Method for preparing cerium indium oxide powder based on electrochemical method, cerium indium oxide powder, target material and application of cerium indium oxide powder and target material

Abstract

The invention belongs to the technical field of new materials, and discloses a method for preparing indium cerium oxide powder based on an electrochemical method, which comprises the following steps: by taking indium cerium alloy as an anode and an inert electrode as a cathode, carrying out electrolytic reaction in an alkaline electrolyte to generate an indium cerium hydroxide precipitate; the hydroxide precipitate is pyrolyzed after being washed, and indium cerium oxide powder is generated. According to the method, an electrolytic method is adopted for preparing mud of indium cerium hydroxide, the grain size of the mud is very small, in the precipitation reaction, the indium cerium hydroxide is evenly mixed, then pyrolysis is conducted, and the indium cerium oxide powder with good uniformity can be obtained. Meanwhile, the invention further provides the cerium indium oxide powder, the target material and the transparent conductive oxide film which are prepared on the basis of the method.

Description

Technical Field

[0001] The present invention relates to the field of new materials, and in particular to a method for preparing indium cerium oxide powder based on an electrochemical method, indium cerium oxide powder and a target material and applications thereof. Background Art

[0002] Transparent conductive oxide films are widely used in displays, solar cells, light-emitting diodes, touch screens, gas sensors, microelectronics, vacuum electronic devices and other fields because of their good metal-like conductivity, glass-like high light transmittance, high reflectivity in the infrared region and other excellent semiconductor properties. Infrared transparent conductive films have important application value in both military and civilian fields. In the civilian field, infrared transparent conductive films can be used in the fields of electronics and energy industry, sensor technology, optoelectronic technology, etc. For example, they can be used as infrared transparent electrodes in infrared solar cells and infrared lasers; in the military field, they can be used in infrared imaging, spacecraft windows and other fields. Therefore, infrared transparent conductive films are materials with very high application value.

[0003] Most of the existing transparent conductive oxide films are prepared by doping indium oxide with tin oxide. Since tin replaces indium, the electron concentration of this target is high and the electron mobility is low, resulting in poor infrared transmittance of the transparent conductive oxide film prepared by this target. Cerium doping can improve the corresponding performance of indium oxide target. The applicant has previously filed a number of applications for indium oxide cerium target, as follows:

[0004] Publication No. CN118878306A, the subject is an indium cerium oxide target and a preparation method thereof;

[0005] Publication No. CN118955091A, the subject is an indium titanium tantalum cerium oxide target material and its preparation method and application;

[0006] Publication No. CN117144310A, the subject is an indium oxide, cerium, tantalum, titanium, holmium target material and its preparation method;

[0007] The above schemes are all prepared by wet powder making. Through this process, the cerium oxide particles are relatively large, which makes it difficult to achieve the same particle size as indium oxide during doping, affecting the poor uniformity of the prepared target material.

[0008] Changes in target uniformity directly affect the target's service life and utilization rate. For example, the target may crack after one or two sputterings, or only a small portion of the target material may be used when it is scrapped.

[0009] The technical problem solved in this case is how to improve the service life and utilization rate of cerium indium oxide. Summary of the invention

[0010] The purpose of the present invention is to provide a method for preparing indium cerium oxide powder based on an electrochemical method. The method adopts an electrolytic method to prepare a sludge of indium cerium hydroxide, and its particle size is very small. In the precipitation reaction, the indium cerium hydroxides are uniformly mixed with each other, and then pyrolyzed to obtain indium cerium oxide powder with good uniformity.

[0011] At the same time, the present invention also provides indium cerium oxide powder, target material and transparent conductive oxide film prepared based on the method.

[0012] To achieve the above objectives, this application discloses:

[0013] A method for preparing indium cerium oxide powder based on an electrochemical method, using an indium cerium alloy as an anode and an inert electrode as a cathode, performing an electrolytic reaction in an alkaline electrolyte to generate a hydroxide precipitate of indium cerium; the hydroxide precipitate is washed and then pyrolyzed to generate indium cerium oxide powder.

