Zinc oxide-based target material as well as preparation method and application thereof

Abstract

The invention discloses a zinc oxide-based target material as well as a preparation method and application thereof, and belongs to the technical field of functional ceramic target materials. The preparation method of the zinc oxide-based target material comprises the following steps: carrying out compression molding on zinc oxide mixed powder prepared from an oxide powder raw material, a dispersant and a binder to obtain a green body; carrying out cold isostatic pressing treatment, glue discharging and microwave sintering on the green body; the microwave sintering comprises the following steps: carrying out first microwave sintering for 2-8 hours under the condition of 1300-1500 DEG C, and then carrying out second microwave sintering for 6-12 hours under the condition of 1200-1350 DEG C. The preparation method is simple, low in cost and high in efficiency, the high-density and high-purity target material can be obtained at the low sintering temperature and the short sintering heat preservation time through two-step microwave sintering, and the target material is small in grain size, uniform in size, low in resistivity and high in yield. The method is suitable for preparing devices such as solar cells, ultraviolet detectors, surface acoustic wave devices, gas sensors or transparent electrodes.

Description

Technical Field

[0001] The present invention relates to the technical field of functional ceramic target materials, and in particular to a zinc oxide-based target material and a preparation method and application thereof. Background Art

[0002] In recent years, due to the rapid development of the photovoltaic industry, the semiconductor industry and the flat panel display industry, the sputtering target material has a broad market. At present, the targets commonly used in the photovoltaic industry are mostly indium oxide-based ceramic targets, but the reserves of metallic indium are limited and non-renewable. For the sustainable development of the solar energy industry, there is an urgent need for a ceramic target that can replace indium oxide.

[0003] Zinc oxide is a wide bandgap metal oxide semiconductor material with a direct bandgap. It has the advantages of high melting point, low deposition temperature and low electron-induced defects, and its raw materials are widely available. As a target material, it has been widely used in solar cells, ultraviolet detectors, surface acoustic wave devices, gas sensors, transparent electrodes, etc.

[0004] However, current zinc oxide-based targets, especially large-sized (3 inches and above) zinc oxide-based targets, usually require sintering for dozens of hours to make the target material fully dense. During this long sintering process, the density of the target material is easily uneven. In addition, the sintering process carried out in the prior art requires continuous gas introduction, which greatly increases the production cost.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The object of the present invention is to provide a zinc oxide-based target material and a preparation method and application thereof, so as to solve or improve the above-mentioned technical problems.

[0007] The present invention can be implemented like this:

[0008] In a first aspect, the present invention provides a method for preparing a zinc oxide-based target material, comprising the following steps:

[0009] The zinc oxide mixed powder prepared from oxide powder raw materials, a dispersant and a binder is molded to obtain a green body; the green body is subjected to cold isostatic pressing, binder removal and microwave sintering;

[0010] The microwave sintering includes: first heating the temperature to 1300-1500°C at a heating rate of 2°C / min-10°C / min for a first microwave sintering for 2h-8h, and then cooling the temperature to 1200-1350°C at a cooling rate of 2°C / min-10°C / min for a second microwave sintering for 6h-14h.

[0011] In an optional embodiment, the oxide powder raw material includes zinc oxide and a doped oxide;

[0012] The mass ratio of zinc oxide to doping oxide is 95:5 to 99:1;

[0013] The doped oxide includes at least one of aluminum oxide, cerium oxide, gallium oxide, and tungsten oxide.

[0014] In an optional embodiment, the purity of the oxide powder raw material is ≥99.99%.

[0015] In an optional embodiment, the particle size of the oxide powder raw material is ≤5 μm.

[0016] In an optional embodiment, the preparation of the zinc oxide mixed powder comprises:

[0017] The oxide powder raw material is sand-milled with a dispersant and a solvent for the first time to obtain a first slurry; the first slurry is sand-milled with a binder for a second time to obtain a second slurry; the second slurry is dried and granulated to obtain a zinc oxide mixed powder.

