Indium titanium cerium niobium oxide ceramic target material, preparation method and application thereof, and transparent conductive oxide film

Abstract

The application discloses an indium-titanium-cerium-niobium oxide ceramic target material and a preparation method and application thereof, and a transparent conductive oxide film, and realizes uniform complexation and inorganic conversion of a precursor by means of EDTA-glycerol complexation and Fe(III)-citric acid / H2O2 free radical in-situ oxidation system, and high-density, high-strength and low-resistivity target material is prepared by adopting a two-stage atmosphere sintering process. ‑4 The relative density of the obtained target material is greater than or equal to 99.5%, the resistivity is less than or equal to 3.5*10 ‑4 Ω*cm, the square resistance of a sputtered film is less than or equal to 8 Ω / sq, and the transmittance is greater than or equal to 88.3%, and the target material is suitable for preparation of a high-performance photovoltaic transparent conductive layer.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic target technology, specifically relating to an indium titanium oxide cerium niobium ceramic target, its preparation method and application, and a transparent conductive oxide thin film. Background Technology

[0002] With the rapid development of the photovoltaic industry, especially the increasingly prominent dominance of heterojunction solar cells in the market, transparent conductive oxide (TCO) thin films, as key components, have seen their performance optimization become a core driving force for improving photoelectric conversion efficiency. Traditionally, indium tin oxide (ITO) targets have been the dominant material, and thin films prepared by magnetron sputtering or reactive sputtering have been widely used in flat panel displays, liquid crystal displays, and photovoltaic devices. However, with the increasing scarcity of indium resources and cost pressures, researchers have turned to developing indium-based alternative TCO materials, such as enhancing infrared transmittance and carrier mobility by doping with elements like tungsten oxide (WO3), cerium oxide (CeO2), or zirconium oxide (ZrO2). These doping strategies are based on defect engineering principles, utilizing dopant ions to control oxygen vacancy concentration and lattice structure, thereby improving the transparency of the thin film in the visible to near-infrared band and significantly increasing mobility. In recent years, multi-element synergistic doping has become a hot topic. For example, the introduction of titanium (Ti), cerium (Ce), and niobium (Nb) to form In-Ti-Ce-Nb-O composite targets has significantly reduced the preparation temperature and shortened the sintering time through liquid-phase assisted sintering and microwave heating techniques. These materials exhibit excellent thermal stability and mechanical strength in photovoltaic applications, making them suitable for large-size sputtering coatings. Related research shows that this multi-doped target can reduce the resistivity of TCO thin films while maintaining high transmittance, supporting further breakthroughs in heterojunction cell efficiency.

[0003] Despite significant progress in TCO sputtering technology, existing preparation methods still have many limitations, particularly the bottlenecks in practical applications caused by insufficient density and strength. Traditional single-element doped sputtering targets have low density and limited bending strength, making them unable to withstand the thermal stress and mechanical impact under high-power sputtering, easily leading to target cracking or uneven film deposition, thus limiting the industrialization of large-size photovoltaic coatings. More critically, in the ball milling process of powder metallurgy preparation, as a core step of mechanical alloying, although it promotes the uniform mixing of multi-component powders through shear and impact forces, it inevitably introduces the problem of media wear contamination. Zirconia (ZrO2) beads are commonly used as ball milling media, and their wear releases Zr. 4+ Ions enter the slurry, and these heterovalent ions are relative to In 3+ Ce 4+ Ti 4+ and Nb 5+Matrix ions can embed into the In₂O₃ lattice, forming substitutional defects or interstitial sites, inducing lattice distortion and point defect clusters. This defect mechanism enhances carrier scattering, significantly reduces Hall mobility of the thin film, and weakens infrared transmittance and conductivity stability, especially amplifying light absorption losses in heterojunction cells. Furthermore, ball milling contamination can trigger phase separation or excessive oxygen vacancy generation, further deteriorating the thermal stability of the target material and the photoelectric properties of the thin film, leading to an overall reduction in photovoltaic device efficiency. These shortcomings highlight the urgent need to optimize the ball milling process and reduce impurity introduction to achieve breakthroughs in high-purity, high-density target materials. Summary of the Invention

[0004] This application provides a method for preparing an indium titanium oxide cerium niobium ceramic target, comprising the following steps:

[0005] Step S1. Dissolve the indium source compound, titanium source compound, cerium source compound, and niobium source compound in a solution containing an aminocarboxylic acid-polyol complexing agent to form a stable organic complex solution, wherein the mass ratio of the indium source compound, titanium source compound, cerium source compound, and niobium source compound is (97.5-98.5):(0.5-0.9):(0.4-0.8):(0.3-0.7).

[0006] Step S2. Add an oxygen-containing free radical in-situ generation system composed of hydrogen peroxide, citric acid and ferric salt to the organic complex solution, so that the ferric salt and citric acid form Fe(III)- complex complex, and generate hydroxyl radicals under heating conditions to obtain the treated indium titanium cerium niobium precursor sol.