[0014] The reaction equation of the electrochemical reaction of the present invention is:

[0015] Anode reaction: In→In 3+ +3e, In 3+ +3OH - →In(OH)3;

[0016] Ce→Ce 4+ +4e, Ce 4+ +4OH - →Ce(OH)4;

[0017] Cathode reaction: H + +2e→H2↑;

[0018] Reaction in electrolyte: NH4 + →NH3+H + ; NH3+H20→NH4 + +OH - ;

[0019] The present invention adopts an electrochemical method to prepare indium hydroxide and cerium hydroxide; indium and cerium are ionized and then precipitated, which can ensure sufficient uniformity of mixing;

[0020] A major advantage of the electrochemical method over the wet powder making process in the existing technology is its good uniformity. The performance of the oxide target prepared by the electrochemical method is significantly better than that of the target prepared by the traditional process.

[0021] Through detection, the BET of the indium cerium oxide precursor (indium cerium hydroxide) is 60-80 m2 / g, D50 is 0.3-0.5 μm, and D90 is 0.7-0.9 μm; the BET of the indium cerium oxide powder after pyrolysis is 25-35 m2 / g, D50 is 0.5-0.7 μm, and D90 is 0.9-1.1 μm.

[0022] At the same time, compared with the traditional hydrothermal method for producing indium cerium oxide, the electrochemical method of the present invention has a larger specific surface area and significantly better uniformity; because in the precipitation process of the hydrothermal method, the reaction is carried out with the addition of metal salts. Compared with the controllable chemical reaction process of point electrochemical reaction, the uniformity of the hydroxide powder is closely related to the drop rate, stirring degree, etc. At the same time, at the microscopic level, the addition of each drop of metal liquid is a reaction gradient process from high to low concentration, and the resulting precipitation will also bring about differences in uniformity of particle size.

[0023] In summary, the indium cerium oxide powder prepared by the process of this case can be used to prepare a target material with high uniformity, and its service life and availability are significantly improved.

[0024] In order to ensure the uniformity of electrolysis, the indium-cerium alloy is formed by dissolving, mixing and casting indium and cerium elements. In order to increase the conductive area, it is preferably made into a plate shape; the inert electrode is an inert electrode commonly used in the art, which can be one of a titanium plate, a graphite plate, a platinum plate, and a gold-plated plate.

[0025] In the above method, the solute in the alkaline electrolyte is a non-metallic salt.

[0026] In the above method, the solute in the alkaline electrolyte is one or more combinations of ammonium sulfate, ammonium nitrate and ammonium chloride.

[0027] In the above method, the concentration of the solute in the alkaline electrolyte is 1.5-2 mol / L, and the pH of the alkaline electrolyte is 4-5.

[0028] In the above method, the alkaline electrolyte further contains 0.5-1.5 wt% of a dispersant; the dispersant is one or more combinations of polyvinyl pyrrolidone, polycarboxylic acid compounds, and polyvinyl salts.

[0029] In the above method, in the indium-cerium alloy, the mass ratio of indium to cerium is 95-99.5:0.5-5.

[0030] In the above method, the pyrolysis temperature is 900°C to 1100°C, the calcination atmosphere is aerobic calcination, and the aerobic calcination is air atmosphere calcination or oxygen atmosphere calcination;

[0031] During the electrolysis process, the current density is 650-750A / ㎡; the electrolysis temperature is 30-40℃.

[0032] Meanwhile, the present invention also discloses an indium cerium oxide powder, which is prepared by any of the above methods.

[0033] In addition, the present invention also discloses an indium cerium oxide target material, which is prepared by using the indium cerium oxide powder as a raw material.

[0034] The applicant has previously proposed many methods for preparing oxide targets, such as cold isostatic pressing, hot isostatic pressing, hot pressing, etc. These methods can be applied to the preparation of the indium cerium oxide target of the present invention.

[0035] Finally, the present invention also discloses a transparent conductive oxide film, which is obtained by sputtering the indium cerium oxide target material as described above.

