Preparation method of high-entropy Kagome material HEV6Sn6

Abstract

The invention discloses a preparation method of a high-entropy Kagome material HEV6Sn6, which comprises the following steps of: 1, mixing Ho, Gd and Tb rare earth powder with V and Sn metal powder, and grinding and uniformly mixing under the protection of Ar atmosphere to obtain uniformly mixed powder; 2, loading the uniformly mixed powder into an Al2O3 crucible, transferring the Al2O3 crucible into a quartz tube, and sealing the quartz tube; 3, heating, sintering and preserving heat; and 4, cooling the quartz tube, and centrifugally separating the redundant Sn fluxing agent to obtain the high-entropy Kagome material HEV6Sn6. According to the method, a self-fluxing agent method is adopted, three different rare earth elements Ho, Gd and Tb are doped into the vanadium-based Kagome material at the same time, all the rare earth elements are evenly distributed on rare earth sites, obvious phase separation does not occur, the high-entropy Kagome material HEV6Sn6 is successfully constructed for the first time, introduction of new impurities can be avoided, phase formation is simple, and the method is suitable for industrial production. The method is suitable for the field of novel high-entropy spinning anti-contusion materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of the synthesis of correlated electronic materials, and particularly relates to a preparation method of a high-entropy Kagome material HEV6Sn6. Background Art

[0002] In the correlated system, the kagome lattice is a kind of lattice that can carry a variety of correlated phenomena. It is composed of vertex-sharing triangular lattices and has the highest degree of frustration in two-dimensional systems. Due to the special lattice structure and electronic energy bands of kagome materials, they have gradually stood out in the research of novel quantum states. In the tight-binding model considering only the nearest-neighbor hopping, the electronic structure of the kagome lattice exhibits three characteristics: Dirac cones located at the corners of the Brillouin zone, van Hove singularities (vHs) located at the center of the Brillouin zone boundary, and flat bands covering the entire Brillouin zone. Due to the special structure of the lattice and electrons, the kagome lattice becomes a system that can carry a variety of correlated phenomena and is widely used in theory and experiments to study the realization of various novel states, including Mott insulators, magnetic order, quantum anomalous Hall effect, superconductivity, and charge density waves.

[0003] Currently, several types of kagome materials have been widely studied, such as the quantum spin liquid candidate material ZnCu3(OH)6Cl2 (Phys.Rev.B 94,060409(2016)), the binary kagome material family T m X n (T represents a 3d transition metal, and X is Sn, Ge, and In) (Nat.Mater.19,163(2020).,Nat.Commun.11,4002(2020)), the ferromagnetic Weyl semimetal CoSn2S2 (Nat.Commun.14,5230(2023).), and the quasi-two-dimensional ternary vanadium-based kagome superconductor AV3Sb5 (A = Cs, Rb, and K) ("135 system") discovered by Ortiz et al. in 2019 (Phys.Rev.Mater.3,094407(2019)). These materials all exhibit a variety of novel physical properties. Therefore, exploring new crystal structures through different regulation means, searching for kagome lattice systems with different doping levels, making the Fermi surface located near the strongly correlated flat band, Dirac point, or vHs, and studying the combined effect of the electronic structure and lattice frustration on the material properties under complex systems to promote the theoretical improvement of the kagome model is an important research method for deeply understanding kagome physics.

[0004] To promote the theoretical improvement of the Kagome model, high-entropization of Kagome materials is a new research idea. Specifically, it combines various correlated behaviors carried by the Kagome lattice, such as massless Dirac fermions, strongly correlated large effective mass fermions, long-range correlated Van Hove quasiparticles, and strong geometric frustration, with the rich degrees of freedom of high-entropy components, such as charge, composition, spin, and magnetic moment, to form a new type of high-entropy Kagome material. The aim is to co-regulate the doping level of the material through multi-atom cooperation, achieve different Fermi surface fillings in the same carrier, and further realize the coexistence of various quantum states and correlated behaviors, such as CDW order, magnetic order, quantum critical behavior, topological surface states, superconductivity, etc., making the new type of high-entropy Kagome material a platform for studying the coexistence or competition relationship of multiple quantum physical properties. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a preparation method of a high-entropy Kagome material HEV6Sn6 in view of the deficiencies of the above-mentioned prior art. The present invention adopts the self-flux method, and simultaneously dopes three different rare earth elements Ho, Gd, and Tb into the vanadium-based Kagome material, so that each rare earth element is evenly distributed on the rare earth sites without obvious phase separation, and for the first time, a high-entropy Kagome material HEV6Sn6 is successfully constructed, filling the blank of the high-entropization of Kagome materials in the prior art.

