A novel barium antimony tellurium sulphur crystal, a preparation method and application thereof

Abstract

The application discloses a novel barium antimony tellurium sulfur crystal and a preparation method and application thereof, the structural formula of the novel barium antimony tellurium sulfur crystal is BaSbTe2S; the structure of the novel barium antimony tellurium sulfur crystal is as follows: in the structure, Ba contains 2 crystallographic sites, Sb contains 2 crystallographic sites, Te contains 4 crystallographic sites, and S contains 2 crystallographic sites; wherein, Sb atoms are connected with 5 Te atoms and 1 S atom respectively to form [SbTe5S] distorted octahedron, and single Te atoms are connected with each other to form a planar square net [Te2] layer; Ba atoms are connected with 5 Te atoms and 4 S atoms respectively to form [BaTe5S4] polyhedron, Ba atoms are filled between layers to balance the electric charge, and Ba atoms are arranged along the c-axis direction to form a two-dimensional layered structure; the novel barium antimony tellurium sulfur crystal prepared by the method has the characteristics of charge density wave and superconductivity, and can be applied to the fields of thermoelectricity, strong correlated electron systems and quantum Hall effect.

Description

Technical Field

[0001] This invention belongs to the field of materials synthesis technology, specifically relating to a novel barium antimony tellurium sulfur crystal, its preparation method, and its application. Background Technology

[0002] Low-dimensional materials have attracted considerable interest due to their unique physical phenomena, such as charge density waves (CDW), superconductivity, spin density waves, anisotropic optical properties, and topological properties. These materials hold great promise for applications in thermoelectrics, strongly correlated electronic systems, magnetoresistance, and the quantum Hall effect. Topological insulators are quantum phases of matter with symmetry-protected Dirac-like surface states. The Dirac-like surface states at the top of the insulator maintain a linear dispersion band, resulting in high carrier mobility. CDW refers to the periodic fluctuations in electron density and atomic arrangement in solid materials. These fluctuations can lead to regular patterns of high or low electron density, which are either synchronized (symmetrical) with the subcellular structure of the crystal lattice or asynchronous (disproportionate). Superconductivity often coexists with or competes with CDW to control the electron density near the Fermi level, as seen in cuprates, 2H-TaS2, etc. Furthermore, superconductivity can be generated by suppressing CDW through various means, including external hydrostatic pressure, carrier doping, or chemical pressure effects of atomic intercalation.

[0003] In recent years, the discovery of graphene has sparked a series of studies. Similarly, similar monolayered atomic structures with layered arrangements have been observed in many naturally occurring minerals, such as pyroxene ([Pb₂BiS₃][AuTe₂]), which has planar layers composed of Au-Te atoms. Therefore, it is possible to create materials with atomically thin thicknesses using tellurium. Recently, the crystal structure ([BiSbS₃]₂[Te]₂) has been reported, consisting entirely of planar layers of Te atoms. These materials exhibit remarkable topological features in their electronic structures, which can be confirmed through theoretical prediction or experiments.

[0004] Therefore, these phenomena were studied in topological structures with a single planar Te layer. A common feature was found in these materials—the positively charged sulfide layer interacts with the negatively charged Au / Te layer ions, and the charge is balanced through excess Te, forming Te-Te bonds, as in planar Te layers. However, materials with this type of structure are still relatively unstudied, and specific studies on their physical properties are lacking. 。 Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a novel barium-antimony-tellurium-sulfur crystal, its preparation method, and its applications.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A novel barium-antimony-tellurium-sulfur crystal, with the structural formula BaSbTe2S, is disclosed. The crystal structure comprises: Ba containing 2 crystallographic atom sites, Sb containing 2 crystallographic atom sites, Te containing 4 crystallographic atom sites, and S containing 2 crystallographic atom sites. Sb atoms are connected to 5 Te atoms and 1 S atom to form a [SbTe5S] distorted octahedron, and individual Te atoms are interconnected to form a planar square network [Te2] layer. Ba atoms are connected to 5 Te atoms and 4 S atoms to form a [BaTe5S4] polyhedron. Ba atoms fill the interlayer space to balance the charge, and the Ba atoms are arranged along the c-axis to form a two-dimensional layered structure.