[0018] In an optional embodiment, the preparation of the zinc oxide mixed powder has at least one of the following characteristics:

[0019] Feature 1: The dispersant includes at least one of sodium dodecylbenzene sulfonate, polyethylene glycol, polyacrylic acid, and polyvinyl pyrrolidone;

[0020] Feature 2: The mass of the dispersant is 0.4% to 0.6% of the oxide powder raw material;

[0021] Feature 3: The binder includes polyvinyl alcohol;

[0022] Feature 4: The mass of the binder is 1.5% to 2.5% of the oxide powder raw material;

[0023] Feature 5: The solid content of the first slurry is 38wt% to 60wt%;

[0024] Feature 6: The first sanding time is 1h to 4h;

[0025] Feature 7: The second sanding time is 0.5h~1h;

[0026] Feature 8: The rotation speeds of the first sanding and the second sanding are independently 2400r / min to 2600r / min;

[0027] Feature 9: The diameters of the grinding balls used in the first sanding and the second sanding are independently 0.2 mm to 0.3 mm;

[0028] Feature 10: The inlet air temperature for drying and granulation is 180℃~250℃, and the outlet air temperature is 90℃~120℃.

[0029] In an optional embodiment, the pressure of the compression molding is 25 MPa to 100 MPa, and the holding time of the compression molding is 5 min to 20 min.

[0030] In an optional embodiment, the pressure of the cold isostatic pressing treatment is 200 MPa to 300 MPa, and the holding time of the cold isostatic pressing treatment is 5 min to 12 min.

[0031] In an optional embodiment, the debinding is performed at a heating rate of 0.5°C / min to 2°C / min and at 600°C to 700°C for 2h to 4h.

[0032] In a second aspect, the present invention provides a zinc oxide-based target material prepared by the preparation method of any one of the aforementioned embodiments.

[0033] In an optional embodiment, the zinc oxide-based target has at least one of the following characteristics:

[0034] Feature 11: The relative density of the zinc oxide-based target is not less than 99.3%;

[0035] Feature 12: The resistivity of the zinc oxide-based target does not exceed 1.72 mΩ·cm;

[0036] Feature 13: The grain size of the zinc oxide-based target does not exceed 5.2 μm;

[0037] Feature 14: The purity of the zinc oxide-based target material is not less than 99.99%.

[0038] In a third aspect, the present invention provides an application of a zinc oxide-based target material as described in the aforementioned embodiment, wherein the zinc oxide-based target material is used to prepare solar cells, ultraviolet detectors, surface acoustic wave devices, gas sensors or transparent electrodes.

[0039] The beneficial effects of the present invention include:

[0040] The present invention adopts a two-step microwave sintering method during the sintering process. The sample is first heated to a higher temperature so that the system obtains a thermodynamic driving force sufficient for grain boundary diffusion, and then the temperature is quickly reduced to a lower temperature for continued heat preservation. The two-step sintering method can effectively inhibit grain boundary migration, avoid grain growth, and use the grain boundary diffusion effect to make the sample dense, and can obtain a sample with high density and fine grains at a lower temperature. In addition, microwave sintering can convert the microwave energy absorbed by the sample into the kinetic energy and potential energy of the internal molecules, so that the sample is uniformly heated as a whole, the temperature difference inside the sample is extremely small, and the heating and sintering speeds are fast. Under the action of microwave electromagnetic energy, the kinetic energy of the molecules or ions inside the sample increases, and the diffusion coefficient is improved, thereby achieving low-temperature rapid sintering.

[0041] The preparation method of the zinc oxide-based target material provided by the present invention is simple, low in cost and high in efficiency. By combining microwave sintering and two-step sintering to form two-step microwave sintering, a target material with high density and purity can be obtained at a lower sintering temperature and a shorter sintering insulation time. The target material has fine grains and uniform size, and is suitable for preparing devices such as solar cells, ultraviolet detectors, surface acoustic wave devices, gas sensors or transparent electrodes. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they 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.