[0007] Step S3. After drying the precursor sol obtained in step S2, calcine it in an oxygen atmosphere to 550-650°C to obtain high-purity indium titanium oxide cerium niobium nanopowder.

[0008] Step S4. The indium titanium oxide cerium niobium nanopowder obtained in step S3 is pre-pressed and cold isostatically pressed, and then sintered in a two-stage atmosphere sintering system to obtain indium titanium oxide cerium niobium ceramic target material.

[0009] It should be noted that in step S1, indium, titanium, cerium, and niobium sources are stably chelated in a mass ratio of 97.5–98.5:0.5–0.9:0.4–0.8:0.3–0.7 using an aminocarboxylic acid-polyol composite complexing agent, forming a molecularly uniform three-dimensional organic complex network. This prevents the hydrolysis and precipitation of high-valence metal ions and ensures the atomic-level distribution of dopant elements. In step S2, a Fe(III)-citric acid / H2O2-type Fenton system is introduced. Under heating, hydroxyl radicals are generated in situ to precisely oxidize and break the CC / CH bonds of organic ligands, promoting the transformation of the precursor into the MOM inorganic network while avoiding carbon residue and excessive oxidation damage. Metal-oxygen bond; after drying in step S3, calcination is carried out in an oxygen atmosphere at 550-650℃. Sufficient oxygen is used to completely burn off residual organic matter and trigger low-temperature crystallization of the In2O3 cubic phase, controlling the grain size at the nanoscale to retain high sintering activity; after pre-pressing-cold isostatic pressing in step S4, two-stage atmosphere sintering is adopted. First, oxygen vacancies are activated in a low oxygen partial pressure reducing environment to increase the carrier concentration and remove pores through grain boundary diffusion. Then, some oxygen vacancies are backfilled in a weak oxidation high temperature section to repair grain boundary defects and activate bulk diffusion to achieve intracrystalline densification. Finally, indium titanium cerium niobium ceramic target material with high density, high strength and low resistivity is obtained.

[0010] In a preferred embodiment of a method for preparing an indium titanium oxide cerium niobium ceramic target, the aminocarboxylic acid-polyol composite complexing agent is composed of ethylenediaminetetraacetic acid (EDTA) and glycerol in a molar ratio of 1:(2.5-3.5).

[0011] It should be noted that when EDTA and glycerol are combined in a molar ratio of 1:2.5 to 3.5, EDTA hexadecimal chelates high-valence metal ions to prevent precipitation, while the trihydroxyl groups of glycerol form a hydrogen bond network to increase sol viscosity and provide spatial shielding. This dual action forms a three-dimensional cage-like complex structure, ensuring that the multiple components are uniformly distributed at the molecular level and inhibiting local hydrolysis, thus providing a stable precursor for subsequent free radical oxidation and low-temperature crystallization.

[0012] In a preferred embodiment of a method for preparing an indium titanium oxide cerium niobium ceramic target, the indium source compound, titanium source compound, cerium source compound, and niobium source compound are independently selected from one or two of their respective nitrates or chlorides.

[0013] It should be noted that when nitrates or chlorides are used as the metal source, thermal decomposition only produces volatile gases (NO). x (or HCl), without introducing residual sulfur impurities from sulfates or SO4 with high decomposition temperatures. 2- This eliminates lattice defects and second phases at the source, ensuring high purity and low resistivity of the target material.

[0014] In a preferred technical solution for the preparation of indium titanium oxide cerium niobium ceramic target, the Fe(Ⅲ)-complex in step S2 is formed by mixing Fe(NO3)3 with citric acid in a molar ratio of 1:(1.5-2.5), and the amount added is 0.05-0.3 wt% of the mass of the organic complex solution.

[0015] It should be noted that Fe(NO3)3 and citric acid form a multidentate complex at a molar ratio of 1:1.5–2.5, which reduces the Fe... 3 + / Fe 2+ Potential is used to control the decomposition rate of H2O2. A small amount (0.05-0.3 wt%) is added to catalyze the generation of an appropriate amount of •OH free radicals, which precisely cleaves the CC / CH bonds of organic ligands, avoiding excessive oxidation and damage to the MOM network. At the same time, Fe is finally released in gaseous form without residue.

[0016] In a preferred embodiment of a method for preparing an indium titanium oxide cerium niobium ceramic target, the heating conditions in step S2 are 70–90°C for 20–40 minutes.

[0017] It should be noted that heating at 70–90°C for 20–40 minutes is within the H2O2 active decomposition window. The temperature is sufficient to activate the Fenton-like reaction but below the solvent boiling point to avoid complex disintegration or sol volatilization. Time control ensures that the organic matter is completely broken, while preventing secondary hydrolysis of metal ions, thus achieving a dynamic balance between complete oxidation and structural stability.

