particle size distribution. In addition, if the electrolytic solution is lower than pH 2.5, indium metal precipitates on the cathode and the production efficiency of the indium hydroxide powder is lowered. Therefore, the pH of the electrolytic solution is preferably in the range of pH 2.5 to 4.0.

The liquid temperature of the electrolytic solution is preferably in the range of 20 to 60 캜. When the temperature of the electrolytic solution is lower than 20 캜 or higher than 60 캜, diffraction peaks of the (220) plane and the (420) plane other than the desired (200) plane, the (400) plane and the (442) plane appear. When the temperature of the electrolytic solution is lower than 20 占 폚, the crystallinity of the indium hydroxide powder is disturbed, the primary particle diameter becomes finer and the powder becomes cohesive. As a result, the width of the particle size distribution becomes wider. Alternatively, when the temperature of the electrolytic solution is higher than 60 占 폚, the primary particle diameter is increased because the particle growth is promoted. The difference in particle diameter affects the degree of agglomeration. As a result, when the powder contains indium hydroxide powder of different particle diameters, the width of the particle size distribution is widened. Therefore, the liquid temperature of the electrolytic solution is preferably in the range of 20 to 60 캜.

The electrolytic condition is not particularly limited, but it is preferable to conduct the current density at 3 to 15 A / dm ² . If the current density is lower than 3 A / dm ² , the production efficiency of the indium hydroxide powder is lowered. If the current density is higher than 15 A / dm ² , the rise of the electrolytic voltage tends to cause rise of the liquid temperature, and the surface of the metal indium becomes passivated and becomes difficult to be electrolyzed. Therefore, it is preferable to set the current density to 3 to 15 A / dm ² .

(1-2) Recovery process of indium hydroxide powder

In the step S2 of recovering the indium hydroxide powder, the indium hydroxide powder produced in the step S1 of producing the indium hydroxide powder is separated from the electrolytic solution by solid-liquid separation, and the separated indium hydroxide powder is washed with purified water and recovered again by solid-liquid separation. The solid-liquid separation method includes, for example, filtration by rotary filter, centrifugation, filter press, pressure filtration, vacuum filtration and the like. On the other hand, the number of times of cleaning is not particularly limited, and is carried out plural times as required.

(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. The drying method is not particularly limited, but is performed by a dryer such as a spray dryer, an air convection type drying furnace, or an infrared drying furnace. The drying conditions are not particularly limited as long as the water content of the indium hydroxide powder can be removed. For example, the drying temperature is preferably in the range of 80 to 150 캜. If the drying temperature is lower than 80 캜, the drying becomes insufficient. If the drying temperature is higher than 150 ° C, indium hydroxide changes to indium oxide, which is not suitable for adjustment of the particle size distribution of the indium oxide powder in the next step. The drying time varies depending on the temperature, but is about 10 to 24 hours.

(1-4) Indium hydroxide powder

The indium hydroxide powder is produced by the aforementioned electrolytic conditions and has a high crystallinity oriented in the (200) plane, the (400) plane and the (442) plane. The indium hydroxide powder preferably has an orientation index of 2.0 or more and a orientation index of the (442) plane of 0.5 or less and a (400) orientation index of the (200) ) Plane is 1.5 or more. The obtained indium hydroxide powder does not have diffraction peaks of (220) plane and (420) plane. Such an indium hydroxide powder has an inhibited aggregation and a narrow particle size distribution. The crystal phase measurement was carried out using an X-ray diffractometer. The orientation indices were calculated by the Wilson equation using the diffraction intensities of the respective surface indices obtained from the X-ray diffraction.

(1-5) Production process of indium oxide powder

In the production step S4 of the indium oxide powder, the indium hydroxide powder after the drying in the drying step S3 of the indium hydroxide powder is calcined to produce indium oxide powder. The calcination conditions are appropriately determined, but preferably calcination temperature is 600 to 800 deg. C and calcination time is 1 to 10 hours.

When the calcination temperature is lower than 600 占 폚, the BET value of the indium oxide powder exceeds 15 m < 2 > / g, and the primary particles are too small, so that the powder becomes cohesive. As a result, a high-density sintered material such as indium tin oxide (ITO) sintered material can not be obtained in the obtained indium oxide powder. If the calcination temperature is higher than 800 DEG C, the BET value of the indium oxide powder becomes less than 10 m < 2 > / g, the primary particle diameter becomes large and the pores formed between the particles become large. As a result, a high-density sintered material can not be obtained in the obtained indium oxide powder. Therefore, in order to obtain a high-density sintered material, it is preferable to set the calcination temperature in the range of 600 占 폚 to 800 占 폚.