[0043] The zinc oxide-based target material provided by the present invention and its preparation method and application are described in detail below.

[0044] The invention provides a method for preparing a zinc oxide-based target material, comprising the following steps: molding a zinc oxide mixed powder prepared from an oxide powder raw material, a dispersant and a binder to obtain a green body; and cold isostatic pressing, debinding and microwave sintering the green body.

[0045] In the present invention, the oxide powder raw material includes zinc oxide and doped oxide.

[0046] Doping zinc oxide with doped oxides is beneficial to increasing the density of zinc oxide-based targets and reducing their resistivity.

[0047] In some optional embodiments, the mass ratio of zinc oxide to doped oxide can be 95:5 to 99:1, such as 95:5, 95.5:4.5, 96:4, 96.5:3.5, 97:3, 97.5:2.5, 98:2, 98.5:1.5 or 99:1, or other values ​​within the range of 95:5 to 99:1.

[0048] If the doping amount of the doped oxide is too low, it cannot effectively increase the density of the zinc oxide-based target and reduce its resistivity; if the doping amount of the doped oxide is too high, it will easily lead to an excessively high carrier concentration in the film, thereby reducing the carrier mobility of the film.

[0049] The doped oxide may illustratively but not limitatively include at least one of aluminum oxide, cerium oxide, gallium oxide and tungsten oxide.

[0050] It should be noted that when the doped oxide is composed of two or more substances, as long as the mass ratio of zinc oxide to the total doped oxide is 95:5 to 99:1, there is no special limitation on the amount of each doped oxide.

[0051] In some typical embodiments, there are two types of doped oxides, and the mass ratio of the two doped oxides can be (0.5-4):(0.5-1). It can also be understood that under this condition, the mass ratio of zinc oxide to the two doped oxides is 95:4:1 to 99:0.5:0.5.

[0052] In some more typical embodiments, the doped oxide is obtained by combining any one of cerium oxide, gallium oxide and tungsten oxide with aluminum oxide, wherein the mass ratio of zinc oxide to aluminum oxide is 95:4 to 99:0.5, and the mass ratio of zinc oxide to any one of cerium oxide, gallium oxide and tungsten oxide is 95:1 to 99:0.5.

[0053] In some optional embodiments, the purity of the oxide powder raw material is ≥99.99%.

[0054] In some optional embodiments, the particle size of the oxide powder raw material is ≤5 μm, such as 5 μm, 4.5 μm, 4 μm, 3.5 μm, 3 μm, 2.5 μm, 2 μm or 1 μm, etc. If the particle size of the oxide powder is greater than 5 μm, it is not conducive to densification during sintering.

[0055] In some optional embodiments, the preparation of the above-mentioned zinc oxide mixed powder may include: sand-milling the oxide powder raw material with the dispersant and the solvent for the first time to obtain a first slurry; sand-milling the first slurry with the binder for the second time to obtain a second slurry; and drying and granulating the second slurry to obtain the zinc oxide mixed powder.

[0056] The dispersant may illustratively but not limitatively include at least one of sodium dodecylbenzene sulfonate, polyethylene glycol, polyacrylic acid, and polyvinyl pyrrolidone.

[0057] The mass of the dispersant may be 0.4% to 0.6% of the oxide powder raw material, such as 0.4%, 0.45%, 0.5%, 0.55% or 0.6%, etc., or may be other values ​​within the range of 0.4% to 0.6%.

[0058] The binder may illustratively but not limitedly include polyvinyl alcohol.

[0059] The mass of the binder can be 1.5% to 2.5% of the oxide powder raw material, such as 1.5%, 2.0% or 2.5%, etc., or can be other values ​​within the range of 1.5% to 2.5%.

[0060] The solid content of the first slurry may be 38 wt% to 60 wt%, such as 38 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt% or 60 wt%, or other values ​​within the range of 38 wt% to 60 wt%.

[0061] The time of the first sanding can be 1 h to 4 h, such as 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h or 4 h, or other values ​​within the range of 1 h to 4 h.