[0018] In a preferred technical solution for the preparation of indium titanium oxide cerium niobium ceramic target, the calcination process in step S3 is carried out under the condition of oxygen flow rate of 0.8 to 1.5 L / min, heating rate of 2 to 5 °C / min, and holding time of 1 to 3 hours.

[0019] It should be noted that an oxygen flow rate of 0.8–1.5 L / min ensures sufficient oxygen for the combustion reaction and eliminates organic matter to generate CO2↑; a heating rate of 2–5 °C / min achieves gradient pyrolysis to avoid instantaneous gas bursts that could cause powder splashing; holding at 550–650 °C for 1–3 hours completes the In2O3 cubic phase crystallization while inhibiting grain growth, resulting in highly active nanoparticles.

[0020] As a preferred technical solution for the preparation method of indium titanium oxide cerium niobium ceramic target, the two-stage atmosphere sintering in step S4 includes: the first stage is an argon-hydrogen mixed atmosphere with an oxygen partial pressure of 10. -5 ~10 -6 Atm, temperature 1100~1300℃; the second stage is an oxygen-argon mixed atmosphere, oxygen partial pressure 10. -2 ~10 -3 atm, temperature 1300~1500℃.

[0021] It should be noted that the first stage of Ar-H2 low oxygen partial pressure (10 -5 ~10 -6 (atm) +1100~1300℃ induces oxygen vacancies to form, increasing carrier concentration, while grain boundary diffusion releases open pores; the second stage is O2-Ar weak oxidation (10 -2 ~10 -3 (atm) +1300~1500℃ partially backfills oxygen vacancies to repair dangling bonds, high temperature activates stereo diffusion to achieve intracrystalline densification, and dual-stage synergistic optimization of conductivity and mechanical properties.

[0022] A preferred technical solution for preparing an indium titanium oxide cerium niobium ceramic target material is provided, wherein the target material has a relative density ≥99.5%, a flexural strength ≥220MPa, and a resistivity ≤3.5×10⁻⁶. -4 Ω·cm.

[0023] In addition, this application provides an application of indium titanium oxide cerium niobium ceramic target material in the photovoltaic industry, which is used to prepare a transparent conductive layer with high mobility and high transmittance. Under AM1.5 illumination, the sheet resistance of the thin film is ≤8 Ω / sq and the average transmittance of visible light is ≥88.3%.

[0024] It should be noted that the target sputtered thin film has a lower resistivity of ≤8 Ω / sq at AM1.5 due to high carrier concentration and mobility, and a visible light transmittance of ≥88% due to bandgap blue shift and low defect scattering. 4+ / Ce 3+ Variable valence buffer photogenerated carrier recombination significantly improves the efficiency and stability of the transparent conductive layer of photovoltaic cells.

[0025] Finally, this application provides a transparent conductive oxide thin film, which is prepared by DC magnetron sputtering of the above-mentioned indium titanium oxide cerium niobium ceramic target.

[0026] This invention utilizes an aminocarboxylic acid-polyol composite complex system composed of ethylenediaminetetraacetic acid (EDTA) and glycerol, and introduces an in-situ oxidation system of Fe(III)-citric acid / H₂O₂ radicals. This achieves molecular-level uniform complexation of metal ions and complete inorganic transformation of the precursor. Combined with a two-stage atmosphere sintering process, the target material can achieve high densification and uniform grain growth at low temperatures. The resulting indium titanium oxide cerium niobium ceramic target material has a relative density ≥99.5%, flexural strength ≥220 MPa, and resistivity ≤3.5×10⁻⁶. -4With excellent Ω·cm performance, the sheet resistance of the sputtered transparent conductive oxide film is ≤8 Ω / sq and the average transmittance is ≥88.3%. This method effectively overcomes the problems of impurity contamination, high porosity and poor conductivity of traditional ball milling methods, and achieves a unity of high purity, high strength and high photoelectric performance, significantly improving the application stability of the target material and the photoelectric conversion efficiency of the film. Attached Figure Description

[0027] Figure 1 The FTIR spectra before and after heating in step S2 of Example 1 are shown.

[0028] Figure 2 Before and after heating in step S2 of Example 1 1 H NMR spectrum. Detailed Implementation

[0029] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0030] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0031] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.

[0032] Example

[0033] Example 1

[0034] This embodiment provides a method for preparing an indium titanium oxide cerium niobium ceramic target, the specific steps of which include the following:

[0035] Step S1: Dissolve indium nitrate, titanium nitrate, cerium nitrate and niobium nitrate in a mass ratio of 97.5:0.5:0.4:0.3 in a solution containing a complex complexing agent of ethylenediaminetetraacetic acid (EDTA) and glycerol (molar ratio 1:2.5) to form a stable organic complex solution.

