CN114438592A - Monoclinic system crystal form substance and preparation method thereof - Google Patents
Monoclinic system crystal form substance and preparation method thereof Download PDFInfo
- Publication number
- CN114438592A CN114438592A CN202011230950.5A CN202011230950A CN114438592A CN 114438592 A CN114438592 A CN 114438592A CN 202011230950 A CN202011230950 A CN 202011230950A CN 114438592 A CN114438592 A CN 114438592A
- Authority
- CN
- China
- Prior art keywords
- crystal
- monoclinic
- pressure
- mop
- boron nitride
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B1/00—Single-crystal growth directly from the solid state
- C30B1/02—Single-crystal growth directly from the solid state by thermal treatment, e.g. strain annealing
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B1/00—Single-crystal growth directly from the solid state
- C30B1/12—Single-crystal growth directly from the solid state by pressure treatment during the growth
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Inorganic Chemistry (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
The invention relates to the technical field of new material preparation, in particular to a monoclinic crystal system crystal form substance and a preparation method thereof. The molecular formula of the monoclinic system crystal form substance is MoP2(ii) a The monoclinic crystal type substance comprises the following unit cell parameters
α＝90°，β＝119.192±0.006°，γ＝90°，
The space group of the crystal form is C2/m, and the crystal system belongs to a monoclinic system. The invention utilizes the conditions of high temperature and high pressure,can overcome the limitation that the red phosphorus vapor pressure is high and easily causes the tube explosion of a quartz tube, thereby preparing the MoP with the bottom core monoclinic structure2The single crystal has good crystallization quality, is single-phase through single crystal X-ray diffraction, and has no impurity and goldenrain crystal in the single crystal.
Description
Technical Field
The invention relates to the technical field of new material preparation, in particular to a monoclinic crystal system crystal form substance and a preparation method thereof.
Background
In recent years, metal phosphorus-rich compounds TPn (T is metal, n has values of 2, 2.5, 3, 4 and the like) have abundant crystal structure types and novel physicochemical properties, and have attracted extensive research interest of researchers. TP2Is an important system in metal phosphorus-rich compounds. In the chemical element cycleIn the table, Cr, Mo and W belong to the same main group, and all three metal elements can react with red phosphorus to generate CrP2，MoP2And WP2. At present, the crystal structures of the three compounds reported in the literature are respectively: CrP2Has a bottom-centered monoclinic structure (space group: C2/m) and MoP2Having a bottom-centered orthogonal structure (space group: Cmc 2)1). And WP2Then two different crystal structures (bottom-centered orthogonal structure (space group: Cmc 2) are present due to the difference in preparation temperature1) And a bottom-centered monoclinic structure (space group: c2/m)). Cr, Mo and W belong to the same main group and have very similar outer electronic structures. WP of2Has crystal polymorphism (i.e. the same chemical composition but different crystal structures). Then with WP2Isoelectronic compound MoP of the same main group2Is there also crystal polymorphism? At present the above-mentioned CrP2，MoP2And WP2The crystal is grown in a high-temperature furnace (a shaft furnace, a box furnace and the like) by using a fluxing agent method, and the pressure for synthesizing the sample is normal pressure. In a Mo-P binary phase diagram reported in literature, MoP with Mo and P in a chemical ratio of 1:22MoP with only orthorhombic structure at bottom center and monoclinic structure at bottom center2No report is found. The problem which cannot be overcome at present is that a high-temperature furnace which is common in a laboratory cannot provide a high-pressure (for example, 5GPa, about 5 ten thousand atmospheric pressures) environment for a sample reactant, and only the MoP can be prepared by a normal-pressure high-temperature preparation method2The basal-centric orthogonal phase of (a).
In addition, since the melting point of red phosphorus is low (590 degrees centigrade), and the melting points of Cr, Mo, and W are high, 1907 degrees centigrade, 2623 degrees centigrade, and 3422 degrees centigrade, respectively. In the synthesis of the metal phosphorus-rich compound, the melting points of red phosphorus and metal elements have large temperature difference, so the temperature must be slowly increased under the premise of putting a large amount of fluxing agent (such as Sn) to prevent the quartz tube from tube explosion, and the sample preparation speed by the normal-pressure solid-phase method is slow (more than half a month). In addition, and most importantly, the vapor pressure of red phosphorus is very high (4357 kPa at 590 ℃ and about 41 atm), and when a metal phosphorus-rich compound is synthesized by a conventional method, there is a risk of tube explosion of a quartz tube at high temperature.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, the present invention aims to provide a monoclinic crystal and a preparation method thereof.
