CN109879667B - Preparation method of dense oxygen-depleted zinc oxide ceramic body - Google Patents

Abstract

The invention provides a preparation method of a compact oxygen-loss zinc oxide ceramic body, which mainly comprises the steps of preparing zinc layer coated zinc oxide granulation powder, preparing a ceramic blank by the zinc layer coated zinc oxide granulation powder and sintering the ceramic blank; the preparation process of the zinc oxide layer coated zinc oxide granulation powder comprises the steps of adding zinc oxide premix into liquid containing a dispersing agent to prepare slurry, carrying out spray granulation on the slurry, and conveying zinc steam to a granulation area to realize zinc layer coating on the surface of the zinc oxide granulation powder, wherein the forming temperature of the zinc steam is 1000-1300 ℃. Compared with the prior art, the preparation method disclosed by the invention has the advantages that the preparation of the compact oxygen-loss zinc oxide ceramic body is realized by adopting a simple method, the used equipment is simple, the cost is low, the compactness is higher, the relative density of the product is more than 95%, the product has lower resistivity, and the resistivity is tested to be less than 1 omega cm, so that the sputtering requirements of DC and MF can be met.

Description

Preparation method of dense oxygen-depleted zinc oxide ceramic body

technical field

The invention relates to the technical field of optoelectronic materials, in particular to a method that can control the oxygen loss rate of a zinc oxide ceramic body while ensuring high densification, and can be used as a target for magnetron sputtering to meet the use requirements of the downstream electroplating industry. .

Background technique

As an environmentally friendly and abundant multifunctional wide-bandgap oxide material, ZnO can become a transparent conductive material with high photoelectric performance after a certain amount of degenerate doping (such as Al, Ga, In, etc.). Oxide material (transparent conductive oxide, TCO), has the advantages of ultraviolet light absorption, visible light transparency, infrared light reflection and adjustable electrical properties, etc. More and more applications in the field of information can be used as transparent electrode layer, intermediate dielectric layer and back electrode high reflection layer in thin film solar cells, functional dielectric layer in energy-saving Low-E glass, transparent electrode layer in smart glass and home appliances. Infrared reflective layer of glass, etc. At present, there are various techniques for depositing zinc oxide-based thin films, among which magnetron sputtering is the most mature film formation, which has the advantages of high film density, good uniformity and repeatability, and easy large-area high-speed deposition. used widely. In the magnetron sputtering process, the ceramic target plays a crucial role, and its performance is closely related to the sputtering stability and the optoelectronic properties of the final film. The basic requirements for high-performance ceramic targets are: high density, fine and uniform grains, and uniform composition. Recently, the new development in the coating industry requires strict control of oxygen vacancies in the target to meet the application requirements of new zinc oxide functional thin films: (1) For CIGS thin film solar cells, it is necessary to deposit a layer of intrinsic i-ZnO , while the traditional intrinsic ZnO ceramic target has poor conductivity and requires expensive radio frequency (RF) power for sputtering. In addition, the sputtering rate is relatively slow, making it difficult to meet the requirements of rapid batch production. Therefore, it is necessary to adjust the ZnO Oxygen vacancies in the crystal can improve the conductivity of the target, and direct current (DC) or intermediate frequency (MF) can be used to achieve high-speed deposition; (2) In the field of multi-layer film deposition such as low-E coating, ZnO targets are required to have certain The oxygen loss rate enables the deposited film to absorb a certain amount of oxygen molecules in the coating cavity, further protecting the underlying metal layer and preventing the metal layer from being oxidized during the coating process.