[0036] Step S2: First, Fe(NO3)3 and citric acid are mixed at a molar ratio of 1:1.5 and stirred at room temperature for 10 minutes to form a Fe(III)-citric acid complex. Then, the complex is added to the solution obtained in step S1 at 0.05 wt% of the organic complex solution mass. Finally, 30 wt% H2O2 (H2O2:Fe molar ratio 10:1) is slowly added dropwise, and the mixture is heated at 70°C for 20 minutes to generate hydroxyl radicals, thus obtaining the treated indium titanium oxide cerium niobium precursor sol.

[0037] Step S3: After drying the precursor sol obtained in step S2, calcine it to 550°C at a heating rate of 2°C / min under an oxygen flow rate of 0.8 L / min, and hold it at that temperature for 1 hour to obtain high-purity indium titanium oxide cerium niobium nanopowder.

[0038] Step S4: The indium titanium oxide cerium niobium nanopowder obtained in step S3 is pre-pressed and cold isostatically pressed, and then sintered in a two-stage atmosphere sintering system. The first stage is an argon-hydrogen mixed atmosphere with an oxygen partial pressure of 10. -5 Atm, temperature 1100℃; the second stage is an oxygen-argon mixed atmosphere, oxygen partial pressure 10. -2 Indium titanium oxide cerium niobium ceramic target material was obtained by applying atm and heating at 1300℃.

[0039] Example 2

[0040] This embodiment provides a method for preparing an indium titanium oxide cerium niobium ceramic target, the specific steps of which include the following:

[0041] Step S1: Dissolve indium chloride, titanium chloride, cerium chloride and niobium chloride in a mass ratio of 98:0.7:0.6:0.5 in a solution containing a complex complexing agent of ethylenediaminetetraacetic acid (EDTA) and glycerol (molar ratio 1:3) to form a stable organic complex solution.

[0042] Step S2: First, Fe(NO3)3 and citric acid are mixed at a molar ratio of 1:2 and stirred at room temperature for 20 minutes to form a Fe(III)-citric acid complex. Then, the complex is added to the solution obtained in step S1 at 0.1 wt% of the mass of the organic complex solution. Finally, 30 wt% H2O2 (H2O2:Fe molar ratio 15:1) is slowly added dropwise, and the mixture is heated at 80°C for 30 minutes to generate hydroxyl radicals, thus obtaining the treated indium titanium oxide cerium niobium precursor sol.

[0043] Step S3: After drying the precursor sol obtained in step S2, calcine it to 600℃ at a heating rate of 3℃ / min under the condition of oxygen flow rate of 1 L / min, and hold it at that temperature for 2 hours to obtain high-purity indium titanium oxide cerium niobium nanopowder.

[0044] Step S4: The indium titanium oxide cerium niobium nanopowder obtained in step S3 is pre-pressed and cold isostatically pressed, and then sintered in a two-stage atmosphere sintering system. The first stage is an argon-hydrogen mixed atmosphere with an oxygen partial pressure of 5 × 10⁻⁶. -6 Atm, temperature 1200℃; the second stage is an oxygen-argon mixed atmosphere, oxygen partial pressure 5×10⁻⁶. -3 Indium titanium oxide cerium niobium ceramic target material was obtained by applying an atm and heating to a temperature of 1400℃.

[0045] Example 3

[0046] This embodiment provides a method for preparing an indium titanium oxide cerium niobium ceramic target, the specific steps of which include the following:

[0047] Step S1: Dissolve indium nitrate, titanium chloride, cerium nitrate and niobium chloride in a mass ratio of 98.5:0.9:0.8:0.7 in a solution containing a complex complexing agent of ethylenediaminetetraacetic acid (EDTA) and glycerol (molar ratio 1:3.5) to form a stable organic complex solution.

[0048] Step S2: First, Fe(NO3)3 and citric acid are mixed at a molar ratio of 1:2.5 and stirred at room temperature for 30 minutes to form a Fe(III)-citric acid complex. Then, the complex is added to the solution obtained in step S1 at 0.3 wt% of the mass of the organic complex solution. Finally, 30 wt% H2O2 (H2O2:Fe molar ratio 20:1) is slowly added dropwise, and the mixture is heated at 90°C for 40 minutes to generate hydroxyl radicals, thus obtaining the treated indium titanium oxide cerium niobium precursor sol.

[0049] Step S3: After drying the precursor sol obtained in step S2, calcine it to 650°C at a heating rate of 5°C / min under an oxygen flow rate of 1.5 L / min, and hold it at that temperature for 3 hours to obtain high-purity indium titanium oxide cerium niobium nanopowder.

[0050] Step S4: The indium titanium oxide cerium niobium nanopowder obtained in step S3 is pre-pressed and cold isostatically pressed, and then sintered in a two-stage atmosphere sintering system. The first stage is an argon-hydrogen mixed atmosphere with an oxygen partial pressure of 10. -6 Atm, temperature 1300℃; the second stage is an oxygen-argon mixed atmosphere, oxygen partial pressure 10. -3 Indium titanium oxide cerium niobium ceramic target material was obtained by applying atm and heating at 1500℃.

