Manganese pentaethylenediamine hydrochloride, process for its preparation and very low temperature magnetic refrigeration applications

Abstract

This invention belongs to the field of magnetic refrigeration materials technology, specifically relating to manganese pentaethylenehexamine hydrochloride, its preparation method, and its application in ultra-low temperature magnetic refrigeration. The chemical formula of the ultra-low temperature magnetic refrigeration material is [Mn(C 10 H 28 [N6)]Cl2; the magnetic phase transition temperature of the ultra-low temperature magnetic refrigeration material is below 0.4K. The ultra-low temperature magnetic refrigeration material of this invention exhibits a large magnetocaloric effect near 1K, and the maximum magnetic entropy change is ≤40.8 J·kg when the magnetic field changes from 0 to 5T. ‑1 ·K ‑1 The aforementioned ultra-low temperature magnetic refrigeration material has abundant raw materials, a simple process, does not contain rare earth elements, is low-cost, and is suitable for industrial-scale production.

Description

Technical Field

[0001] This invention relates to the field of magnetic refrigeration materials, and in particular to a manganese pentaethylene hexaamine hydrochloride, its preparation method, and its application in ultra-low temperature magnetic refrigeration. Background Technology

[0002] Magnetic refrigeration is a solid-state refrigeration technology based on the magnetocaloric effect. It uses changes in an external magnetic field to drive the material to absorb or release heat, achieving a refrigeration cycle through isothermal magnetization and adiabatic demagnetization. The thermodynamic process of the magnetocaloric effect in magnetic refrigeration is highly reversible; theoretically, its thermodynamic efficiency can reach that of a Carnot cycle, and in practice, its efficiency can reach about two-thirds of that of a Carnot cycle. Compared to traditional gas compression refrigeration, which is limited by the expensive strategic resource helium (3He adsorption refrigeration, 3He-4He dilution refrigeration), magnetic refrigeration technology has advantages such as high efficiency, environmental friendliness, low vibration, no phase change or leakage risk, and a more compact system structure. It has significant application advantages and potential in low-temperature (<20K) and ultra-low-temperature (<1K) fields. The low vibration characteristics and high reliability of magnetic refrigeration are crucial for superconducting qubits in quantum computers (which need to be maintained at ~10mK), infrared detectors in space telescopes requiring operating temperatures below 2K, and the continuous and stable low-temperature environment for condensed matter physics experiments (such as topological materials research).

[0003] Low-temperature magnetic refrigeration materials are crucial for the application of magnetic refrigeration technology. Rare-earth-based compounds, due to their large magnetocaloric effect and low magnetic phase transition temperature, are a focus of research in the field of magnetic refrigeration materials. Compared with expensive rare-earth magnetic refrigeration materials, transition metal manganese-based magnetic refrigerants have a low-cost advantage. Magnetic refrigeration materials such as MnFe(P,As) and Ni-Mn-Sn have attracted widespread attention due to their large saturation magnetic moment, high magnetic entropy change, and low thermal hysteresis. For example, J. Am. Chem. Soc. (2008, 130, 11129–11139) reported mixed-valence manganese hypertetrahedral and planar disk-shaped complexes, which, due to ferromagnetic exchange and a high spin ground state, exhibit approximately 25 J·kg⁻¹ in the 0–7 T range. -1 ·K -1Magnetic entropy change. CN117210941A discloses a method for preparing MgMn6Sn6 single crystals, demonstrating the potential application of magnetic refrigeration materials in the room temperature range. CN114085248A discloses a hexamethylenetetramine manganese complex crystal material, its preparation method, and its applications, which can be used as a paramagnetic material in applications such as paramagnetic refrigeration, paramagnetic resonance, paramagnetic probes, and displacement reagents. CN110343934A discloses a Zn-doped Mn-Fe-P-Si based magnetic refrigeration material and its preparation method, applied to room temperature magnetic refrigeration. CN102881393A discloses a MnFePSi based room temperature magnetic refrigeration material and its preparation method. In summary, the preparation of manganese-based magnetic refrigeration materials mostly employs high-temperature smelting methods, and their relatively high refrigeration temperature range is not suitable for low-temperature and ultra-low-temperature applications.