[0036] This application has at least the following beneficial effects:

[0037] The present invention adopts electrolysis to prepare the muddy indium cerium hydroxide, whose particle size is very small. In the precipitation reaction, the indium cerium hydroxides are uniformly mixed with each other, and then pyrolyzed to obtain indium cerium oxide powder with good uniformity.

[0038] The key points of the process control of the present invention are: the electrolytic reaction is carried out in an alkaline electrolyte to ensure that the metal ions can form a precipitate, and at the same time the anode should exist in the form of an alloy to improve the uniformity of the ionization of the single substance.

[0039] The indium cerium oxide powder prepared by the present invention can be used to prepare a target material with high uniformity, and the service life and availability of the target material are significantly improved. DETAILED DESCRIPTION

[0040] The present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. In the description of the present invention, it should be noted that, if no specific conditions are specified in the embodiments, the conditions are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0041] Example 1

[0042] Step 1: Melting metal indium with a metal purity of 4.5N and metal cerium with a metal purity of 4.5N at a mass ratio of 99.7:0.3 at 900° C. in an inert gas environment to form an indium-cerium alloy plate;

[0043] Step 2: using an indium-cerium alloy plate as an electrolytic anode, a graphite plate as an electrolytic cathode, and a 1.5 mol / L ammonium chloride aqueous solution containing 1% dispersant polyvinyl pyrrolidone as an electrolyte for electrolysis, connecting the cathode and the anode and placing them in the electrolyte to form an electrical circuit for electrolysis;

[0044] During the electrolysis process, the electrolyte temperature was controlled at 35°C, the pH was 4, and the current density was set at 700A / ㎡;

[0045] Step 3: After the electrolysis is completed, the electrolytic mud is collected and filtered and washed to obtain an indium cerium oxide precursor with a BET of 77.12 m2 / g, a D50 of 0.352 μm, and a D90 of 0.775 μm;

[0046] Step 4: calcining the indium cerium oxide precursor at 900° C. to obtain indium cerium oxide powder, wherein the indium cerium oxide powder has a BET of 33.32 m2 / g, a D50 of 0.517 μm, and a D90 of 0.961 μm.

[0047] Example 2

[0048] Step 1: Prepare an indium-cerium alloy plate by mixing metal indium with a purity of 4.5N and metal cerium with a purity of 4.5N at a mass ratio of 98:2 in an inert gas environment at 900° C.;

[0049] Step 2: using an indium-cerium alloy plate as an electrolytic anode, a graphite plate as an electrolytic cathode, and a 2.0 mol / L ammonium nitrate aqueous solution containing 1% dispersant polyvinyl pyrrolidone as an electrolyte for electrolysis, connecting the cathode and the anode and placing them in the electrolyte to form an electrical circuit for electrolysis;

[0050] During the electrolysis process, the electrolyte temperature was controlled at 35°C, the pH was 5, and the current density was set at 700A / ㎡;

[0051] Step 3: After the electrolysis is completed, the electrolytic mud is filtered and washed to obtain an indium cerium oxide precursor with a BET of 70.93 m2 / g, a D50 of 0.457 μm, and a D90 of 0.819 μm;

[0052] Step 4: calcining the indium cerium oxide precursor at 1000° C. in an air atmosphere to obtain indium cerium oxide powder, wherein the indium cerium oxide powder has a BET of 29.43 m2 / g, a D50 of 0.682 μm, and a D90 of 1.060 μm.

[0053] Example 3

[0054] Step 1: metal indium with a metal purity of 4.5N and metal cerium with a metal purity of 4.5N are prepared into an indium-cerium alloy plate in a mass ratio of 95:5 at 900° C. in an inert gas environment;

[0055] Step 2: using an indium-cerium alloy plate as an electrolytic anode, a graphite plate as an electrolytic cathode, and a 2.0 mol / L ammonium nitrate aqueous solution containing 1% dispersant polyvinyl pyrrolidone as an electrolyte for electrolysis, connecting the cathode and the anode and placing them in the electrolyte to form an electrical circuit for electrolysis;