To achieve the above and other related objects, an aspect of the present invention provides a monoclinic crystal having a molecular formula of MoP2(ii) a The monoclinic crystal type substance comprises the following unit cell parameters
α＝90°，β＝119.192±0.006°，γ＝90°，
The crystal form space group is C2/m, and the crystal system belongs to a monoclinic system.
In some embodiments of the invention, in the monoclinic crystal form, Mo is in an octadentate field and each Mo atom is coordinated with 8P atoms.
In some embodiments of the invention, the monoclinic crystal type is a black crystal with metallic luster.
In another aspect, the present invention provides a method for preparing the monoclinic crystal form of the present invention, the method comprising the steps of:
1) tabletting elementary molybdenum and red phosphorus and then coating hexagonal boron nitride to prepare a coating body;
2) reacting the inclusion in the step 1) at 900-1100 ℃ under the pressure of 4-6 GPa to obtain a monoclinic crystal type substance.
In some embodiments of the present invention, in the step 1), the molar ratio of the elemental molybdenum to the red phosphorus is 1:2.5 to 3.5.
In some embodiments of the present invention, in step 1), the single molybdenum and red phosphorus are ground and then tabletted to form a cylindrical shape.
In some embodiments of the invention, the diameter of the cylinder is 3.5 to 5.0 mm and the height is 3.2 to 6.0 mm.
In some embodiments of the invention, in step 1), the hexagonal boron nitride is selected from a hexagonal boron nitride wafer or a hexagonal boron nitride tube; the thickness of the hexagonal boron nitride sheet wrapping and pressing sheet is 0.5-0.8 mm; the thickness of the tube wall of the hexagonal boron nitride tube is 0.3-0.5 mm.
In some embodiments of the invention, in the step 2), after the reaction is finished, the temperature is reduced at a rate of 50-100 ℃ per hour, and the temperature of the sample is slowly reduced to 800-900 ℃; then quenching to room temperature, and finally slowly releasing pressure to normal pressure.
In some embodiments of the invention, step 2) is a reaction performed in a large cavity press.
In some embodiments of the present invention, the step 2) is performed by calibrating the pressure and temperature before the reaction; the pressure is calibrated by using a resistance-pressure curve of metal Bi; the temperature is calibrated by phase transition of the crystal structure of the silicon dioxide.
Drawings
FIG. 1 is a schematic view of an apparatus for synthesizing a sample at high temperature and high pressure according to the present invention.
FIG. 2 shows a MoP of the present invention2Single crystal samples and optical photographs of geometry.
FIG. 3 shows a MoP of the present invention2Single crystal sample orientation and high symmetry diffraction crystal face.
FIG. 4 shows a MoP of the present invention2Single crystal diffraction patterns of single crystal samples in three different directions ((a) (hk0), (b) (h0l), (c) (0 kl)).
FIG. 5 shows a bottom-centered monoclinic system MoP of the present invention2The crystal structure is shown schematically.
FIG. 6 is a micro-area image of a sample of the present invention under an electron microscope.
FIG. 7 is a diagram showing the analysis of the chemical element types and chemical compositions of the samples of the present invention.
FIG. 8 shows a bottom-centered monoclinic system MoP of the present invention2Crystal and prior art orthorhombic phase MoP2The band structure of the crystal is simulated.
FIG. 9 shows a bottom-centered monoclinic system MoP of the present invention2Crystal and prior art orthorhombic phase MoP2And (3) simulating the density of states of the crystal.
FIG. 10 shows a bottom-centered monoclinic system MoP of the present invention2Crystal and prior art orthorhombic phase MoP2Resistance test comparison of the crystal.
Detailed Description
The inventor of the invention finds that the difficulties in the prior art can be overcome by adopting a high-temperature high-pressure synthesis method through a large amount of experiments. The large-cavity press has the advantages of physical mechanical pressurization, magnesium oxide octahedral wrapping and pyrophyllite sealing, and can provide a sealed and high-strength sample cavity for a sample. The physical pressure provided by the large chamber press is much greater than the vapor pressure of the sample at high temperature. Therefore, the large-cavity press is very suitable for sealing chemical reactants with high vapor pressure, plays an extremely important role in the research and exploration of new materials, and is an important means for preparing metal phosphorus-rich compounds. The MoP with the monoclinic structure is synthesized for the first time on a Kawai type large-cavity press of 2000 tons by adopting a high-temperature high-pressure method2A single crystal sample. On the basis of this, the present invention has been completed.
The invention provides a monoclinic crystal type substance, the structural formula of which is MoP2(ii) a The monoclinic crystal type substance comprises the following unit cell parameters
α＝90°，β＝119.192±0.006°，γ＝90°，
The crystal form space group is C2/m, and the crystal system belongs to a monoclinic system.