[0004] Therefore, it is necessary to develop manganese-based ultra-low temperature magnetic refrigeration materials with large magnetocaloric effects below 4.2K, and with simple preparation processes and high energy efficiency. Summary of the Invention

[0005] This invention aims to provide manganese pentaethylenehexamine hydrochloride, its preparation method, and its application in ultra-low temperature magnetic refrigeration. The chemical formula of the ultra-low temperature magnetic refrigeration material of this invention is [Mn(C 10 H 28 The ultra-low temperature magnetic refrigeration material described above has a phase transition temperature of <0.4K. This material exhibits a large magnetocaloric effect near 1K, with a maximum magnetic entropy change ≤40.8 J·kg when the magnetic field changes from 0 to 5T. -1 ·K -1 The aforementioned ultra-low temperature magnetic refrigeration material does not contain rare earth elements, requires abundant raw materials, has a simple process, low cost, and is suitable for industrial-scale production.

[0006] To achieve the above objectives, the present invention employs the following technical solution: a method for preparing manganese pentaethylenehexamine hydrochloride, an ultra-low temperature magnetic refrigeration material, comprising the following steps:

[0007] Manganese chloride solution and pentaethylenehexamine (C 10 H 28 The mixture of N6 and other components was thoroughly mixed and heated to the reaction temperature under inert gas protection, and held at that temperature for a period of time. The reaction system was then cooled to room temperature, centrifuged, and washed to obtain the ultra-low temperature magnetic refrigeration material.

[0008] Preferably, the chemical formula of the ultra-low temperature magnetic refrigeration material is [Mn(C 10 H 28 N6)]Cl2.

[0009] Preferably, the manganese chloride is anhydrous MnCl2, MnCl2·4H2O, or a mixture of the two.

[0010] Preferably, the solvent for the manganese chloride solution is water, ethanol, or a mixture of both.

[0011] Preferably, the manganese chloride solution contains 0.1% to 100% manganese chloride by weight.

[0012] Preferably, the molar ratio of manganese chloride to pentaethylenehexamine in the manganese chloride solution is 1:800 to 1:1.

[0013] Preferably, the inert gas includes argon, nitrogen, or a mixture of both.

[0014] Preferably, the reaction temperature is 403-520K.

[0015] Preferably, the heat preservation time is 30-180 minutes.

[0016] This invention also claims protection for the ultra-low temperature magnetic refrigeration material prepared by the method described above.

[0017] Preferably, the ultra-low temperature magnetic refrigeration material exhibits a magnetocaloric effect near the phase transition temperature, and the magnetic phase transition temperature of the ultra-low temperature magnetic refrigeration material is <0.4K.

[0018] Preferably, the ultra-low temperature magnetic refrigeration material has a maximum magnetic entropy change of 22.5 J·kg at a temperature of 0.6 K when the magnetic field changes from 0 to 1 T. -1 ·K -1 .

[0019] Preferably, the ultra-low temperature magnetic refrigeration material has a maximum magnetic entropy change of 30.1 J·kg at a temperature of 1.0 K when the magnetic field changes from 0 to 2 T. -1 ·K -1 .

[0020] Preferably, the ultra-low temperature magnetic refrigeration material has a maximum magnetic entropy change of 40.8 J·kg at a temperature of 1.2 K when the magnetic field changes from 0 to 5 T. -1 ·K -1 .

[0021] The present invention also seeks protection for the application of the aforementioned cryogenic magnetic refrigeration material in the fields of cryogenic physics, quantum computing, and space exploration.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The phase transition temperature of the ultra-low temperature magnetic refrigeration material prepared by this invention is <0.4K; the material exhibits a large magnetocaloric effect in the range of 0.6K and 1.2K, and the maximum magnetic entropy changes under magnetic field changes of 0-1T, 0-2T and 0-5T are 22.5, 30.1 and 40.8 J·kg, respectively. -1·K -1 It is a very promising ultra-low temperature magnetic refrigeration material.

[0024] (2) The ultra-low temperature magnetic refrigeration material provided by the present invention is prepared by manganese chloride and pentaethylenehexamine at a reaction temperature of <530K. The raw materials do not contain expensive rare earth elements and are easy to obtain. The preparation process is simple, the cycle is short, the cost is low, and it is suitable for industrial production and application. Attached Figure Description

[0025] Figure 1 The XRD patterns of the ultra-low temperature magnetic refrigeration materials obtained in Examples 1-3 of this invention are shown below.