[0062] The second sanding time can be 0.5h to 1h, such as 0.5h, 0.8h or 1h, etc., or other values ​​within the range of 0.5h to 1h.

[0063] The rotation speeds of the first sanding and the second sanding independently can be 2400 r / min to 2600 r / min, such as 2400 r / min, 2450 r / min, 2500 r / min, 2550 r / min or 2600 r / min, etc., or other values ​​within the range of 2400 r / min to 2600 r / min.

[0064] The diameters of the grinding balls used in the first sanding and the second sanding can be independently 0.2 mm to 0.3 mm, such as 0.2 mm, 0.25 mm or 0.3 mm, etc., or other values ​​within the range of 0.2 mm to 0.3 mm.

[0065] In some optional embodiments, the inlet air temperature for drying and granulation can be 180°C to 250°C, such as 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C or 250°C, or other values ​​within the range of 180°C to 250°C.

[0066] The air outlet temperature may be 90°C to 120°C, such as 90°C, 95°C, 100°C, 105°C, 110°C, 115°C or 120°C, or other values ​​within the range of 90°C to 120°C.

[0067] For example, the particle size of the zinc oxide mixed powder obtained after granulation may be 40 μm to 60 μm.

[0068] In some optional embodiments, the molding pressure may be 25 MPa to 100 MPa, such as 25 MPa, 30 MPa, 40 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa or 100 MPa, or other values ​​within the range of 25 MPa to 100 MPa.

[0069] The holding time of the compression molding may be 5 min to 20 min, such as 5 min, 10 min, 15 min or 20 min, etc., or may be other values ​​within the range of 5 min to 20 min.

[0070] In some optional embodiments, the pressure of the cold isostatic pressing treatment can be 200 MPa to 300 MPa, such as 200 MPa, 210 MPa, 220 MPa, 230 MPa, 240 MPa, 250 MPa, 260 MPa, 270 MPa, 280 MPa, 290 MPa or 300 MPa, or other values ​​within the range of 200 MPa to 300 MPa.

[0071] The holding time of the cold isostatic pressing treatment can be 5 minutes to 12 minutes, such as 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes or 12 minutes, or other values ​​within the range of 5 minutes to 12 minutes.

[0072] By performing cold isostatic pressing according to the above conditions, the density of the green body can be improved.

[0073] In some optional embodiments, the debinding process may be performed at a temperature of 600° C. to 700° C. for 2 h to 4 h at a heating rate of 0.5° C. / min to 2° C. / min.

[0074] Exemplarily, the heating rate of the debinding process may be 0.5°C / min, 1°C / min, 1.5°C / min or 2°C / min, or other values ​​within the range of 0.5°C / min to 2°C / min.

[0075] The debinding temperature may be 600°C, 620°C, 650°C, 680°C or 700°C, etc., or other values ​​within the range of 600°C to 700°C.

[0076] The debinding time may be 2 h, 2.5 h, 3 h, 3.5 h or 4 h, or other values ​​within the range of 2 h to 4 h.

[0077] In the present invention, microwave sintering is used to replace the conventional pressureless sintering method, and the sintering process is set to two sintering stages, so that a target material with high density and uniform density can be obtained at a lower sintering temperature and a shorter sintering holding time. The target material has fine grains and uniform size. This process can reduce the sintering time of the target material and reduce the production cost.

[0078] In some optional embodiments, microwave sintering includes: first heating the temperature to 1300°C~1500°C at a heating rate of 2°C / min~10°C / min for a first microwave sintering for 2h~8h, and then cooling the temperature to 1200°C~1350°C at a cooling rate of 2°C / min~10°C / min for a second microwave sintering for 6h~14h.

[0079] Exemplarily, the heating rate of the first microwave sintering can be 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min or 10°C / min, or other values ​​within the range of 2°C / min to 10°C / min.