[0056] During the electrolysis process, the electrolyte temperature was controlled at 35°C, the pH was 5, and the current density was set at 700A / ㎡;

[0057] Step 3: After the electrolysis is completed, the electrolytic mud is filtered and washed to obtain an indium cerium oxide precursor with a BET of 67.82 m2 / g, a D50 of 0.480 μm, and a D90 of 0.883 μm;

[0058] Step 4: calcining the indium cerium oxide precursor at 1100° C. in an air atmosphere to obtain indium cerium oxide powder, wherein the indium cerium oxide powder has a BET of 27.35 m2 / g, a D50 of 0.691 μm, and a D90 of 1.066 μm.

[0059] Example 4

[0060] Step 1: Prepare an indium-cerium alloy plate in an inert gas environment by mixing metal indium with a purity of 4.5N and metal cerium with a purity of 4.5N at a mass ratio of 99.7:0.3;

[0061] Step 2: using an indium-cerium alloy plate as an electrolytic anode, a graphite plate as an electrolytic cathode, and a 1.5 mol / L ammonium chloride aqueous solution containing 1% dispersant polyvinyl pyrrolidone as an electrolyte for electrolysis, connecting the cathode and the anode and placing them in the electrolyte to form an electrical circuit for electrolysis;

[0062] During the electrolysis process, the electrolyte temperature was controlled at 35°C, the pH was 4, and the current density was set at 700A / ㎡;

[0063] Step 3: After the electrolysis is completed, the electrolytic mud is filtered and washed to obtain an indium cerium oxide precursor with a BET of 60.98 m2 / g, a D50 of 0.422 μm, and a D90 of 0.793 μm;

[0064] Step 4: calcining the indium cerium oxide precursor at 900° C. in an air atmosphere to obtain indium cerium oxide powder, wherein the indium cerium oxide powder has a BET of 18.15 m2 / g, a D50 of 1.129 μm, and a D90 of 2.438 μm.

[0065] Comparative Example 1

[0066] Step 1: Add 19.49 kg of indium oxide powder, 0.51 kg of cerium oxide powder, 0.7 kg of dispersant and 35.7 kg of pure water into a mixing barrel, disperse for 30 minutes, and then ball mill for 8 hours to obtain a mixed slurry of indium oxide and cerium oxide;

[0067] Step 2: The mixed slurry obtained in step 1 is subjected to spray granulation to obtain a mixed powder of indium oxide and cerium oxide.

[0068] Comparative Example 2

[0069] Step 1: 4.897 L of 1.0 mol / L indium nitrate solution and 0.103 L of 1.0 mol / L cerium nitrate solution were mixed, the pH value was adjusted to 7.5 by adding ammonia water, and the reaction was carried out for 2 hours. After the reaction was completed, solid-liquid separation was carried out, and the separated solid phase was washed with pure water, and then dried and ground at 100° C. to obtain an indium cerium oxide precursor;

[0070] Step 2: The indium cerium oxide precursor obtained in step 1 is calcined at 900° C. to obtain indium cerium oxide powder.

[0071] Preparation of Indium Cerium Oxide Target

[0072] The indium cerium oxide powder of each embodiment and comparative example is first subjected to a molding process at a pressure of 30 MPa, then subjected to a cold isostatic pressing process at a pressure of 300 MPa, and finally sintered at 1500° C. to obtain an indium cerium oxide target.

[0073] Preparation of transparent conductive oxide thin films

[0074] The indium cerium oxide target is mounted on the target holder and then embedded in the target holder of the magnetron sputtering deposition device. The quartz substrate is fixed on the sample stage after cleaning and placed in the sputtering chamber. The distance between the substrate and the target is adjusted to 7 cm, and the substrate and the target are separated by a baffle. The vacuum degree of the growth chamber is evacuated to 3.3E-3Pa, and the substrate is heated to the film growth temperature of 150°C. Pure argon and pure oxygen are introduced, and the pressure is controlled at 0.5Pa, where the purity of pure argon and pure oxygen is more than 99.99%, and the oxygen partial pressure is 5%. Turn on the RF power supply (sputtering power is 150w), pre-deposit for 120s, remove the contamination on the surface of the target, then unscrew the baffle and deposit the film. During the deposition process, the target rotates at a low speed to improve the uniformity of the film. The deposition time is 15min, and the film thickness is about 100nm. After the growth is completed, the film is slowly cooled to room temperature under argon protection.

