Tin oxide target material and preparation method thereof

Abstract

The invention belongs to the technical field of new materials, and discloses a preparation method of a tin oxide target material, which comprises the following steps of: 1, preparing a tin oxide precursor by adopting a precipitation method; 2, calcining the tin oxide precursor in an inert atmosphere at the temperature of 300-400 DEG C to obtain tin oxide powder with the specific surface area of 35-38m < 2 > / g; 3, mixing the tin oxide powder obtained in the step 2 with water and / or alcohol, and carrying out heat treatment by adopting a high-pressure kettle to obtain tin oxide powder with the specific surface area of 30-33m < 2 > / g; 4, the tin oxide powder obtained in the step 3 is placed in a mold, pressurization calcination is carried out in a vacuum environment, and a tin oxide target material is obtained; according to the method, a precipitation method is adopted for preparing a precursor, the precursor is pre-calcined and then subjected to solution method heat treatment, and finally the target material is prepared, so that the segregation phenomenon is effectively reduced, the electrical resistivity is reduced, tin oxide powder rich in oxygen vacancy defects is obtained, and the tin oxide target material low in electrical resistivity and high in oxygen vacancy defects is obtained. Meanwhile, the invention further provides the tin oxide target material 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 tin oxide target material and a preparation method thereof. Background Art

[0002] In the prior art, the preparation of tin oxide targets is generally prepared by compression molding and sintering methods, such as a method for preparing a tin oxide zinc doped zirconium high-density target in CN118271082A, wherein the disclosed preparation method is to prepare a mixed slurry of tin oxide powder, zirconium oxide powder and zinc oxide powder, and then sand mill, granulate, mold, sinter, and obtain a tin oxide zinc doped zirconium high-density target, the resistivity of which is 1.5 to 40 mΩ.cm;

[0003] If we want to further reduce the resistivity, it is already quite difficult to use the existing compression molding and sintering method.

[0004] The technical problem solved in this case is how to further reduce the resistivity. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a tin oxide target material. The method adopts a precipitation method to prepare a precursor, pre-calcines the precursor and then performs a solution method heat treatment, and finally prepares the target material. The segregation phenomenon is effectively reduced, thereby reducing the resistivity, and a tin oxide powder rich in oxygen vacancy defects is obtained, thereby obtaining a tin oxide target material with low resistivity and high oxygen vacancy defects.

[0006] At the same time, the present invention also provides a tin oxide target material prepared based on the method.

[0007] To achieve the above objectives, this application discloses:

[0008] A method for preparing a tin oxide target comprises the following steps:

[0009] Step 1: preparing a tin oxide precursor by a precipitation method;

[0010] Step 2: calcining the tin oxide precursor at 300-400°C in an inert atmosphere to obtain a tin oxide with a specific surface area of ​​35-38 m 2 / g of tin oxide powder;

[0011] Step 3: Mix the tin oxide powder obtained in step 2 with water and / or alcohol, and heat-treat it in an autoclave to obtain a powder with a specific surface area of ​​30 to 33 m 2 / g of tin oxide powder;

[0012] Step 4: Place the tin oxide powder obtained in step 3 in a mold, and calcine it under pressure in a vacuum environment to obtain a tin oxide target.

[0013] The core innovations of the present invention are 2:

[0014] 1. The pre-calcination method is used before heat treatment to obtain a specific surface area of ​​35 to 38 m 2 / g tin oxide powder can reduce segregation and resistivity by pre-calcining.

[0015] 2. Through the heat treatment in step 3, we found that the oxygen vacancies can be increased, the resistivity can be reduced, and the tin oxide powder rich in oxygen vacancy defects can be obtained.

[0016] In the above-mentioned preparation method, the specific method of step 1 is: adjusting the pH value of the precursor solution containing a soluble tin salt so that the tin element is precipitated in the form of tin hydroxide to obtain a tin oxide precursor.

