Novel barium-antimony-tellurium-sulfur crystal as well as preparation method and application thereof

Abstract

The invention discloses a novel barium-antimony-tellurium-sulfur crystal as well as 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 two crystallographic sites, Sb contains two crystallographic sites, Te contains four crystallographic sites, and S contains two crystallographic sites; wherein Sb atoms are respectively connected with five Te atoms and one S atom to form a [SbTe5S] distorted octahedron, and the independent Te atoms are mutually connected to form a planar square net-shaped [Te2] layer; the Ba atoms are respectively connected with the five Te atoms and the four S atoms to form a [BaTe5S4] polyhedron, the Ba atoms are filled between layers and used for balancing charges, and the Ba atoms are arranged in 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 correlation electronic systems and quantum Hall effect.

Description

Technical Field

[0001] The invention belongs to the technical field of material synthesis, and in particular relates to a novel barium antimony tellurium sulfide crystal and a preparation method and application thereof. Background Art

[0002] Low-dimensional materials have attracted great interest due to their unique physical phenomena such as charge density waves (CDW), superconducting properties, spin density waves, anisotropic optical properties, and topological materials. These materials have great potential for application in the fields of thermoelectrics, strongly correlated electron systems, magnetoresistance, and quantum Hall effect. Topological insulators are quantum phases of matter with symmetry-protected Dirac-like surface states that reside on top of the insulator. The Dirac-like surface states preserve linear dispersion bands, leading to high carrier mobility for charge carriers. CDW refers to periodic fluctuations in electron density and atomic arrangement in solid materials. These fluctuations can lead to regular patterns of high or low electron density that are either synchronized (commensurate) or asynchronous (incommensurate) with the subcellular structure of the lattice. Superconductivity often coexists or competes with CDW to control the electron density near the Fermi level, as seen in cuprates, 2H-TaS2, etc. In addition, superconductivity can be generated by suppressing CDW in various ways, including external hydrostatic pressure, carrier doping, or chemical pressure effects of atomic embedding.

[0003] The discovery of graphene has sparked a flurry of research in recent years. Similarly, similar monolayers of atoms with layered arrangements have been observed in many naturally occurring minerals, such as lead pyroxene ([Pb2BiS3][AuTe2]), which has planar layers composed of Au-Te. Therefore, it is possible to create atomically thin materials using tellurium. Recently, the reported crystal structure of ([BiSbS3]2[Te]2) consists of planar layers composed entirely of Te atoms. These materials have extraordinary topological features in their electronic structure that can be predicted theoretically or confirmed experimentally.

[0004] Therefore, these phenomena are studied in topological structures with a single planar Te layer. A common feature is found in these materials - the positively charged sulfide layer interacts with the negatively charged Au / Te layer ions, and the charges are balanced by the excess Te to form Te-Te bonds, such as planar Te layers. However, materials with this type of structure are still less studied, and there is a lack of specific research on their physical properties. Summary of the invention

[0005] In order to solve the above problems, the present invention proposes a novel barium antimony tellurium sulfide crystal and a preparation method and application thereof.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A novel barium antimony tellurium sulfide crystal, the structural formula of the novel barium antimony tellurium sulfide crystal is BaSbTe2S; the structure of the novel barium antimony tellurium sulfide crystal is: in the structure, Ba contains 2 crystallographic degree sites, Sb contains 2 crystallographic degree sites, Te contains 4 crystallographic degree sites, and S contains 2 crystallographic degree sites; wherein, Sb atoms are respectively connected with 5 Te atoms and 1 S atom to form [SbTe5S] distorted octahedron, and individual Te atoms are connected with each other to form a planar square mesh [Te2] layer; Ba atoms are respectively connected with 5 Te atoms and 4 S atoms to form [BaTe5S4] polyhedron, Ba atoms are filled between layers for balancing charges, and Ba atoms are arranged along the c-axis direction to form a two-dimensional layered structure.

[0008] Preferably, the relative molecular weight of the novel barium antimony tellurium sulfide crystal is 546.3, belongs to the orthorhombic centrosymmetric space group Pmm2, and the unit cell parameters are: α=β=γ=90°, Z=2.

[0009] Preferably, in the novel barium antimony tellurium sulfide crystal, the bond lengths of Sb-S and Sb-Te are respectively and The distance of Te-Te bond is The angle is 90.02°; the bond lengths of Ba-S and Ba-Te are and

[0010] A method for preparing a novel barium antimony tellurium sulfide crystal comprises the following steps:

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

[0012] S2. BaS powder, Ba rod, Sb particle, Te particle and S particle are weighed respectively according to the atomic ratio of 0.9:0.1:1:2:0.1, and poured into a quartz tube coated with a carbon film after drying, and the quartz tube is sealed with a hydrogen-oxygen flame after evacuation;

[0013] S3. Carry out high temperature solid phase reaction in a muffle furnace to obtain new barium antimony tellurium sulfide crystals.