[0006] To solve the above technical problem, the technical solution adopted by the present invention is: a preparation method of a high-entropy Kagome material HEV6Sn6, characterized in that HE = Ho, Gd, Tb, and the preparation method includes the following steps:

[0007] Step 1: Mix Ho, Gd, and Tb rare earth powders with V and Sn metal powders, and grind them evenly in an agate mortar under the protection of an Ar atmosphere to obtain a uniformly mixed powder;

[0008] Step 2: Put the uniformly mixed powder obtained in Step 1 into an Al2O3 crucible, then transfer it to a quartz tube, and seal the quartz tube under the condition of ensuring vacuum inside the quartz tube;

[0009] Step 3: Place the sealed quartz tube in a box furnace for heating, sintering, and heat preservation;

[0010] Step 4: After the heat preservation in Step 3 is completed, cool the quartz tube and centrifuge to separate the excess Sn flux to obtain the high-entropy Kagome material HEV6Sn6.

[0011] The preparation method of the above-mentioned high-entropy Kagome material HEV6Sn6 is characterized in that, in step one, the molar ratio of the Ho, Gd, and Tb rare earth powders to the V and Sn metal powders is 1:1:1:18:30 to 60, and the mixing process is carried out under the protection of an Ar atmosphere. In the present invention, an excessive amount of Sn metal powder is added, and the extra Sn metal powder is used as a flux.

[0012] The preparation method of the above-mentioned high-entropy Kagome material HEV6Sn6 is characterized in that, in step two, the vacuum condition inside the quartz tube when the quartz tube is sealed is 1×10 -3 Pa to 1×10 -4 Pa. By controlling the low vacuum condition inside the quartz tube, the melting point of the material is reduced to protect the metal elements from being oxidized.

[0013] The preparation method of the above-mentioned high-entropy Kagome material HEV6Sn6 is characterized in that, in step three, the process of heating, sintering, and heat preservation is as follows: heating to 1050°C to 1100°C in 10 h and maintaining at the highest temperature for 10 h to 24 h. In the present invention, by controlling the heating temperature and process, the quartz tube is prevented from cracking, and maintaining at the highest temperature for a certain time to ensure that the metal powders in the quartz tube can form a uniform molten state with the flux, that is, the extra Sn metal powder.

[0014] The preparation method of the above-mentioned high-entropy Kagome material HEV6Sn6 is characterized in that, in step four, the cooling rate used for cooling is 2 K / h to 3 K / h, and the temperature after cooling is 600°C. In the present invention, by cooling slowly, the growth of single crystals is promoted, which is beneficial to obtaining larger-sized single crystals. At the same time, the temperature after cooling is controlled to avoid other phases such as Sn7Tb3 and GdSn3 precipitating in the system due to too low temperature.

[0015] The preparation method of the above-mentioned high-entropy Kagome material HEV6Sn6 is characterized in that, in step four, the rotation speed used for centrifugation is 3000 rpm and the time is 3 min.

[0016] The present invention has the following advantages compared with the prior art:

[0017] 1. For the first time, the present invention combines high-entropy components with vanadium-based Kagome materials. By using the self-flux method, three different rare-earth elements, Ho, Gd, and Tb, are simultaneously doped into the vanadium-based Kagome materials. Utilizing the characteristic that rare-earth elements have similar electronegativities, phase separation is not likely to occur during the phase formation process, so that each rare-earth element is evenly distributed on the rare-earth sites, and the high-entropy Kagome material HEV6Sn6 (HE = Ho, Gd, Tb) is successfully constructed. In this high-entropy Kagome material HEV6Sn6, rare-earth elements with different magnetocrystalline anisotropies can undergo multiple spin flips under a magnetic field, having the potential for fabricating spintronic devices and being suitable for preparing novel high-entropy spin-frustration materials.