In the monoclinic crystal system crystal form provided by the invention, the measurement of the single crystal data is not particularly limited, and the single crystal measurement known by the person skilled in the art can be adoptedThe instrument was tested. In one embodiment, the single crystal data of the monoclinic crystal is single crystal X-ray diffraction data of the monoclinic crystal collected at 150K on a Bruker (Bruker) D8 Venture double-target small molecule X-ray single crystal diffractometer, wherein Mo Ka radiation
Single crystal diffractometer tube pressure at data acquisition: 50kV and 30mA pipe flow. Analyzing the crystal structure by using ShelXT 2018/2(Sheldrick,2018) to obtain all 3 non-hydrogen atom positions, correcting structure parameters and distinguishing atom types by using a least square method, obtaining all atom positions by using a geometric calculation method and a difference Fourier method, and finally obtaining a reliability factor R1＝0.0557,wR20.1653, Goodness factor (Goodness of fit on F)2) 1.177. Finally determining the stoichiometric formula of the sample as MoP2The calculated molecular weight is 157.88, and the crystal density of the material is 5.726g/cm～3。
In the monoclinic crystal provided by the invention, Mo is in an octadentate field in the monoclinic crystal, and each Mo atom is respectively coordinated with 8P atoms.
The crystal form substance further determines a molecular formula through energy dispersive spectroscopy analysis, wherein the molecular formula is MoP2. The invention adopts an energy dispersive spectroscopy (Desktop Scanning Electron Microscope-Phenom ProX) to analyze the chemical components of the sample.
In a second aspect, the present invention provides a method for preparing a monoclinic crystal according to the first aspect, comprising the steps of:
1) tabletting elementary molybdenum and red phosphorus and then coating hexagonal boron nitride to prepare a coating body;
2) reacting the inclusion in the step 1) at 900-1100 ℃ under the pressure of 4-6 GPa to obtain a monoclinic crystal system crystal form substance.
In the synthesis method of the monoclinic system crystal form substance, step 1) is to perform tabletting on single molybdenum and red phosphorus and then wrap hexagonal boron nitride to prepare the inclusion. Among them, the elemental molybdenum and red phosphorus need to be limited within a suitable ratio range. The molar ratio of the simple substance molybdenum to the red phosphorus is 1:2.5 to 3.5. In one embodiment, the molar ratio of elemental molybdenum to red phosphorus is 1: 2.5-3; or 1:3 to 3.5. In general, the elemental molybdenum and red phosphorus can be mixed in a glove box, for example, the mixture can be uniformly mixed in an argon environment, the mixture is mortar-milled for half an hour in an agate mortar, and the mixture is pressed into a cylinder shape with the diameter of 3.5 to 5.0 mm and the height of 3.2 to 6.0 mm by a powder tablet press (pressure: 5 MPa). In some embodiments, the diameter of the cylinder is 3.5 to 4.0 mm, 4.0 to 4.5 mm, or 4.5 to 5.0 mm, etc. The height of the cylinder is 3.2-4.0 mm, 4.0-5.0 mm, 5.0-6.0 mm, 3.5-5.5 mm, etc.
The hexagonal boron nitride belongs to a substance which is resistant to high temperature and high pressure and has stable chemical properties. In the invention, the hexagonal boron nitride can be a hexagonal boron nitride sheet or a hexagonal boron nitride tube. When a hexagonal boron nitride tube is used, the thickness of the tube wall may be, for example, 0.5 to 0.8 mm, 0.5 to 0.6 mm, 0.6 to 0.7 mm, or 0.7 to 0.8 mm, or 0.55 to 0.75 mm, 0.5 to 0.7 mm, or 0.6 to 0.8 mm. The thickness of the hexagonal boron nitride sheet wrapping the pressing sheet is 0.3-0.5 mm, 0.3-0.4 mm, or 0.4-0.5 mm. Because red phosphorus reacts with the noble metal Pt under high temperature and high pressure, the sample reactant is wrapped by hexagonal boron nitride which is resistant to high temperature and high pressure and stable in chemical property, so that the probability of generating impurity phases is reduced, and the sample reactant is different from the sample wrapped by the noble metal in the existing high-temperature and high-pressure experiment.
In the synthesis method of the monoclinic system crystal form substance, the monoclinic system crystal form substance is prepared by reacting the inclusion in the step 1) at 900-1100 ℃ and under the pressure of 4-6 GPa in the step 2). In some embodiments, the reaction temperature may be 900-1000 ℃, or 1000-1100 ℃, 950-1050 ℃, or the like. The reaction pressure is 4-5 Gpa, or 5-6 Gpa, or 4.5-5.5 Gpa. In the step 2), after the reaction is finished, the temperature is reduced at the rate of 50-100 ℃ per hour, and the temperature of the sample is slowly reduced to 800-900 ℃; then quenching to room temperature, and finally slowly releasing pressure to normal pressure. In some embodiments, the temperature in the foregoing step may be decreased at a rate of 50 to 80 ℃, or 80 to 100 ℃, 60 to 90 ℃, or 70 to 80 ℃ per hour. And slowly cooling the temperature of the sample to 800-850 ℃, or 850-900 ℃ and the like. Then quenching to room temperature, and finally slowly releasing pressure to normal pressure.