[0017] In the above preparation method, the concentration of tin ions in the precursor solution is 1.5 mol / L to 2.5 mol / L;

[0018] The precursor solution further contains doping metal ions; the doping metal ions are one or more of niobium ions, tantalum ions, titanium ions, cerium ions, zirconium ions, and zinc ions;

[0019] The molar ratio of the tin ions to each doping metal ion is 96-99.8:0.1-2.

[0020] Preferably, the precursor solution further contains zinc ions and tantalum ions; the molar ratio of tin ions, zinc ions and tantalum ions is 96-99.8:0.1-2:0.1-2.

[0021] Generally speaking, zinc ions are used in tin oxide targets to improve the density and stability of the targets. Tantalum ions or other metal ions such as zirconium can also be used in tin oxide targets to further improve the performance of the targets.

[0022] When zinc ions exist in the target material, if the traditional method is used for preparation, more obvious ZnSnO3 segregation will occur. After the pre-calcination process is adopted, the segregation phenomenon is significantly suppressed and the resistivity is further reduced.

[0023] In the above preparation method, the pH value of step 1 is 7.0-7.5, the reaction time is 1-4 hours, and the specific surface area of ​​the tin oxide precursor is 75-80 m 2 / g.

[0024] In the above preparation method, before step 2, the tin oxide precursor is washed and dried.

[0025] In the above preparation method, the step 2 is specifically: calcining the tin oxide precursor at 300-400° C. for 10-12 h under a nitrogen atmosphere to obtain a tin oxide precursor having a specific surface area of ​​35-38 m 2 / g of tin oxide powder.

[0026] In the above preparation method, in step 3, tin oxide powder and water and / or alcohol are mixed to obtain a mixed solution, the solid content of the mixed solution is 50wt% to 60wt%; the heat treatment time is 6 to 8h; the heat treatment temperature is 150 to 200°C.

[0027] In the above preparation method, the alcohol is ethanol or ethylene glycol, the filling degree of the autoclave is 70% to 80%, and the pressure of the autoclave is 0.6 to 0.8 MPa.

[0028] In the above preparation method, in step 4, the pressure is increased to 10-20 MPa; the calcination temperature is 1100° C.-1200° C., and the heating rate is 1-2° C. / min;

[0029] In the step 4, after pressurizing to the maximum pressure and heating to the highest temperature, the temperature and pressure are maintained for 6 to 10 hours.

[0030] At the same time, the present invention also discloses a tin oxide target material, which is prepared by any of the above methods.

[0031] This application has at least the following beneficial effects:

[0032] The present invention adopts a precipitation method to prepare a precursor, pre-calcines the precursor and then performs a solution method heat treatment, and finally prepares a target material, which effectively reduces the segregation phenomenon and thus reduces the resistivity, obtains a tin oxide powder rich in oxygen vacancy defects, and then obtains a tin oxide target material with low resistivity and high oxygen vacancy defects.

[0033] More specifically, the specific surface area of ​​the pre-calcined product is 35 to 38 m 2 / g of tin oxide powder can reduce segregation and resistivity by pre-calcination; and the oxygen vacancies can be increased by the heat treatment in step 3 to obtain tin oxide powder and target material rich in oxygen vacancy defects. DETAILED DESCRIPTION

[0034] 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.

[0035] Example 1

[0036] (1) 9.96 L of 2.0 mol / L tin nitrate solution, 0.02 L of 2.0 mol / L zinc nitrate solution and 0.02 L of 2.0 mol / L tantalum nitrate solution were mixed, and the pH value was adjusted to 7.2 by adding ammonia as a neutralizer, and the reaction was carried out for 4 hours. After the reaction was completed, the solid-liquid separation was performed, and the separated solid phase was washed with pure water, and then dried and ground at 80° C. to obtain a tin oxide precursor with a BET of 78.11 m2 / g;

[0037] (2) calcining the tin oxide precursor obtained in step (1) at 350° C. in a nitrogen atmosphere for 11 h to obtain a tin oxide powder having a BET value of 36.40 m2 / g;