[0080] If the heating rate of the first microwave sintering is less than 2°C / min, the heating time is too long, which is not conducive to improving production efficiency; if the heating rate of the first microwave sintering is greater than 10°C / min, the heating rate is too fast, which may lead to uneven heating and cracking of the target material.

[0081] The temperature of the first microwave sintering may be 1300°C, 1350°C, 1400°C, 1450°C or 1500°C, etc., or may be other values ​​within the range of 1300°C to 1500°C.

[0082] If the temperature of the first microwave sintering is lower than 1300°C, the sintering temperature that causes grain boundary migration is not reached, which is not conducive to the densification of the target material; if the temperature of the first microwave sintering is higher than 1500°C, it may cause abnormal growth of target grains and reduce density.

[0083] The time of the first microwave sintering can be 2 h, 3 h, 4 h, 5 h, 6 h, 7 h or 8 h, or other values ​​within the range of 2 h to 8 h.

[0084] The cooling rate of the second microwave sintering can be 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min or 10°C / min, or other values ​​within the range of 2°C / min to 10°C / min.

[0085] The temperature of the second microwave sintering can be 1200°C, 1220°C, 1250°C, 1280°C, 1300°C, 1320°C or 1350°C, etc., or other values ​​within the range of 1200°C to 1350°C.

[0086] If the temperature of the second microwave sintering is lower than 1200° C., it is not conducive to making the target material fully dense; if the temperature of the second microwave sintering is higher than 1350° C., it is not conducive to obtaining fine grains.

[0087] The time of the second microwave sintering can be 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h or 14 h, etc., or other values ​​within the range of 6 h to 14 h.

[0088] In the above, the present invention adopts a two-step microwave sintering method in the sintering process, firstly heats the sample to a higher temperature so that the system obtains a thermodynamic driving force sufficient for grain boundary diffusion, and then quickly cools down to a lower temperature and continues to keep warm. The two-step sintering method can effectively inhibit grain boundary migration, avoid grain growth, and use the grain boundary diffusion effect to make the sample dense, and can obtain a sample with high density and fine grains at a lower temperature. In addition, microwave sintering can convert the microwave energy absorbed by the sample into the kinetic energy and potential energy of the internal molecules, so that the sample is uniformly heated as a whole, the temperature difference inside the sample is extremely small, and the heating and sintering speeds are fast. Under the action of microwave electromagnetic energy, the kinetic energy of the molecules or ions inside the sample increases, and the diffusion coefficient is improved, thereby achieving low-temperature rapid sintering. By combining microwave sintering and two-step sintering to form two-step microwave sintering, a target material with high density and purity can be obtained at a lower sintering temperature and a shorter sintering insulation time, and the target material has fine grains and uniform size.

[0089] Correspondingly, the present invention also provides a zinc oxide-based target material, which is prepared by the above preparation method.

[0090] In some optional embodiments, the relative density of the zinc oxide-based target material is not less than 99.3%, such as 99.36% to 99.87%.

[0091] In some optional embodiments, the resistivity of the zinc oxide-based target material does not exceed 1.72 mΩ·cm, such as 1.15 mΩ·cm to 1.72 mΩ·cm.

[0092] In some optional embodiments, the grain size of the zinc oxide-based target material does not exceed 5.2 μm, such as 3.37 μm to 5.12 μm.

[0093] In some optional embodiments, the purity of the zinc oxide-based target material is not less than 99.99%.

[0094] As mentioned above, the zinc oxide-based target material provided by the present invention has high relative density and purity, fine grain size and low resistivity.

[0095] In addition, the present invention also provides an application of the above zinc oxide-based target material. For example, the above zinc oxide-based target material can be used to prepare solar cells, ultraviolet detectors, surface acoustic wave devices, gas sensors or transparent electrodes, etc.