In general, any reactor capable of providing the above-mentioned high temperature and high pressure may be used. In some embodiments, for example, a large cavity press may be used for the reaction, more specifically, a Kawai type large cavity press, and further, a Kawai type large cavity press of 2000 tons may be selected. When the method is used specifically, as shown in fig. 1, the inclusion is firstly placed in a tantalum heating furnace, the periphery of the inclusion can be sealed by a zirconium dioxide heat insulation plug, the carbon heating furnace is placed in a silicon dioxide heat insulation pipe, finally, the carbon heating furnace is placed in a pressure transmission medium in a magnesium oxide octahedron doped with 5% of cobalt oxide, and sample synthesis is carried out on a 2000-ton Kawai type large-cavity press. And after controlling the high pressure and high temperature conditions, cooling and pressure relief, taking out a sample from the magnesium oxide octahedron, and observing a black crystal with metallic luster under a microscope.
It is further noted that, in the step 2), before the reaction, calibration of pressure and temperature is performed; the pressure is calibrated by using a resistance-pressure curve of metal Bi; the temperature is calibrated by phase transition of the crystal structure of the silicon dioxide. The heating temperature is controlled by a method for controlling the heating power, and the temperature is measured by a tungsten-rhenium thermocouple.
The invention has the following beneficial effects:
the method can overcome the limit that the red phosphorus vapor pressure is high and the quartz tube is easy to explode, thereby preparing the MoP with the monoclinic structure at the bottom core2The single crystal has good crystallization quality, is single-phase through single crystal X-ray diffraction, and has no impurity and goldenrain crystal in the single crystal.
Orthorhombic and monoclinic phase MoP2All belong to compensation type semimetal materials, and are expected to be applied to the fields of magnetic memories, magnetic sensors or magnetic switches and the like. Orthogonal phase MoP2Is a three-dimensional stacked crystal structure (MoP)7The polyhedra are linked along the a-axis by planes (made up of three phosphorus atoms), the b-axis point(phosphorus atom) linkage, c-axis is complex linkage (point linkage and edge linkage)), and the chemical bond is strong. The sample is difficult to be thinned and is not easy to be made into a device. The monoclinic phase belongs to a layered material, and Van der Waals bonds are formed between layers, so that chemical bonds are weak, and the monoclinic phase is easy to be made into a film. In addition, it is also the most important point that, from the thermodynamic viewpoint, the orthorhombic phase belongs to the low-temperature phase, and the monoclinic phase belongs to the high-temperature phase. When the above materials are applied to a device, heat is generated during use. Therefore, the high-temperature monoclinic phase is more stable in performance than the low-temperature orthorhombic phase.
The following examples are provided to further illustrate the advantageous effects of the present invention.
In order to make the objects, technical solutions and advantageous technical effects of the present invention more clear, the present invention is further described in detail below with reference to examples. However, it should be understood that the embodiments of the present invention are only for explaining the present invention and are not for limiting the present invention, and the embodiments of the present invention are not limited to the embodiments given in the specification. The examples were prepared under conventional conditions or conditions recommended by the material suppliers without specifying specific experimental conditions or operating conditions.
Furthermore, it is to be understood that one or more method steps mentioned in the present invention does not exclude that other method steps may also be present before or after the combined steps or that other method steps may also be inserted between these explicitly mentioned steps, unless otherwise indicated; it is also to be understood that a combined connection between one or more devices/apparatus as referred to in the present application does not exclude that further devices/apparatus may be present before or after the combined device/apparatus or that further devices/apparatus may be interposed between two devices/apparatus explicitly referred to, unless otherwise indicated. Moreover, unless otherwise indicated, the numbering of the various method steps is merely a convenient tool for identifying the various method steps, and is not intended to limit the order in which the method steps are arranged or the scope of the invention in which the invention may be practiced, and changes or modifications in the relative relationship may be made without substantially changing the technical content.
In the following examples, reagents, materials and instruments used are commercially available unless otherwise specified.
