1. CuAlO with delafossite structure₂The preparation method is characterized in that copper salt and aluminum salt are added into an organic solvent to be mixed, then ethylene glycol is added to be mixed, then powder is obtained through drying, the powder is sintered under the air atmosphere, then annealing is carried out under the inert atmosphere, and cooling is carried out to obtain the copper-aluminum alloy powder; wherein the sintering temperature is lower than the annealing temperature.

2. Delafossite structure CuAlO according to claim 1₂The preparation method of (1) is characterized in that the copper salt is copper nitrate.

3. Delafossite structure CuAlO according to claim 1₂The method of (1), wherein the aluminum salt is aluminum nitrate.

4. Delafossite structure CuAlO according to claim 1₂The method for producing (1) is characterized in that the molar ratio of the copper salt to the aluminum salt is 1:0.9 to 1.1.

5. Delafossite structure CuAlO according to claim 1₂The method of (1) is characterized in that the organic solvent is ethanol.

6. Delafossite structure CuAlO according to claim 1₂The preparation method is characterized in that copper salt and aluminum salt are added into an organic solvent and mixed for 0.5-1.5 h.

7. Delafossite structure CuAlO according to claim 1₂The preparation method is characterized in that the mixing time after the ethylene glycol is added is 0.5-1.5 h.

8. Delafossite structure CuAlO according to claim 1₂The preparation method is characterized in that the drying temperature is 110-130 ℃; preferably, the drying time is 12-36 h.

9. Delafossite structure CuAlO according to claim 1₂The preparation method is characterized in that the sintering temperature is 400-500 ℃; preferably, the sintering time is 3-5 h;

or the annealing temperature is 800-1000 ℃; preferably, the annealing time is 8-12 h.

10. Delafossite structure CuAlO according to claim 1₂The method of (1) is characterized in that the inert atmosphere is formed with argon gas.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

CuAlO₂Is a crystal material with a delafossite structure, and is a wide-bandgap semiconductor material. The optical performance and chemical composition, energy band structure, oxygen vacancy number and crystallization degree of the material are closely tangentAnd off. CuAlO₂Besides having transparent conductivity, it also has other characteristics such as photovoltaic characteristics, field emission characteristics, gas-sensitive characteristics, photocatalytic characteristics, and thermoelectric characteristics.

In 1997, Kawazoe et al, based on the valence band chemical modification theory, first succeeded in preparing p-type CuAlO₂A film. CuAlO₂The basic structures of the crystal are two types, one is a delafossite type, the other is a spinel type, the delafossite type is mainly researched at present, the direct band gap of the delafossite type is 3.5e V, the indirect band gap of the delafossite type is 1.8e V, and the delafossite type is an intrinsic p-type semiconductor material. Each Cu in its unit cell⁺And 2O^2-Covalently bonded and formed into O-Cu-O linear dumbbell shape, each of Al³⁺Coordinated with 6O in covalent bond form^2-AlO6 octahedral coordination is formed, each O^2-With 4 atoms, one Cu, covalently bound⁺And 3 of Al³⁺A quasi-tetrahedral structure is formed, wherein the AlO6 structure can effectively weaken the local effect of O atoms and increase the mobility of holes, and the Cu-O-Cu linear dumbbell structure can effectively reduce the coordination number of Cu atoms so that CuAlO₂I.e., the optical band gap, increases, increasing the light transmittance in the visible range. Preparation of CuAlO₂There are many methods for thin films such as pulsed laser deposition, chemical vapor deposition, sputtering, sol-gel, and polymer-assisted deposition. The sol-gel method is lower in cost than other methods, however, the inventor researches and discovers that the delafossite type CuAlO is prepared by adopting the method₂The crystals are difficult, especially in the preparation of pure phase crystals free of impurities.