[0038] (3) adding ethylene glycol to the tin oxide powder 1 obtained in step (2) to prepare a solution with a solid content of 55%, then adding the solution into an autoclave, and making the filling degree of the autoclave 75%, the pressure in the autoclave 0.7 MPa, after heat treatment at 170° C. for 7 h, centrifuging, then washing the precipitate with ethylene glycol, and then drying at 80° C. to obtain tin oxide powder 2 with a BET of 32.87 m2 / g;

[0039] (4) placing the tin oxide powder obtained in step (3) into a mold, and then placing it in a vacuum hot pressing furnace;

[0040] (5) The vacuum hot pressing furnace was evacuated to a vacuum degree of 10 Pa, and then the temperature was raised to 1150°C at a rate of 1.5°C / min, and the pressure was increased to 20 MPa. The heat preservation and pressure holding time was 8 hours. Finally, the pressure was released when the temperature dropped to less than 300°C. After the temperature dropped to room temperature, the furnace was taken out of the furnace. The relative density was 99.2%, the resistivity was 1.35 mΩ.cm, and the oxygen vacancy concentration was 7.87E+18cm -3 Tin oxide target.

[0041] Example 2

[0042] (1) 9.8 L of 2.0 mol / L tin nitrate solution, 0.1 L of 2.0 mol / L zinc nitrate solution and 0.1 L of 2.0 mol / L tantalum nitrate solution were mixed, the pH value was adjusted to 7.3 by adding ammonia as a neutralizer, and the reaction was carried out for 4 hours. After the reaction was completed, the solid-liquid separation was performed, and the separated solid phase was washed with pure water, and then dried and ground at 80° C. to obtain a tin oxide precursor with a BET of 77.52 m2 / g;

[0043] (2) calcining the tin oxide precursor obtained in step (1) at 300° C. in a nitrogen atmosphere for 12 h to obtain a tin oxide powder having a BET value of 37.58 m2 / g;

[0044] (3) adding ethylene glycol to the tin oxide powder 1 obtained in step (2) to prepare a solution with a solid content of 55%, then adding the solution into an autoclave, and making the filling degree of the autoclave 75%, the pressure in the autoclave 0.7 MPa, after heat treatment at 150° C. for 8 h, centrifuging, then washing the precipitate with ethylene glycol, and then drying at 80° C. to obtain tin oxide powder 2 with a BET of 34.04 m2 / g;

[0045] (4) placing the tin oxide powder obtained in step (3) into a mold, and then placing it in a vacuum hot pressing furnace;

[0046] (5) The vacuum hot pressing furnace was evacuated to a vacuum degree of 10 Pa, and then the temperature was raised to 1100°C at a rate of 1.5°C / min, and the pressure was increased to 10 MPa. The heat preservation and pressure holding time was 8 hours. Finally, the pressure was released when the temperature dropped to less than 300°C. After the temperature dropped to room temperature, the furnace was taken out of the furnace. The relative density was 99.0%, the resistivity was 0.97 mΩ.cm, and the oxygen vacancy concentration was 7.14E+18cm -3 Tin oxide target.

[0047] Example 3

[0048] (1) 9.6 L of 2.0 mol / L tin nitrate solution, 0.2 L of 2.0 mol / L zinc nitrate solution and 0.2 L of 2.0 mol / L tantalum nitrate solution were mixed, and the pH value was adjusted to 7.5 by adding ammonia as a neutralizer, and the reaction was carried out for 4 hours. After the reaction was completed, the solid-liquid separation was performed, and the separated solid phase was washed with pure water, and then dried and ground at 80° C. to obtain a tin oxide precursor with a BET of 77.21 m2 / g;

[0049] (2) calcining the tin oxide precursor obtained in step (1) at 400° C. in a nitrogen atmosphere for 10 h to obtain a tin oxide powder having a BET value of 35.38 m2 / g;

[0050] (3) adding ethylene glycol to the tin oxide powder 1 obtained in step (2) to prepare a solution with a solid content of 55%, then adding the solution into an autoclave, and making the filling degree of the autoclave 75%, the pressure in the autoclave 0.7 MPa, after heat treatment at 200° C. for 6 h, centrifuging, then washing the precipitate with ethylene glycol, and then drying at 80° C. to obtain tin oxide powder 2 with a BET of 30.75 m2 / g;