[0014] Preferably, the process of the solid phase reaction in step S3 is: raising the temperature to 300°C within 10 hours, then raising it to 750°C within 40 hours, keeping it warm for 48 hours, lowering it to 300°C within 48 hours, and finally lowering it to room temperature within 5 hours, closing the muffle furnace, and obtaining new barium antimony tellurium sulfide crystals.

[0015] The invention discloses an application of a novel barium antimony tellurium sulfide crystal, wherein the novel barium antimony tellurium sulfide crystal has the characteristics of charge density wave and superconductivity, and is applied in the fields of thermoelectricity, strongly correlated electron system and quantum Hall effect.

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

[0017] 1. The structural formula of the novel barium antimony tellurium sulfide crystal prepared by the present invention is BaSbTe2S. The BaSbTe2S crystal structure contains a special planar square mesh [Te2] layer, and its electronic structure has non-trivial topological characteristics. The BaSbTe2S crystal prepared by the present invention belongs to a novel structure containing a planar square mesh [Te2] layer, which has the advantages of simple crystal synthesis, stability at room temperature, melting with the same composition, and easy growth of single crystals. The BaSbTe2S crystal prepared by the present invention has the characteristics of charge density waves, and at the same time, the charge density waves are suppressed under high pressure and transformed into superconducting characteristics, which can be applied to the fields of thermoelectricity, strongly correlated electronic systems and quantum Hall effect.

[0018] 2. The preparation method of the novel barium antimony tellurium sulfide crystal of the present invention has simple and easy-to-obtain raw materials, a simple and easy-to-operate processing process, low production cost, and is easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the crystal structure of the novel BaSbTe2S prepared in the present invention;

[0020] Figure 2 The single crystal powder X-ray diffraction pattern of the novel BaSbTe2S prepared by the present invention;

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

[0022] Figure 4 Schematic diagram of differential thermal analysis of the novel BaSbTe2S crystal prepared in the present invention;

[0023] Figure 5 The figure is a graph showing the resistance and temperature changes of the new BaSbTe2S crystal prepared in the present invention under different pressures. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

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

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

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

[0028] S2. BaS powder, Ba rod, Sb particle, Te particle and S particle are weighed respectively according to the atomic ratio of 0.9:0.1:1:2:0.1, and poured into a quartz tube coated with a carbon film after drying, and the quartz tube is sealed with a hydrogen-oxygen flame after evacuation;

[0029] S3. A high-temperature solid-phase reaction is carried out in a muffle furnace to obtain a black layered new type of barium antimony tellurium sulfide crystal (BaSbTe2S); the process of the solid-phase reaction is: the temperature is raised to 300°C in 10 hours, then raised to 750°C in 40 hours, kept warm for 48 hours, lowered to 300°C in 48 hours, and finally lowered to room temperature in 5 hours, the muffle furnace is closed, and the new type of barium antimony tellurium sulfide crystal is obtained.

[0030] Performance Testing:

[0031] 1) The novel barium antimony tellurium sulfide crystals prepared above are layered crystals, and these crystals are directly subjected to powder X-ray diffraction test, and the test angle range is 5-85 degrees. Figure 2 As shown, through phase analysis, it can be seen that the experimental X-ray diffraction peaks of the new barium antimony tellurium sulfide single crystal have obvious anisotropy and have a good correspondence with the theoretical curve. The main diffraction peaks all belong to the (001) crystal plane, indicating that the growth plane of the new barium antimony tellurium sulfide crystal of the present invention is the (001) crystal plane. Then, the new barium antimony tellurium sulfide crystal prepared above was ground into polycrystalline powder in an agate mortar and X-ray diffraction analysis was performed again. Figure 3 As shown, it can be seen from the phase analysis that the experimental X-ray diffraction peak of the polycrystalline powder also matches the theoretical curve very well, indicating that a relatively pure barium antimony tellurium sulfide phase is obtained by the above method.

[0032] 2) Use a synchronous thermal analysis instrument to test the differential thermal analysis data of barium antimony tellurium sulfide. Before testing the differential thermal analysis, prepare about 45 mg of a powder crystal sample (the new barium antimony tellurium sulfide crystal prepared above), place it in a quartz tube, and evacuate it to 10 - 4 Pa, sealed with oxyhydrogen flame. Alumina crucible with similar mass was used as reference sample. The test procedure was to heat up to 850℃ at a rate of 10℃ / min, keep at that temperature for 2min, and then cool to room temperature at the same cooling rate. Figure 4 This is the differential thermal analysis spectrum of the new barium antimony tellurium sulfide crystal prepared above. It has an endothermic peak and an exothermic peak during heating and cooling, respectively, which indicates that it has melted and recrystallized. At the same time, the results of the second cycle test showed endothermic and exothermic peaks in similar positions as the first test, indicating that the barium antimony tellurium sulfide crystal is a molten compound of the same composition and has the potential to grow large single crystals.