Disclosure of Invention

Preparation of CuAlO by Complex Sol-gel method₂Research on microcrystalline and optical properties (Lei kang et al, inorganic materials bulletin, vol.26, No. 3, 2011 3 months, 275 pages 280) describes that pure-phase CuAlO can be prepared by using citric acid as a complexing agent and copper nitrate trihydrate and aluminum isopropoxide as raw materials through a sol-gel method₂And (4) microcrystals. And the aluminum nitrate is adopted to replace aluminum isopropoxide, so that a CuO mixed phase exists in the prepared product. The inventors have further developedIt has been found that the use of aluminium isopropoxide in the process is difficult to preserve, making it difficult to transport and store directly as a feedstock. If aluminum isopropoxide is prepared in advance, a production line needs to be added, the production line comprises a synthesis process and a purification process, and if the aluminum isopropoxide in the raw material is not pure, the prepared CuAlO is also prepared₂The microcrystals are not pure, so the method has the problem of high cost, and the CuAlO prepared by the method₂The diffraction peak in the microcrystal has wider peak width, and the crystallization performance needs to be improved.

In order to solve the defects of the prior art, the invention aims to provide a delafossite structure CuAlO₂The preparation method of (1) has low preparation cost, and the prepared CuAlO₂The crystallization performance is better.

In order to achieve the purpose, the technical scheme of the invention is as follows:

CuAlO with delafossite structure₂The preparation method comprises the steps of adding copper salt and aluminum salt into an organic solvent for mixing, then adding ethylene glycol for mixing, then drying to obtain powder, sintering the powder in the air atmosphere, then annealing in the inert atmosphere, and cooling to obtain the copper-aluminum-zinc-aluminum alloy powder; wherein the sintering temperature is lower than the annealing temperature.

According to the invention, the organic solvent is adopted to disperse the copper salt and the aluminum salt, so that the contact between copper ions and aluminum ions is facilitated, the glycol is adopted to reduce bivalent copper ions into monovalent copper ions, and the copper ions and the aluminum ions are further combined. Experiments show that the mode of firstly sintering in air and then annealing in inert atmosphere can ensure that the CuAlO with the pure-phase delafossite structure with better crystallization property is formed₂。

The invention has the beneficial effects that:

the invention adopts the ethylene glycol as a reaction auxiliary agent, adopts the mode of firstly sintering under the air and then annealing in inert atmosphere, and can ensure that the CuAlO with a pure-phase delafossite structure with better crystallization property is formed₂. The method can avoid adopting organic salt, only adopts copper nitrate and aluminum nitrate as raw materials, has simple process, simple and convenient operation, cheap and easily obtained raw materials and lower cost, and is suitable for large-scale production and application.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 preparation of CuAlO for example 1₂Scanning Electron Microscope (SEM) images at different magnifications.

FIG. 2 preparation of CuAlO in example 1₂X-ray diffraction (XRD) pattern of (a).

FIG. 3 preparation of CuAlO in example 2₂SEM picture of (1);

FIG. 4 preparation of CuAlO in example 2₂XRD pattern of (a).

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

Aiming at solving the problem that the delafossite CuAlO with good crystallization performance is difficult to prepare by inorganic aluminum salt₂The invention provides a delafossite structure CuAlO₂The preparation method of (1).

In an exemplary embodiment of the present invention, a delafossite-structured CuAlO is provided₂The preparation method comprises the steps of adding copper salt and aluminum salt into an organic solvent for mixing, then adding ethylene glycol for mixing, then drying to obtain powder, sintering the powder in the air atmosphere, then annealing in the inert atmosphere, and cooling to obtain the copper-aluminum-zinc-aluminum alloy powder; wherein, sinteringThe temperature is lower than the annealing temperature.

According to the invention, the organic solvent is adopted to disperse the copper salt and the aluminum salt, so that the contact between copper ions and aluminum ions is facilitated, the glycol is adopted to reduce bivalent copper ions into monovalent copper ions, and the copper ions and the aluminum ions are further combined. Experiments show that the mode of firstly sintering in air and then annealing in inert atmosphere can ensure that the CuAlO with the pure-phase delafossite structure with better crystallization property is formed₂。

The copper salt of the present invention is an inorganic compound having a divalent copper ion as a cation, such as copper nitrate, copper chloride, copper sulfate, and the like. In some embodiments of this embodiment, the copper salt is copper nitrate. CuAlO with delafossite structure obtained by adopting copper nitrate₂The crystallization performance is better.