[0051] Example 4

[0052] This embodiment provides a method for preparing an indium titanium oxide cerium niobium ceramic target, the specific steps of which include the following:

[0053] Step S1: Dissolve indium chloride, titanium nitrate, cerium chloride and niobium nitrate in a mass ratio of 98.2:0.6:0.5:0.4 in a solution containing a complex complexing agent of ethylenediaminetetraacetic acid (EDTA) and glycerol (molar ratio 1:2.8) to form a stable organic complex solution.

[0054] Step S2: First, Fe(NO3)3 and citric acid are mixed at a molar ratio of 1:1.8 and stirred at room temperature for 15 minutes to form a Fe(III)-citric acid complex. Then, the complex is added to the solution obtained in step S1 at 0.2 wt% of the mass of the organic complex solution. Finally, 30 wt% H2O2 (H2O2:Fe molar ratio 12:1) is slowly added dropwise, and the mixture is heated at 75°C for 25 minutes to generate hydroxyl radicals, thus obtaining the treated indium titanium oxide cerium niobium precursor sol.

[0055] Step S3: After drying the precursor sol obtained in step S2, calcine it to 575°C at a heating rate of 4°C / min under an oxygen flow rate of 1.2 L / min, and hold it at that temperature for 1.5 hours to obtain high-purity indium titanium oxide cerium niobium nanopowder.

[0056] Step S4: The indium titanium oxide cerium niobium nanopowder obtained in step S3 is pre-pressed and cold isostatically pressed, and then sintered in a two-stage atmosphere sintering system. The first stage is an argon-hydrogen mixed atmosphere with an oxygen partial pressure of 2 × 10⁻⁶. -5.5 Atm, temperature 1150℃; the second stage is an oxygen-argon mixed atmosphere, oxygen partial pressure 2×10⁻⁶. -2.5 Indium titanium oxide cerium niobium ceramic target material was obtained by applying atm and heating at 1350℃.

[0057] Comparison Example

[0058] Compare with Example 1

[0059] This comparative example provides a method for preparing an indium titanium oxide cerium niobium ceramic target, the specific steps of which include the following:

[0060] Step S1: Dissolve indium nitrate, titanium nitrate, cerium nitrate and niobium nitrate in a mass ratio of 97.5:0.5:0.4:0.3 in a solution containing a complex complexing agent of ethylenediaminetetraacetic acid (EDTA) and glycerol (molar ratio 1:2.5) to form a stable organic complex solution.

[0061] Step S2: Without adding any oxygen-containing free radical generation system to the organic complex solution, heat directly at 70°C for 20 minutes to obtain indium titanium oxide cerium niobium precursor sol (without hydroxyl radical cleavage of organic ligands).

[0062] Step S3: After drying the precursor sol obtained in step S2, calcine it to 550°C at a heating rate of 2°C / min under an oxygen flow rate of 0.8 L / min, and hold it at that temperature for 1 hour to obtain indium titanium oxide cerium niobium nanopowder.

[0063] Step S4: The indium titanium oxide cerium niobium nanopowder obtained in step S3 is pre-pressed and cold isostatically pressed, and then sintered in a two-stage atmosphere sintering system. The first stage is an argon-hydrogen mixed atmosphere with an oxygen partial pressure of 10. -5 Atm, temperature 1100℃; the second stage is an oxygen-argon mixed atmosphere, oxygen partial pressure 10. -2 Indium titanium oxide cerium niobium ceramic target material was obtained by applying atm and heating at 1300℃.

[0064] Compare with Example 2

[0065] This comparative example provides a method for preparing an indium titanium oxide cerium niobium ceramic target, the specific steps of which include the following:

[0066] Step S1: Dissolve indium nitrate, titanium nitrate, cerium nitrate and niobium nitrate in a mass ratio of 97.5:0.5:0.4:0.3 in a solution containing monoethylenediaminetetraacetic acid (EDTA) (without glycerol complex) to form an organic complex solution.

[0067] Step S2: First, Fe(NO3)3 and citric acid are mixed at a molar ratio of 1:1.5 and stirred at room temperature for 10 minutes to form a Fe(III)-citric acid complex. Then, the complex is added to the solution obtained in step S1 at 0.05 wt% of the organic complex solution mass. Finally, 30 wt% H2O2 (H2O2:Fe molar ratio 10:1) is slowly added dropwise, and the mixture is heated at 70°C for 20 minutes to generate hydroxyl radicals, thus obtaining the treated indium titanium oxide cerium niobium precursor sol.

[0068] Step S3: After drying the precursor sol obtained in step S2, calcine it to 550°C at a heating rate of 2°C / min under an oxygen flow rate of 0.8 L / min, and hold it at that temperature for 1 hour to obtain indium titanium oxide cerium niobium nanopowder.