[0026] Figure 2 The EDX spectra of the ultra-low temperature magnetic refrigeration materials prepared in Examples 1-3 of this invention are shown.

[0027] Figure 3 The infrared spectra of the ultra-low temperature magnetic refrigeration materials prepared in Examples 1-3 of this invention;

[0028] Figure 4 The graphs show the magnetization (M)-temperature (T) curves of the ultra-low temperature magnetic refrigeration material prepared in Example 1 of the present invention in the temperature range of 2-300K under a 0.1T magnetic field, with zero field cooling (ZFC) and band field cooling (FC).

[0029] Figure 5 The graph shows the magnetization (M)-temperature (T) curves of the ultra-low temperature magnetic refrigeration material prepared in Example 1 of the present invention under a magnetic field of 0.1T and a temperature range of 0.4-1.8K.

[0030] Figure 6 Isothermal magnetization curves of the ultra-low temperature magnetic refrigeration material prepared in Example 1 of the present invention at different temperatures ranging from 0.4 to 19 K;

[0031] Figure 7 The graph shows the magnetic entropy change curve of the ultra-low temperature magnetic refrigeration material prepared in Example 1 of the present invention at temperatures ranging from 0.4 to 17 K.

[0032] Figure 8 Thermogravimetric curve of the ultra-low temperature magnetic refrigeration material obtained in Example 4 of the present invention;

[0033] Figure 9 The graph shows the isothermal magnetization curves of the ultra-low temperature magnetic refrigeration material prepared in Example 4 of this invention at different temperatures ranging from 2 to 28 K.

[0034] Figure 10 This is a graph showing the magnetic entropy change of the ultra-low temperature magnetic refrigeration material prepared in Example 4 of the present invention at temperatures ranging from 2 to 28 K. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. The described embodiments and accompanying drawings are only some embodiments of the present invention, not all embodiments, and therefore the embodiments are not limited thereto. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0036] Unless otherwise specified, the experimental methods used in this invention are all conventional solvothermal methods, and the materials and reagents used are commercially available unless otherwise specified.

[0037] Example 1

[0038] Mix MnCl2·4H2O (6 mmol), ethanol (10 ml), and pentaethylenehexamine (C 10 H 28 A mixture of N6 (40 ml) was placed in a four-necked flask, and air was purged through the flask with high-purity nitrogen. The mixture was heated to 433 Kelvin with magnetic stirring and held at this temperature for 60 minutes. The reaction system was then cooled to room temperature. The product material was centrifuged at room temperature, washed three times with acetone, and air-dried to obtain the ultra-low temperature magnetic refrigeration material.

[0039] Example 2

[0040] MnCl2·4H2O (3 mmol) and pentaethylenehexamine (C 10 H 28 A mixture of N6 (40 ml) was placed in a four-necked flask, and air was purged through the mixture with high-purity nitrogen. The mixture was heated to 473 Kelvin with magnetic stirring and held at this temperature for 180 minutes. The reaction system was then cooled to room temperature. The product material was centrifuged at room temperature, washed three times with acetone, and air-dried to obtain the ultra-low temperature magnetic refrigeration material.

[0041] Example 3

[0042] MnCl2·4H2O (16 mmol) and pentaethylenehexamine (C 10 H 28 N6 (30 ml) was mixed in a four-necked flask, and high-purity argon gas was purged to purge air. The mixture was heated to 453 Kelvin with magnetic stirring and held at this temperature for 60 minutes. The reaction system was then cooled to room temperature. At room temperature, the product material was centrifuged, washed three times with acetone, and air-dried to obtain the ultra-low temperature magnetic refrigeration material.

[0043] Example 4

[0044] Mix MnCl2·4H2O (6 mmol), deionized water (10 ml), and pentaethylenehexamine (C 10 H28 The mixture (20 ml of N6) was stirred in a reaction vessel, and high-purity nitrogen gas was purged to purge air. The mixture was heated to 433 Kelvin and held at that temperature for 60 minutes. Then, the reaction system was cooled to room temperature. At room temperature, the product material was centrifuged, washed three times with acetone, and dried in air to obtain the ultra-low temperature magnetic refrigeration material.

