CN101264926A - Method for preparing nano-ITO powder by ammonia salt combustion method - Google Patents

Abstract

A method for preparing nano-ITO powder by ammonia salt combustion method, the method is: dissolving metal indium and tin in nitric acid solution to make nitrate solution, adding organic complexing agent and dispersant to the solution, stirring evenly, temperature Control the temperature at 40-70°C, then add ammonia water, adjust the pH value to 1-3.8, and finally add absolute ethanol to the prepared ammonia salt solution as a combustion aid, and then drop the solution into the rotary kiln at 700-1200°C Sinter for 10-30 minutes to obtain nano-ITO powder. The powder prepared by the invention has high purity, the particle size is between 10-30nm, and is a regular spherical particle without other impurities, especially chloride ions. The problem of severe target cracking in the process of preparing ITO targets by static pressure method; and the process cycle is short, the production efficiency is high, continuous feeding, continuous powder production, large-scale production can be achieved, and no pollution to the environment.

Description

Method for preparing nano-ITO powder by ammonia salt combustion method

technical field

The invention relates to a preparation method of high-purity indium tin oxide nanometer powder, which belongs to a kind of wet method preparation of nanometer ITO powder.

Background technique

Indium tin oxide (Indium Tin Oxides, English abbreviation ITO) nanopowder refers to the oxide material composed of 90% In ₂ O ₃ and 10% SnO _2. It is a new type of special functional material and deep processing of metal indium. High-tech products. ITO powder is mainly used to prepare ITO targets and ITO thin films. ITO film has high transmittance to visible light, high reflectivity in the infrared region, high absorption rate in the ultraviolet region, good electrical conductivity, good substrate adhesion and chemical stability. The above-mentioned characteristics of ITO make it widely used in many fields, and become a transparent conductive material with important application and research value at this stage. Usually, only high-quality ITO powders can prepare ITO targets with perfect properties. Therefore, the development of ITO nano-powder is one of the hotspots of material science research at home and abroad.

Chen Shizhu of Central South University et al. (NONFERROUS METALS, 2000, 52, 88-90) used metal indium and tin as raw materials to prepare nano-ITO powder by spray combustion method. This method has high production efficiency and is suitable for mass production. The prepared powder The purity is also very high, but it needs to be atomized under a high pressure of 10-15MPa, which requires high equipment, and the operation has certain risks, and the process operation is complicated. Chi-Hwan et al. (Materials Latters 61 (2007) 1701-1703) successfully prepared powders with a particle size of 16-33 nanometers using the sol-gel method. Nam et al. (Scripta Mater, 2001, 44, 2047-2050) used Nanoscale ITO powder was prepared by co-precipitation method. The sol-gel method and co-precipitation method are commonly used methods for preparing nano-ITO powder, but for the sol-gel method, there are many influencing factors, such as the concentration, temperature, and pH value of the solution, which will affect the formation of colloids; However, the particle size of the powder produced by the co-precipitation method is not uniform. (J.Am.Cerama, Soc, 2001, 84, 251-253) such as Yanagisawa (J.Am.Cerama, Soc, 2001, 84, 251-253) adopts co-precipitation method to obtain the hydroxide precursor of indium and tin by using chloride salt as raw material, then carry out repeated washing to remove chloride ion, and then carry out water heat treatment, and finally heat treatment to obtain ITO powder. In this method, the removal of chloride ions is a key point. If the residual chloride ions will affect the sintering of the ITO target, however, the removal of chloride ions is a time-consuming process that often consumes a lot of water and electricity. It will also cause a large amount of loss of products, increase the production cost of products, and cause serious environmental pollution.

