Two-dimensional antiferromagnetic agvp2s6 nanosheet, preparation method and application thereof

Abstract

This invention relates to a two-dimensional antiferromagnetic AgVP2S6 nanosheet, its preparation method, and its applications. The preparation method includes: mixing silver powder, vanadium powder, phosphorus powder, and sulfur powder in a stoichiometric ratio to obtain a precursor powder; placing the precursor powder and a transport agent in the same vacuum environment for heat treatment, the heat treatment including heating to 700℃~800℃ and holding at that temperature for 6~8 days to obtain AgVP2S6 crystals; and exfoliating the AgVP2S6 crystals to obtain the two-dimensional antiferromagnetic AgVP2S6 nanosheets. This invention utilizes a chemical vapor transport method to prepare bulk AgVP2S6 crystals and then prepares two-dimensional antiferromagnetic AgVP2S6 nanosheets through exfoliation. The obtained nanosheets have high crystal quality, uniform morphology, and regular banded shape, exhibiting stable antiferromagnetic properties.

Description

Technical Field

[0001] This invention relates to the field of magnetic information technology, specifically to two-dimensional magnetic materials, and more particularly to a two-dimensional antiferromagnetic AgVP2S6 nanosheet, its preparation method, and its application. Background Technology

[0002] Two-dimensional materials (such as graphene, transition metal chalcogenides, oxides, and halides) are considered core material systems for extending Moore's Law, constructing ultra-low-power integrated circuits, flexible electronics, and high-performance sensing and optoelectronic devices due to their atomic-level thickness, ultra-high specific surface area, strong light-matter interaction, and quantum confinement effect. In recent years, the discovery of novel two-dimensional magnetic materials such as CrI3, Fe5GeTe2, and Fe3GaTe2 has opened new pathways for fields such as spintronics, magnetic storage, and sensing technologies.

[0003] Among the many two-dimensional materials, emerging two-dimensional transition metal phosphochalcogenides (TMPCs) have attracted much attention due to their wide range of tunable band gaps, coexistence of ferroelectric and antiferromagnetic order, and ionic conductivity.

[0004] CN112678826A discloses a method for synthesizing two-dimensional transition metal chalcogenides, comprising the following steps: a heating step: heating the transition metal compound raw material to a reaction temperature in an inert gas environment; a topological transformation reaction step: introducing a gas containing chalcogen elements, or a mixture of a gas containing chalcogen elements and a gas containing phosphorus elements, and maintaining the reaction temperature for a set time, so that the chalcogen elements, or the chalcogen elements and phosphorus elements, undergo a topological transformation reaction with the transition metal compound raw material to generate a two-dimensional transition metal chalcogenide.

[0005] CN106024861A discloses a two-dimensional black phosphorus / transition metal chalcogenide heterojunction device and its fabrication method. This invention utilizes atmospheric pressure chemical vapor deposition to prepare two-dimensional transition metal chalcogenides. The fabrication process includes: using solids of MoO3, WO3, MoS2, MoSe2, MoTe2, WS2, WSe2, or WTe2 as the raw materials for molybdenum and tungsten sources; using sulfur powder, selenium powder, and tellurium powder as the raw materials for sulfur, selenium, and tellurium sources; and a growth pressure of 10... -6 ~10 -5 Pa, argon flow rate 60-200 sccm, hydrogen flow rate 5-100 sccm, growth temperature 600-1500℃, growth time 1-60 min.

[0006] Furthermore, AgVP2Se6, a typical example of TMPCs, achieved hard ferromagnetic behavior through thickness control, providing experimental verification of ferromagnetic order for the first time in quaternary TMPCs systems and expanding the design space for chemical composition and crystal structure.

[0007] However, current research on TMPCs still faces serious challenges: multi-component components are prone to forming mixed phases, and the polarization direction and ferroelectric / antiferromagnetic coupling mechanism are still unclear, which seriously restricts their application in novel functional device architectures, and thus hinders the evolution of neuromorphic computing towards a more efficient and intelligent direction.