Example 1
1) Preparation of cylindrical reactant of molybdenum and red phosphorus under normal pressure
The chemically pure simple substance molybdenum and red phosphorus are uniformly mixed in a glove box according to the molar ratio of 1:2.5, and are mortar-milled in an agate mortar for half an hour. The reaction powder was pressed into a cylinder having a diameter of 3.5 mm and a height of 3.2 mm by a powder tablet press (pressure: 5 MPa). Because red phosphorus reacts with the noble metal Pt under high temperature and high pressure, the sample reactant is wrapped by hexagonal boron nitride which is resistant to high temperature and high pressure and stable in chemical property, so that the probability of generating impurity phases is reduced, and the sample reactant is different from the sample wrapped by the noble metal in the existing high-temperature and high-pressure experiment.
2) And putting the sample and the hexagonal boron nitride protective sleeve into a tantalum heating furnace. The samples were then loaded into a high pressure assembly for high pressure high temperature synthesis (see FIG. 1 for assembly drawings). Sample synthesis was performed on a 2000 ton Kawai type large chamber press. Slowly increasing the pressure to 5GPa at room temperature, starting a heating program to heat to 1100 ℃, preserving the heat for 2 hours under the condition of high temperature and high pressure, then reducing the temperature at the rate of 100 ℃ per hour, slowly reducing the temperature of the sample to 900 ℃, then quenching to room temperature, and finally slowly releasing the pressure to normal pressure. The sample was taken out of the octahedron of magnesium oxide and was seen under a microscope as a black crystal with metallic luster (see fig. 2).
Single crystal X-ray diffraction analysis of samples obtained after quenching, FIG. 3 is a MoP of the invention2The single crystal sample has crystal orientation and high symmetry diffraction crystal face. From FIG. 4, it can be seen that the single crystal diffraction spots of the samples are small and bright, confirming that the MoP prepared by the present invention is2The single crystal has no impurity and goldenrain crystal phenomena, and has good crystallization quality. A Crystallographic Information File (crystallographical Information File) of the sample was obtained by single crystal analysis software, and the lattice parameters were: space group: c2/m, unit cell parameters:
beta is 119.192 degrees. Based on the resolved crystallographic information file, the inventors drawn a bottom-centered monoclinic system MoP2With 8P atoms around each Mo atom (fig. 5).
Example 2
1) Preparation of cylindrical reactant of molybdenum and red phosphorus under normal pressure
The chemical pure simple substance molybdenum and red phosphorus are uniformly mixed in a glove box according to the molar ratio of 1:3, and are ground in an agate mortar for half an hour. The molybdenum-phosphorus powder was pressed into a cylinder having a diameter of 3.5 mm and a height of 3.2 mm by a powder tablet press. The initial reaction of the cylindrical sample is protected by a hexagonal boron nitride tube and a wafer, so that the probability of generating impurity phases is reduced.
2) And putting the sample and the hexagonal boron nitride protective sleeve into a tantalum heating furnace. The samples were then loaded into a high pressure assembly for high pressure high temperature synthesis on a 2000 ton Kawai type large cavity press. Slowly increasing the pressure to 6GPa at room temperature, starting a heating program to heat to 1200 ℃, preserving the heat for 3 hours under the condition of high temperature and high pressure, then reducing the temperature at the rate of 100 ℃ per hour, slowly reducing the temperature of the sample to 1000 ℃, then quenching to room temperature, and finally slowly releasing the pressure to normal pressure. Excess phosphorus was used as a self-fluxing agent, and after the sample was taken, the fluxing agent was removed with dilute nitric acid.
In the same manner as in example 1, the sample obtained after quenching also had a metallic lustrous single crystal, and it was found that the sample had a monoclinic system and had good crystal quality without the presence of goldenrain tree crystal and impurities by conducting single crystal X-ray diffraction studies.
Example 3
1) Preparation of cylindrical reactant of molybdenum and red phosphorus under normal pressure
The chemical pure simple substance molybdenum and red phosphorus are uniformly mixed in a glove box according to the molar ratio of 1:3.5, and are ground in an agate mortar for half an hour. The molybdenum-phosphorus powder was pressed into a cylinder having a diameter of 3.5 mm and a height of 3.2 mm by a powder tablet press. The initial reaction of the cylindrical sample is protected by a hexagonal boron nitride tube and a wafer, so that the probability of generating impurity phases is reduced.
2) And putting the sample and the hexagonal boron nitride protective sleeve into a tantalum heating furnace. The samples were then loaded into a high pressure assembly for high pressure high temperature synthesis on a 2000 ton Kawai type large cavity press. Slowly increasing the pressure to 4GPa at room temperature, starting a heating program to heat to 1000 ℃, preserving the heat for 3 hours under the condition of high temperature and high pressure, then reducing the temperature at the rate of 100 ℃ per hour, slowly reducing the temperature of the sample to 900 ℃, then quenching to room temperature, and finally slowly releasing the pressure to normal pressure.
