Ternary layered compound as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of materials, and relates to a ternary layered compound as well as a preparation method and application thereof. The molecular formula of the ternary layered compound is MxIn2Se3, M is selected from one or a combination of more of Fe, Co and Ni, and x is more than 0 and less than or equal to 1. The material has a brand-new structure, the ternary layered compound retains the main body structure of In2Se3, and M atomic layers and In2Se3 units are stacked alternately. Compared with In2Se3, the stability and thermoelectric performance of the ternary layered compound are remarkably improved, and the ternary layered compound has important application potential in the field of thermoelectric materials.

Description

Technical Field

[0001] The invention belongs to the technical field of materials and relates to a ternary layered compound and a preparation method and application thereof. Background Art

[0002] In recent years, with the rapid development of materials science, new two-dimensional materials have continuously emerged. Among them, layered compounds, represented by graphene, metal chalcogenides, and MXene, have become the focus of scientific research and in-depth research due to their unique structures and excellent properties. They have wide applications in energy storage, catalysis, optoelectronic devices, electromagnetic absorption / shielding, biomaterials, and other fields. Currently, the synthesis of layered compounds mainly consists of two routes: bottom-up and top-down. The bottom-up route includes powder mixing and sintering, CVD growth, and hydrothermal reaction. The powder mixing and sintering method is relatively simple to operate. The raw material powders mixed in a certain proportion are placed under high temperature. Through solid-phase reaction, the atoms diffuse and combine, gradually forming the desired layered compound crystal structure. The CVD growth method uses gaseous reactants to react chemically on the substrate surface under specific conditions such as high temperature and catalyst, causing atoms or molecules to deposit layer by layer and grow into layered materials. The hydrothermal reaction uses the driving force of chemical reactions in a high-temperature and high-pressure aqueous solution environment to promote the dissolution and recrystallization of the raw materials, thereby growing the layered compound. The core of the top-down approach is to selectively treat the precursor material to remove some atoms or groups, thereby obtaining the target layered product (such as etching the MAX phase to synthesize MXene). The materials synthesized by the above two routes are mainly thermodynamically stable phases. When the target product exists in a competing phase, it is difficult to synthesize it through the above processes.

[0003] Van der Waals layered materials, a key class of layered compounds, are characterized by the presence of van der Waals gaps in their crystal structure, which provide a fertile ground for the insertion of foreign atoms or molecules. When a small number of foreign atoms or molecules successfully intercalate into the van der Waals gap, the previously relatively stable interlayer coupling is disrupted, altering the interactions between the layers and leading to significant changes in the material's properties. For example, electrical conductivity may increase or decrease significantly after intercalation; optical absorption and emission spectra may exhibit significant shifts or changes; and mechanical properties, such as flexibility and hardness, may also be altered. Furthermore, when the amount of intercalated foreign atoms or molecules reaches a certain level, the intercalated objects arrange themselves periodically within the van der Waals gap according to a specific pattern, forming a novel structure. This results in a new layered compound with unique properties. Based on this principle, chemical intercalation technology has emerged, opening up a new avenue for the synthesis and property manipulation of novel layered compounds. By selecting different intercalation objects, controlling the amount of intercalation and the conditions of intercalation, layered compounds with specific properties can be designed and prepared in a targeted manner to meet the application needs of different fields.

[0004] Among numerous layered compounds, In2Se3, due to its unique physicochemical properties, exhibits enormous application potential in optoelectronic devices, solar cells, field-effect transistors, and sensors. However, current research on In2Se3 primarily focuses on its synthesis methods. For example, Chinese patent CN110482498A discloses a method for synthesizing γ-phase indium selenide. This involves first synthesizing a low-selenium selenide from elemental selenium and elemental indium at high temperature under a protective atmosphere, and then synthesizing γ-phase indium selenide from the low-selenium selenide and elemental selenium at high temperature under a protective atmosphere. Another example is Chinese patent CN115012029A, which discloses a method for synthesizing pure β-phase two-dimensional indium selenide crystals using In2O3 and elemental selenium as targets through chemical vapor deposition. Furthermore, CN111211041A employs molecular beam epitaxy (MBE) technology to precisely control the intensity and direction of the atomic beam in an ultra-high vacuum environment, growing In2Se3 polycrystalline thin films layer by layer on a substrate surface. This is then annealed to produce high-quality In2Se3 thin films.

[0005] Currently, there is limited research on the regulation of In2Se3 intercalation structures. This is primarily due to the unique structure of In2Se3 itself, which exhibits weak In-Se bonds. During the intercalation process, using aggressive reaction conditions can easily destroy the main structure of In2Se3, causing the material to lose its original performance and structural integrity. On the other hand, using milder reaction conditions makes it difficult to effectively insert intercalated atoms into the interlayers due to the constraints of the In-Se bonds and the spatial limitations of the van der Waals gap. Consequently, to date, there are few reports on chemical intercalation research based on the In2Se3 system and the synthesis of related new layered materials. Summary of the Invention

[0006] The present invention addresses the problem that there is currently little research on chemical intercalation based on the In2Se3 system, and provides a new ternary layered compound material obtained by intercalating In2Se3 with one or more of Fe, Co, and Ni to overcome the shortcomings of the existing technology.

[0007] One aspect of the present invention provides a ternary layered compound, wherein the molecular formula of the ternary layered compound is M x In2Se3, wherein M is selected from a combination of one or more of Fe, Co, and Ni, and 0<x≤1.

[0008] Preferably, the ternary layered compound has a hexagonal crystal structure, and the crystal structure is formed by alternating stacking of In2Se3 units and M atomic layers.

[0009] Preferably, the ternary layered compound is obtained by intercalating an In2Se3 compound into an intercalation material in a molten salt environment; the intercalation material is a combination of one or more of Fe, Co, and Ni, and the molten salt is formed by melting an inorganic salt into a liquid.

[0010] Preferably, the ternary layered compound is in the form of powder, block or film.

[0011] One aspect of the present invention provides a method for preparing a ternary layered compound, comprising the following steps:

[0012] A mixture of In2Se3 compound, M metal and inorganic salt is reacted at 400-1000°C in an inert atmosphere to obtain a ternary layered compound.

[0013] One aspect of the present invention provides another method for preparing a ternary layered compound, comprising the following steps:

[0014] S1. reacting a mixture of an In2Se3 compound, an M metal, and an inorganic salt at 400-1000° C. in an inert atmosphere to obtain a ternary layered compound powder;

[0015] S2. spark plasma sintering the ternary layered compound powder to obtain a ternary layered compound block;

[0016] The In2Se3 compound is in powder form.