[0008] Therefore, providing a two-dimensional antiferromagnetic AgVP2S6 nanosheet with high crystal quality and uniform morphology and its preparation method is of great significance for the construction of functionalized devices based on transition metal phosphorus chalcogenide systems. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to provide a two-dimensional antiferromagnetic AgVP2S6 nanosheet, its preparation method, and its applications. This invention utilizes a chemical vapor transport method to prepare bulk AgVP2S6 crystals, and then prepares two-dimensional antiferromagnetic AgVP2S6 nanosheets through exfoliation. The preparation method provided by this invention has the advantages of being simple to operate, highly efficient, time-saving, and highly reproducible. The obtained nanosheets have high crystal quality, uniform morphology, and regular banded structure, providing a new pathway for the controllable synthesis of two-dimensional antiferromagnetic AgVP2S6 nanosheets, and also laying a material foundation for the construction of functionalized devices based on transition metal phosphorus chalcogenide systems.

[0010] To achieve this objective, the present invention employs the following technical solution:

[0011] In a first aspect, the present invention provides a method for preparing two-dimensional antiferromagnetic AgVP2S6 nanosheets, the method comprising:

[0012] Silver powder, vanadium powder, phosphorus powder, and sulfur powder are mixed according to stoichiometric ratio to obtain precursor powder; the precursor powder and the transport agent are placed in the same vacuum environment for heat treatment, the heat treatment including heating to 700℃~800℃ and holding for 6~8 days to obtain AgVP2S6 crystals; the AgVP2S6 crystals are exfoliated to obtain the two-dimensional antiferromagnetic AgVP2S6 nanosheets.

[0013] This invention utilizes a chemical vapor transport method to prepare bulk AgVP2S6 crystals, and then prepares two-dimensional antiferromagnetic AgVP2S6 nanosheets by exfoliation. This preparation method has the advantages of simple operation, high efficiency and time saving, and strong reproducibility. The obtained nanosheets have high crystal quality, uniform morphology, and regular banded shape, providing a new route for the controllable synthesis of two-dimensional antiferromagnetic AgVP2S6 nanosheets, and also laying the material foundation for the construction of functionalized devices based on transition metal phosphorus chalcogenide systems.

[0014] Preferably, the transport agent includes iodine powder.

[0015] Preferably, the vacuum degree of the vacuum chamber is 5 Pa to 15 Pa.

[0016] Preferably, the heating rate of the heat treatment is 1.5℃ / min to 3℃ / min.

[0017] Preferably, the heat treatment is carried out in a single-zone tubular furnace.

[0018] Preferably, the preparation method further includes alternately introducing and venting argon gas into the single-temperature zone tubular furnace before heat treatment.

[0019] Preferably, the peeling includes mechanical peeling, which involves repeatedly tearing and thinning the AgVP2S6 crystal using adhesive tape to obtain the two-dimensional antiferromagnetic AgVP2S6 nanosheets.

[0020] Preferably, the preparation method further includes transferring the prepared two-dimensional antiferromagnetic AgVP2S6 nanosheets to a PDMS thin film and accurately transferring them to a target substrate using a transfer platform.

[0021] Secondly, the present invention provides a two-dimensional antiferromagnetic AgVP2S6 nanosheet, which is prepared by the preparation method described in the first aspect; the two-dimensional antiferromagnetic AgVP2S6 nanosheet belongs to the P21 / c space group and has lattice parameters a=5.89Å, b=10.82Å, c=7.48Å, β=104.6°.

[0022] The two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared by this invention have unique antiferromagnetic properties and an electron-ion co-modulation mechanism, and therefore can be widely used in applications such as electron spin devices, quantum information technology and energy devices.

[0023] Thirdly, the present invention provides an application of the two-dimensional antiferromagnetic AgVP2S6 nanosheets as described in the second aspect, wherein the two-dimensional antiferromagnetic AgVP2S6 nanosheets are applied in the fields of electron spin devices, quantum information technology or energy devices.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) This invention uses chemical vapor transport method to prepare bulk AgVP2S6 crystals and prepares two-dimensional antiferromagnetic AgVP2S6 nanosheets by exfoliation, which provides a new path for the controllable synthesis of two-dimensional antiferromagnetic AgVP2S6 nanosheets and lays the material foundation for the construction of functionalized devices of transition metal phosphorus chalcogenide system.

[0026] (2) The preparation method provided by the present invention has the advantages of simple operation, high efficiency and time saving and strong repeatability. The obtained nanosheets have high crystal quality, uniform morphology and regular strip shape.