[0008] Preferably, the novel barium antimony tellurium sulfur crystal has a relative molecular weight of 546.3, belongs to the orthogonal centrosymmetric space group Pmm2, and has the following cell parameters: α=β=γ=90°, Z = 2.

[0009] Preferably, in the novel barium-antimony-tellurium-sulfur crystal, the bond lengths of the Sb-S bonds and Sb-Te bonds range from [values ​​to be filled in]. and The distance between Te-Te bonds is The included angle is 90.02°; the bond length ranges of the Ba-S and Ba-Te bonds are respectively... and

[0010] A novel method for preparing barium antimony tellurium sulfur crystals includes the following steps:

[0011] S1. Prepare raw materials, including BaS powder, Ba rods, Sb granules, Te granules and S granules;

[0012] S2. Weigh out BaS powder, Ba rods, Sb particles, Te particles and S particles according to the atomic ratio of 0.9:0.1:1:2:0.1, and pour them into a dried quartz tube coated with a carbon film. After evacuation, seal the quartz tube with an oxyhydrogen flame.

[0013] S3. A high-temperature solid-state reaction was carried out in a muffle furnace to obtain a novel barium antimony tellurium sulfur crystal.

[0014] Preferably, the solid-phase reaction process in step S3 is as follows: the temperature is raised to 300°C for 10 hours, then raised to 750°C for 40 hours, held at that temperature for 48 hours, then lowered to 300°C for 48 hours, and finally lowered to room temperature for 5 hours, and the muffle furnace is turned off to obtain a novel barium antimony tellurium sulfur crystal.

[0015] An application of a novel barium-antimony-tellurium-sulfur crystal, which possesses charge density wave and superconducting properties, is proposed for use in thermoelectric, strongly correlated electronic systems, and quantum Hall effect fields.

[0016] By adopting the above technical solution, the present invention has the following beneficial effects:

[0017] 1. The novel barium antimony tellurium sulfide crystal obtained by this invention has the structural formula BaSbTe2S. The BaSbTe2S crystal structure contains a special planar square network [Te2] layer, and its electronic structure exhibits nontrivial topological features. The BaSbTe2S crystal obtained by this invention belongs to a novel structure containing a planar square network [Te2] layer, which has advantages such as simple crystal synthesis, stability at room temperature, homogeneous melting, and easy single crystal growth. The BaSbTe2S crystal obtained by this invention exhibits charge density wave characteristics, which are suppressed under high voltage, transforming into superconducting properties. This allows for applications in thermoelectricity, strongly correlated electronic systems, and the quantum Hall effect.

[0018] 2. The preparation method of the novel barium antimony tellurium sulfur crystal of the present invention uses simple and readily available raw materials, the processing is simple and easy to operate, the production cost is low, and it is easy to promote. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the crystal structure of the novel BaSbTe2S obtained in this invention;

[0020] Figure 2 This is an X-ray diffraction pattern of the novel BaSbTe2S single-crystal powder obtained in this invention;

[0021] Figure 3 This is an X-ray diffraction pattern of the polycrystalline powder of the novel BaSbTe2S prepared in this invention;

[0022] Figure 4 This is a schematic diagram of differential thermal analysis of the novel BaSbTe2S crystal obtained in this invention.

[0023] Figure 5 The graph shows the resistance and temperature changes of the novel BaSbTe2S crystal prepared in this invention under different pressures. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] like Figures 1 to 5 As shown. Among them, in Figure 1In the diagram, (a) is a diagram of the BaSbTe2S crystal along the b-axis, (b) is a schematic diagram of the planar square network [Te2] layer, (c) is a diagram of the coordination environment of Ba atoms, and (d) is a diagram of the coordination environment of Sb atoms.

[0026] Preparation of a novel barium antimony tellurium sulfide crystal (BaSbTe2S):

[0027] S1. Prepare raw materials, including BaS powder, Ba rods, Sb granules, Te granules, and S granules; the purity of BaS powder is 99.9% (produced by Aladdin Company), the purity of Ba rods is 99.9% (produced by Aladdin Company), the purity of Sb granules is 99.99% (produced by Hebei Luohong Technology Co., Ltd.), the purity of Te granules is 99.999% (produced by Hebei Luohong Technology Co., Ltd.), and the purity of S granules is 99.999% (produced by Hebei Luohong Technology Co., Ltd.).