[0017] Preferably, the mixture of the In2Se3 compound, the M metal, and the inorganic salt is obtained by the following method: mechanically mixing the In2Se3 compound, the M metal, and the inorganic salt to obtain a mixture; or, mechanically mixing the M metal and the inorganic salt first, and then adding the In2Se3 compound to submerge them, to obtain a mixture of the In2Se3 compound, the M metal, and the inorganic salt;

[0018] The mechanical mixing includes high-energy ball milling, mechanical stirring, mechanical shaking, grinding or roller milling, and the mixing time is 10 minutes to 10 hours.

[0019] Preferably, the In2Se3 compound is in powder, film or block form.

[0020] Preferably, when the ternary layered compound is in the form of a thin film, the preparation method comprises the following steps:

[0021] The M metal and inorganic salt are first mechanically mixed, and then the In2Se3 compound is added to submerge them to obtain a mixture of the In2Se3 compound, the M metal, and the inorganic salt. The mixture is reacted at 400-1000°C in an inert atmosphere to obtain a ternary layered compound film;

[0022] The In2Se3 compound is in the form of a thin film.

[0023] Preferably, when the ternary layered compound is a single crystal, the preparation method comprises the following steps:

[0024] The M metal and inorganic salt are first mechanically mixed, and then the In2Se3 compound is added to submerge them to obtain a mixture of the In2Se3 compound, the M metal, and the inorganic salt, which is reacted at 400-1000°C in an inert atmosphere to obtain a single crystal ternary layered compound;

[0025] The crystal structure of the In2Se3 compound is a single crystal.

[0026] Preferably, the In2Se3 compound is a single crystal and has a bulk shape.

[0027] Preferably, the M metal is a combination of one or more of Fe, Co, and Ni.

[0028] Preferably, the inorganic salt is one or more compounds formed by ion bonding of halide ions, nitrate ions or sulfate ions with metal ions.

[0029] Preferably, the halogen ions in the inorganic salt are one or more of chloride ions, bromide ions, and fluoride ions, and the metal ions are one or more of alkali metal ions, alkaline earth metal ions, and transition metal ions.

[0030] Preferably, the inorganic salt is one or more of LiCl, NaCl, KCl, CaCl2, MgCl2, KF, NaF, LiF, LiBr, NaBr, KBr, CaBr2, MgBr2, and Na2SO4.

[0031] Preferably, the molar ratio of the In2Se3 compound to the M metal is 1:(0,5];

[0032] and / or, the molar ratio of the In2Se3 compound to the inorganic salt is 1:5 to 200;

[0033] and / or, reacting at 400-900° C. in an inert atmosphere for 1-10 hours.

[0034] Preferably, after the high temperature reaction is completed, the product is cooled to room temperature and then subjected to post-treatment. The post-treatment includes washing the reaction product with water to remove residual inorganic salts and then drying.

[0035] Another aspect of the present invention provides the use of the ternary layered compound in thermoelectric materials and ferroelectric memory devices.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The present invention provides a molecular formula M x A ternary layered compound of In2Se3, which is a material with a completely new structure. The ternary layered compound retains the main structure of In2Se3, and the M atomic layers and In2Se3 units are stacked alternately.

[0038] (2) This ternary layered compound cannot be directly synthesized by traditional powder metallurgy, vapor deposition and other methods, but is obtained by intercalating In2Se3 compounds with intercalation materials Fe, Co, and Ni in a molten salt environment. This preparation method effectively inserts intercalation metal atoms between layers while retaining the main structure of In2Se3.

[0039] (3) Compared with the original In2Se3, the ternary layered compound provided by the present invention has higher thermal stability and is less likely to undergo phase change.

[0040] (4) The electrical conductivity, carrier concentration, and thermoelectric figure of merit of the ternary layered compound provided by the present invention are better than those of the original In2Se3, and the thermal conductivity is lower than that of the original In2Se3. Therefore, the thermoelectric performance of the ternary layered compound is significantly improved compared with that of In2Se3, and it has important application potential in the field of thermoelectric materials.

[0041] (5) Compared with In2Se3, the electrical conductivity, thermal conductivity, magnetism, thermal stability and other properties of the ternary layered compound of the present invention are improved, which is conducive to broadening the application field and meeting the needs of high-end applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The ternary layered compound material Ni in Example 1 of the present invention is 0.33 XRD spectra of In2Se3 and pristine In2Se3 materials.

[0043] Figure 2 The ternary layered compound material Ni in Example 1 of the present invention is 0.33 Scanning electron microscope image of In2Se3 material.

[0044] Figure 3 The ternary layered compound material Ni in Example 1 of the present invention is 0.33 EDS spectrum of In2Se3.

[0045] Figure 4 The ternary layered compound material Ni in Example 1 of the present invention is 0.33 High-resolution transmission electron microscopy morphology of In2Se3 material.

[0046] Figure 5 This is the XRD pattern of the direct sintering product of the In, Se, and Ni mixed materials in Comparative Example 1 of the present invention.

[0047] Figure 6 The ternary layered compound Ni in Example 4 of the present invention 0.33 XRD comparison patterns of In2Se3 single crystal material and In2Se3 single crystal material.

[0048] Figure 7 The ternary layered compound Ni in Example 4 of the present invention 0.33 Micromorphology analysis of In2Se3 single crystal material under scanning electron microscope.

[0049] Figure 8 The ternary layered compound Ni prepared in Example 6 of the present invention is 0.33 Macroscopic morphology of In2Se3 bulk material.

[0050] Figure 9 The ternary layered compound Ni prepared in Example 6 of the present invention is 0.33 In2Se3 bulk material and Ni prepared in Example 1 0.33 Comparative XRD patterns of In2Se3 powder.

[0051] Figure 10The ternary layered compound Ni prepared in Example 6 of the present invention is 0.33 DSC spectra of In2Se3 bulk material and In2Se3 bulk material.

[0052] Figure 11 The ternary layered compound Ni prepared in Example 6 of the present invention is 0.33 Temperature variation spectrum of In2Se3 bulk material and In2Se3 bulk material conductivity.

[0053] Figure 12 The ternary layered compound Ni prepared in Example 6 of the present invention is 0.33 Temperature variation spectrum of In2Se3 bulk material and In2Se3 bulk material carrier density.

[0054] Figure 13 The ternary layered compound Ni prepared in Example 6 of the present invention is 0.33 Temperature variation spectrum of thermal conductivity of In2Se3 bulk material and In2Se3 bulk material.