CN1978323A discloses "a method for preparing ITO powder with high sintering activity", which uses alkoxides of indium and tin and other organic and inorganic salts to prepare ITO powder with a particle size of 6-25 nanometers. Although this method does not directly utilize chlorides for preparation, there is a process in the method of performing hydrothermal reaction in a reactor at 130-260° C. for 3-24 hours. The time is too long, resulting in a long cycle of the entire reaction. CN1301911C discloses " a kind of ITO powder preparation method of solid-solution tin in indium oxide ", and it is to use indium nitrate and tin chloride mixed solution as raw material, utilizes spray pyrolysis method to prepare nanometer ITO powder, the powder that this method makes is Spherical, but because it contains chloride ions, it will also affect the sintering of the target.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing nanoscale ITO powder with small grain size, high specific surface area, regular shape, high purity, simple process flow and short preparation cycle. The process flow is shown in Figure 1

The method for preparing nano-ITO powder by the ammonium salt combustion method of the present invention comprises the preparation of the nitrate solution of indium and tin, adding an organic complexing agent, adjusting the pH value and sintering process with ammonia water, and is characterized in that the specific preparation process is as follows:

A. Dissolve indium and tin with a purity of 99.99% in analytically pure nitric acid solution to make a nitrate solution with a concentration of 1 to 4mol/L, wherein the weight ratio of indium and tin is 9.04:1;

B. Add organic complexing agent polyvinyl alcohol and polyacrylamide to the solution, the volume ratio of the two to the solution is 1: (8-15) and 1: (5-10) respectively, and then add dispersant citric acid and fructose, the volume ratio of the two to the solution is 1: (15-20), stir evenly, and the temperature is controlled at 40-70°C;

C. Add ammonia water dropwise, stir continuously with a magnetic stirrer to make it fully react, and adjust the pH value of the solution to 1-3.8;

D, adding the ammonia salt solution prepared by the C operation is 1: (10～18) dehydrated alcohol with the volume ratio of the solution, as a combustion aid;

E. Finally, put the ammonia salt solution prepared in step C into a rotary kiln at 700-1200°C and sinter for 10-30 minutes to obtain nano-ITO powder.

Compared with prior art, the present invention has following advantage or positive effect:

1. The particle size of the prepared nano-ITO powder is between 10 and 30 nanometers, the shape of the particles is uniform and spherical, and the particle size distribution is narrow.

2. The raw materials required in the preparation process are easy to obtain, the operation is simple, the process flow is short and the removal of chloride ions is reduced, which fundamentally solves the problem of sintering and hot isostatic pressing due to the fact that ITO powder is rich in chlorine. During the process of preparing ITO target materials, the problem of severe cracking of the target material occurs, and the environment will not be polluted.

Description of drawings

Figure 1 is a process flow chart for preparing nanometer TIO powder by ammonia salt combustion method.

FIG. 2 is a transmission electron microscope picture of the powder prepared in Example 2. It can be seen from the figure that the powder is a spherical particle with a particle diameter of 20-35 nanometers, and has a regular shape and a good crystal structure.

Fig. 3 is the X-ray diffraction spectrum of the powder prepared in Example 2. It can be seen that there are 11 diffraction peaks in the range of 20° to 80°. According to the PDF card, the spectral lines are all In ₂ O ₃ crystal diffraction lines, and no SnO ₂ and metal Sn The spectral lines and other clutter, the powder is ITO powder of indium oxide solid solution tin oxide.

Detailed ways

The present invention will be further described below with example

Embodiment 1, take by weighing a certain amount of pure metal In10g, Sn1.1062g (weight ratio is In: Sn=9.04: 1) is dissolved in 63% _HNO3 , is mixed with the nitrate solution that 80ml concentration is 1.2mol/L , add organic complexing agent polyvinyl alcohol 10ml (with the volume ratio of solution being 1: 8) and polyacrylamide 13.3ml (with the volume ratio of solution being 1: 6) successively; Then add dispersing agent citric acid 5.3g ( The volume ratio with the solution is 1: 15), fructose 5.3g (the volume ratio with the solution is 1: 15), constantly stirring, the temperature is controlled at 45 ° C, after the complexing agent and dispersant added are completely dissolved, drip Add ammoniacal liquor, adjust pH value to be 3.8, add in the obtained ammonia salt solution and be the dehydrated alcohol 7.3ml of 1: 11 with solution volume ratio, put into the rotary kiln of 800 ℃ and sinter 10 minutes as combustion aid, That is, ITO powder is obtained.

