Ordered inorganic-organic hybrid nanomaterials with high-temperature superconductivity

Abstract

The purpose of this invention is to provide an ordered inorganic-organic hybrid nanomaterial with high-temperature superconductivity and its preparation method. The method employs a two-step chemical liquid-phase method. The ordered inorganic-organic hybrid nanomaterial has a two-dimensional nanosheet-like microstructure, with its inorganic structural unit being iron-selenium sheets possessing a tetragonal β-Fe3Se4 superstructure, and its organic structural unit being divalent iron organic amine complexes. The resulting ordered inorganic-organic hybrid nanomaterial with a periodic crystal structure has a superconducting critical transition temperature in the range of 26-41 K. The preparation method is simple, the raw materials are readily available, and the thickness of the synthesized sheet-like hybrid nanomaterial is 30-300 nm.

Description

Technical Field

[0001] This invention belongs to the field of inorganic-organic hybrid functional nanomaterials, specifically involving a class of ordered inorganic-organic hybrid superconducting nanomaterials with high-temperature superconductivity and their preparation method. Background Technology

[0002] In iron-selenium binary compounds, the NiAs-type FeSe high-temperature phase with a hexagonal crystal structure is a magnetic semiconductor material, while the PbO-type β-FeSe low-temperature phase with a tetragonal crystal structure is an iron-based superconducting material with a layered structure. The zero-resistance temperature of β-FeSe superconducting materials prepared by traditional solid-state reaction methods is around 8K [Hsu, FC, et al. P. Natl. Acad. Sci. USA, 2008, 105, 14262-14264]. Furthermore, bulk β-FeSe superconductors can also be prepared by molten salt methods [Crystal Growth and Design (Cryst. Growth Des.) 2009, 9, 3260-3264] and vapor transport methods [ACSNano Journal (ACSNano) 2013, 7, 1145-1154]. However, these methods require high temperatures (above 700℃) and long reaction times, and magnetic impurity phases often appear in the β-FeSe superconductors. J.T. Greenfield et al. [Chem. Mater. 2015, 27, 588-596] prepared β-FeSe nanoparticles with superconducting properties using insoluble raw materials, iron and selenium particles, with the aid of mineralizing agent NH4Cl via a solvothermal method [Chem. Mater. 2015, 27, 588-596]. Li et al. [Chem. Mater. 2017, 29, 842-848] prepared tetragonal β-FeSe superconducting nanosheets using soluble iron and selenium precursors via a solvothermal method.

[0003] Based on the prepared inorganic β-FeSe superconductor, Zhou Xingjiang et al. [Mou DX, et al. 2011, Phys. Rev. Lett. 106, 107001] synthesized K through a potassium atom intercalation reaction. x Fe2Se2 high-temperature superconductor; Sun Liling et al. [Sun L, et al. 2012, Nature 483, 67] discovered K x Superconductors such as Fe₂Se₂ exhibit a second superconducting phase under high pressure. Swiss scholars Krzton-Maziopa et al. [2011, J. Phys.: Condens. Matter 23, 052203] discovered Cs 0.8 Fe 1.8The superconducting transition temperature of Se2 is 27 K. Chen et al. [2011, Phys. Rev. B 83, 060512] discovered Rb 0.8 The superconducting transition temperature of Fe₂Se₂ superconductors is 32 K. Fang Minghu's research group [2011, Eur. Phys. Lett. 94, 27009] discovered that Tl... 1-x K x The superconducting transition temperature of Fe₂Se₂ superconductors is 31 K. Wen Haihu et al. [2011, Phys. Rev. B83, 184521] discovered Rb 0.8 The anisotropic transport properties of Fe2Se2. Researchers have also successfully inserted alkali metals (Li, Na), alkaline earth metals (Ca, Sr, Ba), and rare earth elements (Eu, Yb) into FeSe layers at room temperature using the liquid ammonia method, preparing a series of FeSe layers with superconducting transition temperatures of 30-47 K that are unattainable by high-temperature methods. x (NH3) y Fe2Se2 (A=Li,Na,Ca,Sr,Ba,Eu,Yb) superconductor [2012, Sci.Rep.2, 426]. The research group of Chen Xianhui [2014, Phys.Rev.B 89, 020507] discovered a stable FeSe-based high-temperature superconductor in air—LiOHFeSe—with a superconducting transition temperature exceeding 40K. Using various organic amines as intercalation media, researchers have successfully synthesized superconducting compounds by embedding them into FeSe layers under the influence of alkali metals. These compounds include Pyridine [2012, J. Phys.: Condens. Matter 24, 382202], EDA (ethylenediamine) [2017 Phys. Rev. B 96, 014502; 2014, Physica C, 504, 8; 2015, Inorg. Chem. 54, 3346], HMDA (hexamethylenediamine) [2016, J. Phys. Soc. Jpn. 85, 104701], DAP (propylenediamine) and putrescine (butanediamine) [2017, Chem. Comm. 53, 9729]. Hosono et al. [2014, J. Phys. Soc. Jpn. 83, 113704] used hexamethylenediamine (C6H) to intercalate... 16 N2) intercalation of FeSe, but the superconducting critical transition temperature is reduced to 38K.