[0045] Example of effect

[0046] X-ray powder diffraction analysis was performed on the ultra-low temperature magnetic refrigeration material samples prepared in the examples using a Brucker D / Max-2400 X-ray diffractometer (XRD). Figure 1 These are the XRD patterns of the ultra-low temperature magnetic refrigeration materials prepared in Examples 1-3. It can be seen that the XRD patterns of the samples conform to a monoclinic crystal structure with space group P21 / c. The samples have high phase purity, consisting of a single [Mn(C]... 10 H 28 The N6)]Cl2 phase composition, and the refined cell parameters are as follows: β = 107.63°.

[0047] The Fourier transform infrared (FTIR) absorption-wavenumber spectra of the sample from Example 1 were recorded on a Nicolet iN10MX & iS10 spectrometer using the KBr pellet method. Figure 2 It can be seen that the sample contains pentaethylenehexamine molecules. Compared to the bending vibration of free pentaethylenehexamine molecules, the -NH2 band position is 1573 cm⁻¹. -1 In Example 1, the -NH2 band of the sample shifted to 1605 cm⁻¹. -1 This indicates that Mn 2+ The combination of ions and pentaethylenehexamine molecules forms [Mn(C 10 H 28 N6)] 2+ Complexed cations.

[0048] The elemental composition of the sample from Example 1 was determined at room temperature using Oxford energy-dispersive X-ray (EDX) spectroscopy. Since hydrogen cannot be detected by EDX, the ultra-low temperature magnetic refrigeration material sample contained Mn and Cl in addition to carbon, nitrogen, and gold (derived from a conductive gold film). Figure 3 As shown, the molar ratio of Mn to Cl is 1:2.

[0049] The samples from Examples 1-3 were tested using a Quantum Design MPMS XL7 magnetic measurement system under conditions ranging from 2-300 K in temperature and 0-5 T in external magnetic field. The following uses Example 1 as an example; the test results are as follows: Figure 4-7 As shown.

[0050] Figure 4 [Mn(C)] prepared in Example 1 10 H 28 The zero-field cold (ZFC) and magnetic field cold (FC) magnetization (M) of the N6)]Cl2 sample under a 0.1T magnetic field (μOH) as a function of temperature (T) show that the ZFC and FC magnetization curves of the compound overlap well above 2K. No magnetic phase transition was observed on the DC magnetic susceptibility reciprocal-temperature curve, indicating that the phase transition temperature of this compound is below 2K. Then, the ultra-low temperature magnetic refrigeration material was tested using the MPMS system He3 option-iHelium3 under conditions of temperature 0.4–2.0K and an external magnetic field (μOH) of 0.1 Tesla (T). Figure 5 The figure shows the cold (FC) magnetization intensity of the sample under a 0.1T magnetic field as a function of temperature. The inset shows the reciprocal of the DC magnetic susceptibility versus temperature curve obtained from the curve. The fitted line follows Curie-Weiss's law, further indicating that the phase transition temperature of this compound is below 0.4K. According to the Curie-Weiss fit, the fitted line intersects the horizontal axis at -0.16K, indicating that the [Mn(C 10 H 28 [N6)]Cl2 exhibits antiferromagnetic interactions below the phase transition temperature. At temperatures above 0.4 K, the [Mn(C)Cl2] prepared in Example 1... 10 H 28 The N6)]Cl2 sample is in a paramagnetic state, indicating that there is no thermal hysteresis, which is very important for the practical application of the material.

[0051] Figure 6 [Mn(C)] prepared in Example 1 10 H 28 The isothermal magnetization curves of the N6)]Cl2 sample at different temperatures ranging from 0.4 to 19 K are shown in the figure. As can be seen, the magnetization of the material at 0.4 K increases rapidly with the increase of the external magnetic field, and tends to saturate at a magnetic field of 5 T. Using Maxwell's relation, the magnetic entropy change under different magnetic field variations can be calculated based on the isothermal magnetization curves at different temperatures. Figure 7 It is [Mn(C 10 H 28 The magnetic entropy change of the N6)]Cl2 compound varies with temperature from 0.42 to 1.78 K. As shown in the figure, this material exhibits a large magnetocaloric effect above the magnetic phase transition temperature. The maximum magnetic entropy change at 0.6 K with a magnetic field change of 0-1 T is 22.5 J·kg⁻¹. -1 ·K -1 The maximum magnetic entropy changes at 1.2 K with magnetic field variations of 0-2 T and 0-5 T are 30.1 and 40.8 J·kg, respectively.-1 ·K -1 It is an ultra-low temperature magnetic refrigeration material with great application potential.