[0055] Figure 14 The ternary layered compound Ni prepared in Example 6 of the present invention is 0.33 Temperature variation spectrum of In2Se3 bulk material and In2Se3 bulk material thermoelectric figure of merit.

[0056] Figure 15 The XRD spectra of the product prepared in Comparative Example 2 of the present invention are compared with the XRD spectra of the original In2Se3. DETAILED DESCRIPTION

[0057] Hereinafter, embodiments of the present invention will be described in detail with respect to the ternary layered compound and its preparation method. However, these embodiments are exemplary and the present disclosure is not limited thereto. Furthermore, the accompanying drawings are provided solely for the purpose of illustrating the present disclosure and do not limit the scope of protection.

[0058] The following is a detailed description of the ternary layered compound:

[0059] In some embodiments of the present invention, a novel ternary layered compound is provided, whose molecular formula is M x In2Se3, wherein M is selected from a combination of one or more of Fe, Co, and Ni, and 0<x≤1.

[0060] M is selected from one or more combinations of Fe, Co, and Ni, which is represented by M being any one of Fe, Co, and Ni, or M being a combination of any two of Fe, Co, and Ni, or M being a combination of Fe, Co, and Ni.

[0061] Molecular formula Mx In In2Se3, x, 2, and 3 represent atomic ratios. In other words, the ratio of M atoms, indium atoms, and selenium atoms in the ternary layered compound is x:2:3. When M is a combination of any two or three of Fe, Co, and Ni, x represents the total atomic ratio of any two or three of these elements.

[0062] Preferably, the ternary layered compound has a hexagonal crystal structure, and the crystal structure is formed by alternating stacking of In2Se3 units and M atomic layers.

[0063] The In2Se3 unit cell has a layered structure. Each In2Se3 unit cell is formed by alternating layers of two indium atoms and three selenium atoms, forming a two-dimensional layer. The M atomic layer consists of M atoms uniformly distributed in layers between two adjacent In2Se3 layers. The In2Se3 unit layers and the M atomic layers alternate along the c-axis of the hexagonal crystal system, forming a periodic structure.

[0064] When M is a combination of any two or three of Fe, Co, and Ni, any two or three of Fe, Co, and Ni form an alloy layer, which is evenly distributed between two adjacent In2Se3 layers.

[0065] Preferably, the M atomic layer is connected to the In2Se3 unit by van der Waals forces and / or chemical bonds, which helps to maintain the stability of the intercalation structure.

[0066] Preferably, the ternary layered compound is obtained by intercalating an In2Se3 compound into an intercalation material in a molten salt environment, and the intercalation material is a combination of one or more of Fe, Co, and Ni.

[0067] Preferably, the molten salt is formed by melting an inorganic salt into a liquid under high temperature conditions. The inorganic salt is one or more compounds formed by halogen ions, nitrate ions or sulfate ions and metal ions through ionic bonds.

[0068] The halogen ion in the inorganic salt is preferably one or more of chloride ion, bromide ion, and fluoride ion, and the metal ion is preferably one or more of alkali metal ion, alkaline earth metal ion, and transition metal ion. The metal ion is further preferably one or more of Li ion, Na ion, K ion, Ca ion, and Mg ion.

[0069] The inorganic salt is preferably one or more of LiCl, NaCl, KCl, CaCl2, MgCl2, KF, NaF, LiF, LiBr, NaBr, KBr, CaBr2, MgBr2, and Na2SO4.

[0070] More preferably, the inorganic salt is one or more of LiCl, NaCl, and KCl.

[0071] The ternary layered compound may be in any form, preferably a powder, block, or film. A powder is a collection of fine particles, typically ranging in size from 1 nanometer to 999 micrometers. A block is a three-dimensional continuous structure, typically with a particle size greater than 1 millimeter. A film is a two-dimensional sheet with a thickness ranging from 1 nanometer to 999 micrometers.

[0072] The ternary layered compound may be single crystal, polycrystalline, or a mixture of the two.

[0073] The preparation method of the ternary layered compound is described in detail below:

[0074] In some embodiments of the present invention, a method for preparing a ternary layered compound is provided, comprising the following steps:

[0075] A mixture of In2Se3 compound, M metal and inorganic salt is reacted at 400-1000°C in an inert atmosphere to obtain a ternary layered compound.

[0076] Preferably, the mixture of In2Se3 compound, M metal and inorganic salt is obtained by the following method: mechanically mixing the In2Se3 compound, M metal and inorganic salt to obtain a mixture; or, mechanically mixing the M metal and inorganic salt first, and then adding the In2Se3 compound to submerge them to obtain a mixture of In2Se3 compound, M metal and inorganic salt.

[0077] The mechanical mixing includes high-energy ball milling, mechanical stirring, mechanical shaking, grinding or roller milling, and the mixing time is 10 minutes to 10 hours.

[0078] Preferably, the In2Se3 compound is in powder, film or block form.

[0079] Preferably, the D50 particle size of the powdered In2Se3 compound is 100 nm to 100 μm, more preferably 0.5 to 50 μm, and even more preferably 1 to 10 μm.

[0080] Preferably, the thickness of the thin film In2Se3 compound is 200nm to 200μm, more preferably 0.5 to 100μm, and even more preferably 1 to 50μm. The area of the thin film In2Se3 compound is 1 to 1000mm 2 , more preferably 1 to 500 mm 2 , and further preferably 5 to 300 mm 2 .

[0081] Through the above preparation method, using powdered In2Se3 compound as raw material, ternary layered compound powder can be prepared; using thin film In2Se3 compound as raw material, ternary layered compound film can be prepared; using block In2Se3 compound as raw material, ternary layered compound block can be prepared.

[0082] Specifically, when the ternary layered compound is in powder form, the preparation method includes the following steps:

[0083] A mixture of an In2Se3 compound, an M metal, and an inorganic salt is reacted at 400 to 1000° C. in an inert atmosphere to obtain a ternary layered compound powder;

[0084] The In2Se3 compound is in powder form.

[0085] When the ternary layered compound is in block form, the preparation method comprises the following steps:

[0086] A mixture of an In2Se3 compound, an M metal, and an inorganic salt is reacted at 400 to 1000° C. in an inert atmosphere to obtain a ternary layered compound block;

[0087] The In2Se3 compound is in block form.

[0088] Preferably, when the ternary layered compound is in the form of a thin film, the preparation method comprises the following steps:

[0089] The M metal and inorganic salt are first mechanically mixed, and then the In2Se3 compound is added to submerge the mixture to obtain a mixture of the In2Se3 compound, the M metal, and the inorganic salt. The mixture is reacted at 400-1000°C in an inert atmosphere to obtain a ternary layered compound thin film; the In2Se3 compound is in thin film form. When the In2Se3 compound is in thin film form, the M metal and inorganic salt are first mechanically mixed, and then the thin film of the In2Se3 compound is submerged in the mixture. Mechanical mixing is not required to prevent the film morphology from being destroyed.