[0004] This invention employs a two-step chemical liquid-phase method to synthesize an ordered inorganic-organic hybrid superconductor with high-temperature superconductivity by self-assembling inorganic and organic structural units. This is based on the synthesis of organic structural units (iron-organic amine complexes) and two-dimensional layered inorganic structural units with a tetragonal β-Fe3Se4 superstructure, with the superconducting critical transition temperature ranging from 26 to 41 K. This method has not been previously reported. This invention offers advantages such as simple process and non-toxic, harmless raw materials. Summary of the Invention

[0005] The purpose of this invention is to provide a novel organic-inorganic hybrid superconducting nanomaterial with high-temperature superconductivity and its chemical liquid-phase preparation method. This method is simple to operate, the raw materials are easy to obtain, and it can be used to synthesize inorganic-organic hybrid superconducting nanomaterials with sheet-like microstructures.

[0006] The technical solution of this invention is as follows:

[0007] An ordered organic-inorganic hybrid superconducting nanomaterial with high-temperature superconductivity is characterized by being prepared by a two-step chemical liquid-phase method. The ordered inorganic-organic hybrid nanomaterial is a novel superconducting material with a tetragonal crystal structure. Its inorganic structural unit is a two-dimensional iron selenium sheet with a tetragonal β-Fe3Se4 superstructure, and its organic structural unit is a divalent iron organic amine complex, wherein the organic amine is one of triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.

[0008] The ordered inorganic-organic hybrid nanomaterials have a two-dimensional nanosheet microstructure with a thickness of 30-300 nanometers.

[0009] The ordered organic-inorganic hybrid superconducting nanomaterial with high-temperature superconductivity of the present invention is characterized in that: the inorganic-organic hybrid nanomaterial has superconducting properties and has a periodically arranged tetragonal crystal structure.

[0010] This invention also provides a method for preparing the ordered organic-inorganic hybrid superconducting nanomaterial with high-temperature superconductivity, characterized by a two-step chemical liquid-phase method, the specific steps of which are as follows:

[0011] (1) Mix some iron raw materials, all selenium raw materials and organic amine, place them in a four-necked flask to dissolve them, and obtain a uniform precursor solution; introduce inert gas to remove air, and heat to 100-140 degrees Celsius under magnetic stirring, and keep at the temperature for 30-120 minutes; then slowly heat the precursor solution to the reaction temperature and keep at the reaction temperature for 0.5-24 hours. After the reaction is completed, cool the reaction system to a temperature range of room temperature to 160 degrees Celsius.