[0027] (3) The two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared by this invention have stable antiferromagnetic properties and an electron-ion co-modulation mechanism, and therefore can be widely used in fields such as electron spin devices, quantum information technology and energy devices. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the synthesis of the two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in Example 1.

[0029] Figure 2 The image shows the XRD pattern of the two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in Example 1.

[0030] Figure 3 This is an optical morphology photograph of the two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in Example 1.

[0031] Figure 4 This is an optical morphology photograph of the two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in Example 1.

[0032] Figure 5 This is an atomic force image of the two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in Example 1.

[0033] Figure 6 This is the height profile curve of the two-dimensional antiferromagnetic AgVP2S6 nanosheet sample prepared in Example 1.

[0034] Figure 7 This is an EDS elemental distribution map of the two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in Example 1.

[0035] Figure 8 This is the energy spectrum of the two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in Example 1.

[0036] Figure 9 This is the Raman spectrum of the two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in Example 1.

[0037] Figure 10 This is a contour color mapping of the polarization Raman intensity of the two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in Example 1.

[0038] Figure 11The curves show the in-plane magnetization of the two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in Example 1 as a function of temperature under zero field cooling and 1000 Oe field cooling.

[0039] Figure 12 The curve shows the out-of-plane magnetization of the two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in Example 1 as a function of temperature under a field cooling of 1000 Oe.

[0040] Figure 13 The curves show the in-plane magnetization (M) of the two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in Example 1 as a function of magnetic field (H) at different temperatures.

[0041] Figure 14 The curves show the out-of-plane magnetization (M) of the two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in Example 1 as a function of magnetic field (H) at different temperatures.

[0042] Among them, 1-transporter and precursor powder; 2-two-dimensional antiferromagnetic AgVP2S6 nanosheets. Detailed Implementation

[0043] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0044] The scope of this invention can be defined by lower and upper limits. The selected lower and upper limits define the boundaries of a specific range. The range defined in this way can be defined by the inclusion or exclusion of endpoints. Any endpoint can be independently selected for inclusion or exclusion, and all lower and upper limits can be arbitrarily combined to form new ranges. That is, any lower limit can be combined with any upper limit to form an effective range. For example, if the ranges of 60~120 and 80~110 are listed for specific parameters, it should be understood that the ranges of 60~110 and 80~120 also fall within the scope of this invention. In addition, if the minimum range values ​​1 and 2 are listed, and the maximum range values ​​3, 4 and 5 are also listed, then all ranges of 1~3, 1~4, 1~5, 2~3, 2~4 and 2~5 fall within the scope of this invention. In this invention, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0~5" means that all real numbers between 0 and 5 have been fully listed in this document, and "0~5" is only a shortened representation of this set of numerical combinations. When a parameter is expressed as an integer ≥2, it is equivalent to listing positive integers that meet the requirements, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. When a parameter is expressed as an integer selected from "2~10", it is equivalent to listing any integer among 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0045] In this invention, "a combination of at least two" refers to a quantity greater than or equal to 2 unless otherwise specified. For example, "any one or a combination of at least two" means that any one of the listed items can be selected, or a combination of at least two of the listed items formed in a manner that does not conflict and enables the implementation of this invention. In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" cover any one of two or more related listed items, as well as any and all combinations of the related listed items. The arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" means a set consisting of A, B, and combinations of A and B, where "containing A and / or B" can be understood, depending on the context of the statement, as containing A, containing B, or simultaneously containing both A and B. In this invention, "optional" means that the corresponding feature, component, step or solution is not necessary, that is, it is selected from either "with" or "without". If there are multiple "optional" limitations in a technical solution, unless otherwise specified and there is no technical conflict or mutual constraint, each "optional" limitation is independent and does not affect the others.