[0051] (4) placing the tin oxide powder obtained in step (3) into a mold, and then placing it in a vacuum hot pressing furnace;

[0052] (5) The vacuum hot pressing furnace was evacuated to a vacuum degree of 10 Pa, and then the temperature was raised to 1200°C at a rate of 1.5°C / min, and the pressure was increased to 15 MPa. The heat preservation and pressure holding time was 8 hours. Finally, the pressure was released when the temperature dropped to less than 300°C. After the temperature dropped to room temperature, the furnace was taken out of the furnace. The relative density was 99.3%, the resistivity was 1.14 mΩ.cm, and the oxygen vacancy concentration was 7.74E+18cm -3 Tin oxide target.

[0053] Example 4

[0054] (1) 9.8 L of 2.0 mol / L tin nitrate solution, 0.1 L of 2.0 mol / L zinc nitrate solution and 0.1 L of 2.0 mol / L tantalum nitrate solution were mixed, and the pH value was adjusted to 7.3 by adding ammonia as a neutralizer, and the reaction was carried out for 4 hours. After the reaction was completed, the solid-liquid separation was performed, and the separated solid phase was washed with pure water, and then dried and ground at 80° C. to obtain a tin oxide precursor with a BET of 77.64 m2 / g;

[0055] (2) calcining the tin oxide precursor obtained in step (1) at 300° C. in a nitrogen atmosphere for 12 h to obtain a tin oxide powder having a BET value of 37.67 m2 / g;

[0056] (3) adding ethylene glycol to the tin oxide powder 1 obtained in step (2) to prepare a solution with a solid content of 55%, then adding the solution into an autoclave, and making the filling degree of the autoclave 75%, the pressure in the autoclave 0.7 MPa, after heat treatment at 100° C. for 19 h, centrifuging, then washing the precipitate with ethylene glycol, and then drying at 80° C. to obtain tin oxide powder 2 with a BET of 34.08 m2 / g;

[0057] (4) placing the tin oxide powder obtained in step (3) into a mold, and then placing it in a vacuum hot pressing furnace;

[0058] (5) The vacuum hot pressing furnace was evacuated to a vacuum degree of 10 Pa, and then the temperature was raised to 1100°C at a rate of 1.5°C / min, and the pressure was increased to 10 MPa. The heat preservation and pressure holding time was 8 hours. Finally, the pressure was released when the temperature dropped to less than 300°C. After the temperature dropped to room temperature, the furnace was taken out of the furnace. The relative density was 99.0%, the resistivity was 1.01 mΩ.cm, and the oxygen vacancy concentration was 7.09E+18cm -3 Tin oxide target.

[0059] Example 5

[0060] (1) 9.8 L of 2.0 mol / L tin nitrate solution, 0.1 L of 2.0 mol / L zinc nitrate solution and 0.1 L of 2.0 mol / L tantalum nitrate solution were mixed, and the pH value was adjusted to 7.3 by adding ammonia as a neutralizer, and the reaction was carried out for 4 hours. After the reaction was completed, the solid-liquid separation was performed, and the separated solid phase was washed with pure water, and then dried and ground at 80° C. to obtain a tin oxide precursor with a BET of 77.38 m2 / g;

[0061] (2) calcining the tin oxide precursor obtained in step (1) at 300° C. in a nitrogen atmosphere for 12 h to obtain a tin oxide powder having a BET value of 37.45 m2 / g;

[0062] (3) adding ethylene glycol to the tin oxide powder 1 obtained in step (2) to prepare a solution with a solid content of 55%, then adding the solution into an autoclave, and making the filling degree of the autoclave 75%, the pressure in the autoclave 0.7 MPa, after heat treatment at 300° C. for 4 h, centrifuging, then washing the precipitate with ethylene glycol, and then drying at 80° C. to obtain tin oxide powder 2 with a BET of 33.84 m2 / g;