[0012] (2) Inject the remaining iron raw material and organic amine mixture into the above reaction product solution and mix evenly. Under inert gas protection and magnetic stirring, slowly heat to the reaction temperature II and keep warm for 1-12 hours. After the reaction is completed, cool the reaction system to room temperature.

[0013] (3) Centrifuge the reaction product solution, discard the supernatant, and obtain the precipitate;

[0014] (4) After washing with isopropanol, dry in vacuum to obtain product powder.

[0015] in:

[0016] The raw materials mentioned in step (1) include iron and selenium precursors that are soluble in organic amines;

[0017] In the iron precursor, the raw materials for iron are ferric acetylacetone and ferrous acetylacetone.

[0018] The precursor of selenium is one or more of selenium powder, sodium selenide, selenium dioxide powder, etc., with selenium dioxide powder being preferred.

[0019] In step (1), the molar ratio of iron atoms to selenium atoms is between (5-6):8; the total amount of some iron raw materials and selenium raw materials used is 0.05-120 mmol, and the amount of organic amine used is 20-1000 ml.

[0020] The organic amine mentioned in step (1) is a reducing organic amine solvent, preferably one or more of triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine (most preferably tetraethylenepentamine).

[0021] The reaction temperature described in step (1) is 250-310 degrees Celsius.

[0022] The reaction temperature in step (2) is 250-300 degrees Celsius.

[0023] After the remaining iron raw materials in step (2) are added to the reaction system, the molar ratio of iron atoms to selenium atoms in the reaction system reaches (7-10):8, preferably 7:8, and the corresponding organic amine is tetraethylenepentamine.

[0024] In step (1), the precursor solution is heated to reaction temperature one at a heating rate of 0.06-0.5 K / min (preferably 0.06 K / min); in step (2), the mixture is heated to reaction temperature two at a heating rate of 0.06-0.5 K / min (preferably 0.2 K / min).

[0025] This invention uses a chemical liquid phase method to prepare ordered organic-inorganic hybrid superconducting nanomaterials with high-temperature superconductivity. The advantages are: the process is simple, the cost is low, and no expensive or special reagents or equipment are required, thus obtaining ordered organic-inorganic hybrid superconducting nanomaterials with high-temperature superconductivity. Attached Figure Description

[0026] Figure 1 The X-ray diffraction pattern of the organic-inorganic hybrid superconducting nanomaterial prepared in Example 1;

[0027] Figure 2 Scanning electron microscope (SEM) image of the organic-inorganic hybrid superconducting nanomaterials prepared in Example 1;

[0028] Figure 3 Transmission electron microscopy (TEM) image of the organic-inorganic hybrid superconducting nanomaterials prepared in Example 1;

[0029] Figure 4 Thermogravimetric analysis curves of the organic-inorganic hybrid superconducting nanomaterials prepared in Example 1;

[0030] Figure 5 The relationship between zero-field-cooled (ZFC) and field-cooled (FC) magnetization of the organic-inorganic hybrid superconducting nanomaterials prepared in Example 1 and temperature.

[0031] Figure 6 The AC magnetic susceptibility of the organic-inorganic hybrid superconducting nanomaterial prepared in Example 1;

[0032] Figure 7 The hysteresis loop of the organic-inorganic hybrid superconducting nanomaterial prepared in Example 1 at 2K;

[0033] Figure 8 X-ray diffraction pattern of the organic-inorganic hybrid superconducting nanomaterial prepared in Example 2;

[0034] Figure 9 The hysteresis loop of the organic-inorganic hybrid superconducting nanomaterial prepared in Example 2 at 2K;

[0035] Figure 10 The relationship between zero-field-cooled (ZFC) and field-cooled (FC) magnetization of the inorganic-organic hybrid superconducting nanomaterials prepared in Example 2 and temperature.