[0046] In this invention, technical features or solutions described using open-ended terms such as "comprising" or "including" do not exclude additional non-conflicting elements beyond the listed elements unless otherwise specified. They are considered to disclose both closed-ended features or solutions consisting solely of the listed elements and open-ended features or solutions that may include additional non-conflicting elements beyond the listed elements. For example, if A includes a1, a2, and a3, unless otherwise specified, this means that A can consist only of a1, a2, and a3, or it can include other non-conflicting elements based on a1, a2, and a3. This corresponds to the disclosure of technical solutions such as "A consists of a1, a2, and a3," "A is selected from a1, a2, and a3," and "A not only includes a1, a2, and a3, but may also include other non-conflicting elements." All embodiments and optional embodiments of this invention, unless otherwise specified and without technical conflict, can be combined to form new technical solutions, and such combinations fall within the scope of this invention. The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various locations throughout the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this invention can be combined with other embodiments that do not conflict with the technology. The ordinal numbers "first," "second," "third," and "fourth," etc., used in the expressions "first aspect," "second aspect," "third aspect," and "fourth aspect" in this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly specifying the importance or quantity of the indicated technical features. They serve only as a non-exhaustive enumeration and do not constitute a closed limitation on quantity.

[0047] In this invention, the order in which the steps are written in the methods described in each embodiment does not imply a strict execution order. The actual execution order of each step should be determined based on its function and possible internal logic. Unless otherwise specified, all steps of this invention can be executed in the order they are written, or in any order without technical conflict. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) executed sequentially, or it may include steps (b) and (a) executed sequentially. If the method also includes step (c), then step (c) can be added to the method in any order without conflict, including but not limited to the execution order of steps (a), (b), and (c), steps (a), (c), and (b), steps (c), (a), and (b), etc.

[0048] In one specific embodiment, the present invention provides a method for preparing two-dimensional antiferromagnetic AgVP2S6 nanosheets, the method comprising:

[0049] Silver powder, vanadium powder, phosphorus powder, and sulfur powder are mixed according to stoichiometric ratio to obtain precursor powder; the precursor powder and the transport agent are placed in the same vacuum environment for heat treatment, the heat treatment including heating to 700℃~800℃ and holding for 6~8 days to obtain AgVP2S6 crystals; the AgVP2S6 crystals are exfoliated to obtain the two-dimensional antiferromagnetic AgVP2S6 nanosheets.

[0050] This invention utilizes a chemical vapor transport method to prepare bulk AgVP2S6 crystals, and then prepares two-dimensional antiferromagnetic AgVP2S6 nanosheets by exfoliation. This preparation method has the advantages of simple operation, high efficiency and time saving, and strong reproducibility. The obtained nanosheets have high crystal quality, uniform morphology, and regular banded shape, providing a new route for the controllable synthesis of two-dimensional antiferromagnetic AgVP2S6 nanosheets, and also laying the material foundation for the construction of functionalized devices based on transition metal phosphorus chalcogenide systems.

[0051] In this invention, the heat treatment temperature is 700℃~800℃, for example, 700℃, 710℃, 720℃, 730℃, 740℃, 750℃, 760℃, 770℃, 780℃, 790℃, or 800℃, and the heat treatment time is 6 days~8 days, for example, 6 days, 6.5 days, 7 days, 7.5 days, or 8 days. In this invention, through chemical vapor phase transport, silver powder, vanadium powder, phosphorus powder, and sulfur powder react and crystallize at 700℃~800℃ for 6~8 days under the transport of a transport agent, to obtain AgVP2S6 crystals.

[0052] In some embodiments, the transport agent includes iodine powder. In this invention, the transport agent may be placed separately from the precursor powder or mixed with the precursor powder.

[0053] In some embodiments, the vacuum degree of the vacuum chamber is 5 Pa to 15 Pa, for example, it can be 5 Pa, 7 Pa, 9 Pa, 11 Pa, 13 Pa or 15 Pa.

[0054] In some embodiments, the heating rate of the heat treatment is 1.5℃ / min to 3℃ / min, for example, it can be 1.5℃ / min, 2℃ / min, 2.5℃ / min or 3℃ / min.

[0055] In some embodiments, the heat treatment is performed in a single-zone tube furnace. In this invention, the heat treatment is performed in a single-zone tube furnace, requiring only a single heating program and ensuring stable reaction and crystallization at the same temperature. This can, to some extent, avoid the formation of byproducts during crystal growth, and is beneficial to the uniformity and purity of the sample preparation.