[0090] The crystal structure of the In2Se3 compound can be single crystal, polycrystalline or amorphous. The ternary layered compound prepared by the above preparation method can be single crystal or polycrystalline.

[0091] Preferably, when the ternary layered compound is a single crystal, the preparation method comprises the following steps:

[0092] The M metal and inorganic salt are first mechanically mixed, and then the In2Se3 compound is added to submerge the mixture, resulting in a mixture of the In2Se3 compound, the M metal, and the inorganic salt. The mixture is then reacted at 400-1000°C in an inert atmosphere to obtain a single-crystal ternary layered compound; the In2Se3 compound has a single-crystal structure. When the In2Se3 compound is a single crystal, the M metal and inorganic salt are first mechanically mixed, and then the single-crystal In2Se3 compound is submerged in the mixture. Mechanical mixing is not required to prevent the single crystal morphology from being destroyed.

[0093] The crystal structure of the In2Se3 compound is a single crystal, and its form can be powder, film, or block. Correspondingly, a single crystal ternary layered compound in the form of powder, film, or block can be obtained.

[0094] Preferably, the In2Se3 compound is a single crystal in a block-like form. A single crystal ternary layered compound block is obtained by the above preparation method.

[0095] Preferably, in the preparation method of the present invention, the In2Se3 compound used has a layered structure.

[0096] Preferably, the M metal is a combination of one or more of Fe, Co, and Ni.

[0097] Preferably, the M metal is in powder form, and its D50 particle size is 100 nm to 100 μm, more preferably 0.5 to 50 μm, and even more preferably 1 to 10 μm.

[0098] Preferably, the purity of the In2Se3 compound is ≥99%. The purity of the M metal is ≥99%.

[0099] In the preparation method of the present invention, the inorganic salt primarily functions to provide a liquid reaction environment at a certain temperature, promoting the intercalation reaction, and does not itself participate in the reaction. Preferably, the inorganic salt is one that can dissolve into a liquid state at a reaction temperature of 400-1000°C, at which temperature the inorganic salt does not decompose and does not participate in the reaction.

[0100] Preferably, the inorganic salt is one or more compounds formed by ion bonding of a halide ion, a nitrate ion, or a sulfate ion with a metal ion. The halide ion in the inorganic salt is preferably one or more of chloride ion, bromide ion, and fluoride ion, and the metal ion is preferably one or more of alkali metal ion, alkaline earth metal ion, and transition metal ion. The metal ion is further preferably one or more of Li ion, Na ion, K ion, Ca ion, and Mg ion.

[0101] The inorganic salt is preferably one or more of LiCl, NaCl, KCl, CaCl2, MgCl2, KF, NaF, LiF, LiBr, NaBr, KBr, CaBr2, MgBr2, and Na2SO4.

[0102] More preferably, the inorganic salt is one or more of LiCl, NaCl, KCl, LiBr, NaBr, and KBr.

[0103] Preferably, the molar ratio of the In2Se3 compound to the M metal is 1:(0,5], where (0,5] is expressed as a value greater than 0 and less than or equal to 5. Further preferably, the molar ratio of the In2Se3 compound to the M metal is 1:(0.001-3). For example, it can be any ratio of 1:0.001, 1:0.005, 1:0.01, 1:0.05, 1:0.08, 1:0.1, 1:0.2, 1:0.3, 1:0.5, 1:0.8, 1:1, 1:1.5, 1:2, 1:2.5, or 1:3.

[0104] Preferably, the molar ratio of the In2Se3 compound to the inorganic salt is 1:5 to 200. More preferably, it is 1:10 to 100. For example, it can be any ratio of 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, 1:60, 1:65, 1:70, 1:80, 1:90, or 1:100.

[0105] The inert atmosphere in the present invention is argon and / or nitrogen.

[0106] The reaction is carried out in an inert atmosphere at 400-1000°C, more preferably 400-900°C, for example, 400, 450, 500, 550, 600, 650, 700, 750, 800, or 900°C. The reaction time is 1-10 hours, more preferably 2-8 hours, for example, 2, 3, 4, 5, 6, 7, or 8 hours.

[0107] The reaction is carried out at 400-1000° C. in an inert atmosphere, and then cooled to room temperature, followed by post-treatment. The post-treatment includes washing the reaction product with water to remove residual inorganic salts, and then drying.

[0108] Specifically, the post-treatment includes the following steps: placing the reaction product in a container, adding water, stirring and ultrasonically cleaning for 1 to 500 minutes, then standing for 1 to 500 minutes, and pouring out the supernatant; repeating the above steps for 2 to 5 times, and then placing it in an oven at 40 to 100° C. for drying.

[0109] In some embodiments of the present invention, another method for preparing a ternary layered compound is provided, comprising the following steps:

[0110] S1. reacting a mixture of an In2Se3 compound, an M metal, and an inorganic salt at 400-1000° C. in an inert atmosphere to obtain a ternary layered compound powder;

[0111] S2. performing spark plasma sintering, hot pressing sintering, or pressureless sintering on the ternary layered compound powder to obtain a ternary layered compound block;

[0112] The In2Se3 compound is in powder form.

[0113] The detailed description of step S1 is the same as above.

[0114] In step S2, spark plasma sintering is performed in a vacuum or inert atmosphere. Preferably, the parameters of spark plasma sintering include: a heating rate of 20-200°C / min, a holding temperature of 400-650°C, a holding time of 1-20 minutes, and a pressure of 10-100 MPa.

[0115] Hot pressing sintering is usually carried out in a vacuum or inert atmosphere. Preferably, the parameters of hot pressing sintering are as follows: heating rate: generally 5-50°C / min, holding temperature: 700-1000°C, holding time: 30-120 min, pressure: 20-80 MPa.

[0116] Pressureless sintering is usually carried out in an inert atmosphere. The parameters for pressureless sintering are as follows: heating rate: 2-50°C / min, holding temperature: 800-1200°C, holding time: 40-180 minutes.

[0117] Below by specific embodiment and accompanying drawing, technical scheme of the present invention is further described explanation, it should be understood that specific embodiment described herein is only for helping to understand the present invention, is not used for specific limitation of the present invention.And accompanying drawing used herein, is only for better illustrating the disclosure of the present invention, does not have limiting effect on protection scope.If no special instructions, the raw materials adopted in the embodiment of the present invention are all raw materials commonly used in this area, and the method adopted in the embodiment is all conventional method in this area.