[0063] (4) placing the tin oxide powder obtained in step (3) into a mold, and then placing it in a vacuum hot pressing furnace;

[0064] (5) The vacuum hot pressing furnace was evacuated to a vacuum degree of 10 Pa, and then the temperature was raised to 1100°C at a rate of 1.5°C / min, and the pressure was increased to 10 MPa. The heat preservation and pressure holding time was 8 hours. Finally, the pressure was released when the temperature dropped to less than 300°C. After the temperature dropped to room temperature, the furnace was taken out of the furnace. The relative density was 99.1%, the resistivity was 1.12 mΩ.cm, and the oxygen vacancy concentration was 7.03E+18cm -3 Tin oxide target.

[0065] Comparative Example 1

[0066] (1) 9.96 L of 2.0 mol / L tin nitrate solution, 0.02 L of 2.0 mol / L zinc nitrate solution and 0.02 L of 2.0 mol / L tantalum nitrate solution were mixed, and the pH value was adjusted to 7.2 by adding ammonia as a neutralizer, and the reaction was carried out for 4 hours. After the reaction was completed, the solid-liquid separation was performed, and the separated solid phase was washed with pure water, and then dried and ground at 80° C. to obtain a tin oxide precursor with a BET of 78.32 m2 / g;

[0067] (2) calcining the tin oxide precursor obtained in step (1) at 350° C. in a nitrogen atmosphere for 11 h to obtain a tin oxide powder with a BET value of 36.69 m2 / g;

[0068] (3) placing the tin oxide powder obtained in step (3) into a mold, and then placing it into a vacuum hot pressing furnace;

[0069] (4) The vacuum hot pressing furnace is evacuated to a vacuum degree of 10 Pa, and then the temperature is raised to 1150° C. at a rate of 1.5° C. / min, and the pressure is increased to 20 MPa. The heat and pressure holding time is 8 hours. Finally, the pressure is released when the temperature drops to less than 300° C., and after cooling to room temperature, the target is taken out of the furnace to obtain a tin oxide target with a relative density of 99.1%, a resistivity of 171.45 mΩ.cm, and an oxygen vacancy concentration of 4.87E+16 cm-3.

[0070] Comparative Example 2

[0071] (1) 9.8 L of 2.0 mol / L tin nitrate solution, 0.1 L of 2.0 mol / L zinc nitrate solution and 0.1 L of 2.0 mol / L tantalum nitrate solution were mixed, and the pH value was adjusted to 7.3 by adding ammonia as a neutralizer, and the reaction was carried out for 4 hours. After the reaction was completed, the solid-liquid separation was performed, and the separated solid phase was washed with pure water, and then dried and ground at 80° C. to obtain a tin oxide precursor with a BET of 76.98 m2 / g;

[0072] (2) calcining the tin oxide precursor obtained in step (1) at 300° C. in a nitrogen atmosphere for 12 h to obtain a tin oxide powder having a BET value of 37.61 m2 / g;

[0073] (3) adding ethylene glycol to the tin oxide powder 1 obtained in step (2) to prepare a solution with a solid content of 55%, then adding the solution into an autoclave, and making the filling degree of the autoclave 75%, the pressure in the autoclave 0.7 MPa, after heat treatment at 150° C. for 8 h, centrifuging, then washing the precipitate with ethylene glycol, and then drying at 80° C. to obtain tin oxide powder 2 with a BET of 34.56 m2 / g;

[0074] (4) The tin oxide powder obtained in step (3) is placed in a mold and subjected to cold isostatic pressing to obtain a target material blank;

[0075] (5) After the target blank is placed in a pressureless sintering furnace, the temperature is raised to 1100°C at a rate of 1.5°C / min and the temperature is kept at this temperature for 8 hours. Finally, the temperature is lowered to room temperature and the target blank is taken out of the furnace to obtain a tin oxide target having a relative density of 91.6%, a resistivity of 1254.21 mΩ.cm and an oxygen vacancy concentration of 7.68E+15cm-3.