[0056] like Figure 1As shown, during heat treatment, the transport agent and precursor powder 1 are placed in the central heating zone of a single-temperature zone tube furnace. When the furnace tubes extend to both ends, a temperature gradient of 100℃~200℃ is formed to provide a reaction zone. Two-dimensional antiferromagnetic AgVP2S6 nanosheets 2 are obtained at a position away from the central heating zone.

[0057] In some embodiments, the preparation method further includes alternately introducing and venting argon gas into the single-temperature zone tube furnace before heat treatment, which can effectively remove oxygen and water in the furnace tube, reduce the formation of oxide layers on the surface of silver powder and vanadium powder, and also reduce the generation of impurity phases during crystal growth. The number of times argon gas is alternately introduced and vented can be, for example, once, twice, three times or four times, preferably more than twice, and the vacuum degree in the furnace tube is controlled at 5 Pa to 15 Pa during the last argon gas venting.

[0058] In some embodiments, the peeling includes mechanical peeling, which involves repeatedly tearing and thinning the AgVP2S6 crystal using tape to obtain the two-dimensional antiferromagnetic AgVP2S6 nanosheets.

[0059] In some embodiments, the preparation method further includes transferring the prepared two-dimensional antiferromagnetic AgVP2S6 nanosheets to a PDMS thin film and then precisely transferring them to a target substrate using a transfer platform.

[0060] In another specific embodiment, the present invention provides a two-dimensional antiferromagnetic AgVP2S6 nanosheet, which is prepared by the preparation method described in the aforementioned specific embodiment; the two-dimensional antiferromagnetic AgVP2S6 nanosheet belongs to the P21 / c space group, and has lattice parameters a=5.89Å, b=10.82Å, c=7.48Å, and β=104.6°.

[0061] The two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared by this invention have unique antiferromagnetic properties and an electron-ion co-modulation mechanism, and therefore can be widely used in applications such as electron spin devices, quantum information technology and energy devices.

[0062] In yet another embodiment, the present invention provides an application of the two-dimensional antiferromagnetic AgVP2S6 nanosheets as described in the other embodiment above, wherein the two-dimensional antiferromagnetic AgVP2S6 nanosheets are applied in the fields of electron spin devices, quantum information technology or energy devices.

[0063] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0064] Example 1

[0065] This embodiment provides a method for preparing two-dimensional antiferromagnetic AgVP2S6 nanosheets, including the following steps:

[0066] (1) Silver powder, vanadium powder, phosphorus powder, and sulfur powder were thoroughly ground and mixed in a molar ratio of 1:1:2:6 to obtain precursor powder. The precursor powder and iodine powder were then placed adjacent to each other in a quartz furnace tube of a single-temperature zone tube furnace. High-purity argon gas was alternately introduced and discharged into the quartz furnace tube, and the gas was repeatedly purged three times to remove residual oxygen and moisture. During the last discharge, the vacuum degree inside the quartz furnace tube was evacuated to 10 Pa.

[0067] (2) Set the heating rate to 2.5℃ / min, heat to 750℃, keep the temperature constant for 7 days to achieve crystal growth, and then cool naturally to room temperature to obtain bulk AgVP2S6 crystal.

[0068] (3) Press the AgVP2S6 crystal onto the adhesive side of the 3M tape and repeatedly peel it off to thin it. Then transfer the nanosheets on the tape to the PDMS film. Use the transfer platform to accurately align with the target substrate to obtain two-dimensional antiferromagnetic AgVP2S6 nanosheets.

[0069] The XRD pattern of the two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in this embodiment is as follows: Figure 2 As shown, the XRD pattern shows only pure sample peaks without any other impurity peaks, confirming the synthesis of high-quality AgVP2S6 nanosheets. The two diffraction peaks at 13.7° and 27.4° correspond to the (001) and (002) crystal planes of AgVP2S6, respectively. The calculated lattice parameters are a=5.89Å, b=10.82Å, c=7.48Å, β=104.6°, belonging to the P21 / c space group.

[0070] Optical morphology images of two-dimensional antiferromagnetic AgVP2S6 nanosheets are shown below. Figure 3 and Figure 4 As shown, the two-dimensional antiferromagnetic AgVP2S6 nanosheets are in the form of regular strips.