[0096] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0097] Example 1

[0098] This embodiment provides a zinc oxide-based target material, and the preparation method thereof comprises the following steps:

[0099] S1: 98 parts by mass of zinc oxide, 1.5 parts by mass of aluminum oxide and 0.5 parts by mass of cerium oxide powder were mixed, and 150 parts by mass of water and 0.5 parts by mass of dispersant (polyacrylic acid) were added and stirred evenly to obtain a raw material mixture. The raw material mixture was poured into a sand mill (with a grinding ball diameter of 0.2 mm) and the first sand milling was performed at a speed of 2500 r / min for 4 hours to reduce the solid matter D in the first slurry to 1.50 g / cm2. 50 ≤0.3 μm, and a first slurry was obtained. 2 parts by mass of polyvinyl alcohol was added to the first slurry as a binder and a second sand grinding was performed for 0.5 h to make the mixture uniform, and a second slurry was obtained.

[0100] S2: The obtained second slurry is subjected to spray granulation treatment, with an air inlet temperature of 220° C. and an air outlet temperature of 90° C., and zinc oxide mixed powder is obtained after sieving.

[0101] S3: Pour the zinc oxide mixed powder into a compression mold, and perform compression molding at a pressure of 50 MPa for 5 minutes to obtain a green body; and place the block-shaped green body into a cold isostatic press and pressurize it at 250 MPa for 10 minutes.

[0102] S4: Subsequently, the green body after the cold isostatic pressing treatment is heated to 600°C at a heating rate of 2°C / min and kept for 4 hours for debinding to remove lipids inside the green body.

[0103] S5: The green body after debinding is placed in a microwave sintering furnace, and the temperature is increased to 1400°C at a heating rate of 2°C / min and kept at this temperature for 4 hours for the first microwave sintering. The temperature is then decreased to 1350°C at a cooling rate of 5°C / min and kept at this temperature for 14 hours for the second microwave sintering. After cooling in the furnace, a zinc oxide-based target is obtained.

[0104] Example 2

[0105] The difference between this embodiment and embodiment 1 is that in S1, an equal amount of gallium oxide is used to replace cerium oxide.

[0106] Example 3

[0107] This embodiment provides a zinc oxide-based target material, and the preparation method thereof comprises the following steps:

[0108] S1: 95 parts by mass of zinc oxide, 4 parts by mass of aluminum oxide and 1 part by mass of cerium oxide powder were mixed, and 60 parts by mass of water and 0.6 parts by mass of dispersant (polyvinyl pyrrolidone) were added and stirred evenly to obtain a raw material mixture. The raw material mixture was poured into a sand mill (with a grinding ball diameter of 0.3 mm) and the first sand milling was performed at a speed of 2400 r / min for 3 hours to reduce the solid matter D in the first slurry to 1.50 g / cm2. 50 ≤0.3 μm, and a first slurry was obtained. 1.5 parts by mass of polyvinyl alcohol was added to the first slurry as a binder and a second sand grinding was performed for 1 hour to make the mixture uniform, and a second slurry was obtained.

[0109] S2: The obtained second slurry is subjected to spray granulation treatment, with an air inlet temperature of 180° C. and an air outlet temperature of 100° C., and zinc oxide mixed powder is obtained after sieving.

[0110] S3: Pour the zinc oxide mixed powder into a compression mold, and perform compression molding at a pressure of 25 MPa for 20 minutes to obtain a green body; and place the block-shaped green body into a cold isostatic press and pressurize it at 200 MPa for 12 minutes.

[0111] S4: Subsequently, the green body after the cold isostatic pressing treatment is heated to 650°C at a heating rate of 0.5°C / min and kept for 3 hours for debinding to remove lipids inside the green body.

[0112] S5: The green body after debinding is placed in a microwave sintering furnace, and the temperature is increased to 1300°C at a heating rate of 2°C / min and kept at this temperature for 8 hours for the first microwave sintering. The temperature is then decreased to 1200°C at a cooling rate of 2°C / min and kept at this temperature for 10 hours for the second microwave sintering. After cooling in the furnace, a zinc oxide-based target is obtained.

[0113] Example 4

[0114] The difference between this embodiment and embodiment 1 is that in S1, the oxide powder raw material consists of 98 parts by mass of zinc oxide and 2 parts by mass of aluminum oxide.