[0028] S2. Weigh out BaS powder, Ba rods, Sb particles, Te particles and S particles according to the atomic ratio of 0.9:0.1:1:2:0.1, and pour them into a dried quartz tube coated with a carbon film. After evacuation, seal the quartz tube with an oxyhydrogen flame.

[0029] S3. A high-temperature solid-state reaction was carried out in a muffle furnace to obtain a novel black layered barium antimony tellurium sulfur crystal (BaSbTe2S). The solid-state reaction process was as follows: the temperature was raised to 300℃ for 10 hours, then raised to 750℃ for 40 hours, held at that temperature for 48 hours, then lowered to 300℃ for 48 hours, and finally lowered to room temperature for 5 hours. The muffle furnace was then turned off to obtain the novel barium antimony tellurium sulfur crystal.

[0030] Performance testing:

[0031] 1) The novel barium-antimony-tellurium-sulfur crystals obtained above are layered crystals. These crystals were directly subjected to powder X-ray diffraction testing, with the testing angle range being 5-85 degrees. For example... Figure 2 As shown, phase analysis reveals that the experimental X-ray diffraction peaks of the novel barium-antimony-tellurium-sulfur single crystal exhibit significant anisotropy and correspond well with the theoretical curves. The main diffraction peaks belong to the (001) crystal plane, indicating that the growth plane of the novel barium-antimony-tellurium-sulfur crystal is the (001) crystal plane. Then, the novel barium-antimony-tellurium-sulfur crystal prepared above was ground into polycrystalline powder in an agate mortar, and X-ray diffraction analysis was performed again. Figure 3 As shown in the figure, phase analysis reveals that the experimental X-ray diffraction peaks of the polycrystalline powder also match the theoretical curves well, indicating that a relatively pure barium-antimony-tellurium-sulfur phase was obtained through the above method.

[0032] 2) Differential thermal analysis (DTA) data of barium antimony tellurium sulfur were tested using a synchronous thermal analysis instrument. Before the DTA test, approximately 45 mg of powder crystal sample (the novel barium antimony tellurium sulfur crystals prepared above) was prepared, placed inside a quartz tube, and evacuated to 10 °C. - 4 Pa, sealed with an oxyhydrogen flame. An alumina crucible of similar mass was used as a reference sample. The test procedure was to heat to 850 °C at a rate of 10 °C / min, hold for 2 min, and then cool to room temperature at the same cooling rate. Figure 4 The differential thermal analysis (DTA) spectrum of the novel barium-antimony-tellurium-sulfur crystal obtained above shows an endothermic peak and an exothermic peak during heating and cooling, respectively, indicating that melting and recrystallization occurred. Furthermore, the second cycle test showed endothermic and exothermic peaks at similar positions to the first test, suggesting that the barium-antimony-tellurium-sulfur crystal is a homologous molten compound with the potential to grow large single crystals.