[0071] Atomic force images of two-dimensional antiferromagnetic AgVP2S6 nanosheets are shown below. Figure 5 As shown in the figure, the height profile curves of samples 1 and 2 are as follows: Figure 6 As shown, Figure 5 The thickness of sample 1 is between 35nm and 44nm, and the thickness of sample 2 is 16nm.

[0072] EDS spectra of two-dimensional antiferromagnetic AgVP2S6 nanosheets are as follows: Figure 7 As shown in the figure, Ag, V, P, and S elements are uniformly distributed on the strip-shaped nanosheets. Figure 8 The energy spectrum shown and the ratio of Ag, V, P, and S elements shown in Table 1 confirm that the stoichiometric ratio of Ag, V, P, and S elements is approximately 1:1:2:6, which is consistent with the XRD pattern test results, indicating that AgVP2S6 was successfully prepared.

[0073] Table 1

[0074]

[0075] Raman spectra of two-dimensional antiferromagnetic AgVP2S6 nanosheets at 77K and 297K are as follows: Figure 9 As shown, two-dimensional antiferromagnetic AgVP2S6 nanosheets are found in the 70-500 cm⁻¹ range. -1 There are a total of 12 characteristic peaks (P1-P) within the range. 12 As the temperature decreases, the intensity of the characteristic peaks increases and there is a slight blue shift, indicating that the vibrational mode is stable and no phase transition occurs during the temperature decrease process.

[0076] The contour color mapping of polarization Raman intensity of two-dimensional antiferromagnetic AgVP2S6 nanosheets is shown below. Figure 10 As shown, the 12 Raman characteristic peaks of the two-dimensional antiferromagnetic AgVP2S6 nanosheets exhibit a periodic angle dependence of π or π / 2 on the polarization angle, indicating that the prepared two-dimensional antiferromagnetic AgVP2S6 nanosheets have obvious optical anisotropy in the plane.

[0077] Combination Figures 2 to 10 It can be confirmed that the preparation method provided by the present invention can prepare high-quality two-dimensional antiferromagnetic AgVP2S6 nanosheets with stable structure and obvious optical anisotropy.

[0078] Example 2

[0079] This embodiment provides a method for preparing two-dimensional antiferromagnetic AgVP2S6 nanosheets, including the following steps:

[0080] (1) Silver powder, vanadium powder, phosphorus powder, and sulfur powder were thoroughly ground and mixed in a molar ratio of 1:1:2:6 to obtain precursor powder. The precursor powder and iodine powder were then placed adjacent to each other in a quartz furnace tube of a single-temperature zone tube furnace. High-purity argon gas was alternately introduced and discharged into the quartz furnace tube, and the gas was repeatedly purged three times to remove residual oxygen and moisture. During the last discharge, the vacuum degree inside the quartz furnace tube was evacuated to 5 Pa.

[0081] (2) Set the heating rate to 1.5℃ / min, heat to 700℃, keep the temperature constant for 8 days to achieve crystal growth, and then cool naturally to room temperature to obtain bulk AgVP2S6 crystal.

[0082] (3) Press the AgVP2S6 crystal onto the adhesive side of the 3M tape and repeatedly peel it off to thin it. Then transfer the nanosheets on the tape to the PDMS film. Use the transfer platform to accurately align with the target substrate to obtain two-dimensional antiferromagnetic AgVP2S6 nanosheets.

[0083] The two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in this embodiment have lattice parameters of a=5.89Å, b=10.82Å, c=7.48Å, β=104.6°, and belong to the P21 / c space group.

[0084] Example 3

[0085] This embodiment provides a method for preparing two-dimensional antiferromagnetic AgVP2S6 nanosheets, including the following steps:

[0086] (1) Silver powder, vanadium powder, phosphorus powder, and sulfur powder were thoroughly ground and mixed in a molar ratio of 1:1:2:6 to obtain precursor powder. The precursor powder and iodine powder were then placed adjacent to each other in a quartz furnace tube of a single-temperature zone tube furnace. High-purity argon gas was alternately introduced and discharged into the quartz furnace tube, and the gas was repeatedly purged three times to remove residual oxygen and moisture. During the last discharge, the vacuum degree inside the quartz furnace tube was evacuated to 15 Pa.