[0115] Example 5

[0116] The difference between this comparative example and Example 1 is that in S1, the oxide powder raw material is composed of 98 parts by mass of zinc oxide and 2 parts by mass of cerium oxide, that is, the doped oxide does not contain aluminum oxide.

[0117] Example 6

[0118] The difference between this comparative example and Example 1 is that in S1, the oxide powder raw material is a mixture of 92 parts by mass of zinc oxide, 6 parts by mass of aluminum oxide and 2 parts by mass of cerium oxide powder.

[0119] Comparative Example 1

[0120] The difference between this comparative example and Example 1 is that in S5, microwave sintering is not used, but traditional pressureless sintering is used, and the sintering conditions are: heating to 1400°C at a heating rate of 2°C / min and keeping warm for 4 hours for the first pressureless sintering, then cooling to 1350°C at a cooling rate of 5°C / min and keeping warm for 14 hours for the second pressureless sintering, and cooling with the furnace.

[0121] Comparative Example 2

[0122] The difference between this comparative example and Example 1 is that in S5, two-step sintering is not performed, and a microwave sintering furnace is used to directly keep the temperature at 1400° C. for 18 h.

[0123] Comparative Example 3

[0124] The difference between this comparative example and Example 1 is that in S5, two-step sintering is not performed, and a microwave sintering furnace is used to directly keep the temperature at 1350° C. for 18 h.

[0125] Comparative Example 4

[0126] The difference between this comparative example and Example 1 is that in S5, the temperature of the first microwave sintering is 1200°C.

[0127] Comparative Example 5

[0128] The difference between this comparative example and Example 1 is that in S5, the temperature of the first microwave sintering is 1600°C.

[0129] Comparative Example 6

[0130] The difference between this comparative example and Example 1 is that in S5, the temperature of the second microwave sintering is 1100°C.

[0131] Comparative Example 7

[0132] The difference between this comparative example and Example 1 is that in S1, the preparation raw material is 100 parts by mass of zinc oxide without other doped oxides.

[0133] Test example

[0134] The performances of the zinc oxide-based targets (with a size of 3-inch round targets) prepared in Examples 1 to 6 and Comparative Examples 1 to 7 were compared, and the results are shown in Table 1.

[0135] The relative density is tested by the Archimedes drainage method, the resistivity is tested by a four-probe test instrument, and the grain size is tested by a scanning electron microscope.

[0136] Table 1 Test results

[0137]

[0138] It can be seen from Table 1 that the zinc oxide-based targets obtained in Examples 1 to 6 have better comprehensive performance than the zinc oxide-based targets obtained in Comparative Examples 1 to 7, indicating that the preparation method provided by the present invention can obtain a zinc oxide-based target having a higher relative density, a smaller grain size and a lower resistivity.

[0139] By comparing Example 1 with Examples 4 to 6 and Comparative Example 7, it can be seen that the effects of Example 1 and Examples 4 to 6 are better than those of Comparative Example 7, indicating that combining zinc oxide with doped oxides is beneficial to improving the density of zinc oxide-based targets and reducing their resistivity. In addition, the effect of Example 1 is better than that of Examples 4 to 5, indicating that when the doped oxide contains at least one of cerium oxide, gallium oxide and tungsten oxide and aluminum oxide, it can have better effects than containing only aluminum oxide or only containing at least one of cerium oxide and gallium oxide. In addition, the effect of Example 1 is better than that of Example 6, indicating that the mass ratio of zinc oxide to doped oxide in the range of 95:5 to 99:1 can make the zinc oxide-based target have better performance effects.

[0140] By comparing Example 1 and Comparative Examples 1 to 6, it can be seen that when the sintering method is changed or the sintering conditions are improperly set, the comprehensive performance of the zinc oxide-based target material will deteriorate.