[0069] Step S4: The indium titanium oxide cerium niobium nanopowder obtained in step S3 is pre-pressed and cold isostatically pressed, and then sintered in a two-stage atmosphere sintering system. The first stage is an argon-hydrogen mixed atmosphere with an oxygen partial pressure of 10. -5 Atm, temperature 1100℃; the second stage is an oxygen-argon mixed atmosphere, oxygen partial pressure 10. -2 Indium titanium oxide cerium niobium ceramic target material was obtained by applying atm and heating at 1300℃.

[0070] Compare with Example 3

[0071] This comparative example provides a method for preparing an indium titanium oxide cerium niobium ceramic target, the specific steps of which include the following:

[0072] Step S1: Dissolve indium nitrate, titanium nitrate, cerium nitrate and niobium nitrate in a mass ratio of 97.5:0.5:0.4:0.3 in a solution containing a complex complexing agent of ethylenediaminetetraacetic acid (EDTA) and glycerol (molar ratio 1:2.5) to form a stable organic complex solution.

[0073] Step S2: First, Fe(NO3)3 and citric acid are mixed at a molar ratio of 1:1.5 and stirred at room temperature for 10 minutes to form a Fe(III)-citric acid complex. Then, the complex is added to the solution obtained in step S1 at 0.05 wt% of the organic complex solution mass. Finally, 30 wt% H2O2 (H2O2:Fe molar ratio 10:1) is slowly added dropwise, and the mixture is heated at 70°C for 20 minutes to generate hydroxyl radicals, thus obtaining the treated indium titanium oxide cerium niobium precursor sol.

[0074] Step S3: After drying the precursor sol obtained in step S2, calcine it to 550°C at a heating rate of 2°C / min under an oxygen flow rate of 0.8 L / min, and hold it at that temperature for 1 hour to obtain high-purity indium titanium oxide cerium niobium nanopowder.

[0075] Step S4: The indium titanium oxide cerium niobium nanopowder obtained in step S3 is pre-pressed and cold isostatically pressed, and then sintered in a single-stage argon-hydrogen mixed atmosphere (oxygen partial pressure 10). -5 (atm, temperature 1100℃), to obtain indium titanium cerium niobium ceramic target material.

[0076] Compare with Example 4

[0077] This comparative example provides a method for preparing an indium titanium oxide cerium niobium ceramic target, the specific steps of which include the following:

[0078] Step S1: Instead of using the dissolution method, indium oxide, titanium oxide, cerium oxide and niobium oxide powders are ball-milled in a zirconium oxide ball mill at a mass ratio of 97.5:0.5:0.4:0.3 for 24 hours to form a mixed powder (introducing Zr impurity contamination).

[0079] Step S2: Skip this step (no sol-gel process, use the mixed powder directly).

[0080] Step S3: The mixed powder obtained in step S1 is calcined to 550°C at a heating rate of 2°C / min under an oxygen flow rate of 0.8 L / min and held for 1 hour to obtain indium titanium cerium niobium powder.

[0081] Step S4: The indium titanium oxide cerium niobium powder obtained in step S3 is pre-pressed and cold isostatically pressed, and then sintered in a two-stage atmosphere sintering system. The first stage is an argon-hydrogen mixed atmosphere with an oxygen partial pressure of 10. -5 Atm, temperature 1100℃; the second stage is an oxygen-argon mixed atmosphere, oxygen partial pressure 10. -2 Indium titanium oxide cerium niobium ceramic target material was obtained by applying atm and heating at 1300℃.

[0082] Performance testing methods

[0083] 1. Relative density: The prepared indium titanium oxide cerium niobium ceramic target sample was cut into standard size (e.g., 10 mm × 10 mm × 5 mm) and tested using Archimedes' displacement method.

[0084] 2. Bending strength: The bending strength of the ceramic target was tested using the three-point bending method in accordance with GB / T 4741-1999 standard.

[0085] 3. Resistivity: The ceramic sample is made into a disc shape, and metal electrodes are deposited on the surface as contact points. A constant current is applied using a precision current source, and the voltage drop between the two internal probes is measured with a voltmeter. The resistivity is calculated according to Ohm's law.

[0086] 4. Sheet resistance of thin films: A transparent conductive oxide thin film was prepared from the target material using DC magnetron sputtering (sputtering conditions: working pressure 0.3 Pa, argon flow rate 30 sccm, power density 2.5 W / cm²). 2 The substrate temperature is 200℃. Then, the sheet resistance of the thin film is tested using a four-probe sheet resistance meter (such as ST-2258). Four probes are evenly placed on the surface of the thin film, and the current is applied to measure the voltage. The sheet resistance R_s = (V / I)×4.532 is calculated. Multiple points (at least 10 points) are tested under AM1.5 illumination and the average value is taken to evaluate the conductivity of the thin film.