[0087] (2) Set the heating rate to 3℃ / min, heat to 800℃, keep the temperature constant for 7 days to achieve crystal growth, and then cool naturally to room temperature to obtain bulk AgVP2S6 crystal.

[0088] (3) Press the AgVP2S6 crystal onto the adhesive side of the 3M tape and repeatedly peel it off to thin it. Then transfer the nanosheets on the tape to the PDMS film. Use the transfer platform to accurately align with the target substrate to obtain two-dimensional antiferromagnetic AgVP2S6 nanosheets.

[0089] The two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in this embodiment have lattice parameters of a=5.89Å, b=10.82Å, c=7.48Å, β=104.6°, and belong to the P21 / c space group.

[0090] Example 4

[0091] This embodiment provides a method for preparing two-dimensional antiferromagnetic AgVP2S6 nanosheets. Except for the heat treatment temperature of step (2) being 650℃, the rest is the same as in Example 1.

[0092] Example 5

[0093] This embodiment provides a method for preparing two-dimensional antiferromagnetic AgVP2S6 nanosheets. Except for the heat treatment temperature of step (2) being 850℃, the rest is the same as in Example 1.

[0094] Example 6

[0095] This embodiment provides a method for preparing two-dimensional antiferromagnetic AgVP2S6 nanosheets. Except for the heat treatment time of 5 days in step (2), the rest is the same as in Example 1.

[0096] Example 7

[0097] This embodiment provides a method for preparing two-dimensional antiferromagnetic AgVP2S6 nanosheets. Except for the heat treatment time of step (2), which is 9 days, the rest is the same as in Example 1.

[0098] Comparative Example 1

[0099] This comparative example provides a method for preparing two-dimensional antiferromagnetic AgVP2S6 nanosheets. Except for step (2), which uses a dual-temperature zone tube furnace for heat treatment and sets the growth end temperature to 750℃ and the reaction end temperature to 850℃, the rest is the same as in Example 1.

[0100] Performance testing:

[0101] The magnetic properties of the two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in all the above embodiments and comparative examples were tested.

[0102] The curves showing the magnetization (M) of the two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in Example 1 as a function of temperature (T) under zero field cooling (ZFC) and 1000 Oe field cooling (FC) in the in-plane direction (magnetic field parallel to the nanosheet) are as follows: Figure 11 As shown, the ZFC and FC curves completely overlap. With decreasing temperature, the magnetization decreases rapidly below 32.5 K, corresponding to the Nell temperature (T0). N The magnetization (M) of the two-dimensional antiferromagnetic AgVP2S6 nanosheet exhibits typical antiferromagnetic characteristics. The curve showing the magnetization (M) as a function of temperature (T) of the nanosheet under out-of-plane (field perpendicular to the nanosheet) 1000 Oe field cooling (FC) is shown below. Figure 12 As shown, it also exhibits typical antiferromagnetic characteristics.

[0103] The magnetization (M) of the two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in Example 1 varies with the magnetic field (H) at different temperatures along the in-plane direction, as shown in the following curves. Figure 13 As shown, the in-plane magnetization of AgVP2S6 exhibits a linear relationship with the magnetic field, while the magnetic susceptibility decreases with increasing temperature, a characteristic indicative of antiferromagnetism. The curves showing the magnetization (M) versus magnetic field (H) of two-dimensional antiferromagnetic AgVP2S6 nanosheets at different temperatures in the out-of-plane direction are shown below. Figure 14As shown, below 20 K, when the magnetic field strength is less than 4.6 kOe, the out-of-plane magnetization of AgVP2S6 exhibits a nonlinear relationship with the magnetic field, indicating that AgVP2S6 has a small magnetic susceptibility. When the magnetic field strength is increased to 4.6 kOe, the magnetization increases linearly with the magnetic field, indicating that AgVP2S6 undergoes spin flipping. Above 20 K, the magnetization increases linearly with the increase of the magnetic field, and the magnetic susceptibility decreases with increasing temperature. This characteristic indicates that the prepared two-dimensional antiferromagnetic AgVP2S6 nanosheets exhibit antiferromagnetism.

[0104] Therefore, according to Figures 11 to 14 It can be confirmed that the two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared by the preparation method provided by the present invention have stable antiferromagnetism.