[0018] 2. The present invention uses the self-flux method, that is, one of the raw materials, Sn metal powder, is used as a flux at the same time, avoiding the introduction of new impurities into the product and ensuring the obtaining of high-purity and high-quality HEV6Sn6 single crystals.

[0019] 3. The present invention uses the self-flux method to prepare the HEV6Sn6 (HE = Ho, Gd, Tb) single crystal, which has the characteristic of simple phase formation and is suitable for being popularized to prepare other high-entropy spin-frustration materials.

[0020] The technical solution of the present invention will be further described in detail below through the drawings and examples. Description of the Drawings

[0021] Figure 1 Optical photograph of the high-entropy Kagome material HEV6Sn6 single crystal prepared in Example 1 of the present invention.

[0022] Figure 2 SEM image of the high-entropy Kagome material HEV6Sn6 single crystal prepared in Example 1 of the present invention.

[0023] Figure 3 EDS spectrum of the high-entropy Kagome material HEV6Sn6 single crystal prepared in Example 1 of the present invention.

[0024] Figure 4 Raman spectrum of the high-entropy Kagome material HEV6Sn6 single crystal prepared in Example 1 of the present invention. Detailed Embodiments

[0025] Example 1

[0026] In the high-entropy Kagome material HEV6Sn6 of this example, HE = Ho, Gd, Tb, and the preparation method of this material includes the following steps:

[0027] Step 1. In a glove box under Ar atmosphere, 100 mg of Gd, 104.6 mg of Tb, 108.5 mg of Ho rare earth powder, 603.4 mg of V, and 4686.4 mg of Sn metal powder were weighed and mixed according to the molar ratio of Gd:Tb:Ho:V:Sn=1:1:1:18:60, and the mixture was placed in an agate mortar under Ar atmosphere and ground for 5 min until the mixture was uniform to obtain a mixed powder;

[0028] Step 2: Place the mixed powder obtained in step 1 into an Al2O3 crucible, cover the Al2O3 crucible with quartz wool, and then transfer it to a quartz tube. Vacuum the quartz tube to 5×10 -4 Pa, and the quartz tube is sealed under vacuum inside the quartz tube;

[0029] Step 3: Place the sealed quartz tube in step 2 in a box furnace, heat it to 1100°C over 10 hours and keep it warm for 24 hours;

[0030] Step 4: After the insulation in step 3 is completed, the quartz tube is slowly cooled at a cooling rate of 3K / h. When the temperature drops to 600°C, the quartz tube is taken out of the box furnace, and the quartz tube is placed upside down in a centrifuge at a high temperature of around 600°C. Centrifuge at a speed of 3000 rpm for 3 minutes to remove excess Sn flux. After cooling, the sample is collected to obtain a high-entropy Kagome material HEV6Sn6 single crystal.

[0031] Figure 1 and Figure 2 The optical photograph and SEM image of the high entropy Kagome material HEV6Sn6 single crystal prepared in this embodiment are as follows: Figure 1 It can be seen that the high entropy Kagome material HEV6Sn6 single crystal, namely (Gd, Ho, Tb)V6Sn6 single crystal, shows obvious metallic luster and a special geometric configuration of the hexagonal crystal system. Figure 2 It can be seen that the crystal exhibits a smooth and flat surface, and the bulk impurities adsorbed on the surface are unseparated Sn, which has a clear boundary with the crystal.

[0032] Figure 3 This is the EDS spectrum of the high entropy Kagome material HEV6Sn6 single crystal prepared in this example. Figure 3 It can be seen that the characteristic energy in the EDS spectrum is attributed to Gd, Tb, Ho, V and Sn elements (the unmarked peaks in the spectrum are attributed to O and C respectively); further integration calculation shows that the chemical formula of the single crystal sample is: (Gd 0.46 Tb 0.35 Ho 0.19 )V 6.04 Sn 6.18 .