[0087] 5. Average transmittance: The prepared indium titanium oxide cerium niobium ceramic target was processed into a polished sheet with a thickness of approximately 1 mm and a smooth surface. Using a quartz plate as a blank reference, the transmittance spectrum was scanned and measured in the wavelength range of 300–2400 nm under AM1.5 standard illumination conditions. The transmittance T(λ) values ​​at each wavelength were recorded, and the average transmittance was calculated by integrating the full spectrum transmittance. Each sample was tested three times, and the average value was taken to characterize the overall light transmittance performance of the material in the visible to near-infrared region.

[0088] Table 1

[0089]

[0090] In conjunction with Example 1, Figure 1 (FTIR) and Figure 2 (NMR) analysis shows that after heating, the organic ligands of the sample significantly decomposed and underwent structural transformation. 1 In the 1H NMR spectrum, the untreated sample showed strong signals at δ = 3.3–4.0 ppm (–CH2OH, –CHOH) and δ = 2.8–3.0 ppm (–NCH2–), indicating the presence of abundant hydroxyl and amino groups in the molecule. After treatment, these signals significantly weakened or even disappeared, replaced by oxidation product peaks at δ = 9.6 ppm (–CHO) and δ = 8.2 ppm (–COOH), indicating that the organic skeleton was oxidized and broken, partially forming carboxyl and aldehyde terminal groups. Correspondingly, in the infrared spectrum, the untreated sample showed strong signals at 3400 cm⁻¹. -1 There is a strong O–H stretching vibration peak at 1700–1600 cm⁻¹. -1 The characteristic absorptions of C=O and CN are present in the range, but after treatment, the peaks of these organic groups are significantly weakened, and the peaks in the 500–700 cm⁻¹ range are also significantly weakened. -1 The enhanced MO stretching vibrations in the region indicate a transformation from organic complexes to an inorganic metal oxide framework. In summary, the NMR and FTIR results corroborate each other, demonstrating that the sample underwent a transformation from an organic complex structure to an inorganic networked framework structure.

[0091] As can be seen from Examples 1 to 4 and Table 1, the relative density of the indium titanium oxide cerium niobium ceramic target material prepared in this application is between 99.5% and 99.8%, the flexural strength is 220 to 245 MPa, and the resistivity is (2.8 to 3.5) × 10⁻⁶. -4 The sheet resistance of the thin film is 6.8–8.0 Ω / sq, and the average transmittance is 88.3%–90.1%. This data range indicates that by optimizing the Fe(III)-citric acid / H2O2 in-situ free radical system and the EDTA-glycerol composite complexation conditions, a target material with high density, high strength, low resistivity, and high transmittance can be obtained, exhibiting excellent and stable overall performance.

[0092] Based on Example 1, Comparative Example 1, and Table 1, it can be seen that the relative density of Example 1 is 99.5%, the flexural strength is 220 MPa, and the resistivity is 3.5 × 10⁻⁶. -4 The sheet resistance of the thin film is 8.0 Ω / sq, and the average transmittance is 88.3%; while the relative density of the control example 1 is only 98.2%, the flexural strength is 170 MPa, and the resistivity is 5.2 × 10⁻⁶. -4The film sheet resistance is 11.5 Ω / sq, and the average transmittance is 84.5%. It is evident that Example 1 significantly outperforms the control sample in terms of density, mechanical strength, and photoelectric properties. This is because Example 1 introduces the Fe(III)-citric acid / H₂O₂ radical in-situ oxidation system, which effectively cleaves organic ligands, promotes uniform distribution of metal ions and full conversion of precursors to the inorganic framework, thereby achieving higher density and a purer crystalline phase during sintering, reducing porosity and impurity scattering, and significantly improving conductivity and transmittance.

[0093] Combining Example 1, Comparative Example 2, and Table 1, it can be seen that Example 1 has a relative density of 99.5%, a flexural strength of 220 MPa, and a resistivity of 3.5 × 10⁻⁶. -4 The sheet resistance of the film was 8.0 Ω·cm, and the average transmittance was 88.3%; while that of control example 2 was 98.7%, 185 MPa, and 4.8 × 10⁻⁶ MPa, respectively. -4 Ω·cm, 10.6 Ω / sq, and 85.3%. Example 1 showed superior performance in all aspects, especially in terms of flexural strength and light transmittance. This is mainly attributed to the use of an EDTA-glycerol composite complexing agent system in Example 1. The polyhydroxy structure of glycerol can form a hydrogen bond network, stabilize the distribution of metal ions and prevent agglomeration, making the precursor more uniform and refined. This results in higher density and lower grain boundary defects during sintering, ultimately exhibiting superior mechanical and photoelectric properties.