The copper salt of the present invention is an inorganic compound having an aluminum ion as a cation, such as aluminum nitrate, aluminum chloride, aluminum sulfate, and the like. In some embodiments of this embodiment, the aluminum salt is aluminum nitrate. CuAlO with delafossite structure obtained by adopting aluminum nitrate₂The crystallization performance is better.

In some examples of this embodiment, the molar ratio of the copper salt to the aluminum salt is 1:0.9 to 1.1.

The organic solvent is methanol, ethanol, acetone, dimethyl sulfoxide, N-dimethylformamide, etc., and in some examples of this embodiment, the organic solvent is ethanol.

In some examples of this embodiment, the copper salt and the aluminum salt are added to the organic solvent and mixed for 0.5 to 1.5 hours.

In some examples of this embodiment, the time for mixing after adding the ethylene glycol is 0.5 to 1.5 hours.

In some examples of this embodiment, the drying temperature is 110 to 130 ℃. The drying time is 12-36 h.

In some examples of this embodiment, the sintering temperature is 400 to 500 ℃. The sintering time is 3-5 h.

In some examples of this embodiment, the annealing temperature is 800 to 1000 ℃. The annealing time is 8-12 h.

The inert atmosphere is a protective atmosphere formed by nitrogen, helium, argon, neon or the like, and in some examples of the embodiment, the inert atmosphere is formed by argon.

In order to make the technical solution of the present invention more clearly understood by those skilled in the art, the technical solution of the present invention will be described in detail below with reference to specific examples and comparative examples.

Example 1

CuAlO with delafossite structure₂The preparation method comprises the following steps:

1) mixing copper nitrate and aluminum nitrate solution in the molar ratio of 1:1 in ethanol solution, stirring with magneton for one hour, adding glycol (the molar ratio to the total amount of copper nitrate and aluminum nitrate is 2:1), and stirring for one hour. Drying in an oven at 120 deg.C for 24 hr, and grinding the obtained powder.

2) Sintering the powder in a muffle furnace at 450 ℃ for 4h under the air atmosphere condition with the heating rate of 5 ℃/min, then transferring the powder into a tubular furnace to anneal for 10 hours under the argon protection atmosphere condition at 800 ℃ (the heating rate of 10 ℃/min), then naturally cooling to room temperature to obtain a gray product, namely the finished product of the delafossite structure CuAlO₂。

Delafossite structure CuAlO prepared in this example₂As shown in FIGS. 1-2. As can be seen from FIG. 1, CuAlO prepared in this example₂The grains are larger and the grains are more loose. As can be seen from FIG. 2, the facets characterized by the diffraction peaks include (003), (006), (101), (012), (104), (009), (107), (018), (110), (202), (119), are more comprehensive, and have narrow peak widths and sharp peak shapes, indicating that the CuAlO prepared in this example is CuAlO₂The crystallization property is very good, the structure is a typical delafossite structure, the structure is matched with a standard map (PDF #35-1401), the phase is single, no impurity peak exists, and the prepared CuAlO is shown₂Is a single phase material.

Example 2

CuAlO with delafossite structure₂The preparation method comprises the following steps:

1) mixing copper nitrate and aluminum nitrate solution in the molar ratio of 1:1 in ethanol solution, stirring with magneton for one hour, adding glycol (the molar ratio to the total amount of copper nitrate and aluminum nitrate is 2:1), and stirring for one hour. Drying in an oven at 120 deg.C for 24 hr, and grinding the obtained powder.