[0118] In the following examples and comparative examples, powdered In2Se3 compounds, thin-film In2Se3 compounds and single-crystalline In2Se3 compound blocks are respectively prepared by the following methods: the powdered In2Se3 compound is obtained by mixing In powder and Se powder in proportion, heating to 500°C and keeping warm for 10 hours. The thin-film In2Se3 compound is obtained by introducing InCl3 and H2Se precursor gases into a reaction chamber, and conducting a chemical reaction on a SiO2 substrate heated to 500°C. The single-crystalline In2Se3 compound can be obtained by mixing In powder and Se powder in proportion, placing in a conical crucible, heating to 500 degrees for 24 hours, and cooling to room temperature at a cooling rate of 0.5°C / min.

[0119] The purity of the above In2Se3 compounds is ≥99.5%. The purity of Fe, Ni, and Co powders is 99.9%.

[0120] Example 1

[0121] In this embodiment, the novel ternary layered compound is Ni 0.33 In2Se3 powder, the intercalation raw material is In2Se3 powder, the intercalation material is Ni powder, and the inorganic salt is a mixed salt of KCl and LiCl. The preparation method of the ternary layered compound is as follows:

[0122] (1) Weigh 1.401 g of In2Se3 powder, 4.47 g of KCl, 3.825 g of LiCl, and 0.05847 g of Ni powder, and grind and mix the above materials (grinding speed is 3000 rpm, time is 5 min) to obtain a mixed product.

[0123] (2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. Reaction conditions are: 400°C, 5 hours, argon protection. After the tube furnace temperature drops to room temperature, remove the reaction product from the crucible.

[0124] (3) Washing the reaction product with deionized water: Place the reaction product in a beaker, add deionized water, stir and ultrasonically clean for 30 minutes, then let it stand for 1 hour and discard the supernatant; repeat the above steps to wash the product three times, place it in an oven at 60°C, and dry it for 2 hours to obtain a ternary layered compound powder.

[0125] Figure 1 Ni prepared in Example 1 0.33Comparison of XRD patterns of In2Se3 powder material and original In2Se3 material. From the comparison, it can be seen that the XRD peaks of the two are similar, indicating that the insertion of Ni does not destroy the overall structure of the In2Se3 material. The (00l) diffraction peak shifts at a high angle, indicating that the insertion of Ni leads to a decrease in the interlayer spacing of In2Se3. The position of the (003) diffraction peak can be used to determine the Ni 0.33 The c value of the In2Se3 lattice constant is 0.9246nm, which is reduced compared with 0.9349nm of the original In2Se3. Meanwhile, the enhancement of the (003) and (015) diffraction peak intensities indicates the intercalation of Ni.

[0126] Figure 2 It is a ternary layered compound Ni 0.33 The micromorphology analysis diagram of In2Se3 under a scanning electron microscope shows that the sample after intercalation is still a layered compound and the structure has not been destroyed.

[0127] Figure 3 It is a ternary layered compound Ni 0.33 The energy spectrum data of In2Se3 shows the specific atomic ratio, which is Ni:In:Se=1:6:9.

[0128] Figure 4 It is a ternary layered compound Ni 0.33 High-resolution transmission electron microscopy morphology of In2Se3 can be clearly seen from the figure. 0.33 The layered crystal structure of In2Se3. The brighter atoms in the figure are the In layer with a higher atomic number, the lower-brightness layer is the Se layer, and the Ni layer is inserted between the Se-Se layers.

[0129] Comparative Example 1

[0130] The preparation method of Comparative Example 1 is as follows:

[0131] Weigh 0.194g of Ni powder, 2.3g of In powder, and 2.37g of Se powder and grind them together (grinding at 3000rpm for 5 minutes) to obtain a mixture. This mixture was then subjected to high-temperature solid-phase sintering at a heating rate of 5°C / min, a holding temperature of 450°C, and a holding time of 5 hours. After the reaction was complete, remove the sintered sample.

[0132] Figure 5 This is the XRD spectrum of the sample directly synthesized by high temperature solid phase sintering. It can be observed from the figure that In2Se3 did not proceed according to the intercalation. Some In reacted with Se to form In6Se7, and Ni reacted with Se to form compounds NiSe, Ni3Se4, etc. This shows the failure of intercalation. Ni cannot be synthesized by high temperature solid phase sintering. 0.33In2Se3.

[0133] Example 2

[0134] In this embodiment, the novel ternary layered compound is Ni 0.5 In2Se3 powder, the intercalation raw material is In2Se3 powder, the intercalation material is Ni powder, and the inorganic salt is a mixed salt of KCl and LiCl. The preparation method of the ternary layered compound is as follows:

[0135] (1) Weigh 1.401 g of In2Se3 powder, 4.47 g of KCl, 3.825 g of LiCl, and 0.0885 g of Ni, and grind and mix the above materials (grinding speed is 3000 rpm, time is 5 min) to obtain a mixed product.

[0136] (2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. Reaction conditions are: 400°C, 5 hours, argon protection. After the tube furnace temperature drops to room temperature, remove the reaction product from the crucible.

[0137] (3) Washing the reaction product with deionized water: Place the reaction product in a beaker, add deionized water, stir and ultrasonically clean for 30 minutes, then let it stand for 1 hour and discard the supernatant. Repeat the above steps three times, then place it in a 60°C oven and dry it for 2 hours to obtain a ternary layered compound powder.

[0138] Example 3

[0139] In this embodiment, the novel ternary layered compound is NiIn2Se3 powder, the intercalation raw material is In2Se3 powder, the intercalation material is Ni powder, and the inorganic salt is a mixed salt of KCl and LiCl. The preparation method of the ternary layered compound is as follows:

[0140] (1) Weigh 1.401 g of In2Se3 powder, 4.47 g of KCl, 3.825 g of LiCl, and 0.177 g of Ni, and grind and mix the above materials (grinding speed is 3000 rpm, time is 5 min) to obtain a mixed product.

[0141] (2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. Reaction conditions are: 400°C, 5 hours, argon protection. After the tube furnace temperature drops to room temperature, remove the reaction product from the crucible.

[0142] (3) Washing the reaction product with deionized water: Place the reaction product in a beaker, add deionized water, stir and ultrasonically clean for 30 minutes, then let it stand for 1 hour and discard the supernatant. Repeat the above steps three times, then place it in a 60°C oven and dry it for 2 hours to obtain a ternary layered compound powder.