[0033] Figure 4 Raman spectrum of the high-entropy Kagome material HEV6Sn6 single crystal prepared in this example, where the right figure is the enlarged Raman spectrum corresponding to the Raman shift of 220 cm -1 ~250 cm -1 in the wavenumber range of the left figure, and it can be seen from Figure 4 the figure that the Raman spectrum shows the characteristic vibration peak of the V atoms out of the plane in the V-based Kagome material, which belongs to the A 1g symmetric mode, and the characteristic peak shifts towards the low-frequency direction, proving that rare earth elements with different atomic radii are successfully inserted into the interlayer.

[0034] Comprehensively Figures 1 to 4 it can be seen that the high-entropy material HEV6Sn6 (HE = Ho, Gd, Tb) single crystal is successfully prepared in this example.

[0035] Example 2

[0036] In the high-entropy Kagome material HEV6Sn6 of this example, HE = Ho, Gd, Tb, and the preparation method of this material includes the following steps:

[0037] Step 1: In a glove box under Ar atmosphere protection, weigh 100 mg of Gd, 104.6 mg of Tb, 108.5 mg of Ho rare earth powders and 603.4 mg of V, 2343.2 mg of Sn metal powders respectively according to the molar ratio of Gd:Tb:Ho:V:Sn = 1:1:1:18:30, mix them, and place them in an agate mortar under Ar atmosphere protection and grind for 5 min until evenly mixed to obtain a uniformly mixed powder;

[0038] Step 2: Load the uniformly mixed powder obtained in Step 1 into an Al2O3 crucible, cover the Al2O3 crucible with quartz wool, then transfer it to a quartz tube, evacuate the quartz tube to 1×10 -4 Pa, and seal the quartz tube under vacuum inside the quartz tube;

[0039] Step 3: Place the sealed quartz tube in a box furnace, heat it to 1100 °C at a rate of 10 h and hold for 10 h;

[0040] Step 4: After the heat preservation in Step 3 is completed, cool the quartz tube slowly at a cooling rate of 3 K / h. When the temperature drops to 600 °C, take out the quartz tube from the box furnace, invert the quartz tube into a centrifuge at a high temperature near 600 °C, centrifuge at a speed of 3000 rpm for 3 min to remove the excess Sn flux, cool it and collect the sample to obtain the high-entropy Kagome material HEV6Sn6 single crystal.

[0041] After testing, the properties of the product high-entropy Kagome material HEV6Sn6 single crystal (HE = Ho, Gd, Tb) obtained in this example are basically the same as those in Example 1.

[0042] Example 3

[0043] In the high-entropy Kagome material HEV6Sn6 of this example, HE = Ho, Gd, Tb. The preparation method of this material includes the following steps:

[0044] Step 1: In a glove box under Ar atmosphere protection, weigh 100 mg of Gd, 104.6 mg of Tb, 108.5 mg of Ho rare earth powder and 603.4 mg of V, 3124.2 mg of Sn metal powder respectively according to the molar ratio Gd:Tb:Ho:V:Sn = 1:1:1:18:40, mix them, and place them in an agate mortar and grind for 10 min until evenly mixed to obtain a uniformly mixed powder.

[0045] Step 2: Put the uniformly mixed powder obtained in Step 1 into an Al2O3 crucible, cover the Al2O3 crucible with quartz wool, then transfer it to a quartz tube, evacuate the quartz tube to 1×10 -3 Pa, and seal the quartz tube under vacuum in the quartz tube.

[0046] Step 3: Place the sealed quartz tube obtained in Step 2 in a box furnace, heat it to 1050 °C at a rate of 10 h and keep it at this temperature for 10 h.

[0047] Step 4: After the heat preservation in Step 3 is completed, slowly cool the quartz tube at a cooling rate of 2 K / h. When the temperature drops to 600 °C, take out the quartz tube from the box furnace, invert the quartz tube into a centrifuge at a high temperature near 600 °C, centrifuge at a speed of 3000 rpm for 3 min to remove the excess Sn flux, cool it and collect the sample to obtain the high-entropy Kagome material HEV6Sn6 single crystal.