In the same manner as in example 1, the sample obtained after quenching also had a metallic lustrous single crystal, and it was found that the sample had a monoclinic system and had good crystal quality without the presence of goldenrain tree crystal and impurities by conducting single crystal X-ray diffraction studies.
The crystal obtained in example 1 was subjected to single crystal X-ray diffraction test as follows:
MoP was collected at 150K on a Bruker (Bruker) D8 Venture double target small molecule X-ray single crystal diffractometer2Single crystal X-ray diffraction data of (1), in which a molybdenum target is irradiated
Single crystal diffractometer tube pressure at data acquisition: 50kV and 30mA pipe flow. Analyzing the crystal structure by using ShelXT 2018/2(Sheldrick,2018) to obtain all 3 non-hydrogen atom positions, correcting structure parameters and distinguishing atom types by using a least square method, obtaining all atom positions by using a geometric calculation method and a difference Fourier method, and obtaining a final reliability factor R1＝0.0557,wR20.1653, Goodness factor (Goodness of fit on F)2) 1.177. The final structural optimization is done using the SHELL program, using full matrix techniques to minimize F2The square sum deviation of. The results are detailed in table 1.
TABLE 1 MoP2Crystal data and structure refinement (150K)
The crystals obtained in example 1 were subjected to energy dispersive x-ray spectroscopy as follows:
the invention is provided withEnergy dispersive X-ray spectroscopy (test conditions: area size: 112 μm, voltage, 15KV, point detector (BSD Full)) analyzed the chemical composition of the samples. FIG. 6 is a microzone image of a sample under an electron microscope (FOV:112 μm, Mode:15kV-Point, Detector: BSD Full, Time: OCT 27202015: 09). Fig. 7 shows the chemical element species and chemical composition analysis of the samples. The experimental result shows that the sample only contains two elements of molybdenum and phosphorus. As shown in Table 2, the ratio of molybdenum is 33.51%, the ratio of phosphorus is 66.49%, the chemical ratio of molybdenum to phosphorus is 1:2, the energy dispersive X-ray energy spectrum analysis result is consistent with the single crystal structure analysis result of the invention, and the chemical formula of the sample is verified to be MoP2。
TABLE 2 analysis of the chemical elements contained in the samples
Example 4
Monoclinic phase MoP of the invention2And prior art quadrature phase MoP2Simulation of band structure and density of states
Simulation software name: cambridge Serial Total Energy Package (CAStep)
1) Simulation parameters: exchange association energy: generalized Gradient Approximation (GGA);
2) energy cutoff: 290 electron volts (monoclinic phase);
3) size of the inverse space grid: 8 by 4;
4) energy error: 1*10-6Electron volts per atom.
The test results are shown in FIGS. 8 and 9.
Orthogonal phase MoP2And monoclinic phase MoP2Are all of compensated semi-metallic material, as shown in FIG. 8, quadrature phase MoP2And monoclinic phase MoP2The valence band top and the conduction band bottom of (A) are not overlapped near the Fermi surface, and are expected to be applied to the fields of magnetic memories, magnetic sensors, magnetic switches and the like. Orthogonal phase MoP2Is a three-dimensional stacked crystal structure (MoP)7The polyhedron being planar along the a-axis (three phosphorus atoms)Constituent), b-axis point (phosphorus atom) linkage, c-axis is complex linkage (point linkage and edge linkage)), and the chemical bond is strong. Therefore, it is difficult to thin the sample and to make the device. And monoclinic phase MoP2The composite material belongs to a layered material, and Van der Waals bonds are bonded between layers, so that the chemical bonds are weak, and the composite material is easy to be made into a film. FIG. 8 shows the band structure of the orthorhombic phase (black dashed line) and the monoclinic phase (red solid line) MoP2, and it can be seen from FIG. 8 that although the orthorhombic phase MoP2The crystal symmetry (space group No. 36) is higher than that of the monoclinic phase (space group No. 12), but by contrast, the orthorhombic phase MoP2With monoclinic phase MoP2The applicant finds that the band structure of the orthogonal phase is more complex than that of the monoclinic phase, the electronic structure of a sample is difficult to analyze, and the future device planning and design are not facilitated. FIG. 9 shows the results of comparing the state densities of the orthorhombic phase (black dashed line) and the monoclinic phase (red solid line), the monoclinic phase MoP being near the Fermi surface2The density of states of (a) is 2 electron/electron volts, and the density of states of the orthogonal phase is 1 electron/electron volt. The above results show that the monoclinic phase MoP2And the method has more advantages in future device development than the orthogonal phase.