[0143] Example 4

[0144] In this embodiment, the novel ternary layered compound is Ni 0.33 In2Se3 single crystal, the intercalation raw material is In2Se3 single crystal block, the intercalation material is Ni powder, and the inorganic salt is a mixed salt of KCl and LiCl. The preparation method of the ternary layered compound is as follows:

[0145] (1) Weigh 5.934 g of KCl, 3.384 g of LiCl, and 0.039 g of Ni powder, grind and mix the above materials (grinding speed is 3000 rpm, time is 5 min) to obtain a mixture, then weigh 0.93 g of In2Se3 single crystal block and submerge the In2Se3 single crystal block in the mixture.

[0146] (2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. Reaction conditions are: 600°C, 5 hours, argon protection. After the temperature of the tube furnace drops to room temperature, remove the reaction product from the crucible.

[0147] (3) Washing the reaction product with deionized water: Place the reaction product in a beaker, add deionized water, stir and ultrasonically clean for 30 minutes, then let it stand for 1 hour and discard the supernatant. Repeat the above steps three times, then place it in a 60°C oven and dry it for 2 hours to obtain a single crystal block of the ternary layered compound.

[0148] Figure 6 Ni prepared in Example 4 0.33 Comparison of the XRD patterns of the In2Se3 single crystal and the original In2Se3 single crystal. The XRD patterns of the two materials are similar, with a distinct (00l) diffraction peak, indicating that the insertion of Ni does not disrupt the overall structure of the In2Se3 single crystal. The (00l) diffraction peak exhibits a high-angle shift, indicating that the insertion of Ni reduces the interlayer spacing of the In2Se3.

[0149] Figure 7 Ni prepared in Example 4 0.33 Microscopic morphology analysis of In2Se3 single crystal material under scanning electron microscope. It can be seen from the figure that the sample after intercalation is still a layered compound, the structure has not been destroyed, and the layering is obvious.

[0150] Example 5

[0151] In this example, the new ternary layered compound is Ni 0.33 In2Se3 thin film, the intercalation raw material is In2Se3 thin film, the intercalation material is Ni powder, and the inorganic salt is a mixed salt of KCl and LiCl. The preparation method of the ternary layered compound is as follows:

[0152] (1) Weigh 1.978 g of KCl, 1.128 g of LiCl, and 0.039 g of Ni, grind and mix the above materials (grinding speed is 3500 rpm, time is 7 min) to obtain a mixture, then weigh 0.93 g of In2Se3 film and submerge the In2Se3 film in the mixture.

[0153] (2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. Reaction conditions are: 500°C, 5 hours, argon protection. After the temperature of the tube furnace drops to room temperature, remove the reaction product from the crucible.

[0154] (3) Wash the reaction product with deionized water: put the reaction product into a beaker, add deionized water, stir and ultrasonically clean for 30 minutes, then let it stand for 1 hour and discard the supernatant. Repeat the above steps to wash the product three times, then put it into a 60℃ oven and dry it for 2 hours to obtain the product Ni 0.33 In2Se3 thin film.

[0155] Example 6

[0156] In this embodiment, the novel ternary layered compound is Ni 0.33 In2Se3 block, the intercalation raw material is In2Se3 powder, the intercalation material is Ni powder, and the inorganic salt is a mixed salt of KCl and LiCl. The preparation method of the ternary layered compound is as follows:

[0157] (1) Weigh 9.34 g of In2Se3 powder, 29.8 g of KCl, 25.5 g of LiCl, and 0.3898 g of Ni powder, and grind and mix the above materials (grinding speed is 3000 rpm, time is 5 min) to obtain a mixed product.

[0158] (2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. Reaction conditions are: 400°C, 5 hours, argon protection. After the tube furnace temperature drops to room temperature, remove the reaction product from the crucible.

[0159] (3) Washing the reaction product with deionized water: put the reaction product into a beaker, add deionized water, stir and ultrasonically clean for 30 minutes, then let it stand for 1 hour, and pour out the supernatant; repeat the above steps to wash the product three times, put it into a 60°C oven, and dry it for 2 hours to obtain Ni 0.33 In2Se3 powder.

[0160] (4) Weigh Ni 0.339g of In2Se3 powder was subjected to spark plasma sintering. The reaction conditions were: heating rate of 100℃ / min, holding temperature of 500℃, 40MPa, holding time of 10min, and argon protection. After sintering, the block sample was taken out and polished. The conductive layer wrapped on the surface was cleaned to obtain Ni 0.33 In2Se3 bulk.

[0161] Figure 8 Ni prepared in Example 6 0.33 Macroscopic morphology of In2Se3 bulk material. Each small grid in the figure is 1mm, and the diameter of the bulk sample is 20mm.

[0162] Figure 9 Ni prepared in Example 6 0.33 In2Se3 bulk material and Ni prepared in Example 1 0.33 In2Se3 powder XRD diffraction pattern. From the comparison chart, it can be seen that the bulk sample after spark plasma sintering did not undergo phase change and impurity generation, and the structure still maintained the original Ni 0.33 Structure of In2Se3 powder.

[0163] Figure 10 Ni prepared in Example 6 0.33 DSC spectra of In2Se3 bulk material and In2Se3 bulk material obtained by the same sintering process of In powder and Se powder. The X axis is the temperature during the test, and the Y axis represents the thermal change of the material at different temperatures. From the spectrum, it can be observed that the original In2Se3 bulk material has a thermal event at 200℃, indicating the existence of phase transition or thermal decomposition. The new structure ternary layered compound Ni 0.33 In2Se3 bulk material has no thermal events and maintains a stable state, indicating that the new structure of ternary layered compound Ni 0.33 The thermal stability of In2Se3 is superior to that of In2Se3 material.

[0164] Figure 11 Ni prepared in Example 6 0.33 The conductivity spectrum of In2Se3 bulk material and In2Se3 bulk material changes with temperature. It can be observed from the figure that with the increase of temperature, the new ternary layered compound Ni 0.33 The electrical conductivity of In2Se3 is greater than that of In2Se3 bulk samples, and this advantage increases with increasing temperature.

[0165] Figure 12 Ni prepared in Example 6 0.33The carrier concentration of In2Se3 bulk material and In2Se3 bulk material changes with temperature. From the figure, it can be observed that as the temperature increases, the new ternary layered compound Ni 0.33 The carrier concentration of In2Se3 is greater than that of In2Se3, indicating that the insertion of Ni significantly increases the carrier concentration of In2Se3.