[0075] Performance Testing

[0076] The test items include: basic performance of target materials, target material life, and target material utilization rate;

[0077] The basic properties of the target material are bending strength and uniformity;

[0078] The target life and target utilization rate are verified in the above-mentioned sputtering process to verify the usable period (with target cracking as the end point) and utilization rate (with target cracking as the end point) of each target.

[0079] The detection method of the basic performance of the target material is:

[0080] Bending strength: three-point bending test method; uniformity: EDS

[0081] The test results are shown in Table 1 below;

[0082] Table 1 Test results

[0083] Case Flexural strength(MPa) Uniformity (%) Available cycle (h) Utilization rate (%) Example 1 132.4 ±0.1 129 29.77 Example 2 141.5 ±0.2 126 29.08 Example 3 135.5 ±0.2 128 29.54 Example 4 129.3 ±0.15 122 28.15 Comparative Example 1 130.9 ±0.4 109 25.15 Comparative Example 2 130.3 ±0.5 95 21.92

[0084] Result analysis:

[0085] It can be seen from Examples 1 to 3 that the target material and the film prepared by the process of the present invention have good application performance. At the same time, during use, the use period is long and the utilization rate is high. It can be seen from Examples 1 to 3 and Example 4 that the component ratio of the target material is also a key factor for its stability.

[0086] It can be seen from Example 1 and Comparative Examples 1 and 2 that the basic properties of the target material prepared by the indium cerium oxide powder prepared by the electrochemical method are relatively similar, but have obvious advantages in service life and utilization rate. The reason is that a very important defect of the indium cerium oxide target material is its poor stability. It is very easy to crack during the sputtering process. The cracking is at least related to the specific surface area and uniformity of the powder. Through the process optimization of the present invention, the prepared powder has high uniformity, small particle size, and large specific surface area. The prepared target material has better stability and can withstand long-term sputtering processing.

[0087] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A method for preparing indium cerium oxide powder based on an electrochemical method, characterized in that: An indium-cerium alloy is used as an anode and an inert electrode is used as a cathode. An electrolytic reaction is carried out in an alkaline electrolyte to generate a hydroxide precipitate of indium-cerium. The hydroxide precipitate is washed and then pyrolyzed to generate indium-cerium oxide powder.

2. The method according to claim 1, characterized in that The solute in the alkaline electrolyte is a non-metallic salt.

3. The method according to claim 2, characterized in that The solute in the alkaline electrolyte is one or more combinations of ammonium sulfate, ammonium nitrate and ammonium chloride.

4. The method according to claim 2, characterized in that: The concentration of the solute in the alkaline electrolyte is 1.5-2 mol / L, and the pH of the alkaline electrolyte is 4-5.

5. The method according to claim 2, characterized in that: The alkaline electrolyte also contains 0.5-1.5 wt% of a dispersant; the dispersant is one or more combinations of polyvinyl pyrrolidone, polycarboxylic acid compounds, and polyvinyl salts.

6. The method according to claim 1, characterized in that In the indium-cerium alloy, the mass ratio of indium to cerium is 95-99.5:0.5-5.

7. The method according to claim 1, characterized in that The pyrolysis temperature is 900°C to 1100°C, and the calcination atmosphere is oxygen calcination; During the electrolysis process, the current density is 650-750A / ㎡; the electrolysis temperature is 30-40℃.

8. An indium cerium oxide powder, characterized in that: The method is prepared by any one of claims 1 to 7.

9. An indium cerium oxide target, characterized in that: The cerium indium oxide powder as claimed in claim 8 is used as a raw material for preparation.

10. A transparent conductive oxide film obtained by sputtering the indium cerium oxide target material as claimed in claim 9.