2) Sintering the powder in a muffle furnace at 450 ℃ for 4h under the air atmosphere condition with the heating rate of 5 ℃/min, then transferring the powder into a tubular furnace to anneal for 10 hours under the argon protection atmosphere condition at 900 ℃ (the heating rate of 10 ℃/min), then naturally cooling to room temperature to obtain a gray product, namely the finished product of the delafossite structure CuAlO₂。

Delafossite structure CuAlO prepared in this example₂As shown in FIGS. 3 to 4, it is shown that CuAlO prepared in this example₂The crystallization property is very good, the structure is a typical delafossite structure, the structure is matched with a standard map (PDF #35-1401), the phase is single, no impurity peak exists, and the prepared CuAlO is shown₂Is a single phase material. In addition, fig. 3a, 3b, and 3c are pictures at different positions with the same magnification, and indicate CuAlO₂The distribution is relatively uniform, and the particle size is within 5 microns.

Example 3

CuAlO with delafossite structure₂The preparation method comprises the following steps:

1) mixing copper nitrate and aluminum nitrate solution in the molar ratio of 1:1 in ethanol solution, stirring with magneton for one hour, adding glycol (the molar ratio to the total amount of copper nitrate and aluminum nitrate is 2:1), and stirring for one hour. Drying in an oven at 120 deg.C for 24 hr, and grinding the obtained powder.

2) Sintering the powder in a muffle furnace at 450 ℃ for 4h under the air atmosphere condition with the heating rate of 5 ℃/min, then transferring the powder into a tubular furnace to anneal for 10 hours under the argon protection atmosphere condition at 1000 ℃ (with the heating rate of 10 ℃/min), then naturally cooling to room temperature to obtain a gray product, namely the finished product of the delafossite structure CuAlO₂。

Characterization by SEM and XRD showed that CuAlO prepared in this example₂Is a single-phase substance with a typical delafossite structure, and has very high crystallization propertyGood results are obtained.

Comparative example 1

1) Mixing copper nitrate and aluminum nitrate solution in the molar ratio of 1:1 in ethanol solution, stirring with magneton for one hour, adding glycol (the molar ratio to the total amount of copper nitrate and aluminum nitrate is 2:1), and stirring for one hour. Drying in an oven at 120 deg.C for 24 hr, and grinding the obtained powder.

2) And (3) sintering the powder in a muffle furnace at 1000 ℃ for 14h in an air atmosphere, and naturally cooling to room temperature to obtain a finished product.

XRD characterization shows that other oxide impurities such as alumina exist in the finished product prepared by the comparative example.

Comparative example 2

1) Mixing copper nitrate and aluminum nitrate solution in the molar ratio of 1:1 in ethanol solution, stirring with magneton for one hour, adding glycol (the molar ratio to the total amount of copper nitrate and aluminum nitrate is 2:1), and stirring for one hour. Drying in an oven at 120 deg.C for 24 hr, and grinding the obtained powder.

2) And (3) sintering the powder in a muffle furnace at the temperature of 1000 ℃ under the argon atmosphere for 14h, and naturally cooling to room temperature to obtain a finished product.

XRD characterization shows that the finished product prepared by the comparative example contains impurities and has poor crystallization performance.

Comparative example 3

1) Mixing copper nitrate and aluminum nitrate solution in an ethanol solution according to the molar ratio of copper to aluminum of 1:1, uniformly stirring for one hour by using magnetons, adding citric acid aqueous solution (the molar ratio of citric acid to the total amount of copper nitrate and aluminum nitrate is 3:1), continuously stirring until sol is clear and uniform, then aging, drying in a drying oven at 120 ℃ for 24 hours to obtain dry gel, and grinding the dry gel into powder.

2) And (3) placing the powder in a muffle furnace, sintering for 4h at the temperature of 450 ℃ in an air atmosphere, heating at the rate of 5 ℃/min, then transferring the powder into a tubular furnace, annealing for 10 hours at the temperature of 1000 ℃ (heating at the rate of 10 ℃/min) in an argon protective atmosphere, and naturally cooling to room temperature to obtain the product.

XRD (X-ray diffraction) characterization shows that CuO phase exists in the product and CuAlO cannot be obtained₂A single phase material.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.