[0141] In summary, the preparation method of the zinc oxide-based target material provided by the present invention is simple, low in cost and high in efficiency. Through two-step microwave sintering, a target material with high density and purity can be obtained at a lower sintering temperature and a shorter sintering holding time. The target material has fine and uniform grains and low resistivity, and is suitable for preparing devices such as solar cells, ultraviolet detectors, surface acoustic wave devices, gas sensors or transparent electrodes.

[0142] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a zinc oxide-based target material, characterized in that: The following steps are involved: The zinc oxide mixed powder prepared from oxide powder raw materials, a dispersant and a binder is molded to obtain a green body; The green body is subjected to cold isostatic pressing, binder removal and microwave sintering; The microwave sintering includes: first heating the temperature to 1300-1500°C at a heating rate of 2°C / min-10°C / min for a first microwave sintering for 2h-8h, and then cooling the temperature to 1200-1350°C at a cooling rate of 2°C / min-10°C / min for a second microwave sintering for 6h-14h.

2. The preparation method according to claim 1, characterized in that: The oxide powder raw material includes zinc oxide and doped oxide; The mass ratio of the zinc oxide to the doped oxide is 95:5 to 99:1; The doped oxide includes at least one of aluminum oxide, cerium oxide, gallium oxide and tungsten oxide; Preferably, the particle size of the oxide powder raw material is ≤5 μm.

3. The preparation method according to claim 1, characterized in that: The preparation of the zinc oxide mixed powder comprises: The oxide powder raw material is sand-milled with the dispersant and the solvent for the first time to obtain a first slurry; the first slurry is sand-milled with the binder for the second time to obtain a second slurry; the second slurry is dried and granulated to obtain the zinc oxide mixed powder.

4. The preparation method according to claim 3, characterized in that: The preparation of the zinc oxide mixed powder has at least one of the following characteristics: Feature 1: The dispersant includes at least one of sodium dodecylbenzene sulfonate, polyethylene glycol, polyacrylic acid, and polyvinyl pyrrolidone; Feature 2: The mass of the dispersant is 0.4% to 0.6% of the oxide powder raw material; Feature 3: The binder includes polyvinyl alcohol; feature 4: The mass of the binder is 1.5% to 2.5% of the oxide powder raw material; Feature 5: The solid content of the first slurry is 38wt% to 60wt%; Feature 6: The first sanding time is 1h to 4h; Feature 7: The second sanding time is 0.5h~1h; Feature 8: The rotation speeds of the first sanding and the second sanding are independently 2400r / min to 2600r / min; Feature 9: The diameters of the grinding balls used in the first sanding and the second sanding are independently 0.2 mm to 0.3 mm; Feature 10: The inlet air temperature for drying and granulation is 180℃~250℃, and the outlet air temperature is 90℃~120℃.

5. The preparation method according to claim 1, characterized in that: The pressure of compression molding is 25MPa to 100MPa, and the holding time of compression molding is 5min to 20min.

6. The preparation method according to claim 1, characterized in that: The pressure of the cold isostatic pressing treatment is 200MPa to 300MPa, and the holding time of the cold isostatic pressing treatment is 5min to 12min.

7. The preparation method according to claim 1, characterized in that: The debinding is carried out at a heating rate of 0.5°C / min to 2°C / min and at 600°C to 700°C for 2h to 4h.

8. A zinc oxide-based target material, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 7.

9. The zinc oxide-based target material according to claim 8, characterized in that: The zinc oxide-based target has at least one of the following characteristics: Feature 11: The relative density of the zinc oxide-based target material is not less than 99.3%; Feature 12: The resistivity of the zinc oxide-based target material does not exceed 1.72 mΩ·cm; Feature 13: The grain size of the zinc oxide-based target material does not exceed 5.2 μm; Feature 14: The purity of the zinc oxide-based target material is not less than 99.99%.

10. Use of the zinc oxide-based target material as claimed in claim 8 or 9, characterized in that: The zinc oxide-based target material is used for preparing solar cells, ultraviolet detectors, surface acoustic wave devices, gas sensors or transparent electrodes.

Images