(1-6) Indium oxide powder

The obtained indium oxide powder was controlled so that the BET value of the specific surface area was controlled within the range of 10 to 15 m 2 / g, the cumulative particle size 10% diameter D 10 of the particle size distribution was 0.2 μm or more, the cumulative particle size 90% diameter D 90 2.7 탆 or less. Such indium oxide powder has a controlled specific surface area, good dispersibility, and less aggregation, so that a high-density sintered material can be produced.

Further, in the production step S4 of the indium oxide powder, the indium hydroxide powder may be crushed or pulverized as necessary in order to obtain a more desirable particle diameter. Further, in the production step S4 of the indium oxide powder, when ammonium nitrate is used in the electrolytic solution at the time of electrolysis of the indium hydroxide powder, decomposition of ammonium nitrate occurs, and mixing into the indium oxide powder can be prevented.

As described above, in the method for producing indium oxide powder, when an indium hydroxide powder is obtained by an electrolytic reaction using an anode containing indium, an aqueous solution of ammonium nitrate, for example, is used as an electrolytic solution and the pH of the electrolytic solution is adjusted to 2.5 to 4.0, It is possible to obtain a highly crystalline indium hydroxide powder oriented on the (200) plane, the (400) plane and the (442) plane by controlling it to be in the range of 20 to 60 ° C. The obtained indium hydroxide powder is inhibited from aggregation and has a narrow particle size distribution. In the method for producing indium oxide powder, the obtained indium hydroxide powder is calcined to have a specific surface area in the range of 10 to 15 m < 2 > / g, good dispersibility, a narrow particle size distribution in which D10 is 0.2 mu m or more, D90 is 2.7 mu m or less An indium oxide powder can be produced. Therefore, when a sputtering target is produced using the obtained indium oxide powder, a high-density sintered body can be obtained.

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

2. Manufacturing method of sputtering target

In the sputtering target manufacturing method, first, the indium oxide powder obtained by the above-mentioned production method of the indium oxide powder is mixed with other raw materials of the target such as tin oxide powder at a predetermined ratio to prepare a granulated powder. Next, a compact is produced by, for example, a cold press method using the granulated powder. Next, sintering is performed in a temperature range of, for example, 1300 to 1600 캜 under atmospheric pressure. Next, the sintered body is subjected to processing such as grinding the plane or the side face, if necessary. Then, an 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 specific surface area of the indium oxide powder as a raw material is controlled and the dispersibility is good, a high-density sintered body can be obtained and the density of the sputtering target can be increased. Thereby, the sputtering target does not cause cracking during machining, and it is also possible to suppress occurrence of abnormal discharge during sputtering.

Example

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

≪ Example 1 >

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

Next, electrolysis of indium hydroxide was performed using the adjusted electrolytic solution. A metal indium plate having a purity of 99.99% was used for the positive electrode, and an insoluble Ti / Pt electrode was used for the negative electrode. The current density was set to 10 A / dm < ^{2 &} gt ;. Next, the obtained indium hydroxide slurry was repeatedly subjected to filtration and washing, and then dried at 100 DEG C for 15 hours to obtain 3.6 kg of indium hydroxide powder. The crystallization efficiency of the indium hydroxide powder by electrolysis was 100%.

Next, the obtained indium hydroxide powder was subjected to X-ray diffraction measurement (X'Pert-PRO, manufactured by PANalytical Co., Ltd.), and the orientation index was evaluated from the diffraction peak intensity of each crystal plane. Orientation index was obtained from Wilson equation.

Next, the obtained indium hydroxide powder was calcined at 700 占 폚 for 5 hours to obtain 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 (macsorb 1210: manufactured by Matsutec Co.).

Thereafter, 337 g of the obtained indium oxide powder and 33 g of tin oxide powder were mixed, and then a compact was obtained by the cold press method and sintered at 1400 DEG C for 30 hours under atmospheric pressure to obtain a sintered body of indium tin oxide. The relative density of the sintered body was measured by the Archimedes method.

≪ Examples 2 to 7 and Comparative Examples 1 to 9 >

In Examples 2 and 3 and Comparative Examples 5 and 6, indium hydroxide powders were prepared in the same manner as in Example 1, and indium oxide powders and sintered bodies were prepared by adjusting the calcination temperature of indium hydroxide powder as shown in Table 2 .