[0166] Figure 13 Ni prepared in Example 6 0.33 The thermal conductivity of In2Se3 bulk material and In2Se3 bulk material changes with temperature. From the figure, we can observe that the new structure ternary layered compound Ni 0.33 The thermal conductivity of In2Se3 is smaller than that of bulk In2Se3 and remains stable when the temperature changes, indicating that Ni 0.33 The thermal conductivity of In2Se3 is stable, and the thermoelectric performance it brings is better than that of In2Se3 bulk materials.

[0167] Figure 14 Ni prepared in Example 6 0.33 The ZT value of In2Se3 bulk material and In2Se3 bulk material changes with temperature. It can be observed from the figure that as the temperature increases, Ni 0.33 The thermoelectric figure of merit of In2Se3 bulk materials and In2Se3 bulk materials gradually increases, and Ni 0.33 The thermoelectric figure of merit of In2Se3 bulk material increases faster than that of In2Se3 bulk material. At 500°C, the thermoelectric figure of merit of In2Se3 material is increased from 0.21 to 0.63, which greatly improves the thermoelectric performance of the material.

[0168] Example 7

[0169] In this embodiment, the novel ternary layered compound is Fe 0.33 In2Se3 powder, the intercalation raw material is In2Se3 powder, the intercalation material is Fe powder, and the inorganic salt is LiCl. The preparation method of the ternary layered compound is as follows:

[0170] (1) Weigh 1.401 g of In2Se3 powder, 6.345 g of LiCl, and 0.05544 g of Fe powder, and grind and mix the above materials (grinding speed is 2500 rpm, time is 8 min) to obtain a mixed product.

[0171] (2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. Reaction conditions are: 650°C, 5 hours, argon protection. After the temperature of the tube furnace cools to room temperature, remove the reaction product from the crucible.

[0172] (3) Washing the reaction product with deionized water: Place the reaction product in a beaker, add deionized water, stir and ultrasonically clean for 30 minutes, then let it stand for 1 hour and discard the supernatant; repeat the above steps to wash the product three times, place it in an oven at 60°C, and dry it for 2 hours to obtain a ternary layered compound powder.

[0173] Example 8

[0174] In this embodiment, the novel ternary layered compound is Fe 0.33 In2Se3 block, the intercalation raw material is In2Se3 powder, the intercalation material is Fe powder, and the inorganic salt is LiCl. The preparation method of the ternary layered compound is as follows:

[0175] Steps (1)-(3) are the same as in Example 7 to obtain Fe 0.33 In2Se3 powder.

[0176] (4) Weigh Fe 0.33 In2Se3 powder was subjected to spark plasma sintering, and the reaction conditions were: heating rate 150℃ / min, holding temperature 450℃, 50MPa, holding time 15min, argon protection. After sintering, the block sample was taken out, polished, and the conductive layer wrapped on the surface was cleaned to obtain Fe 0.33 In2Se3 bulk.

[0177] Example 9

[0178] In this embodiment, the novel ternary layered compound is Co 0.33 In2Se3 powder, the intercalation raw material is In2Se3 powder, the intercalation material is Co powder, and the inorganic salt is LiBr. The preparation method of the ternary layered compound is as follows:

[0179] (1) Weigh 1.401 g of In2Se3 powder, 13.035 g of LiBr, and 0.0589 g of Co powder, and grind and mix the above materials (grinding speed is 3500 rpm, time is 5 min) to obtain a mixed product.

[0180] (2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. Reaction conditions are: 600°C, 6 hours, argon protection. After the temperature of the tube furnace cools to room temperature, remove the reaction product from the crucible.

[0181] (3) Washing the reaction product with deionized water: Place the reaction product in a beaker, add deionized water, stir and ultrasonically clean for 30 minutes, then let it stand for 1 hour and discard the supernatant; repeat the above steps to wash the product three times, place it in a 70°C oven, and dry it for 2 hours to obtain a ternary layered compound powder.

[0182] Example 10

[0183] In this embodiment, the novel ternary layered compound is Co 0.33 In2Se3 block, the intercalation raw material is In2Se3 powder, the intercalation material is Co powder, and the inorganic salt is LiBr. The preparation method of the ternary layered compound is as follows:

[0184] Steps (1)-(3) are the same as in Example 9 to obtain Co 0.33 In2Se3 powder.

[0185] (4) Weigh Co 0.33 In2Se3 powder was subjected to spark plasma sintering, and the reaction conditions were: heating rate 120℃ / min, holding temperature 550℃, 30MPa, holding time 12min, argon protection. After sintering, the block sample was taken out, polished, and the conductive layer wrapped on the surface was cleaned to obtain Co 0.33 In2Se3 bulk.

[0186] Example 11

[0187] In this embodiment, the novel ternary layered compound is Ni 0.33 Fe 0.5 In2Se3 powder, the intercalation raw material is In2Se3 powder, the intercalation material is Ni powder and Fe powder, and the inorganic salt is a mixed salt of KCl and LiCl. The preparation method of the ternary layered compound is as follows:

[0188] (1) Weigh 1.401 g of In2Se3 powder, 4.85 g of KCl, 4.15 g of LiCl, 0.05847 g of Ni powder, and 0.08377 g of Fe powder, and grind and mix the above materials (grinding speed is 3000 rpm, time is 7 min) to obtain a mixed product.

[0189] (2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. Reaction conditions are: 450°C, 7 hours, argon protection. After the temperature of the tube furnace cools to room temperature, remove the reaction product from the crucible.

[0190] (3) Washing the reaction product with deionized water: Place the reaction product in a beaker, add deionized water, stir and ultrasonically clean for 40 minutes, then let it stand for 1.5 hours and discard the supernatant; repeat the above steps to wash the product three times, place it in a 70°C oven, and dry it for 2 hours to obtain a ternary layered compound powder.

[0191] Comparative Example 2

[0192] The preparation method of Comparative Example 2 is as follows:

[0193] (1) Weigh 1.401 g of In2Se3 powder, 4.47 g of KCl, and 3.825 g of LiCl, and grind and mix the above materials (grinding speed is 3000 rpm, time is 5 min) to obtain a mixed product.

[0194] (2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. The reaction conditions are: 400°C, 5 hours, argon protection. After the temperature of the tube furnace drops to room temperature, remove the reaction product from the crucible.

[0195] (3) Washing the reaction product with deionized water: Place the reaction product in a beaker, add deionized water, stir and ultrasonically clean for 30 minutes, then let it stand for 1 hour and discard the supernatant; repeat the above steps to wash the product three times, then place it in a 60°C oven and dry it for 2 hours to obtain a product powder.