[0076] Comparative Example 3

[0077] (1) 9.6 L of 2.0 mol / L tin nitrate solution, 0.2 L of 2.0 mol / L zinc nitrate solution and 0.2 L of 2.0 mol / L tantalum nitrate solution were mixed, and the pH value was adjusted to 7.5 by adding ammonia as a neutralizer, and the reaction was carried out for 4 hours. After the reaction was completed, the solid-liquid separation was performed, and the separated solid phase was washed with pure water, and then dried and ground at 80° C. to obtain a tin oxide precursor with a BET of 77.56 m2 / g;

[0078] (2) calcining the tin oxide precursor obtained in step (1) at 400° C. in an oxygen atmosphere for 10 h to obtain a tin oxide powder having a BET value of 33.35 m2 / g;

[0079] (3) adding ethylene glycol to the tin oxide powder 1 obtained in step (2) to prepare a solution with a solid content of 55%, then adding the solution into an autoclave, and making the filling degree of the autoclave 75%, the pressure in the autoclave 0.7 MPa, after heat treatment at 200° C. for 6 h, centrifuging, then washing the precipitate with ethylene glycol, and then drying at 80° C. to obtain tin oxide powder 2 with a BET of 28.61 m2 / g;

[0080] (4) placing the tin oxide powder obtained in step (3) into a mold, and then placing it in a vacuum hot pressing furnace;

[0081] (5) The vacuum hot pressing furnace is evacuated to a vacuum degree of 10 Pa, and then the temperature is raised to 1200° C. at a rate of 1.5° C. / min, and the pressure is increased to 15 MPa. The heat and pressure holding time is 8 hours. Finally, the pressure is released when the temperature drops to less than 300° C., and the target is taken out of the furnace after cooling to room temperature. A tin oxide target having a relative density of 99.3%, a resistivity of 110.58 Ω.cm, and an oxygen vacancy concentration of 3.43E+10cm-3 can be obtained.

[0082] Comparative Example 4

[0083] (1) 9.8 L of 2.0 mol / L tin nitrate solution, 0.1 L of 2.0 mol / L zinc nitrate solution and 0.1 L of 2.0 mol / L tantalum nitrate solution were mixed, the pH value was adjusted to 7.3 by adding ammonia as a neutralizer, and the reaction was carried out for 4 hours. After the reaction was completed, the solid-liquid separation was performed, and the separated solid phase was washed with pure water, and then dried and ground at 80° C. to obtain a tin oxide precursor with a BET of 77.41 m2 / g;

[0084] (2) calcining the tin oxide precursor obtained in step (1) at 200° C. in a nitrogen atmosphere for 12 h to obtain a tin oxide powder having a BET value of 53.82 m2 / g;

[0085] (3) adding ethylene glycol to the tin oxide powder 1 obtained in step (2) to prepare a solution with a solid content of 55%, then adding the solution into an autoclave and making the filling degree of the autoclave 75%, heat treating at 150° C. for 8 h, centrifuging, washing the precipitate with ethylene glycol, and then drying at 80° C. to obtain tin oxide powder 2 with a BET of 50.37 m2 / g;

[0086] (4) placing the tin oxide powder obtained in step (3) into a mold, and then placing it in a vacuum hot pressing furnace;

[0087] (5) The vacuum hot pressing furnace was evacuated to a vacuum degree of 10 Pa, and then the temperature was raised to 1100°C at a rate of 1.5°C / min, and the pressure was increased to 10 MPa. The heat preservation and pressure holding time was 8 hours. Finally, the pressure was released when the temperature dropped to less than 300°C. After the temperature dropped to room temperature, the furnace was taken out of the furnace. The relative density was 97.9%, the resistivity was 63.9 mΩ.cm, and the oxygen vacancy concentration was 9.76E+17 cm -3 Tin oxide target.