Embodiment 2, take a certain amount of pure metal In10g, Sn1.1062g (weight ratio is In: Sn=9.04:1) is dissolved in the _HNO of 63% , is configured into the nitrate solution that 60ml concentration is 1.6mol/L , add organic complexing agent polyvinyl alcohol 5ml (with the volume ratio of solution is 1: 12) and polyacrylamide 7.5ml (with the volume ratio of solution is 1: 8) successively; Then add dispersant citric acid 3.75g ( The volume ratio with the solution is 1: 16), fructose 3.75g (the volume ratio with the solution is 1: 16), constantly stirring, the temperature is controlled at 60 ° C, after the complexing agent and dispersant added are completely dissolved, drop Add ammonia water to adjust the pH value to 3.5, add 5ml of absolute ethanol with a solution volume ratio of 1:12 to the prepared ammonia salt solution, as a combustion aid, put it in a rotary kiln at 1000 ° C for 20 minutes to obtain ITO powder.

Embodiment 3, take by weighing a certain amount of pure metal In10g, Sn1.1062g (weight ratio is In: Sn=9.04:1) is dissolved in 63% _HNO3 , is configured into the nitrate solution that 50ml concentration is 1.92mol/L, Add organic complexing agent polyvinyl alcohol 3.6ml (with the volume ratio of solution being 1: 14) and polyacrylamide 5ml (with the volume ratio of solution being 1: 10) successively; The volume ratio of the solution is 1: 18), fructose 2.8g (the volume ratio of the solution is 1: 18), stirring constantly, the temperature is controlled at 70 ° C, after the complexing agent and dispersant added are completely dissolved, add dropwise Ammonia, adjust the pH value to 2.5, add 3.8ml of absolute ethanol with a solution volume ratio of 1:13 to the prepared ammonia salt solution, put it into a rotary kiln at 1100°C as a combustion aid and sinter for 30 minutes to obtain ITO powder .

Embodiment 4, take a certain amount of pure metal In10g, Sn1.1062g (weight ratio is In: Sn=9.04:1) is dissolved in 63%HNO ₃ , is configured into the nitrate solution that 30ml concentration is 3.21mol/L, Add 3.6ml of organic complexing agent polyvinyl alcohol (with the volume ratio of the solution is 1: 14) and polyacrylamide 5ml (with the volume ratio of the solution is 1: 10); The volume ratio of the solution is 1:20), fructose 1.5g (the volume ratio of the solution is 1:20), stirring constantly, the temperature is controlled at 70 ° C, after the complexing agent and dispersant added are completely dissolved, add dropwise Ammonia, adjust the pH value to 1.5, add 2ml of absolute ethanol with a solution volume ratio of 1:15 to the prepared ammonia salt solution, put it into a rotary kiln at 1200°C as a combustion aid and sinter for 30 minutes to obtain ITO powder.

Claims (1)

1, a method for preparing nano-ITO powder by ammonia salt combustion method, comprising the preparation of the nitrate solution of indium and tin, adding organic complexing agent, adjusting pH value and sintering process with ammoniacal liquor, it is characterized in that, concrete preparation process is as follows: A. Dissolve indium and tin with a purity of 99.99% in analytically pure nitric acid solution to make a nitrate solution with a concentration of 1 to 4mol/L, wherein the weight ratio of indium and tin is 9.04:1; B. Add organic complexing agent polyvinyl alcohol and polyacrylamide to the solution, the volume ratio of the two to the solution is 1: (8-15) and 1: (5-10) respectively, and then add dispersant citric acid and fructose, the volume ratio of the two to the solution is 1: (15-20), stir evenly, and the temperature is controlled at 40-70°C; C. Add ammonia water dropwise, stir continuously with a magnetic stirrer to make it fully react, and adjust the pH value of the solution to 1-3.8; D, adding the ammonia salt solution prepared by the C operation is 1: (10～18) dehydrated alcohol with the volume ratio of the solution, as a combustion aid; E. Finally, put the ammonia salt solution prepared in step D into a rotary kiln at 700-1200°C for sintering for 10-30 minutes to obtain nano-ITO powder.

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