[0196] Figure 15 This is a comparison of the XRD patterns of the product from Comparative Example 2 and the original In2Se3. When Ni is absent from the reactants, the In2Se3 undergoes a phase transition to the γ phase, while the (003) diffraction peak intensity remains unchanged. This comparison of Comparative Example 2 and Example 1 demonstrates that Ni intercalation was achieved in Example 1.

[0197] Comparative Example 3

[0198] The preparation method of Comparative Example 3 is as follows:

[0199] (1) Weigh 1.401 g of In2Se3 powder and 0.05847 g of Ni powder, and grind and mix the above materials (grinding speed is 3000 rpm, time is 5 min) to obtain a mixed product.

[0200] (2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. Reaction conditions are: 400°C, 5 hours, argon protection. After the temperature of the tube furnace cools to room temperature, remove the reaction product from the crucible.

[0201] (3) Washing the reaction product with deionized water: Place the reaction product in a beaker, add deionized water, stir and ultrasonically clean for 30 minutes, then let it stand for 1 hour and discard the supernatant; repeat the above steps to wash the product three times, then place it in a 60°C oven and dry it for 2 hours to obtain a product powder.

[0202] Comparative Example 3 was not carried out in a molten salt environment, and the obtained product had very low purity and poor uniformity.

[0203] The various aspects, embodiments, and features of the present invention should be considered in all respects as illustrative and not limiting, the scope of which is defined solely by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0204] In the preparation method of the present invention, the order of the steps is not limited to the order listed. Persons skilled in the art will appreciate that variations in the order of the steps are within the scope of the present invention without inventive effort. Furthermore, two or more steps or actions may be performed simultaneously.

[0205] Finally, it should be noted that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit its implementation. Persons skilled in the art may make various modifications, additions, or substitute similar methods for the described specific embodiments. It is not necessary and impossible to provide comprehensive examples of all implementations here. However, obvious variations or modifications arising from the essential spirit of the present invention remain within the scope of protection of the present invention, and interpreting them as any additional limitations would be contrary to the spirit of the present invention.

Claims

1. A ternary layered compound, characterized in that: The molecular formula of the ternary layered compound is M x In2Se3, wherein M is selected from a combination of one or more of Fe, Co, and Ni, and 0<x≤1.

2. A ternary layered compound according to claim 1, characterized in that: The ternary layered compound has a hexagonal crystal structure, and the crystal structure is formed by alternating stacking of In2Se3 units and M atomic layers.

3. The ternary layered compound according to claim 1, characterized in that: The ternary layered compound is obtained by intercalating an In2Se3 compound into an intercalation material in a molten salt environment; the intercalation material is a combination of one or more of Fe, Co, and Ni, and the molten salt is formed by melting an inorganic salt into a liquid state.

4. The ternary layered compound according to claim 1, characterized in that: The ternary layered compound is in the form of powder, block or film.

5. The method for preparing a ternary layered compound according to claim 1, wherein: The following steps are involved: A mixture of In2Se3 compound, M metal and inorganic salt is reacted at 400-1000°C in an inert atmosphere to obtain a ternary layered compound.

6. The method for preparing a ternary layered compound according to claim 1, wherein: The following steps are involved: S1. reacting a mixture of an In2Se3 compound, an M metal, and an inorganic salt at 400-1000° C. in an inert atmosphere to obtain a ternary layered compound powder; S2. performing spark plasma sintering, hot pressing sintering, or pressureless sintering on the ternary layered compound powder to obtain a ternary layered compound block; The In2Se3 compound is in powder form.

7. The preparation method according to claim 5 or 6, characterized in that: The mixture of the In2Se3 compound, the M metal, and the inorganic salt is obtained by mechanically mixing the In2Se3 compound, the M metal, and the inorganic salt to obtain a mixture; or, the M metal and the inorganic salt are first mechanically mixed, and then the In2Se3 compound is added to submerge them to obtain a mixture of the In2Se3 compound, the M metal, and the inorganic salt; The mechanical mixing includes high-energy ball milling, mechanical stirring, mechanical shaking, grinding or roller milling, and the mixing time is 10 minutes to 10 hours.

8. The preparation method according to claim 5, characterized in that The In2Se3 compound is in powder, film or block form; The M metal is a combination of one or more of Fe, Co, and Ni.

9. The preparation method according to claim 5, characterized in that When the ternary layered compound is in the form of a thin film, the preparation method comprises the following steps: The M metal and inorganic salt are first mechanically mixed, and then the In2Se3 compound is added to submerge them to obtain a mixture of the In2Se3 compound, the M metal, and the inorganic salt. The mixture is reacted at 400-1000°C in an inert atmosphere to obtain a ternary layered compound film; The In2Se3 compound is in the form of a thin film.

10. The preparation method according to claim 5, characterized in that When the ternary layered compound is a single crystal, the preparation method comprises the following steps: The M metal and inorganic salt are first mechanically mixed, and then the In2Se3 compound is added to submerge them to obtain a mixture of the In2Se3 compound, the M metal, and the inorganic salt, which is reacted at 400-1000°C in an inert atmosphere to obtain a single crystal ternary layered compound; The crystal structure of the In2Se3 compound is single crystal.

11. The preparation method according to claim 10, characterized in that: The In2Se3 compound is a single crystal and has a block shape.

12. The preparation method according to claim 5 or 6, characterized in that: The inorganic salt is one or more compounds formed by ion bonding of halide ions, nitrate ions or sulfate ions with metal ions.

13. The preparation method according to claim 12, characterized in that The halogen ions in the inorganic salt are one or more of chloride ions, bromide ions, and fluoride ions, and the metal ions are one or more of alkali metal ions, alkaline earth metal ions, and transition metal ions.

14. The preparation method according to claim 14, characterized in that The inorganic salt is one or more of LiCl, NaCl, KCl, CaCl2, MgCl2, KF, NaF, LiF, LiBr, NaBr, KBr, CaBr2, MgBr2, and Na2SO4.

15. The preparation method according to claim 5 or 6, characterized in that: The molar ratio of the In2Se3 compound to the M metal is 1:(0,5]; and / or, the molar ratio of the In2Se3 compound to the inorganic salt is 1:5 to 200; and / or, reacting at 400-900° C. in an inert atmosphere for 1-10 hours.

16. The preparation method according to claim 5 or 6, characterized in that: The reaction is carried out at 400-1000° C. in an inert atmosphere, and then cooled to room temperature, followed by post-treatment. The post-treatment includes washing the reaction product with water to remove residual inorganic salts, and then drying.

17. Use of the ternary layered compound according to claim 1 in thermoelectric materials and ferroelectric memory devices.

Images