[0094] Combining Example 1, Comparative Example 3, and Table 1, it can be seen that Example 1 has a relative density of 99.5%, a flexural strength of 220 MPa, and a resistivity of 3.5 × 10⁻⁶. -4 The sheet resistance of the film was 8.0 Ω·cm, the average transmittance was 88.3%, and the corresponding data for Comparative Example 3 were 97.9%, 160 MPa, and 5.6 × 10⁻⁶ MPa, respectively. -4 Ω·cm, 12.1 Ω / sq, and 83.8%. The overall performance of Example 1 is significantly better than that of Control Example 3. The reason for this difference is that Control Example 3 only uses a single-stage reducing atmosphere sintering, which cannot repair grain boundary defects in the later oxidation stage; while the two-stage atmosphere sintering process of Example 1 promotes the formation of oxygen vacancies under low oxygen partial pressure to increase carrier concentration, and fills some oxygen vacancies in a high-temperature weak oxidizing atmosphere to improve grain boundary bonding, thereby achieving a synergistic improvement in density, conductivity, and transmittance.

[0095] Combining Example 1, Comparative Example 4, and Table 1, it can be seen that Example 1 has a relative density of 99.5%, a flexural strength of 220 MPa, and a resistivity of 3.5 × 10⁻⁶. -4The sheet resistance of the film is 8.0 Ω·cm, and the average transmittance is 88.3%; while the control example 4 has only 96.5%, 150 MPa, and 6.3 × 10⁻⁶. -4 Ω·cm, 13.4 Ω / sq, and 81.6%. The performance differences are significant; Example 1 shows substantial improvements in structural compactness, electrical conductivity, and optical properties. The fundamental reason lies in the fact that Comparative Example 4 uses a conventional oxide ball milling mixing method, where zirconium oxide beads, the milling media, introduce Zr. 4+ Impurities cause lattice distortion and carrier scattering, leading to increased resistivity and decreased transmittance. However, Example 1 uses a sol-gel route, which avoids mechanical contamination, achieves atomic-level uniform distribution and high-purity crystallization, and obtains excellent photoelectric performance.

[0096] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an indium titanium oxide cerium niobium ceramic target, characterized in that, Includes the following steps: Step S1. Dissolve the indium source compound, titanium source compound, cerium source compound, and niobium source compound in a solution containing an aminocarboxylic acid-polyol complexing agent to form a stable organic complex solution, wherein the mass ratio of the indium source compound, titanium source compound, cerium source compound, and niobium source compound is (97.5-98.5):(0.5-0.9):(0.4-0.8):(0.3-0.7). Step S2. Add an oxygen-containing free radical in-situ generation system composed of hydrogen peroxide, citric acid and ferric salt to the organic complex solution, so that the ferric salt and citric acid form Fe(III)- complex complex, and generate hydroxyl radicals under heating conditions to obtain the treated indium titanium cerium niobium precursor sol. Step S3. After drying the precursor sol obtained in step S2, calcine it in an oxygen atmosphere to 550-650°C to obtain high-purity indium titanium oxide cerium niobium nanopowder. Step S4. The indium titanium oxide cerium niobium nanopowder obtained in step S3 is pre-pressed and cold isostatically pressed, and then sintered in a two-stage atmosphere sintering system to obtain indium titanium oxide cerium niobium ceramic target material; wherein, the aminocarboxylic acid-polyol composite complexing agent is composed of ethylenediaminetetraacetic acid (EDTA) and glycerol, and the molar ratio is 1:(2.5~3.5). In step S2, the Fe(III)-complex is formed by mixing Fe(NO3)3 and citric acid in a molar ratio of 1:(1.5-2.5), with the amount added being 0.05-0.3 wt% of the organic complex solution; the heating conditions are 70-90°C for 20-40 minutes; the two-stage atmosphere sintering in step S4 includes: the first stage is an argon-hydrogen mixed atmosphere with an oxygen partial pressure of 10. -5 ~10 -6 Atm, temperature 1100~1300℃; the second stage is an oxygen-argon mixed atmosphere, oxygen partial pressure 10. -2 ~10 -3 atm, temperature 1300~1500℃.

2. The preparation method according to claim 1, characterized in that, The indium source compound, titanium source compound, cerium source compound, and niobium source compound are independently selected from one or two of their respective nitrates or chlorides.

3. The preparation method according to claim 1, characterized in that, The calcination process in step S3 is carried out under the condition of an oxygen flow rate of 0.8 to 1.5 L / min, a heating rate of 2 to 5 °C / min, and a holding time of 1 to 3 hours.

4. The indium titanium oxide cerium niobium ceramic target prepared by the method of claim 1, characterized in that, The target material has a relative density ≥99.5%, a flexural strength ≥220MPa, and a resistivity ≤3.5×10⁻⁶. -4 Ω·cm.

5. The application of the indium titanium oxide cerium niobium ceramic target material according to claim 4 in the photovoltaic industry is used to prepare a transparent conductive layer with high mobility and high transmittance. Under AM1.5 illumination, the sheet resistance of the thin film is ≤8Ω / sq and the average transmittance of visible light is ≥88.3%.

6. A transparent conductive oxide thin film, characterized in that, The indium titanium oxide cerium niobium ceramic target described in claim 5 was prepared by DC magnetron sputtering.

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