[0052] Figure 8 The thermogravimetric (weight%-T) curves and derivative weight curves of the ultra-low temperature magnetic refrigeration material prepared in Example 4 are shown in the range of 300-860 K. It can be seen that below 450 K, there is a weight loss of approximately 7.0% due to the evaporation of low-melting-point solvents. In the range of 520-780 K, the material decomposes and releases pentaethylenehexamine molecules, resulting in a weight loss of approximately 60%, with the remaining weight accounting for 33.0%. Based on the molecular weight of manganese chloride (125.84 g / mol) and pentaethylenehexamine (232.37 g / mol), we can calculate that the molar ratio of manganese chloride to pentaethylenehexamine is 1:1. Figure 9 The ultra-low temperature magnetic refrigeration material [Mn(C)] prepared in Example 4 is... 10 H 28 Isothermal magnetization curves of the N6)]Cl2 sample at different temperatures ranging from 2-28 K were obtained. Using Maxwell's relations, the magnetic entropy change under different magnetic field variations can be calculated from the isothermal magnetization curves at different temperatures, such as... Figure 10 As shown.

[0053] The above embodiments are merely illustrative of the technical concept, principle, features, and effects 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. Therefore, all equivalent changes or modifications made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. The application of an ultra-low temperature magnetic refrigeration material, dichloride [(pentaethylenehexamine)manganese(II)], in the fields of low-temperature physics, quantum computing, and space exploration, characterized in that: The method for preparing the ultra-low temperature magnetic refrigeration material [(pentaethylenehexamine)manganese(II)] includes the following steps: Manganese chloride solution and pentaethylenehexamine were mixed evenly, and the mixture was heated to the reaction temperature under inert gas protection and held at that temperature for a period of time. The reaction system was then cooled to room temperature, centrifuged, and washed to obtain the ultra-low temperature magnetic refrigeration material. The chemical formula of the ultra-low temperature magnetic refrigeration material is [Mn(pentaethylenehexamine)]Cl2; the manganese chloride is anhydrous manganese chloride or MnCl2. 4H2O or a mixture of the two.

2. The application of the ultra-low temperature magnetic refrigeration material dichloride [(pentaethylenehexamine)manganese(II)] as described in claim 1, characterized in that: It must include at least one of the following features (1) to (4): (1) The molar ratio of manganese chloride and pentaethylenehexamine in the manganese chloride solution is 1:800~1:1; (2) The inert gas includes argon, nitrogen, or a mixture of the two; (3) The reaction temperature is 403-520K; (4) The heat preservation time is 30-180 min.

3. Use of the extremely low temperature magnetic refrigeration material [(pentaethylenehexamine) manganese (II) dichloride] according to claim 1 or 2, characterized in that: The ultra-low temperature magnetic refrigeration material dichloride [(pentaethylenehexamine)manganese(II)] exhibits a large magnetocaloric effect near the phase transition temperature, and the magnetic phase transition temperature of the ultra-low temperature magnetic refrigeration material is <0.4K.

4. Use of the extremely low temperature magnetic refrigeration material [(pentaethylenehexamine) manganese (II) dichloride] according to claim 3, characterized in that: It must include at least one of the following (1) to (3): (1) The maximum magnetic entropy change of the ultra-low temperature magnetic refrigeration material is 22.5 J at a temperature of 0.6 K when the magnetic field changes from 0 to 1 T. kg -1 K -1 ; (2) The maximum magnetic entropy change of the ultra-low temperature magnetic refrigeration material is 30.1 J when the magnetic field changes from 0 to 2 T at a temperature of 1.0 K. kg -1 K -1 ; (3) The maximum magnetic entropy change of the ultra-low temperature magnetic refrigeration material at 1.2K temperature when the magnetic field changes from 0 to 5T is 40.8J. kg -1 K -1 .

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