[0036] Figure 11 The zero-field-cooled (ZFC) and field-cooled (FC) magnetization of the ordered organic-inorganic hybrid superconducting nanomaterial prepared in Example 3 is shown as a function of temperature. The measured magnetic field is 50 Oersted. Detailed Implementation

[0037] The following embodiments will further illustrate the present invention, but are not intended to limit the invention.

[0038] Example 1

[0039] Ferric acetylacetone (3 mmol) and selenium dioxide (4 mmol) were dissolved in tetraethylenepentamine (TEPA, 80 mL) in a four-necked flask. After purging with high-purity nitrogen to remove air, the mixture was heated to 110 °C and held for 1 hour with magnetic stirring. The mixture was then heated to 300 °C (heating rate 0.06 K / min) and held for 3 hours, before cooling to room temperature. At room temperature, the remaining 0.5 mmol of ferrous acetylacetone and 5 mL of tetraethylenepentamine mixture were added to the above reaction product solution. Under inert gas protection and magnetic stirring, the mixture was slowly heated to 280 °C (heating rate 0.2 K / min) and held for 3 hours to obtain ordered inorganic-organic hybrid superconducting nanomaterials. After cooling to room temperature, the nanomaterials were centrifuged, washed three times with isopropanol, dried in vacuum, and stored.

[0040] The crystal structure of the product was determined by X-ray diffraction, confirming that the phase has a tetragonal crystal structure, such as... Figure 1 As shown. Its scanning electron microscope (SEM) image, as follows. Figure 2 As shown. Transmission electron microscopy (TEM) images of ordered inorganic-organic hybrid superconducting nanomaterials are shown below. Figure 3 As shown. The thermogravimetric analysis curves of the prepared ordered inorganic-organic hybrid superconducting nanomaterials are as follows. Figure 4 As shown, measurements indicate that the hybrid material undergoes thermal decomposition above 570 K. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization of the prepared ordered inorganic-organic hybrid superconducting nanomaterials varies with temperature, as shown below. Figure 5 As shown. The AC magnetic susceptibility of ordered organic-inorganic hybrid superconducting nanomaterials is as follows: Figure 6 As shown. The hysteresis loop at a temperature of 2K is as follows. Figure 7 As shown, the ordered inorganic-organic hybrid superconducting material prepared using ferric acetylacetone and ferrous acetylacetone as iron precursors and selenium dioxide as a selenium precursor, at a reaction temperature of 280°C for 3 hours, exhibits a superconducting critical transition temperature as high as 41 K. At 2 K, the lower critical magnetic field of the ordered inorganic-organic hybrid superconducting material is approximately 70 ohms; the upper critical magnetic field is higher than 140 kilo-ohms.

[0041] Example 2

[0042] Ferric acetylacetone (6 mmol) and selenium dioxide (8 mmol) were dissolved in tetraethylenepentamine (TEPA, 60 mL) in a four-necked flask. After purging with high-purity nitrogen to remove air, the mixture was heated to 110 °C and held for 1 hour with magnetic stirring. The mixture was then heated to 300 °C (heating rate 0.06 K / min) and held for 3 hours, before cooling to room temperature. At room temperature, the remaining 1 mmol of ferrous acetylacetone and 5 mL of tetraethylenepentamine mixture were added to the above reaction product solution. Under inert gas protection and magnetic stirring, the mixture was slowly heated to 300 °C (heating rate 0.2 K / min) and held for 3 hours to obtain ordered inorganic-organic hybrid superconducting nanomaterials. After cooling to room temperature, the nanomaterials were centrifuged, washed three times with isopropanol, dried in vacuum, and stored.

[0043] The phase composition of the product was determined by X-ray diffraction, such as... Figure 8 As shown, besides a small amount of decomposed inorganic impurity phase β-Fe7Se8, there are also two ordered inorganic-organic hybrid phases with similar lattice parameters. The hysteresis loop of the prepared ordered inorganic-organic hybrid superconducting nanomaterial at 2K is shown in the figure. Figure 9 As shown. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization of the prepared ordered inorganic-organic hybrid superconducting nanomaterials varies with temperature, as shown in the figure. Figure 10 As shown, two superconducting transitions are displayed, with superconducting critical transition temperatures of 26 K and 41 K, respectively.