[0048] After testing, the properties of the product high-entropy Kagome material HEV6Sn6 single crystal (HE = Ho, Gd, Tb) obtained in this example are basically the same as those in Example 1.

[0049] Example 4

[0050] In the high-entropy Kagome material HEV6Sn6 of this example, HE = Ho, Gd, Tb. The preparation method of this material includes the following steps:

[0051] Step 1: In a glove box under Ar atmosphere protection, weigh 100 mg of Gd, 104.6 mg of Tb, 108.5 mg of Ho rare earth powders and 603.4 mg of V, 3905.3 mg of Sn metal powders respectively according to the molar ratio Gd:Tb:Ho:V:Sn = 1:1:1:18:50, mix them, and place them in an agate mortar and grind for 10 min until evenly mixed to obtain a uniformly mixed powder;

[0052] Step 2: Put the uniformly mixed powder obtained in Step 1 into an Al2O3 crucible, cover the Al2O3 crucible with quartz wool, then transfer it to a quartz tube, evacuate the quartz tube to 5×10 -3 Pa, and seal the quartz tube under vacuum inside the quartz tube;

[0053] Step 3: Place the sealed quartz tube in a box furnace, heat it to 1050 °C at a rate of 10 h and keep it warm for 24 h;

[0054] Step 4: After the heat preservation in Step 3 is completed, slowly cool the quartz tube at a cooling rate of 2 K / h. When the temperature drops to 600 °C, take out the quartz tube from the box furnace, invert the quartz tube into a centrifuge at a high temperature near 600 °C, centrifuge at a speed of 3000 rpm for 3 min to remove the excess Sn flux, cool it and collect the sample to obtain the high-entropy Kagome material HEV6Sn6 single crystal.

[0055] After testing, the properties of the high-entropy Kagome material HEV6Sn6 single crystal (HE = Ho, Gd, Tb) obtained in this example are basically the same as those in Example 1.

[0056] The above are only the preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modifications, changes and equivalent changes made to the above embodiments according to the technical essence of the invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A preparation method of a high-entropy Kagome material HEV6Sn6, characterized in that HE = Ho, Gd, Tb, and the preparation method includes the following steps: Step 1: Mix Ho, Gd, Tb rare earth powders with V and Sn metal powders, and grind them in an agate mortar under Ar atmosphere protection until they are evenly mixed to obtain a uniformly mixed powder; Step 2: Load the uniformly mixed powder obtained in Step 1 into an Al2O3 crucible, then transfer it to a quartz tube, and seal the quartz tube under the condition of ensuring vacuum inside the quartz tube; Step 3: Place the sealed quartz tube in a box furnace for heating and sintering and holding; Step 4: After the holding in Step 3 is completed, cool the quartz tube and then centrifuge to separate the excess Sn flux to obtain the high-entropy Kagome material HEV6Sn6.

2. The preparation method of a high-entropy Kagome material HEV6Sn6 according to claim 1, characterized in that, In Step 1, the molar ratio of the Ho, Gd, Tb rare earth powders to the V and Sn metal powders is 1:1:1:18:30 - 60, and the mixing process is carried out under Ar atmosphere protection.

3. The preparation method of a high-entropy Kagome material HEV6Sn6 according to claim 1, characterized in that, In step two, the vacuum condition inside the quartz tube during sealing is 1×10 -3 Pa~1×10 -4 Pa.

4. The preparation method of a high-entropy Kagome material HEV6Sn6 according to claim 1, characterized in that, In Step 3, the process of heating, sintering, and holding is as follows: heat to 1050 °C - 1100 °C in 10 h, and hold at the highest temperature for 10 h - 24 h.

5. The preparation method of a high-entropy Kagome material HEV6Sn6 according to claim 1, characterized in that, In Step 4, the cooling rate used for cooling is 2 K / h - 3 K / h, and the temperature after cooling is 600 °C.

6. The preparation method of a high-entropy Kagome material HEV6Sn6 according to claim 1, characterized in that, In Step 4, the rotation speed used for centrifugation is 3000 rpm, and the time is 3 min.

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