Example 5
Monoclinic phase MoP of the invention2And the existing orthorhombic phase MoP2Resistance test experiment of
The instrumentation used was tested: physical Property Measurement System (PPMS)
The test method comprises the following steps: the four-electrode method is calibrated, namely two electrodes are electrified, and the other two electrodes test voltage.
A link wire: gold wire, attached to the sample with conductive silver paste.
Temperature range: 2-300 opener
The current magnitude is as follows: 50 milliamp
And (3) testing results: FIG. 10, orthogonal phase MoP2With monoclinic phase MoP2The resistance value is between 0.09 ohm and 0.18 ohm which is equivalent to the resistance value of common metal. Orthogonal phase MoP2Resistance value ratio of (1) to monoclinic phase MoP2The temperature is higher in the whole temperature test range, and the experimental result is consistent with the theoretical simulation result of the invention. The monoclinic phase resistance has a low value, so that when the monoclinic phase resistance is made into a device in the future, the monoclinic phase resistance has low power consumption and low heat effect, and the safety operation of the device is facilitated.
MoP of the invention2The monoclinic system belongs to a compensation type semimetal material and is expected to be applied to the fields of magnetic memories, magnetic sensors, magnetic switches and the like.
The above embodiments are merely illustrative of the principles and utilities of the present application and are not intended to limit the application. Any person skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present application. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical concepts disclosed in the present application shall be covered by the claims of the present application.
Claims (10)
1. A monoclinic crystal substance, the molecular formula of which is MoP2；
The monoclinic crystal type substance comprises the following unit cell parameters
α＝90°，β＝119.192±0.006°，γ＝90°，
The space group of the crystal form is C2/m, and the crystal system belongs to a monoclinic system.
2. The monoclinic crystal of claim 1, wherein Mo is in an octadentate field and each Mo atom is coordinated with 8P atoms;
and/or the monoclinic crystal type substance is a black crystal with metallic luster.
3. A method for preparing a monoclinic crystal according to any one of claims 1 to 2, comprising the steps of:
1) tabletting elementary molybdenum and red phosphorus and then coating hexagonal boron nitride to prepare a coating body;
2) reacting the inclusion in the step 1) at 900-1100 ℃ under the pressure of 4-6 GPa to obtain a monoclinic crystal system crystal form substance.
4. The method according to claim 3, wherein the molar ratio of elemental molybdenum to red phosphorus in step 1) is 1:2.5 to 3.5.
5. The method according to claim 3, wherein in the step 1), the single molybdenum and red phosphorus are ground and then tabletted to form a cylindrical shape.
6. The method according to claim 5, wherein the diameter of the cylindrical shape is 3.5 to 5.0 mm and the height thereof is 3.2 to 6.0 mm.
7. The method according to claim 3, wherein in step 1), the hexagonal boron nitride is selected from hexagonal boron nitride flakes or hexagonal boron nitride tubes; the thickness of the hexagonal boron nitride sheet wrapping and pressing sheet is 0.5-0.8 mm; the thickness of the tube wall of the hexagonal boron nitride tube is 0.3-0.5 mm.
8. The method according to claim 3, wherein in the step 2), the temperature of the sample is slowly reduced to 800-900 ℃ at a rate of 50-100 ℃ per hour after the reaction; then quenching to room temperature, and finally slowly releasing pressure to normal pressure.