[0088] Comparative Example 5

[0089] (1) 9.8 L of 2.0 mol / L tin nitrate solution, 0.1 L of 2.0 mol / L zinc nitrate solution and 0.1 L of 2.0 mol / L tantalum nitrate solution were mixed, and the pH value was adjusted to 7.3 by adding ammonia as a neutralizer, and the reaction was carried out for 4 hours. After the reaction was completed, the solid-liquid separation was performed, and the separated solid phase was washed with pure water, and then dried and ground at 80° C. to obtain a tin oxide precursor with a BET of 77.65 m2 / g;

[0090] (2) calcining the tin oxide precursor obtained in step (1) at 600° C. in a nitrogen atmosphere for 12 h to obtain a tin oxide powder having a BET value of 22.96 m2 / g;

[0091] (3) adding ethylene glycol to the tin oxide powder 1 obtained in step (2) to prepare a solution with a solid content of 55%, then adding the solution into an autoclave and making the filling degree of the autoclave 75%, heat treating at 150° C. for 8 h, centrifuging, washing the precipitate with ethylene glycol, and then drying at 80° C. to obtain tin oxide powder 2 with a BET of 19.53 m2 / g;

[0092] (4) placing the tin oxide powder obtained in step (3) into a mold, and then placing it in a vacuum hot pressing furnace;

[0093] (5) The vacuum hot pressing furnace was evacuated to a vacuum degree of 10 Pa, and then the temperature was raised to 1100°C at a rate of 1.5°C / min, and the pressure was increased to 10 MPa. The heat preservation and pressure holding time was 8 hours. Finally, the pressure was released when the temperature dropped to less than 300°C. After the temperature dropped to room temperature, the furnace was taken out of the furnace. The relative density was 94.6%, the resistivity was 7.04Ω.cm, and the oxygen vacancy concentration was 6.43E+15cm -3 Tin oxide target.

[0094] Performance Testing

[0095] The test items include relative density, resistivity, and oxygen vacancy concentration;

[0096] The test method for relative density is: relative density = density (drainage method) / true density (immersion method)

[0097] The resistivity test method is: four-probe method

[0098] The test method for oxygen vacancy concentration is: chemical capacitance method

[0099] The test results are shown in Table 1 below;

[0100] Table 1 Test results

[0101] Case Relative density Resistivity Oxygen vacancy concentration Example 1 99.2％ 1.35mΩ.cm <![CDATA[7.87E+18cm -3 ]]> Example 2 99.0％ 0.97mΩ.cm <![CDATA[7.14E+18cm -3 ]]> Example 3 99.3％ 1.14mΩ.cm <![CDATA[7.74E+18cm -3 ]]> Example 4 99.0％ 1.01mΩ.cm <![CDATA[7.09E+18cm -3 ]]> Example 5 99.1％ 1.12mΩ.cm <![CDATA[7.03E+18cm -3 ]]> Comparative Example 1 99.1％ 171.45mΩ.cm <![CDATA[4.87E+16cm -3 ]]> Comparative Example 2 91.6％ 1254.21mΩ.cm <![CDATA[7.68E+15cm -3 ]]> Comparative Example 3 99.3％ 110.58Ω.cm <![CDATA[3.43E+10cm -3 ]]> Comparative Example 4 97.9％ 63.9mΩ.cm <![CDATA[9.76E+17cm -3 ]]> Comparative Example 5 94.6％ 7.04Ω.cm <![CDATA[6.43E+15cm -3 ]]>

[0102] Result analysis:

[0103] 1. It can be seen from Examples 1 to 5 that the method of pre-calcination combined with solution heat treatment can effectively reduce resistivity and increase oxygen vacancies; it can be seen from Examples 1 to 3 and Examples 4 and 5 that the solution heat treatment temperature has a slight effect on the oxygen vacancy concentration and relative density, and this effect is acceptable in terms of process selection and product results.