In order to control the content of the oxygen loss rate of the zinc oxide ceramic target, the relevant literature provides the following preparation techniques. Wan Dongyun et al. in "Chinese Optical Letters" (Volume 9, No. 10, Page 103102, 2011) announced a method for preparing a pure ZnO target with oxygen defects. In this method, the dry-pressed ZnO blank was first After sintering at 1350°C for 4 hours, take it out and place it in a small crucible. The small crucible is placed in an upside-down large crucible, and carbon powder is placed between the two layers of crucibles. During the heating process, the carbon powder reacts with residual oxygen to form reducing CO gas, the gas and ZnO undergo a reduction reaction to invert the oxygen in the ZnO lattice to lose, forming a zinc oxide ceramic target with oxygen vacancies. Ming-Wei Wu et al. in "Journal of Alloys and Compounds" (2015, No. 650, pages 514-519) published a method to prepare aluminum-doped zinc oxide (AZO) with a certain oxygen loss rate by means of hot isostatic pressing For ceramic targets, in this method, the AZO body is first sintered at 1300 °C for 3 hours in air, and then placed in a hot isostatic pressing equipment, pressurized by argon gas, and sintered at 1250 °C for 3 hours. In addition, there is also a preparation method of using a special atmosphere sintering furnace to reduce the ceramic material to form a ceramic target with a certain oxygen loss rate. However, the above three methods are still difficult to apply to the large-scale production of large-scale AZO targets, and their shortcomings are as follows: (1) Limited by the crucible and the cavity of the hot isostatic pressing equipment, they can only be used for small-scale experiments (2) The operation process is cumbersome, and it needs to be sintered into a block and then placed in another equipment for secondary treatment, which indirectly increases the target's sintering capacity. Preparation cost; and the relatively dense surface of the first sintered ceramic has a certain blocking effect on the reducing atmosphere in the second sintering, which is prone to the phenomenon of uneven oxygen loss inside and on the surface, which in turn affects the uniformity of the target material; (3 ) The equipment cost of hot isostatic pressing and special atmosphere sintering is high, which will also increase the cost of target preparation.

SUMMARY OF THE INVENTION

In order to solve the above technical problems, the present invention starts from the treatment of the zinc oxide raw material powder, realizes the coating of the zinc layer on the surface of the zinc oxide granulated powder, the green body is formed, and uses xZn+(1-x) in the subsequent sintering process. The diffusion reaction of ZnO→ZnO _1-x realizes the preparation of dense oxygen-depleted ZnO ceramic body.

The technical scheme of the present invention is to provide a method for preparing a dense oxygen-depleted zinc oxide ceramic body, which mainly includes the preparation of zinc oxide granulated powder coated with a zinc layer, and the zinc layer coated zinc oxide granulated powder to prepare a ceramic body and then Sintering; the preparation process of zinc oxide granulated powder coated with zinc layer is as follows: zinc oxide premix is added to liquid containing dispersant to prepare slurry, slurry is granulated by jet, and then zinc vapor is transported to the granulator. The granulation area realizes the coating of zinc layer on the surface of the zinc oxide granulated powder, wherein the formation temperature of zinc vapor is 1000-1300°C.

Further, the zinc oxide premix is made by mixing zinc oxide powder and doped oxide powder, and the mass of the doped oxide powder in the mixture/(the mass of the zinc oxide powder+the mass of the doped oxide powder)= 0-10wt%; when the mass fraction of the doped oxide powder is 0, the zinc oxide premix is only composed of zinc oxide powder.

Further, the mass fraction of the dispersant in the liquid containing the dispersant is 0.1-3wt%, and the solvent is deionized water; the slurry is prepared by ball milling, and the ball milling time is 8-24h.

Further, the average particle size of the zinc oxide powder in the zinc oxide premix is 200-500 nm, and the purity is 99.95-99.99%; it belongs to high-purity zinc oxide powder; the doped oxide is aluminum oxide, gallium oxide, and indium oxide. One or both of them, the average particle size is 100-400nm, and the purity is 99.95-99.99%;

Further, the dispersant is one or both of polyvinylpyrrolidone, polyvinyl alcohol, and carboxymethyl cellulose;

Further, the average particle size of the zinc oxide granulated powder coated with the zinc layer is 10-100 μm, and the thickness of the zinc layer is 0.5-2 μm;

Further, the above-mentioned zinc-coated zinc oxide granulated powder preparation device includes: a slurry container with a liquid nozzle at the bottom, a carrier gas unit with a gas nozzle distributed around the liquid nozzle, and at least one gas nozzle for carrying At least one gas unit, and a zinc vapor forming pool; wherein the angle α between the gas flow ejected from the gas nozzle and the liquid flow ejected from the liquid nozzle is 20° to 90°, so as to crush and atomize the liquid particles to a desired particle size;

Further, the hole diameter of the liquid nozzle hole is 0.5-2mm, and the flow rate of the slurry flowing out of the hole is 0.01-5L/min;

Further, the gas carried in the carrier gas unit is one of argon gas or nitrogen gas, the gas pressure is 0.8～30MPa, the temperature of heating the carrier gas is 80～120℃, and the slurry liquid flow is further broken and atomized by the carrier gas flow. At the same time, the carrier gas with a certain temperature can evaporate the moisture in some liquid particles, which is beneficial to the subsequent adhesion of zinc vapor on the surface of the zinc oxide granulated powder particles.

Further, the relative density of the ceramic body made of the zinc oxide granulated powder coated with the zinc layer is 60-75%, and the sintering process is to raise the temperature at a heating rate of 0.5-10° C./min to the first set temperature of 1000°C. ～1250℃, keep the temperature for 30～90min; then raise the temperature to 1300～1450℃ in the second step at the heating rate of 10～100℃/min, keep the temperature for 120～480min, and finally decrease the temperature at the cooling rate of 0.5～10℃/min. At room temperature, the sintering atmosphere is one or a mixture of air, nitrogen and argon.

Further, the green body forming method is cold isostatic pressing, the pressure is 120-300MPa, and the pressure holding time is 60-600s.

According to actual needs, the prepared dense oxygen-depleted zinc oxide ceramic body can be cut, polished and other post-processing, and the color of the post-processed product is black.

Advantages and beneficial effects of the invention: the preparation of dense oxygen-depleted zinc oxide ceramic body is realized by a simple method, the equipment used is simple, the cost is low, the density is high, the relative density of the product is over 95%, and the The resistivity, after testing, its resistivity is less than 1Ω·cm, which can meet the sputtering requirements of DC and MF.

Description of drawings

Fig. 1 is the schematic diagram of the preparation device of the zinc-coated zinc oxide granulated powder of the present invention.

In the figure, 1-slurry container, 2-slurry, 3-carrier gas, 4-gas nozzle, 5-heating coil, 61-zinc oxide granulated powder, 62-zinc layer coated zinc oxide granulated powder , 7-zinc vapor, 8-zinc vapor forming pool

Detailed ways

The present invention will be further described below in conjunction with specific embodiments.

The invention provides a preparation method of a dense oxygen-depleted zinc oxide ceramic body, which mainly comprises the preparation of a zinc layer-coated zinc oxide granulated powder, and the zinc layer-coated zinc oxide granulated powder to prepare a ceramic body and then sintered. The preparation process of the zinc oxide granulated powder coated with the zinc layer is as follows: the zinc oxide premix is added to the liquid containing the dispersant to prepare a slurry 2; The granulation area realizes the zinc layer coating on the surface of the zinc oxide granulated powder, wherein the formation temperature of the zinc vapor 7 is 1000-1300 ° C; the preparation device of the zinc layer coated zinc oxide granulated powder adopted in the present invention is shown in Figure 1 shown, comprising: a slurry container 1 with liquid nozzles at the bottom, at least one carrier gas unit with gas nozzles 4 distributed around the liquid nozzles, two gas nozzles 4 are shown in FIG. 1, and zinc vapor formation Pool 8; wherein the angle α between the air flow sprayed by the gas nozzle 4 and the liquid flow sprayed by the liquid nozzle is 20 to 90°, so as to crush and atomize the liquid particles of the slurry 2 to a desired particle size; the carrier gas 3 and the zinc The steam 7 is formed by heating the heating coil 5 .

As a further improvement, the hole diameter of the liquid nozzle is 0.5-2mm, and the flow rate of the slurry 2 out of the hole is 0.01-5L/min;

As a further improvement, the carrier gas 3 of the carrier gas unit is one of argon or nitrogen, the gas pressure is 0.8-30MPa, the temperature of the heating carrier gas 3 is 80-120°C, and the slurry liquid flows through the carrier gas 3 and is further broken. Atomization, and at the same time the carrier gas 3 has a certain temperature to evaporate the moisture in some liquid particles, which is beneficial to the subsequent adhesion of the zinc vapor 7 on the surface of the zinc oxide granulated powder particles.

Example 1

The invention provides a preparation method of a dense oxygen-depleted zinc oxide ceramic body, the steps comprising:

Step 1: Preparation of Zinc Coated Zinc Oxide Granulated Powder

1. Weigh a certain amount of high-purity zinc oxide powder and mix with the doped oxide powder, the mass of the doped oxide powder in the mixture/(the mass of the zinc oxide powder + the mass of the doped oxide powder)=5wt %; wherein the high-purity zinc oxide powder has an average particle size of 200 nm and a purity of 99.95-99.99%, and the doped oxide powder is aluminum oxide with an average particle size of 100 nm and a purity of 99.95-99.99%;

2. After mixing the powder, pour it into deionized water containing 1wt% dispersant, and form slurry 2 through ball milling for 8 hours; wherein the dispersant is polyvinylpyrrolidone;

3. Place the slurry 2 in the granulation device shown in Figure 1, the slurry 2 is sprayed through the liquid nozzle while the carrier gas 3 is sprayed through the gas nozzle 4, the gas disperses the liquid particles, and because the gas has its own At a certain temperature, the moisture of the liquid particles can be evaporated to complete the granulation, that is, the zinc oxide granulated powder 61 is obtained, and then the zinc vapor 7 is formed from the zinc vapor forming pool 8 (the temperature is maintained at 1000-1300 ° C, which is convenient for the zinc vapor 7 ). The zinc oxide granulation powder 61 is coated with a zinc layer on the surface of the zinc oxide granulated powder 61, and the zinc oxide granulated powder 62 is formed; the obtained zinc layer coated zinc oxide granulation The average particle size of the powder 62 is 10-100 μm, and the thickness of the zinc layer is 0.5-2 μm;

Step 2, the preparation of the green body and its sintering

1. The zinc-coated zinc oxide granulated powder 62 obtained in step 1 is placed in a mold and formed by cold isostatic pressing at 120 to 300 MPa, and the pressure holding time is 60 to 600 s to form a granulated powder with a relative density of 60 to 75%. ceramic body;

2. Place the ceramic body in the sintering furnace in an atmosphere (the sintering atmosphere in this embodiment is air), and the electric furnace is raised from room temperature to the first set temperature of 1000-1250 ℃ at a heating rate of 0.5-10 ℃/min, and the temperature is kept warm. 30 to 90 minutes. Then, the temperature is raised to the second step set temperature of 1300-1450°C at a heating rate of 10-100°C/min, and kept for 120-480min, and finally, the temperature is lowered to room temperature at a cooling rate of 0.5-10°C/min;

3. Cut and grind the sample to the specified size, which is the dense oxygen-depleted zinc oxide ceramic body; after grinding, the color of the ceramic body is dark black.

Example 2

The invention provides a preparation method of a dense oxygen-depleted zinc oxide ceramic body, the steps comprising:

Step 1: Preparation of Zinc Coated Zinc Oxide Granulated Powder

1. Weigh a certain amount of high-purity zinc oxide powder and mix with the doped oxide powder, the mass of the doped oxide powder in the mixture/(the mass of the zinc oxide powder + the mass of the doped oxide powder)=10wt %; wherein the average particle size of the high-purity zinc oxide powder is 500nm, and the purity is 99.95-99.99%; the doped oxide powder is aluminum oxide and gallium oxide, the average particle size is 400nm, and the purity is 99.95-99.99%;

2. After the powder is mixed, pour it into deionized water containing 2wt% dispersant, and form slurry 2 through ball milling for 16 hours; wherein the dispersant is polyvinyl alcohol;

3. Place the slurry 2 in the granulation device shown in Figure 1, the slurry 2 is sprayed through the liquid nozzle while the carrier gas 3 is sprayed through the gas nozzle 4, the gas disperses the liquid particles, and because the gas has its own At a certain temperature, the moisture of the liquid particles can be evaporated to complete the granulation, that is, the zinc oxide granulated powder 61 is obtained, and then the zinc vapor 7 is formed from the zinc vapor forming pool 8 (the temperature is maintained at 1000-1300 ° C, which is convenient for the zinc vapor 7 ). The zinc oxide granulation powder 61 is coated with a zinc layer on the surface of the zinc oxide granulated powder 61, and the zinc oxide granulated powder 62 is formed; the obtained zinc layer coated zinc oxide granulation The average particle size of the powder 62 is 10-100 μm, and the thickness of the zinc layer is 0.5-2 μm;

Step 2, the preparation of the green body and its sintering

1. The zinc-coated zinc oxide granulated powder 62 obtained in step 1 is placed in a mold and formed by cold isostatic pressing at 120 to 300 MPa, and the pressure holding time is 60 to 600 s to form a granulated powder with a relative density of 60 to 75%. ceramic body;

2. Place the ceramic body in the sintering furnace in an atmosphere (the sintering atmosphere in this embodiment is air), and the electric furnace is raised from room temperature to the first set temperature of 1000-1250 ℃ at a heating rate of 0.5-10 ℃/min, and the temperature is kept warm. 30 to 90 minutes. Then, the temperature is raised to the second step set temperature of 1300-1450°C at a heating rate of 10-100°C/min, and kept for 120-480min, and finally, the temperature is lowered to room temperature at a cooling rate of 0.5-10°C/min;

3. Cut and grind the sample to the specified size, which is the dense oxygen-depleted zinc oxide ceramic body; after grinding, the color of the ceramic body is dark black.

Example 3

The invention provides a preparation method of a dense oxygen-depleted zinc oxide ceramic body, the steps comprising:

Step 1: Preparation of Zinc Coated Zinc Oxide Granulated Powder

1. Weigh a certain amount of high-purity zinc oxide powder, the average particle size of the high-purity zinc oxide powder is 300nm, the purity is 99.95-99.99%, the doped oxide powder is aluminum oxide and indium oxide, and the average particle size is is 200nm, and the purity is 99.95-99.99%;

2. After mixing the powder, pour it into deionized water containing 0.5wt% dispersant, and form slurry 2 after 24h ball milling; wherein the dispersant is carboxymethyl cellulose;

3. Place the slurry 2 in the granulation device shown in Figure 1, the slurry 2 is sprayed through the liquid nozzle while the carrier gas 3 is sprayed through the gas nozzle 4, the gas disperses the liquid particles, and because the gas has its own At a certain temperature, the moisture of the liquid particles can be evaporated to complete the granulation, that is, the zinc oxide granulated powder 61 is obtained, and then the zinc vapor 7 is formed from the zinc vapor forming pool 8 (the temperature is maintained at 1000-1300 ° C, which is convenient for the zinc vapor 7 ). The zinc oxide granulation powder 61 is coated with a zinc layer on the surface of the zinc oxide granulated powder 61, and the zinc oxide granulated powder 62 is formed; the obtained zinc layer coated zinc oxide granulation The average particle size of the powder 62 is 10-100 μm, and the thickness of the zinc layer is 0.5-2 μm;

Step 2, the preparation of the green body and its sintering

1. The zinc-coated zinc oxide granulated powder 62 obtained in step 1 is placed in a mold and formed by cold isostatic pressing at 120 to 300 MPa, and the pressure holding time is 60 to 600 s to form a granulated powder with a relative density of 60 to 75%. ceramic body;

2. Place the ceramic body in the sintering furnace in an atmosphere (the sintering atmosphere in this embodiment is air), and the electric furnace is raised from room temperature to the first set temperature of 1000-1250 ℃ at a heating rate of 0.5-10 ℃/min, and the temperature is kept warm. 30 to 90 minutes. Then, the temperature is raised to the second step set temperature of 1300-1450°C at a heating rate of 10-100°C/min, and kept for 120-480min, and finally, the temperature is lowered to room temperature at a cooling rate of 0.5-10°C/min;

3. Cut and grind the sample to the specified size, which is the dense oxygen-depleted zinc oxide ceramic body; after grinding, the color of the ceramic body is dark black.

Use the Archimedes method to measure the density and calculate the relative density of the target according to the percentage between the measured density and the theoretical density. The relative density of the target is greater than 95%. For example, for the ceramic target of Example 1, it is determined that the ceramic body is Its density is 5.553 g/cm ³ , and its theoretical density is 5.58 g/cm ³ , so the relative density is 99.5%. The relative density results of other examples are similar and all are greater than 95%. For a dense zinc oxide ceramic body with a certain doping content, the resistivity change comes from the formation of oxygen vacancies, so the resistivity of the material can be used to characterize the number of oxygen vacancies. After testing, the resistivity of the ceramic target of the present invention is less than 1Ω cm, thus meeting the sputtering requirements of DC and MF.

The materials, reagents and experimental equipment involved in the embodiments of the present invention, unless otherwise specified, are all commercially available products in the field of optoelectronic materials.