[0044] Example 3

[0045] Ferric acetylacetone (6 mmol) and selenium dioxide (8 mmol) were dissolved in triethylenetetramine (teta, 80 ml) in a four-necked flask. After purging with high-purity nitrogen, the mixture was heated to 120°C and held for 1 hour under magnetic stirring. The mixture was then heated to 260°C (heating rate 0.1 K / min) and held for 6 hours, before cooling to room temperature. At room temperature, the remaining 1 mmol of ferrous acetylacetone and 5 ml of triethylenetetramine mixture were added to the above reaction product solution. Under inert gas protection and magnetic stirring, the mixture was slowly heated to 260°C (heating rate 0.15 K / min) and held for 6 hours to obtain ordered inorganic-organic hybrid superconducting nanomaterials. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization under a 50°Oerster magnetic field as a function of temperature is shown below. Figure 11 As shown.

[0046] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An ordered inorganic-organic hybrid nanomaterial with high-temperature superconductivity, characterized in that: The ordered inorganic-organic hybrid nanomaterial is a novel superconducting material with a tetragonal crystal structure. Its inorganic structural unit is a two-dimensional iron selenium sheet with a tetragonal β-Fe3Se4 superstructure; the organic structural unit is a divalent iron organic amine complex, wherein the organic amine is one of triethylenetetramine, tetraethylenepentamine or pentaethylenehexamine. Ordered inorganic-organic hybrid nanomaterials with high-temperature superconductivity were prepared using a chemical liquid-phase method, the specific steps of which are as follows: (1) Mix some iron raw materials, selenium dioxide and organic amine, place them in a four-necked flask to dissolve them, and obtain a uniform precursor solution; introduce inert gas to remove air, and heat to 100-140 degrees Celsius under magnetic stirring, and keep warm for 30-120 minutes; then heat the precursor solution to the reaction temperature and keep warm at the reaction temperature for 0.5-24 hours. After the reaction is completed, cool the reaction system to the temperature range of room temperature to 160 degrees Celsius. (2) Inject the remaining iron raw material and organic amine mixture into the above reaction product solution and mix evenly. Under inert gas protection and magnetic stirring, heat to the reaction temperature II and keep warm for 1-12 hours. After the reaction is completed, cool the reaction system to room temperature. (3) Centrifuge the reaction product solution, discard the supernatant, and obtain the precipitate; (4) After washing with isopropanol, the product powder is dried in a vacuum. The iron raw material mentioned in step (1) is acetylacetone iron; The remaining iron raw material mentioned in step (2) is ferrous acetylacetone; The molar ratio of some of the iron raw materials and selenium raw materials mentioned in step (1) is 5-6:8; The reaction temperature described in step (1) is 250-310 degrees Celsius; The reaction temperature in step (2) is 250-300 degrees Celsius; The total molar ratio of iron atoms to selenium atoms in the raw materials is in the range of 7-10:

8.

2. The ordered inorganic-organic hybrid nanomaterial with high-temperature superconductivity according to claim 1, characterized in that: The superconducting critical transition temperature of the inorganic-organic hybrid nanomaterial is in the range of 26-41 K.

3. The ordered inorganic-organic hybrid nanomaterial with high-temperature superconductivity according to claim 1, characterized in that: The amount of organic amine used in step (1) is 20-1000 ml.

4. The ordered inorganic-organic hybrid nanomaterial with high-temperature superconductivity according to claim 1, characterized in that: In step (1), the precursor solution is heated to reaction temperature one at a heating rate of 0.06-0.5 K / min; in step (2), the mixture is heated to reaction temperature two at a heating rate of 0.06-0.5 K / min.

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