[0104] 2. It can be seen from Example 1 and Comparative Example 1 that when the solution heat treatment process is not used, the resistivity is significantly increased and the oxygen vacancy concentration is significantly reduced; it can be seen from Example 2 and Comparative Example 2 that in the subsequent target sintering process, the vacuum pressure sintering method is used compared with the atmospheric pressure sintering method, and its relative density is significantly increased and the resistivity is significantly reduced. We believe that the vacuum pressure sintering method is more conducive to controlling the relative density, which is a direct factor affecting the resistivity; it can be seen from the comparison between Example 3 and Comparative Example 3 that when the pre-calcination atmosphere is changed to an oxygen atmosphere, the oxygen vacancy concentration is significantly reduced. Low, the reduction of oxygen vacancy concentration brings about an increase in electronic materials; combined with comparative examples 2 and 3, the effect of relative density on resistivity is far greater than the effect of oxygen vacancy concentration on resistivity; through comparative examples 4 and 5, it can be seen that the precursor heating temperature is also a very critical process indicator. Too low temperature reduces relative density, and too low temperature affects oxygen vacancy concentration and relative density; pre-calcination mainly converts hydroxide into oxide, and too high temperature easily forms zinc stannate (non-conductive), and oxygen enrichment will lead to excessive oxygen partial pressure, inhibiting the generation of oxygen vacancies. The increase in oxygen vacancy concentration will lead to a decrease in lattice constant and volume, which is conducive to promoting carrier separation, thereby reducing the resistivity of the material.

[0105] 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 a tin oxide target, characterized in that: The steps include: Step 1: preparing a tin oxide precursor by a precipitation method; Step 2: calcining the tin oxide precursor at 300-400°C in an inert atmosphere to obtain a tin oxide with a specific surface area of ​​35-38 m 2 / g of tin oxide powder; Step 3: Mix the tin oxide powder obtained in step 2 with water and / or alcohol, and heat-treat it in an autoclave to obtain a powder with a specific surface area of ​​30 to 33 m 2 / g of tin oxide powder; Step 4: Place the tin oxide powder obtained in step 3 in a mold, and calcine it under pressure in a vacuum environment to obtain a tin oxide target.

2. The preparation method according to claim 1, characterized in that: The specific method of step 1 is: adjusting the pH value of the precursor solution containing a soluble tin salt so that the tin element is precipitated in the form of tin hydroxide to obtain a tin oxide precursor.

3. The preparation method according to claim 2, characterized in that: The concentration of tin ions in the precursor solution is 1.5 mol / L to 2.5 mol / L; The precursor solution further contains doping metal ions; the doping metal ions are one or more of niobium ions, tantalum ions, titanium ions, cerium ions, zirconium ions, and zinc ions; The molar ratio of the tin ions to each doping metal ion is 96-99.8:0.1-2.

4. The preparation method according to claim 2, characterized in that: The pH value of step 1 is 7.0-7.5, and the reaction time is 1-4 hours; the specific surface area of ​​the tin oxide precursor is 75-80 m 2 / g.

5. The preparation method according to claim 2, characterized in that: Prior to step 2, the tin oxide precursor is washed and dried.

6. The preparation method according to claim 1, characterized in that: The step 2 is specifically as follows: calcining the tin oxide precursor at 300-400° C. for 10-12 hours under a nitrogen atmosphere to obtain a tin oxide precursor having a specific surface area of ​​35-38 m 2 / g of tin oxide powder.

7. The preparation method according to claim 1, characterized in that: In step 3, tin oxide powder and water and / or alcohol are mixed to obtain a mixed solution, wherein the solid content of the mixed solution is 50wt% to 60wt%; the heat treatment time is 6 to 8h; and the heat treatment temperature is 150 to 200°C.

8. The preparation method according to claim 1, characterized in that: The alcohol is ethanol or ethylene glycol, the filling degree of the autoclave is 70% to 80%, and the pressure of the autoclave is 0.6 to 0.8 MPa.

9. The preparation method according to claim 1, characterized in that: In step 4, the pressure is increased to 10-20 MPa; the calcination temperature is 1100° C. to 1200° C., and the heating rate is 1-2° C. / min; In the step 4, after pressurizing to the maximum pressure and heating to the highest temperature, the temperature and pressure are maintained for 6 to 10 hours.

10. A tin oxide target, characterized in that: The method is prepared by any one of claims 1 to 9.