In Examples 4 to 7 and Comparative Examples 1 to 4 and 7 to 9, ammonium nitrate concentration, pH and liquid temperature of the electrolytic solution were adjusted as shown in Table 1, and the calcining temperature of the indium hydroxide powder was adjusted as shown in Table 2 In addition, indium hydroxide powder, indium oxide powder and sintered body were produced in the same manner as in Example 1.

Table 1 below shows the orientation index and crystallization efficiency of the indium hydroxide powder, and Table 2 shows the BET value of the indium oxide powder and the relative density of the sintered body.

From the results shown in Tables 1 and 2, it is understood that in Examples 1 to 7, the orientation indices of the (200) plane and the (400) plane obtained from the Wilson equation are 2.0 or more, the orientation index of the (442) A highly crystalline indium hydroxide powder 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. Further, in Examples 1 to 7, the diffraction peaks of the (220) plane and the (420) plane did not appear.

In Examples 1 to 7, the resulting indium hydroxide powder was calcined in a temperature range of 600 ° C to 800 ° C to have a BET value of 10 to 15 m 2 / g, a D 10 of 0.2 μm or more, a D90 An indium oxide powder having a particle size distribution of 2.7 탆 or less was obtained. In Examples 1 to 7, the relative density of the sintered body was very high as compared with the comparative example.

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

On the other hand, in Comparative Examples 2 to 4, diffraction peaks of the (200) plane, the (400) plane and the (420) plane other than the (442) plane appeared in the indium hydroxide powder, It became a powder having coherency. In Comparative Examples 2 to 4, indium oxide powder prepared at a calcination temperature of 700 占 폚 had a BET value of 10 to 15 m < 2 > / g, D10 of 0.4 m or more, D90 of 4.2 m or more, lost. Therefore, in Comparative Examples 2 to 4, the sinterability was lowered and the relative density of the sintered body was lowered.

In addition, as shown in Comparative Example 5, when the calcination temperature of the indium hydroxide powder was 500 DEG C, the BET value of the indium oxide powder was increased, and the powder became cohesive. Also in Comparative Example 5, D10 was 0.4 mu m, D90 was 6.7 mu m, 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 占 폚 became too low, D10 became 0.5 占 퐉, D90 became 9.8 占 퐉, and the particle size distribution became wider. In Comparative Examples 5 and 6, the sinterability was lowered, and the relative density of the sintered body was lowered.

In Comparative Examples 7 and 8, diffraction peaks of the surfaces other than the desired (200), (400), and (442) planes appeared in the indium hydroxide powder, and the crystallinity was disturbed, Powder. In Comparative Examples 7 and 8, the BET value of the indium oxide powder produced at a calcining temperature of 1100 ° C was too low, D10 was 0.5 탆 and 0.3 탆, D90 was 14.8 탆 and 10.2 탆, lost. In Comparative Examples 7 and 8, the sinterability was lowered, and the relative density of the sintered body was extremely low.

In Comparative Example 9, indium hydroxide powder oriented on the (200) plane but not oriented on the (400) plane and the (442) plane was obtained, and a powder having cohesive properties was obtained. In Comparative Example 9, the BET value of the indium oxide powder produced at a calcining temperature of 700 占 폚 was in the range of 10 to 15 m2 / g, but D10 was 0.4 占 퐉, D90 was 12.6 占 퐉, the particle size distribution was wide, ≪ / RTI > In Comparative Example 9, the sinterability was lowered, and the relative density of the sintered body was lowered.

From the above results, it was confirmed that by using an anode containing indium and using an ammonium nitrate aqueous solution as an electrolytic solution and controlling the pH of the electrolytic solution to be in the range of 2.5 to 4.0 and the liquid temperature in the range of 20 to 60 ° C, (400) plane and (442) plane, the indium hydroxide powder having a high crystallinity and a narrow particle size distribution can be obtained. By using the indium hydroxide powder, it is possible to obtain indium oxide powder whose specific surface area is controlled and dispersibility is good, and it can be seen that a high-density sintered body can be obtained by using the indium oxide powder.

Claims (2)

The orientation indices 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, Wherein the ratio of orientation indices is not less than 1.5 and does not have diffraction peaks of (220) plane and (420) plane. Wherein the BET value is 10 to 15 m < 2 > / g, the cumulative particle size 10% diameter D10 of the particle size distribution is 0.2 m or more, and the cumulative particle size 90% diameter D90 is 2.7 m or less.

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