9. The method according to claim 3, wherein the step 2) is carried out in a large chamber press.
10. The method according to claim 3, wherein the step 2) comprises calibrating the pressure and temperature before the reaction; the pressure is calibrated by using a resistance-pressure curve of metal Bi; the temperature is calibrated by phase transition of the crystal structure of the silicon dioxide.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011230950.5A CN114438592B (en) | 2020-11-06 | 2020-11-06 | Monoclinic system crystal form substance and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011230950.5A CN114438592B (en) | 2020-11-06 | 2020-11-06 | Monoclinic system crystal form substance and preparation method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114438592A true CN114438592A (en) | 2022-05-06 |
| CN114438592B CN114438592B (en) | 2022-11-22 |
Family
ID=81361471
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011230950.5A Active CN114438592B (en) | 2020-11-06 | 2020-11-06 | Monoclinic system crystal form substance and preparation method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114438592B (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020062858A1 (en) * | 1992-09-21 | 2002-05-30 | Thomas Mowles | High efficiency solar photovoltaic cells produced with inexpensive materials by processes suitable for large volume production |
| KR20150057239A (en) * | 2013-11-19 | 2015-05-28 | 한국전기연구원 | Anode Active Materials comprising Mo-Si-P Systems For Li Ion Batteries And Manufacturing Methods Thereof |
| US20200043978A1 (en) * | 2018-07-31 | 2020-02-06 | International Business Machines Corporation | Magnetic field controlled transistor |
| CN111495399A (en) * | 2020-05-08 | 2020-08-07 | 桂林理工大学 | S-doped WP2Nanosheet array electrocatalyst and preparation method thereof |
-
2020
- 2020-11-06 CN CN202011230950.5A patent/CN114438592B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020062858A1 (en) * | 1992-09-21 | 2002-05-30 | Thomas Mowles | High efficiency solar photovoltaic cells produced with inexpensive materials by processes suitable for large volume production |
| KR20150057239A (en) * | 2013-11-19 | 2015-05-28 | 한국전기연구원 | Anode Active Materials comprising Mo-Si-P Systems For Li Ion Batteries And Manufacturing Methods Thereof |
| US20200043978A1 (en) * | 2018-07-31 | 2020-02-06 | International Business Machines Corporation | Magnetic field controlled transistor |
| CN111495399A (en) * | 2020-05-08 | 2020-08-07 | 桂林理工大学 | S-doped WP2Nanosheet array electrocatalyst and preparation method thereof |
Non-Patent Citations (3)
| Title |
|---|
| AIFENG WANG ET AL.: "Magnetotransport properties of MoP2", 《PHYSICAL REVIEW》 * |
| MINGYU PI ET AL.: "Phase-controlled synthesis and comparative study of α- and β-WP2 submicron particles as efficient electrocatalysts for hydrogen evolution", 《ELECTROCHIMICA ACTA》 * |
| NITESH KUMAR ET AL.: "Extremely high magnetoresistance and conductivity in the type-II Weyl semimetals WP2 and MoP2", 《NATURE COMMUNICATIONS》 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114438592B (en) | 2022-11-22 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Zhang et al. | Pressure induced color change and evolution of metallic behavior in nitrogen-doped lutetium hydride | |
| Yamanaka et al. | Structure and superconductivity of the intercalation compounds of TiNCl with pyridine and alkali metals as intercalants | |
| CN114180970B (en) | Nitrogen-containing medium-entropy or high-entropy MAX phase material and preparation method and application thereof | |
| Moury et al. | Pressure-induced phase transitions in Na2B12H12, structural investigation on a candidate for solid-state electrolyte | |
| CN114180969A (en) | Preparation method and application of novel nitrogen-containing MAX phase material and two-dimensional material | |
| Niewa et al. | High-pressure high-temperature phase transition of γ′-Fe4N | |
| CN109678512B (en) | MAX phase conductive ceramic material and preparation method thereof | |
| CN114438592B (en) | Monoclinic system crystal form substance and preparation method thereof | |
| Htet et al. | Atomic structural mechanism for ferroelectric-antiferroelectric transformation in perovskite NaNbO 3 | |
| CN103911660B (en) | A kind of dilute magnetic semiconductor material and preparation method thereof | |
| Ma et al. | Investigation the origin and mechanical properties of unusual rigid diamond-like net analogues in manganese tetraboride | |
| Li et al. | Design and synthesis of three-dimensional hybrid Ruddlesden-Popper nickelate single crystals | |
| CN114197052B (en) | Orthorhombic crystal material and preparation method thereof | |
| Maruyama et al. | Electronic properties of black phosphorus single crystals and intercalation compounds. | |
| Ma | Reinvestigation of the olivine‐spinel transformation in Ni2SiO4 and the incongruent melting of Ni2SiO4 olivine | |
| Hu et al. | Pressure-induced phase transitions, amorphization and alloying in Sb 2 S 3 | |
| CN101608340B (en) | Iron-based high-temperature superconductive crystal and preparation method thereof | |
| Brown et al. | New Compounds In3Ti2AO10, In6Ti6BO22, and Their Solid Solutions (A: Al, Cr, Mn, Fe, or Ga; B: Mg, Mn, Co, Ni, Cu, or Zn): Synthesis and Crystal Structures | |
| JP2003095642A (en) | Magnesium borate and its manufacturing method | |
| Cheng et al. | Pressure-induced structural transitions, alloying and superconductivity in topological insulators Bi 2 Te 2 Se and Bi 2 Se 2 Te | |
| Binns et al. | Reactivity of lithium and platinum at elevated densities | |
| Amano et al. | Synthesis and crystal structure analysis of titanium bismuthide oxide, Ti8BiO7 | |
| Du et al. | Single crystal growth of MgB2 by using Mg-self-flux method at ambient pressure | |
| KR102639462B1 (en) | Hydride and manufacturing method for the same | |
| Cardoso-Gil et al. | Crystal structure, chemical bonding and magnetic properties of the new antimonides Ce2Ir3Sb4, La2Ir3Sb4, and Ce2Rh3Sb4 |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |