Preparation method for indium-free low-density high-conductivity RPD target and product thereof
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-07-09
- Publication Date
- 2026-08-13
Smart Images
Figure CN2025107659_13082026_PF_FP_ABST
Abstract
Description
A method for preparing an indium-free, low-density, high-conductivity RPD target and its product. Technical Field
[0001] This application relates to the field of optoelectronic materials technology, and in particular to a method for preparing an indium-free, low-density, high-conductivity RPD target and its product. Background Technology
[0002] Transparent conductive oxide (TCO) is a thin-film material with high transmittance and low resistivity in the visible light spectrum. It can be widely used as a transparent conductive functional layer in optoelectronic devices such as flat panel displays, touch screens, energy-saving glass, and photovoltaic cells. In traditional industrial applications, TCO thin films are generally prepared using magnetron sputtering, employing a highly dense target (close to the material's theoretical density) as the sputtering source material. In recent years, reactive plasma deposition (RPD) has emerged as a new TCO coating process, gaining widespread use due to its advantages such as extremely high film uniformity, fast growth rate, and large deposition area. Regarding target requirements, unlike magnetron sputtering, RPD generally uses targets with relatively low density. This is because excessively dense targets are prone to cracking during RPD deposition, making it impossible to obtain high-quality films. Indium tin oxide (ITO) is currently the most widely used TCO thin film material on the market. It has good optical and electrical properties. However, due to the extremely limited reserves of indium, and the large-scale use of indium in solar cells in recent years, as well as its important application prospects in flat panel displays, LEDs, transparent thin film transistors and flexible electronics, the demand for indium has increased significantly, resulting in a sharp decrease in indium reserves, which can no longer meet market demand. Therefore, it is necessary to find new materials to replace ITO.
[0003] Currently, indium-free targets such as aluminum-doped zinc oxide (AZO) and Al / Ga co-doped zinc oxide (AGZO) have been developed on the market. Although they possess certain optoelectronic properties, their film thickness, resistivity, and electron mobility are far inferior to the electrical properties of ITO, failing to meet the requirements of market applications. Therefore, this application proposes a method for preparing an indium-free, low-density, high-conductivity RPD target and its product. Summary of the Invention
[0004] The main objective of this application is to provide a method for preparing an indium-free, low-density, high-conductivity RPD target and its product, aiming to solve the technical problem that the electrical properties of existing RPD targets need to be improved.
[0005] To achieve the above objectives, this application proposes a method for preparing an indium-free, low-density, high-conductivity RPD target, comprising the following steps:
[0006] Modified tetraneedle-shaped zinc oxide whiskers were prepared by using zinc as raw material, molecular sieve as nucleating agent, and inert gas through heating reaction.
[0007] The modified tetraneedle zinc oxide whiskers were mixed with the doped material, and a wetting agent and a dispersant were added. The mixture was then ball-milled to obtain a doped slurry.
[0008] After drying the doped slurry, it is crushed, sieved, and then calcined to obtain calcined powder material.
[0009] The calcined powder material is subjected to sand milling, and a forming agent is added. After drying, it is granulated to obtain granules.
[0010] The granules are pressed into target green bodies and then sintered to obtain RPD target products.
[0011] Optionally, the step of preparing modified tetraneedle-shaped zinc oxide whiskers by using zinc as a raw material, molecular sieve as a nucleating agent, and introducing an inert gas through heating reaction includes:
[0012] Zinc granules were placed on molecular sieve particles and then placed in a box-type resistance furnace. Inert gas was introduced at a flow rate of 10 mL / min to 100 mL / min, and the temperature was raised to 500℃ to 1100℃. The reaction was carried out for 10 min to 25 min to obtain modified tetraneedle-shaped zinc oxide whiskers.
[0013] Optionally, the zinc granules have a purity of 99% and a diameter of 2.5 mm to 3.5 mm; the molecular sieve particles have a diameter of 2.2 mm to 2.8 mm and a loose bulk density of ≥0.66 g / mL; and the modified tetraneedle-shaped zinc oxide whiskers have a needle diameter of 8 μm to 20 μm.
[0014] Optionally, the doping material includes at least one selected from aluminum oxide, gallium oxide, germanium oxide, selenium oxide, tin oxide, tantalum oxide, graphene, silicon, nickel, and copper.
[0015] Optionally, the step of mixing the modified tetraneedle-shaped zinc oxide whiskers with the doped material, adding a wetting agent and a dispersant, and ball milling the mixture to obtain a doped slurry includes:
[0016] The modified tetra-needle zinc oxide whiskers and doped materials were mixed at a mass ratio of (95-99):(1-5), and then a wetting agent and a dispersant were added to obtain a mixture.
[0017] Mechanical ball milling was used, and alumina grinding balls were selected. The mixture, alumina grinding balls, and water were ball milled at a mass ratio of (1-2):(2-3):(2-3) for 15-25 hours to obtain a mixed slurry.
[0018] The wetting agent is a mixture of triethanolamine and tromethamine; the dispersant includes at least one of ammonium polyacrylate, sodium hydroxycitrate and polycarboxylate.
[0019] Optionally, the step of drying the doped slurry, crushing and sieving it, and then calcining it to obtain calcined powder material includes:
[0020] The doped slurry is dried at 80℃-90℃, crushed, sieved through a 100-200 mesh screen, and then calcined at 1050℃-1250℃ for 3-6 hours to obtain calcined powder material.
[0021] Optionally, the step of milling the calcined powder material, adding a forming agent, drying it, and then granulating it to obtain granules includes:
[0022] Zirconia beads with a particle size of 0.5 mm to 1.0 mm were used as the grinding media, and the rotation speed was controlled at 400 rpm to 800 rpm. The calcined powder material was ground for 1.0 h to 1.5 h, then a forming agent was added, and grinding continued for another 0.5 h to 1.0 h to obtain a grinding slurry. The grinding slurry was then dried at 80℃ to 90℃ for 16 h to 24 h, and then rolled granulation was performed for 15 min to 30 min to obtain granules.
[0023] The molding agent is polyvinyl alcohol modified with carboxymethyl cellulose.
[0024] Optionally, the step of pressing the granules into a target green body includes:
[0025] The granules are formed by cold isostatic pressing, wherein the pressure is 150MPa-300MPa and the holding time is 5min-15min.
[0026] Optionally, the step of performing the sintering process includes:
[0027] The target green blank is placed in a sintering furnace, and the vacuum is evacuated to a vacuum degree of 0.1Pa-0.3Pa. The temperature is increased to 500℃-700℃ at a rate of 2℃ / min-4℃ / min, and held at that temperature for 4h-8h for low-temperature sintering.
[0028] Oxygen is then introduced at a gas flow rate of 3 mL / min-10 mL / min, and the temperature is increased to 1300℃-1500℃ at a rate of 5℃ / min-7℃ / min, and held at that temperature for 8h-16h for high-temperature sintering.
[0029] Then, cool the temperature to 700℃-800℃ at a rate of 1℃ / min-3℃ / min, stop the oxygen supply, and allow it to cool naturally to room temperature.
[0030] This application also proposes an indium-free, low-density, high-conductivity RPD target product, obtained by the above-mentioned preparation method of the indium-free, low-density, high-conductivity RPD target.
[0031] This application includes at least the following beneficial effects:
[0032] This application uses tetrapter-shaped zinc oxide whiskers as the main raw material for RPD targets. Since zinc oxide is a polycrystalline one-dimensional material with disordered atomic arrangement, grain boundaries and interface defects lead to low conductivity. This is because electron scattering at grain boundaries significantly reduces the effective movement of charge carriers, thus lowering electron mobility and conductivity. In contrast, tetrapter-shaped zinc oxide whiskers are single-crystal three-dimensional materials. Unlike the defects present in polycrystalline zinc oxide, single-crystal atoms are arranged in a tightly ordered manner, with the distance between adjacent atoms being only a few angstroms, and its radius approaching the Bohr radius. Therefore, the electron orbits moving around the atomic nucleus meet and overlap. Electrons that were originally only affected by a single atomic nucleus are now simultaneously affected by multiple atomic nuclei and their electrons. Under the influence of multiple atomic and electron interactions, electrons can not only rotate around their own atomic nucleus, but some electrons can also move around another atom under orbital hybridization coupling. That is, the same electron can be shared by multiple atoms and can also move throughout the entire crystal. Due to its regular lattice structure, charge carriers in a single crystal are almost unaffected by scattering, resulting in smoother carrier migration and extremely high conductivity.
[0033] In preparing tetraneedle-shaped zinc oxide whiskers, this application uses molecular sieves as nucleating agents and introduces inert gas. The unique adsorption and sieving properties of molecular sieves provide nucleation sites for the tetraneedle-shaped zinc oxide and regulate its crystal morphology. Furthermore, the introduction of molecular sieves allows for the introduction of impurity energy levels into the band gap of the tetraneedle-shaped zinc oxide whiskers, enabling them to respond to longer wavelength photons, thus broadening their light utilization range. They also act as traps for electrons or holes, extending carrier lifetime and improving the photoelectric performance of the target material. Simultaneously, the inert gas reduces the oxygen concentration in the furnace, controlling the reduction in the diameter of the generated tetraneedle-shaped zinc oxide whiskers. This reduction in whisker diameter further reduces damage to the whiskers during the pressing and molding process in the mold.
[0034] This application prepares RPD targets by blending doped materials with modified tetra-needle zinc oxide whiskers. The doped materials do not change the tetra-needle crystal structure of zinc oxide, but help to improve the conductivity of the target, reduce the resistivity, and improve the uniformity of the coating, thereby improving the coating quality.
[0035] The target material prepared in this application can be coated with RPD film to obtain a thin film with good light transmittance and electron mobility and excellent conductivity, which can be used as an ideal choice for photovoltaic devices and high light transmittance display technology. Attached Figure Description
[0036] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.
[0037] Figure 1 is a flowchart of the preparation method of the indium-free low-density high-conductivity RPD target according to the embodiments of this application;
[0038] Figure 2 is a scanning image of the modified tetrane needle-like zinc oxide whiskers of Example 1 of this application under a 10 μm electron microscope;
[0039] Figure 3 is a scanning image of the four needle-like zinc oxide whiskers of Comparative Example 1 under a 20 μm electron microscope.
[0040] Figure 4 shows the transmittance of each group of films in different wavelength bands.
[0041] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0042] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0043] To address the technical problems existing in the prior art, embodiments of this application provide a method for preparing an indium-free, low-density, high-conductivity RPD target, comprising the following steps:
[0044] S10. Modified tetraneedle-shaped zinc oxide whiskers are prepared by using zinc as raw material, molecular sieve as nucleating agent, and inert gas through heating reaction.
[0045] In the specific implementation process, in order to improve the effective separation of photogenerated electrons and holes in the tetra-needle zinc oxide whiskers and broaden the spectral response range, this application modifies the tetra-needle zinc oxide whiskers to prepare modified tetra-needle zinc oxide whiskers. The specific steps are as follows:
[0046] Zinc granules are placed on molecular sieve particles, which are then placed at the bottom of a crucible. The crucible is then placed in a box-type resistance furnace, and an inert gas is introduced at a flow rate of 10 mL / min to 100 mL / min. The temperature is raised to 500℃ to 1100℃, and the reaction is carried out for 10 min to 25 min to obtain modified tetraneedle-shaped zinc oxide whiskers.
[0047] After the reaction is complete, the molecular sieve particles remain in the crucible. The four-needle zinc oxide whiskers are removed, and zinc particles are added in a certain amount. The temperature is raised as required to continue preparing four-needle zinc oxide whiskers. This process is repeated three times before new molecular sieve particles are added to the crucible for repeated use.
[0048] Specifically, the mass ratio of zinc particles to molecular sieve particles is 2:1; nitrogen or argon is used as the inert gas.
[0049] The zinc granules have a purity of 99% and a diameter of 2.5mm-3.5mm; the molecular sieve particles have a diameter of 2.2mm-2.8mm and a loose bulk density of ≥0.66g / mL.
[0050] Because molecular sieves possess strong polarity and a Coulomb field, they preferentially adsorb polar and unsaturated molecules, which is beneficial for the nucleation process of tetraneedle zinc oxide. Furthermore, the uniform pore size distribution of molecular sieves allows only molecules with diameters smaller than the pore size to enter the crystal cavities, influencing the nucleation density and morphology of tetraneedle zinc oxide. The channels and cavities of the molecular sieve provide ideal nucleation sites for tetraneedle zinc oxide, promoting the uniform distribution and growth of tetraneedle zinc oxide crystals. Simultaneously, the polarity and pore size of the molecular sieve interact to affect the crystal morphology of tetraneedle zinc oxide, contributing to the formation of tetraneedle zinc oxide crystals with specific properties. It can serve as a nucleating agent for tetraneedle zinc oxide. Furthermore, this application utilizes inert gas to consume some of the oxygen in the surrounding air, thereby reducing the oxygen concentration in the furnace and meeting the conditions required for the growth of tetraneedle zinc oxide whiskers. This also reduces the diameter of the generated tetraneedle zinc oxide whiskers. The reduced whisker diameter is more beneficial in minimizing damage to the whiskers during the pressing and molding process when the target material is filled into the mold. Specifically, the modified tetraneedle zinc oxide whiskers obtained in this application have a needle diameter of 8μm-35μm, which is lower than the needle diameter of tetraneedle zinc oxide whiskers prepared without the introduction of molecular sieves (35μm-200μm).
[0051] S20. The modified tetraneedle zinc oxide whiskers are mixed with the doped material, and a wetting agent and a dispersant are added. The mixture is then ball-milled to obtain a doped slurry.
[0052] In the specific implementation process, the modified tetra-needle zinc oxide whiskers and the doped material are mixed at a mass ratio of (95-99):(1-5), and then a wetting agent and a dispersant are added to obtain a mixture;
[0053] Mechanical ball milling was employed, and a material with a density of 3.9 g / cm³ was selected. 3 The mixture is ball-milled with alumina grinding balls and water at a mass ratio of (1-2):(2-3):(2-3) for 15-25 hours to obtain a mixed slurry.
[0054] The doped material includes at least one of aluminum oxide, gallium oxide, germanium oxide, selenium oxide, tin oxide, tantalum oxide, graphene, silicon, nickel, and copper.
[0055] RPD targets were prepared by mixing the above-mentioned doping materials with modified tetrapter zinc oxide whiskers. The doping materials do not change the tetrapter crystal structure of zinc oxide, but help the obtained target to have better conductivity and lower resistivity, improve coating uniformity, and improve coating quality.
[0056] Preferably, the modified tetra-needle zinc oxide whiskers are mixed with aluminum oxide, gallium oxide and graphene in a mass ratio of 97:1:2:2. The resulting target material is then subjected to RPD coating to obtain a thin film with good light transmittance and electron mobility and excellent conductivity.
[0057] Specifically, the wetting agent is a mixture of triethanolamine and tromethamine; the dispersant includes at least one of ammonium polyacrylate, sodium hydroxycitrate, and polycarboxylate.
[0058] Both triethanolamine and tromethamine contain hydroxyl and amino groups in their molecular structures, which can form an adsorption hydration layer on the surface of zinc oxide whisker powder particles. Furthermore, the combined use of triethanolamine and tromethamine can further enhance the wetting effect on the zinc oxide whisker powder by forming a "hydrogen bond"-like effect. The dispersants used are tetramethylammonium hydroxide silanolate, sodium hydroxycitrate, and polycarboxylate. Tetramethylammonium hydroxide silanolate, as a silicon-containing polymer, has a certain wetting effect on the zinc oxide whisker powder, which can enhance its dispersion. Sodium hydroxycitrate contains both hydroxyl and citrate ions. The hydroxyl groups can enhance the hydration of the zinc oxide whisker powder particles, while the citrate ions can improve the stability of the dispersion system through electrostatic stabilization. Polycarboxylate, as a high-molecular-weight dispersant, has long carbon chains, numerous active adsorption sites, and branched chains that can play a steric stabilizing role in the dispersion system, resulting in good dispersion performance.
[0059] S30. After drying the doped slurry, crush and sieve it, and then calcine it to obtain calcined powder material.
[0060] Specifically, the doped slurry is dried at 80℃-90℃, crushed, sieved through a 100-200 mesh screen, and then calcined at 1050℃-1250℃ for 3-6 hours to obtain calcined powder material.
[0061] By crushing and sieving the doped slurry, and then calcining it, the powder material can be uniformly filled into the mold during the subsequent pressing and molding process. This helps to control the molding density of the target green body, ensures the uniformity of the target structure, and thus improves the quality of the RPD film.
[0062] S40. The calcined powder material is subjected to sand milling, and a forming agent is added. After drying, it is granulated to obtain granules.
[0063] Specifically, zirconia beads with a particle size of 0.5mm-1.0mm are used as the grinding medium, and the rotation speed is controlled at 400rpm-800rpm. The calcined powder material is ground for 1.0h-1.5h, then a forming agent is added, and grinding continues for another 0.5h-1.0h to obtain a grinding slurry. The grinding slurry is then dried at 80℃-90℃ for 16h-24h, and then rolled granulation is performed for 15min-30min to obtain granules.
[0064] This application uses ball milling to eliminate soft agglomerates in tetra-needle zinc oxide whisker powder and reduce hard agglomerates, followed by sand milling to further remove hard agglomerates, and adds a forming agent to improve the flowability of the granules, which is beneficial for the pressing and forming of the target green body.
[0065] The molding agent in this application is polyvinyl alcohol modified with carboxymethyl cellulose. During target molding, the molding agent needs to impart sufficient fluidity and plasticity to the mixture to facilitate the formation of a uniform target. Introducing carboxymethyl cellulose into polyvinyl alcohol effectively increases its viscosity and rheological properties, allowing for better mixing with other components, while also enhancing stability and workability during molding. Furthermore, while polyvinyl alcohol itself has good moldability, its thermoplasticity and mechanical strength are relatively limited. The polyvinyl alcohol composite material modified with carboxymethyl cellulose provides better adhesion and lower friction during molding, promoting more uniform material distribution in the mold. Simultaneously, the introduction of carboxymethyl cellulose improves the solubility of the molding agent, making it easier to remove with water or other solvents during subsequent sintering, ensuring the purity and performance of the target.
[0066] S50. The granules are pressed into target green bodies and then sintered to obtain RPD target products.
[0067] The step of pressing the granules into a target green body includes:
[0068] The granules are formed by cold isostatic pressing, wherein the pressure is 150MPa-300MPa and the holding time is 5min-15min.
[0069] The sintering process includes:
[0070] The target green blank is placed in a sintering furnace, and the vacuum is evacuated to a vacuum degree of 0.1Pa-0.3Pa. The temperature is increased to 500℃-700℃ at a rate of 2℃ / min-4℃ / min, and held at that temperature for 4h-8h for low-temperature sintering.
[0071] Oxygen is then introduced at a gas flow rate of 3 mL / min-10 mL / min, and the temperature is increased to 1300℃-1500℃ at a rate of 5℃ / min-7℃ / min, and held at that temperature for 8h-16h for high-temperature sintering.
[0072] Then, cool the temperature to 700℃-800℃ at a rate of 1℃ / min-3℃ / min, stop the oxygen supply, and allow it to cool naturally to room temperature.
[0073] This application employs cold isostatic pressing to press the target material into shape, and then sinters the target material in a pressureless oxygen atmosphere. Furthermore, this application uses a slow heating method to ensure the stability of the target material's green body quality changes and promote the homogenization of the modified tetra-needle zinc oxide whiskers and doped materials during sintering, which helps to form a target material with a uniform structure, thereby improving the quality of the RPD film.
[0074] The embodiments of this application also provide an indium-free low-density high-conductivity RPD target product, which is obtained by the above-mentioned preparation method of indium-free low-density high-conductivity RPD target, and the relative density of the final target product is 45%-60%.
[0075] The application areas of the target material products in this application may include:
[0076] 1. In the photovoltaic industry, applications include: front electrodes in perovskite solar cells (PSCs) to provide conductivity and light transmission; transparent conductive layers in thin-film solar cells (CIGS, a-Si, etc.) to ensure light transmission and current collection; heterojunction cells and back contact cells in crystalline silicon cells (such as HJT, IBC, etc.) to enhance conductivity and efficiency; and tandem solar cells, such as perovskite / silicon tandems, to improve efficiency and optimize conductivity and light transmittance.
[0077] 2. Display and touch technologies, such as: the transparent conductive layer in OLED displays for current collection, ensuring display quality and transparency; the conductive layer in LCD displays for current distribution, maintaining screen clarity and transparency; and the electrode in touchscreens (such as smartphones and tablets) to provide touch response capabilities.
[0078] 3. Emerging technologies, such as: Quantum Dot Films, which optimize color performance and brightness to improve display effects; Flexible Displays, which support screen bending or folding while maintaining high transparency and conductivity; Smart Windows, which are used to adjust light transmittance and provide intelligent control functions (such as electrochromic windows); and Solar Window Films, which serve as integrated transparent conductive materials to generate photovoltaic power while maintaining the window's light transmittance.
[0079] 4. Automotive industry, such as: for in-vehicle displays and HUD (head-up display) systems, providing transparent electrode functionality; for heated windows to prevent frost and freezing.
[0080] The technical solutions described above in this application will be explained in detail below with reference to specific embodiments.
[0081] Example 1
[0082] A method for preparing an indium-free, low-density, high-conductivity RPD target includes the following steps:
[0083] Zinc granules were placed on molecular sieve particles, and then the molecular sieve particles were placed at the bottom of a crucible. The crucible was then placed in a box-type resistance furnace, and nitrogen gas was introduced at a flow rate of 50 mL / min. The temperature was raised to 800℃ and the reaction was carried out for 17 min to obtain modified tetraneedle-shaped zinc oxide whiskers.
[0084] The zinc granules have a purity of 99% and a diameter of 3.0 mm; the molecular sieve particles have a diameter of 2.3 mm and a loose bulk density of ≥0.66 g / mL.
[0085] The modified tetraneedle-shaped zinc oxide whiskers were mixed with aluminum oxide, gallium oxide and graphene in a mass ratio of 97:1:1:1, and then a wetting agent and a dispersant sodium hydroxycitrate were added to obtain a mixture; wherein the wetting agent was a mixture of triethanolamine and tromethamine.
[0086] Mechanical ball milling was used, and alumina grinding balls were selected. The mixture was ball milled with alumina grinding balls and water at a mass ratio of 1:2:3 for 20 hours to obtain a mixed slurry.
[0087] The doped slurry was dried at 85°C, crushed, sieved through a 150-mesh sieve, and then calcined at 1150°C for 4.5 hours to obtain calcined powder material.
[0088] Zirconia beads with a particle size of 0.7 mm were used as the grinding media, and the rotation speed was controlled at 600 rpm. The calcined powder material was ground for 1.2 h, then a forming agent was added, and grinding continued for another 0.7 h to obtain a grinding slurry. The grinding slurry was then dried at 85°C for 20 h, and then rolled granulation was performed for 22 min to obtain granules. The forming agent was polyvinyl alcohol modified with carboxymethyl cellulose.
[0089] The granules were formed by cold isostatic pressing at a pressure of 220 MPa for a holding time of 10 min to obtain a target green.
[0090] The target green blank is placed in a sintering furnace, the vacuum is evacuated to a vacuum degree of 0.2 Pa, the temperature is increased to 600°C at a rate of 3°C / min, and held at that temperature for 6 hours for low-temperature sintering.
[0091] Oxygen was then introduced at a gas flow rate of 6 mL / min, and the temperature was increased to 1350℃ at a rate of 6℃ / min, held for 12 hours, and then subjected to high-temperature sintering.
[0092] After cooling to 750℃ at a rate of 2℃ / min, the oxygen supply is stopped, and the material is allowed to cool naturally to room temperature to obtain the RPD target product.
[0093] Example 2
[0094] A method for preparing an indium-free, low-density, high-conductivity RPD target includes the following steps:
[0095] Zinc granules were placed on molecular sieve particles, and then the molecular sieve particles were placed at the bottom of a crucible. The crucible was then placed in a box-type resistance furnace, and argon gas was introduced at a flow rate of 10 mL / min. The temperature was raised to 960℃ and the reaction was carried out for 25 min to obtain modified tetraneedle-shaped zinc oxide whiskers.
[0096] The zinc granules have a purity of 99% and a diameter of 2.5 mm; the molecular sieve particles have a diameter of 2.2 mm and a loose bulk density of ≥0.66 g / mL.
[0097] The modified tetrane-shaped zinc oxide whiskers and alumina were mixed at a mass ratio of 96:4, and then a wetting agent and a dispersant, ammonium polyacrylate, were added to obtain a mixture; wherein the wetting agent was a mixture of triethanolamine and tromethamine.
[0098] Mechanical ball milling was used, and alumina grinding balls were selected. The mixture was ball milled with alumina grinding balls and water at a mass ratio of 2:2:2 for 15 hours to obtain a mixed slurry.
[0099] The doped slurry was dried at 80°C, crushed, sieved through a 100-mesh sieve, and then calcined at 1050°C for 6 hours to obtain calcined powder material.
[0100] Zirconia beads with a particle size of 0.5 mm were used as the grinding media, and the rotation speed was controlled at 400 rpm. The calcined powder material was ground for 1.0 h, and then a forming agent was added. The grinding was continued for another 0.5 h to obtain a grinding slurry. The grinding slurry was then dried at 80°C for 24 h and then rolled granulation was performed for 15 min to obtain granules. The forming agent was polyvinyl alcohol modified with carboxymethyl cellulose.
[0101] The granules were formed by cold isostatic pressing at a pressure of 150 MPa and a holding time of 15 min to obtain a target green.
[0102] The target green blank is placed in a sintering furnace, evacuated to a vacuum degree of 0.1 Pa, heated to 500 °C at a rate of 2 °C / min, and held at that temperature for 8 hours for low-temperature sintering.
[0103] Oxygen was then introduced at a gas flow rate of 3 mL / min, and the temperature was increased to 1300℃ at a rate of 5℃ / min, held for 16 hours, and then subjected to high-temperature sintering.
[0104] After cooling to 700℃ at a rate of 1℃ / min, the oxygen supply is stopped, and the material is allowed to cool naturally to room temperature to obtain the RPD target product.
[0105] Example 3
[0106] A method for preparing an indium-free, low-density, high-conductivity RPD target includes the following steps:
[0107] Zinc granules were placed on molecular sieve particles, and then the molecular sieve particles were placed at the bottom of a crucible. The crucible was then placed in a box-type resistance furnace, and nitrogen gas was introduced at a flow rate of 100 mL / min. The temperature was raised to 1100℃ and the reaction was carried out for 25 min to obtain modified tetraneedle-shaped zinc oxide whiskers.
[0108] The zinc granules have a purity of 99% and a diameter of 3.5 mm; the molecular sieve particles have a diameter of 2.8 mm and a loose bulk density of ≥0.66 g / mL.
[0109] The modified tetra-needle zinc oxide whiskers were mixed with gallium oxide and germanium oxide at a mass ratio of 96:2:2, and then a wetting agent and a dispersant polycarboxylate were added to obtain a mixture; wherein the wetting agent was a mixture of triethanolamine and tromethamine.
[0110] Mechanical ball milling was used, and alumina grinding balls were selected. The mixture was ball milled with alumina grinding balls and water at a mass ratio of 1:3:3 for 25 hours to obtain a mixed slurry.
[0111] The doped slurry was dried at 90°C, crushed, sieved through a 200-mesh sieve, and then calcined at 1250°C for 3 hours to obtain calcined powder material.
[0112] Zirconia beads with a particle size of 1.0 mm were used as the grinding media, and the rotation speed was controlled at 800 rpm. The calcined powder material was ground for 1.0 h, and then a forming agent was added. The grinding was continued for another 1.0 h to obtain a grinding slurry. The grinding slurry was then dried at 90°C for 16 h, and then rolled and granulated for 30 min to obtain granules. The forming agent was polyvinyl alcohol modified with carboxymethyl cellulose.
[0113] The granules were formed by cold isostatic pressing at a pressure of 300 MPa and a holding time of 5 min to obtain a target green.
[0114] The target green blank is placed in a sintering furnace, the vacuum is evacuated to a vacuum degree of 0.3 Pa, the temperature is raised to 700°C at a rate of 4°C / min, and held at that temperature for 4 hours for low-temperature sintering.
[0115] Oxygen was then introduced at a gas flow rate of 10 mL / min, and the temperature was increased to 1500℃ at a rate of 7℃ / min, held for 8 hours, and then subjected to high-temperature sintering.
[0116] After cooling to 800℃ at a rate of 3℃ / min, the oxygen supply is stopped, and the material is allowed to cool naturally to room temperature to obtain the RPD target product.
[0117] Comparative Example 1
[0118] A method for preparing an indium-free, low-density, high-conductivity RPD target includes the following steps:
[0119] After placing the zinc granules at the bottom of the crucible, it was placed in a box-type resistance furnace, heated to 800℃, and reacted for 17 minutes to obtain four needle-like zinc oxide whiskers.
[0120] The subsequent steps are the same as in Example 1.
[0121] Comparative Example 2
[0122] Compared to Example 1, the modified tetraneedle zinc oxide whiskers were replaced with zinc oxide, while the other steps remained the same.
[0123] Experimental Example 1
[0124] The modified tetra-needle zinc oxide whiskers of Example 1 and the tetra-needle zinc oxide whiskers of Comparative Example 1 were subjected to electron microscopy to observe their microstructure, and the electron microscopy scan images shown in Figure 2 and Figure 3 were obtained. Figure 2 is the scan image of the modified tetra-needle zinc oxide whiskers of Example 1 under a 10 μm electron microscope, and Figure 3 is the scan image of the tetra-needle zinc oxide whiskers of Comparative Example 1 under a 20 μm electron microscope.
[0125] As shown in Figures 2 and 3, Pa and R represent different whisker groups, Pa represents the microscopic diameter of each whisker group, and Pb represents the included angle of each whisker group. In Figure 2, the lowest microscopic diameter of the whisker group is 8.990 μm, and the highest is 32.10 μm. In Figure 3, the lowest microscopic diameter of the whisker group is 37.75 μm, and the highest is 56.44 μm. It can be seen that this application uses molecular sieves as nucleating agents and introduces inert gas to reduce the oxygen concentration, resulting in modified tetraneedle-shaped zinc oxide whiskers with smaller needle diameters. The smaller diameter whiskers are more beneficial in reducing damage to the needles during target pressing.
[0126] Experiment Example 2
[0127] The RPD target material in Example 1 and the RPD target material in Comparative Example 2 were subjected to reactive plasma coating, while a control group (using ordinary tin oxide for reactive plasma coating) was set up.
[0128] The specific coating steps are as follows: Place each group of target materials in the water-cooled crucible of the RPD equipment, use white glass as the sample substrate, and evacuate the vacuum pressure to 0.5 × 10⁻⁶. -3 A mixture of argon and oxygen was introduced, with an oxygen flow rate of 80 sccm and a content of 20%. After filling, the cavity pressure was 0.5 Pa, and the current was 140 A. The electron gun rotation and tilt angles were adjusted to focus the plasma beam onto the target surface for stable ignition, and coating began, resulting in three different thin films. The transmittance, sheet resistance, and carrier mobility of each group of films were tested at different wavelengths. The test results are shown in Figure 4 and Table 1 below.
[0129] Table 1
[0130] As shown in Figure 4 and Table 1, the thin film prepared by the RPD target in Example 1 of this application has an electron mobility of 26.8 cm⁻¹. 2 The sheet resistance of the film prepared in Example 1 is higher than that of the zinc oxide-based film in Comparative Example 2 and the tin oxide-based film in the control group, and the sheet resistance of the film prepared in Example 1 is only 18.2 Ω / m. 2The transmittance of the film in Example 1 is significantly lower than that of the other two films, indicating that the film exhibits excellent conductivity. Furthermore, the film in Example 1 demonstrates stable transmittance in the short-wavelength range of 300nm-400nm and the long-wavelength range of 800nm, with an average transmittance of 81.09% in the 200nm-800nm range, which is also higher than that of the other two films. Therefore, RPD deposition of the target material prepared in this application can yield a film with good light transmittance and electron mobility, as well as excellent conductivity.
[0131] The above are merely optional embodiments of this application and do not limit the patent scope of this application. Any equivalent structural transformations made based on the inventive concept of this application and the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.
Claims
1. A method for preparing an indium-free, low-density, high-conductivity RPD target, characterized in that, Includes the following steps: Modified tetraneedle-shaped zinc oxide whiskers were prepared by using zinc as raw material, molecular sieve as nucleating agent, and inert gas through heating reaction. The modified tetra-needle zinc oxide whiskers were mixed with the doped material, and a wetting agent and a dispersant were added. The mixture was then ball-milled to obtain a doped slurry. After drying the doped slurry, it is crushed, sieved, and then calcined to obtain calcined powder material. The calcined powder material is subjected to sand milling, and a forming agent is added. After drying, it is granulated to obtain granules. The granules are pressed into target green bodies and then sintered to obtain RPD target products.
2. The method for preparing the indium-free, low-density, high-conductivity RPD target according to claim 1, characterized in that, The step of preparing modified tetraneedle-shaped zinc oxide whiskers by using zinc as raw material, molecular sieve as nucleating agent, and introducing inert gas through heating reaction includes: Zinc granules were placed on molecular sieve particles and then placed in a box-type resistance furnace. Inert gas was introduced at a flow rate of 10 mL / min to 100 mL / min, and the temperature was raised to 500℃ to 1100℃. After reacting for 10 min to 25 min, modified tetraneedle-shaped zinc oxide whiskers were obtained.
3. The method for preparing the indium-free, low-density, high-conductivity RPD target according to claim 2, characterized in that, The zinc granules have a purity of 99% and a diameter of 2.5 mm to 3.5 mm; the molecular sieve particles have a diameter of 2.2 mm to 2.8 mm and a loose bulk density of ≥0.66 g / mL; the modified tetraneedle-shaped zinc oxide whiskers have a needle diameter of 8 μm to 20 μm.
4. The method for preparing the indium-free, low-density, high-conductivity RPD target according to claim 1, characterized in that, The doped material includes at least one of aluminum oxide, gallium oxide, germanium oxide, selenium oxide, tin oxide, tantalum oxide, graphene, silicon, nickel, and copper.
5. The method for preparing the indium-free, low-density, high-conductivity RPD target according to claim 4, characterized in that, The step of mixing the modified tetra-needle-shaped zinc oxide whiskers with the doped material, adding a wetting agent and a dispersant, and ball milling the mixture to obtain a doped slurry includes: The modified tetra-needle zinc oxide whiskers and doped materials were mixed at a mass ratio of (95-99):(1-5), and then a wetting agent and a dispersant were added to obtain a mixture. Mechanical ball milling was used, and alumina grinding balls were selected. The mixture, alumina grinding balls, and water were ball milled at a mass ratio of (1-2):(2-3):(2-3) for 15-25 hours to obtain a mixed slurry. The wetting agent is a mixture of triethanolamine and tromethamine; the dispersant includes at least one of ammonium polyacrylate, sodium hydroxycitrate and polycarboxylate.
6. The method for preparing the indium-free, low-density, high-conductivity RPD target according to claim 1, characterized in that, The step of drying the doped slurry, crushing and sieving it, and then calcining it to obtain calcined powder material includes: The doped slurry is dried at 80℃-90℃, crushed, sieved through a 100-200 mesh screen, and then calcined at 1050℃-1250℃ for 3-6 hours to obtain calcined powder material.
7. The method for preparing the indium-free, low-density, high-conductivity RPD target according to claim 1, characterized in that, The steps of milling the calcined powder material, adding a forming agent, drying it, and then granulating it to obtain granules include: Zirconia beads with a particle size of 0.5 mm to 1.0 mm were used as the grinding media, and the rotation speed was controlled at 400 rpm to 800 rpm. The calcined powder material was ground for 1.0 h to 1.5 h, then a forming agent was added, and grinding continued for another 0.5 h to 1.0 h to obtain a grinding slurry. The grinding slurry was then dried at 80℃ to 90℃ for 16 h to 24 h, and then rolled granulation was performed for 15 min to 30 min to obtain granules. The molding agent is polyvinyl alcohol modified with carboxymethyl cellulose.
8. The method for preparing the indium-free, low-density, high-conductivity RPD target according to claim 1, characterized in that, The step of pressing the granules into a target green body includes: The granules are formed by cold isostatic pressing, wherein the pressure is 150MPa-300MPa and the holding time is 5min-15min.
9. The method for preparing the indium-free, low-density, high-conductivity RPD target according to claim 1, characterized in that, The sintering process includes: The target green blank is placed in a sintering furnace, and the vacuum is evacuated to a vacuum degree of 0.1Pa-0.3Pa. The temperature is increased to 500℃-700℃ at a rate of 2℃ / min-4℃ / min, and held at that temperature for 4h-8h for low-temperature sintering. Oxygen is then introduced at a gas flow rate of 3 mL / min-10 mL / min, and the temperature is increased to 1300℃-1500℃ at a rate of 5℃ / min-7℃ / min, and held at that temperature for 8h-16h for high-temperature sintering. Then, cool the temperature to 700℃-800℃ at a rate of 1℃ / min-3℃ / min, stop the oxygen supply, and allow it to cool naturally to room temperature.
10. An indium-free, low-density, high-conductivity RPD target product, characterized in that, The indium-free, low-density, high-conductivity RPD target was prepared using the method described in any one of claims 1-9.