[0033] 3) To test the electrical transport properties of barium antimony tellurium sulfide crystals under high pressure, the van der Bauer four-electrode method was used with NaCl as the pressure transfer medium. All measurements were performed in a 500 μm diameter diamond anvil cell (DAC). A stainless steel liner with a diameter of ~250 μm and a hole thickness of ~60 μm was used as the liner material, and a mixture of fine alumina and epoxy resin was used as the insulating material. A hole of ~120 μm was laser-drilled in the compressed insulating liner. Fine sodium chloride powder was added, and the pressure was increased to 2.0 GPa until the sample became transparent. Then, the sheet-like barium antimony tellurium sulfide crystals were carefully loaded onto the transparent NaCl, and four platinum electrodes were arranged in contact with the sample. The temperature-resistance relationship of the barium antimony tellurium sulfide crystals was measured using an SR830 digital phase-locked loop (PLL) in a closed-loop refrigeration system (2.4–300 K) with a current of 200 μA. The pressure at room temperature and at a low temperature of ~4.2K was measured using ruby ​​fluorescence. Figure 5 The graph shows the resistance versus temperature changes of the novel barium-antimony-tellurium-sulfur crystal prepared above under different pressures. At 1.7 GPa, it was observed that the resistance steadily increased by approximately one order of magnitude in the range of 300 K to 2.4 K as the temperature decreased, indicating the semiconductor behavior of the novel barium-antimony-tellurium-sulfur crystal prepared in this invention. Furthermore, as the pressure gradually increased, a significant decrease in resistance and a significant reduction in the resistance's dependence on temperature were observed, indicating that the novel barium-antimony-tellurium-sulfur crystal prepared in this invention gradually transitioned from semiconductor behavior to weak metallic behavior. Interestingly, when the pressure was further increased to 13.6 GPa, the resistance of the novel barium-antimony-tellurium-sulfur crystal prepared in this invention suddenly decreased at 7.5 K without thermal hysteresis, exhibiting superconducting characteristics, indicating that the novel barium-antimony-tellurium-sulfur crystal prepared in this invention transformed into a superconductor.

[0034] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A barium antimony tellurium sulphide crystal characterised in that: The structural formula of the barium antimony tellurium sulfur crystal is BaSbTe2S; the structure of the barium antimony tellurium sulfur crystal is as follows: Ba contains 2 crystal atom points, Sb contains 2 crystal atom points, Te contains 4 crystal atom points, and S contains 2 crystal atom points. In this structure, Sb atoms are connected to 5 Te atoms and 1 S atom to form a [SbTe5S] distorted octahedron, and individual Te atoms are connected to each other to form a planar square network [Te2] layer; Ba atoms are connected to 5 Te atoms and 4 S atoms to form a [BaTe5S4] polyhedron, and Ba atoms fill the interlayer to balance the charge. The Ba atoms are arranged along the c-axis to form a two-dimensional layered structure. The relative molecular weight of the barium antimony tellurium sulfur crystal is 546.3, which belongs to the orthorhombic center-symmetric space group Pmm 2, the cell parameters are: a=4.469 Å, b=4.468 Å, c=15.99 Å, α=β=γ=90°, V=319.5 Å 3 , Z=2.

2. The barium antimony tellurium sulfur crystal as described in claim 1, characterized in that: In the barium-antimony-tellurium-sulfur crystal, the bond lengths of the Sb-S bonds and Sb-Te bonds range from 2.447 to 2.509 Å and 3.177 to 3.559 Å, respectively. The distance between Te-Te bonds is 3.160 Å, and the included angle is 90.02°; the bond lengths of Ba-S bonds and Ba-Te bonds range from 3.237 to 3.241 Å and 3.517 to 3.537 Å, respectively.

3. A method for preparing barium antimony tellurium sulfur crystals as described in any one of claims 1-2, characterized in that, Includes the following steps: S1. Prepare raw materials, including BaS powder, Ba rods, Sb granules, Te granules and S granules; S2. Weigh out BaS powder, Ba rods, Sb particles, Te particles and S particles according to the atomic ratio of 0.9:0.1:1:2:0.1, and pour them into a dried quartz tube coated with a carbon film. After evacuation, seal the quartz tube with an oxyhydrogen flame. S3. A high-temperature solid-state reaction is carried out in a muffle furnace to obtain barium antimony tellurium sulfur crystals.

4. The method for preparing barium antimony tellurium sulfur crystals as described in claim 3, characterized in that, The solid-phase reaction process described in step S3 is as follows: the temperature is raised to 300 ℃ for 10 hours, then raised to 750 ℃ ​​for 40 hours, held at that temperature for 48 hours, then lowered to 300 ℃ for 48 hours, and finally lowered to room temperature for 5 hours. The muffle furnace is then turned off to obtain barium antimony tellurium sulfur crystals.

5. An application of the barium antimony tellurium sulfide crystal as described in any one of claims 1-2, characterized in that: The barium-antimony-tellurium-sulfur crystal possesses charge density wave and superconducting properties, and can be applied in the fields of thermoelectricity, strongly correlated electronic systems, and the quantum Hall effect.

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