[0033] 3) In order to test the electrical transport properties of barium antimony telluride sulfide crystals under high pressure. The barium antimony telluride sulfide single crystals were tested using the van der Pauw four-electrode method with NaCl as the pressure transmission medium. All measurements were performed in a diamond anvil press (DAC) with a diameter of 500μm. Stainless steel with a diameter of ~250μm and a hole thickness of ~60μm was used as the liner material, and a mixture of fine alumina and epoxy resin was used as the insulating material. A ~120μm hole was laser drilled on the compressed insulating liner. Fine sodium chloride powder was added and the pressure was increased to 2.0GPa until it became transparent. Then, the sheet-like barium antimony telluride sulfide single crystal was carefully loaded on the transparent NaCl, and 4 platinum electrodes were arranged to contact the sample. The relationship between temperature and resistance of the barium antimony telluride sulfide single crystal was measured using an SR830 digital phase-locked detector in a closed-cycle refrigerator system (2.4-300K) with a current of 200μA. The pressure was measured at room temperature and low temperature of ~4.2K using ruby ​​fluorescence. Figure 5 The resistance and temperature variation diagram of the novel barium antimony tellurium sulfide crystals prepared above under different pressures. At 1.7 GPa, it was observed that as the temperature decreased, the resistance in the range of 300K to 2.4K increased steadily by about one order of magnitude, indicating the semiconductor behavior of the novel barium antimony tellurium sulfide crystals prepared by the present invention. In addition, when the pressure was gradually increased, it was observed that the resistance decreased significantly, and the dependence of the resistance on temperature decreased significantly, indicating that the novel barium antimony tellurium sulfide crystals prepared by the present invention gradually changed from semiconductor behavior to weak metallic behavior. Interestingly, when further pressurized to 13.6 GPa, the resistance of the novel barium antimony tellurium sulfide crystals prepared by the present invention suddenly dropped at 7.5 K, without thermal hysteresis, showing superconducting characteristics, indicating that the novel barium antimony tellurium sulfide crystals prepared by the present invention were transformed into superconductors.

[0034] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A new type of barium antimony tellurium sulfide crystal, characterized in that: The structural formula of the novel barium antimony tellurium sulfide crystal is BaSbTe2S; the structure of the novel barium antimony tellurium sulfide crystal is: in the structure, Ba contains 2 crystallographic degree sites, Sb contains 2 crystallographic degree sites, Te contains 4 crystallographic degree sites, and S contains 2 crystallographic degree sites; Among them, Sb atoms are connected with 5 Te atoms and 1 S atom to form a distorted octahedron [SbTe5S], and individual Te atoms are connected to each other to form a planar square mesh [Te2] layer; Ba atoms are connected with 5 Te atoms and 4 S atoms to form a [BaTe5S4] polyhedron, and Ba atoms are filled between the layers to balance the charge. Ba atoms are arranged along the c-axis to form a two-dimensional layered structure.

2. The novel barium antimony tellurium sulfide crystal according to claim 1, characterized in that: The relative molecular weight of the novel barium antimony tellurium sulfide crystal is 546.3, belongs to the orthorhombic centrosymmetric space group Pmm2, and the unit cell parameters are: α=β=γ=90°, Z=2.

3. The novel barium antimony tellurium sulfide crystal according to claim 1, characterized in that: In the novel barium antimony telluride sulfide crystal, the bond lengths of Sb-S bond and Sb-Te bond are respectively and The distance of the Te-Te bond is The angle is 90.02°; the bond lengths of Ba-S and Ba-Te are and 4. A method for preparing the novel barium antimony tellurium sulfide crystal according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Prepare raw materials, including BaS powder, Ba rod, Sb granules, Te granules and S granules; S2. BaS powder, Ba rod, Sb particle, Te particle and S particle are weighed respectively according to the atomic ratio of 0.9:0.1:1:2:0.1, and poured into a quartz tube coated with a carbon film after drying, and the quartz tube is sealed with a hydrogen-oxygen flame after evacuation; S3. Carry out high temperature solid phase reaction in a muffle furnace to obtain new barium antimony tellurium sulfide crystals.

5. The method for preparing a novel barium antimony tellurium sulfide crystal according to claim 4, characterized in that: The process of the solid phase reaction in step S3 is: raising the temperature to 300°C in 10 hours, then raising it to 750°C in 40 hours, keeping it warm for 48 hours, lowering it to 300°C in 48 hours, and finally lowering it to room temperature in 5 hours, closing the muffle furnace, and obtaining a new type of barium antimony tellurium sulfide crystal.

6. An application of the novel barium antimony tellurium sulfide crystal according to any one of claims 1 to 3, characterized in that: The new barium antimony tellurium sulfide crystal has the characteristics of charge density wave and superconductivity, and is used in the fields of thermoelectricity, strongly correlated electron systems and quantum Hall effect.

Images