[0105] The crystallinity of the two-dimensional antiferromagnetic AgVP2S6 nanosheets prepared in all embodiments and comparative examples of this invention is shown in Table 2.

[0106] Table 2

[0107]

[0108] In summary, this invention utilizes chemical vapor transport to prepare bulk AgVP2S6 crystals and then prepares two-dimensional antiferromagnetic AgVP2S6 nanosheets through exfoliation, which possess stable antiferromagnetic properties.

[0109] Based on the test results of Examples 1, 2, and 4, if the heat treatment temperature is too low, the reaction between the raw materials is slow, resulting in impurities in the prepared two-dimensional antiferromagnetic AgVP2S6 nanosheets. If the heat treatment temperature is too high, it will lead to excessive loss of volatile elements, thereby introducing a large number of defects such as vacancies. Furthermore, the extremely high molecular thermal motion will cause grain aggregation or surface thermal etching, resulting in the loss of the surface microstructure of the prepared two-dimensional antiferromagnetic AgVP2S6 nanosheets, which is not conducive to improving the magnetic properties of the two-dimensional antiferromagnetic AgVP2S6 nanosheets.

[0110] Based on the test results of Examples 1, 6, and 7, if the heat treatment time is too short, the reaction will be insufficient, resulting in unreacted precursor impurities in the prepared two-dimensional antiferromagnetic AgVP2S6 nanosheets, leading to a decrease in the magnetic properties of the two-dimensional antiferromagnetic AgVP2S6 nanosheets. Conversely, if the heat treatment time is too long, it will reduce the crystallinity of the crystals, causing P and S elements to volatilize from the crystal surface, and the element ratio will change from a stoichiometric ratio to a non-stoichiometric ratio. Furthermore, excessive grain growth and agglomeration will not only form byproducts such as V5S8, but also disrupt the magnetic exchange within the material, which is also detrimental to improving the magnetic properties of the two-dimensional antiferromagnetic AgVP2S6 nanosheets.

[0111] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing two-dimensional antiferromagnetic AgVP2S6 nanosheets, characterized in that, The preparation method includes: According to the stoichiometric ratio, silver powder, vanadium powder, phosphorus powder and sulfur powder are mixed to obtain precursor powder; The precursor powder and the transport agent were placed in the same vacuum environment for heat treatment, which included heating to 700℃~800℃ and holding for 6~8 days to obtain AgVP2S6 crystals. The AgVP2S6 crystal was peeled off to obtain the two-dimensional antiferromagnetic AgVP2S6 nanosheets.

2. The preparation method according to claim 1, characterized in that, The transport agent includes iodine powder.

3. The preparation method according to claim 1 or 2, characterized in that, The vacuum level of the vacuum chamber is 5 Pa to 15 Pa.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The heating rate of the heat treatment is 1.5℃ / min to 3℃ / min.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The heat treatment is carried out in a single-temperature zone tubular furnace.

6. The preparation method according to claim 5, characterized in that, The preparation method further includes alternately introducing and venting argon gas into the single-temperature zone tubular furnace before heat treatment.

7. The preparation method according to any one of claims 1 to 6, characterized in that, The peeling includes mechanical peeling, which involves repeatedly tearing and thinning the AgVP2S6 crystal using adhesive tape to obtain the two-dimensional antiferromagnetic AgVP2S6 nanosheets.

8. The preparation method according to claim 7, characterized in that, The preparation method further includes transferring the prepared two-dimensional antiferromagnetic AgVP2S6 nanosheets to a PDMS thin film, and then precisely transferring them to the target substrate using a transfer platform.

9. A two-dimensional antiferromagnetic AgVP2S6 nanosheet, characterized in that, The two-dimensional antiferromagnetic AgVP2S6 nanosheets were prepared by the preparation method according to any one of claims 1 to 8; The two-dimensional antiferromagnetic AgVP2S6 nanosheets belong to the P21 / c space group and have lattice parameters of a=5.89Å, b=10.82Å, c=7.48Å, and β=104.6°.

10. An application of the two-dimensional antiferromagnetic AgVP2S6 nanosheet as described in claim 9, characterized in that, The two-dimensional antiferromagnetic AgVP2S6 nanosheets are applied in the fields of electron spin devices, quantum information technology, or energy devices.

Images