The above are only preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, improvements and modifications can be made without departing from the core technology of the present invention. These improvements and Retouching should also belong to the scope of patent protection of the present invention. Any changes within the meaning and scope equivalent to the claims of the present invention should be construed as being included in the scope of the claims.

Claims (10)

1. the preparation method of dense oxygen-depleted zinc oxide ceramic body, is characterized in that, mainly comprises the preparation of zinc layer coating zinc oxide granulated powder, the zinc layer coating zinc oxide granulated powder body prepares ceramic body and then sinters; The preparation process of zinc oxide granulated powder coated with zinc layer is as follows: adding zinc oxide premix into a liquid containing dispersant to prepare a slurry, granulating the slurry by spraying, and then transporting zinc vapor to the granulation area to achieve The surface of the zinc oxide granulated powder is coated with a zinc layer, wherein the formation temperature of the zinc vapor is 1000~1300 ° C, the average particle size of the zinc oxide granulated powder coated with the zinc layer is 10~100 μm, and the thickness of the zinc layer is 0.5~ 2μm. 2 . The method for preparing a dense oxygen-depleted zinc oxide ceramic body according to claim 1 , wherein the zinc oxide premix is made by mixing zinc oxide powder and doped oxide powder, and the mixture is mixed with doped oxide powder. 3 . The mass of the mixed oxide powder/(the mass of the zinc oxide powder + the mass of the doped oxide powder)=0~10wt%. 3. The method for preparing a dense oxygen-depleted zinc oxide ceramic body according to claim 1, wherein the dispersant mass fraction in the liquid containing the dispersant is 0.1 to 3wt%, and the solvent is deionized water; The slurry was obtained, and the ball milling time was 8~24h. 4. The preparation method of dense oxygen-depleted zinc oxide ceramic body as claimed in claim 2, wherein the average particle size of the zinc oxide powder in the zinc oxide premix is 200～500nm, and the purity is 99.95～99.99 %; the doped oxide is one or two of aluminum oxide, gallium oxide and indium oxide, the average particle size is 100~400nm, and the purity is 99.95~99.99%. 5 . The method for preparing a dense oxygen-depleted zinc oxide ceramic body according to claim 1 , wherein the dispersant is one or both of polyvinylpyrrolidone, polyvinyl alcohol, and carboxymethyl cellulose. 6 . 6 . The method for preparing a dense oxygen-depleted zinc oxide ceramic body according to claim 1 , wherein the zinc-coated zinc oxide granulated powder preparation device comprises: a slurry container with a liquid nozzle at the bottom, A carrier gas unit with gas nozzles distributed around the liquid nozzle, and at least one of the gas nozzles, at least one carrier gas unit, and a zinc vapor forming pool; wherein the gas flow sprayed from the gas nozzle is sprayed with the liquid nozzle. The angle α between the outgoing liquid flows is 20° to 90°. 7 . The method for preparing a dense oxygen-depleted zinc oxide ceramic body according to claim 6 , wherein the hole diameter of the liquid nozzle hole is 0.5-2 mm, and the flow rate of the slurry flowing out of the hole is 0.01-5 L. 8 . /min. 8. The preparation method of the dense oxygen-depleted zinc oxide ceramic body according to claim 6 or 7, wherein the gas carried in the carrier gas unit is a kind of argon gas or nitrogen gas, and the gas pressure is 0.8～30MPa , the temperature of heating the carrier gas is 80~120℃. 9 . The method for preparing a dense oxygen-depleted zinc oxide ceramic body according to claim 1 , wherein the relative density of the ceramic body is 60-75%, and the sintering process is a temperature increase of 0.5-10° C./min. 10 . The rate rises to the set temperature of the first step of 1000-1250°C, and the temperature is kept for 30-90min; then the temperature rises to the set temperature of the second step of 1300-1450°C at a heating rate of 10-100°C/min, and the temperature is kept for 120-480min. The cooling rate of 0.5-10°C/min is lowered to room temperature, and the sintering atmosphere is one or a mixture of air, nitrogen and argon. 10 . The method for preparing a dense oxygen-depleted zinc oxide ceramic body according to claim 1 , wherein the molding method for the ceramic body is cold isostatic pressing, the pressure is 120-300 MPa, and the pressure holding time is 60- 600s.

Images