CN109516444B - Preparation method of tungsten ditelluride - Google Patents

Abstract

The invention discloses a preparation method of tungsten ditelluride, which comprises: a tungsten raw material liquid composed of a first solvent with complexation effect and a tungsten raw material and a tellurium raw material liquid composed of a second solvent with reducing effect and a tellurium raw material After mixing evenly, react at high temperature under the protection of inert gas, and obtain after cooling; the tungsten raw material is tungsten hexachloride and/or tungsten powder, the first solvent is ethylenediamine, and the tellurium raw material is tellurium powder and/or tellurium dioxide, The second solvent is ethylenediamine and/or hydrazine hydrate. The present invention provides a preparation method of tungsten ditelluride which adopts new raw materials and has a milder preparation process, which effectively overcomes the defects of high energy consumption and long time in the preparation method in the prior art, and the equipment of the preparation method of the present invention And the instrument is simple and common, and has important promotion value; the product of the invention has good crystallinity, large yield, high purity, and has great theoretical and practical significance.

Description

A kind of preparation method of tungsten ditelluride

technical field

The invention belongs to the technical field of preparation of non-magnetic semi-metal materials, relates to a preparation method of transition metal chalcogenide compounds, and in particular relates to a preparation method of tungsten ditelluride.

Background technique

Transition-metal Dichalcogenides (TMDCs) are typical graphene-like layered materials, usually denoted as MX ₂ (M represents a transition metal, X represents a chalcogen) , Tungsten ditelluride is one of them.

The focus of tungsten ditelluride is that in 2014, the research group of Princeton University professor R.J. Cava discovered its large magnetoresistance effect (LMR) at atmospheric pressure and low temperature, and it is still unsaturated under extremely high external magnetic field. In 2015, Lv H Y et al. calculated the electronic structure of tungsten ditelluride through first-principles, and confirmed the existence of perfect electron-hole compensation in tungsten ditelluride material; in the same year, researchers from the Institute of Physics, Chinese Academy of Sciences The superconductivity of tungsten ditelluride was explored.

The exploration and research on the thermoelectric properties, giant magnetoresistance effect and superconductivity of tungsten ditelluride have been ongoing. However, for the preparation process of tungsten ditelluride, it is mainly synthesized in laboratory conditions, including chemical vapor phase. Deposition method, high temperature and high pressure method and chemical vapor transport method purification, etc., but only thin film products can be prepared, or the size of single crystal samples is basically only 1.5mm*0.7mm*0.02mm, and the reaction holding time is one to two weeks. It can even take up to three months to grow tungsten ditelluride. At the same time, the above method may also prepare a mixed product doped with tellurium tetrachloride impurities, which needs to be processed by impurity removal and repurification.

So far, there is no relevant report on the method for the rapid and large-scale preparation of tungsten ditelluride.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a milder preparation method of tungsten ditelluride, which is suitable for the future two The application of tungsten telluride in the rapid and mass production of electromagnetic components provides some possible references.

The present invention adopts following technical scheme:

A method for preparing tungsten ditelluride, comprising: after uniformly mixing a tungsten raw material solution composed of a first solvent with complexation and a tungsten raw material and a tellurium raw material solution composed of a second solvent with reducing action and a tellurium raw material, It is reacted at high temperature under the protection of inert gas and obtained after cooling.

In the above technical solution, the tungsten raw material is tungsten hexachloride and/or tungsten powder, and the purity is greater than or equal to 99.5%.

In the above technical solution, the tellurium raw material is tellurium powder and/or tellurium dioxide, and the purity is greater than or equal to 99.95%.

In the above technical solution, the first solvent is ethylenediamine, and the purity is greater than or equal to 99.5%.

In the above technical solution, the second solvent is ethylenediamine and/or hydrazine hydrate, and the purity is greater than or equal to 99.5%.

Further, in the above technical solution, in the tungsten raw material solution, the ratio of the tungsten raw material to the first solvent is 1 g: 12-18 ml.

Further, in the above technical solution, in the tellurium raw material solution, the material-to-liquid ratio of the tellurium raw material to the second solvent is 1g:6-15ml.

In the above technical solution, the inert gas is argon or nitrogen.

Preferably, in the above technical solution, the purity of the inert gas is greater than or equal to 99.99%, and the flow rate of the inert gas is 10-400 SCCM.

In the above technical solution, the reaction temperature and reaction time of the high temperature reaction are respectively 750-850° C. and 10-20 h.

Further, in the above technical solution, the preparation method further includes, before the high temperature reaction, centrifuging the uniformly mixed tungsten raw material liquid and the tellurium raw material liquid, and then placing them in a vacuum drying box for low-temperature drying.

Still further, in the above technical solution, the centrifugal rotation speed of the centrifugal separation is 3000-4500 rpm, and the centrifugal time is 3-5 min.

Still further, in the above technical solution, the drying temperature of the low-temperature drying is 29-55° C., and the drying time is 4.5-8.5 h.

Still further, in the above technical solution, the high temperature reaction process also includes an operation of opening the closed furnace tube of the atmosphere furnace, specifically, introducing an inert gas at 120-205 ° C, and using a method of loosening the rubber tube. Open the air outlet by means of the method, keep it for 5-20min, do not pass inert gas, resume the closed operation, and then pass in the inert gas at 320-410 ℃, and then open the air outlet by loosening the rubber tube, keep it for 5-20min, do not let in Inert gas, resume closed operation.

Still further, in the above-mentioned technical scheme, the preparation method comprises the following steps:

S1, the first solvent with complexation is added dropwise to the tungsten raw material, the tungsten raw material solution is obtained after mixing, the second solvent with reducing action is added dropwise to the tellurium raw material, and the tellurium raw material is obtained after mixing liquid;

S2, the tungsten raw material liquid and the tellurium raw material liquid in step S1 are mixed uniformly and centrifuged to obtain a reaction mixture, which is then placed in a vacuum drying oven for low-temperature drying;

S3. The oven-dried reaction mixture in step S2 is placed in an atmosphere furnace, reacted at a high temperature in an inert atmosphere, and obtained after cooling.

Compared with the prior art, the beneficial effects of the present invention are as follows:

(1) the present invention provides a kind of preparation method of tungsten ditelluride which adopts new raw material and the preparation process is milder, effectively overcomes the defects of high energy consumption and long time of the preparation method in the prior art, and the preparation method of the present invention The equipment and instruments are simple and common, and have important promotion value;

(2) The tungsten ditelluride product prepared by the preparation method provided by the present invention has good crystallinity, large yield, high purity and no doping of other elements, and does not require a series of steps such as water washing and alcohol washing, which is suitable for mass production. High-quality thermoelectric properties, giant magnetoresistance effect, and superconductive tungsten ditelluride materials provide theoretical references.

Description of drawings

Fig. 1 is the X-ray diffraction pattern of self-doping non-stoichiometric tungsten ditelluride prepared in Example 1-3 of the present invention;

FIG. 2 is the Raman spectrum of the pure phase tungsten ditelluride in the stoichiometric ratio prepared in Example 2 of the present invention.

Detailed ways

In order to facilitate the understanding of the present invention, the preparation method of tungsten ditelluride of the present invention will be described in a more comprehensive and detailed manner below with reference to the accompanying drawings and examples.

Preferred embodiments of the present invention are shown in the accompanying drawings; however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein; rather, these embodiments are provided for the purpose of This is to make the understanding of the disclosure of the present invention more thorough and complete.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The raw materials and related experimental equipment used in the examples and comparative examples of the present invention are all commercially available products.

Example 1

The embodiment of the present invention provides a preparation method of tungsten ditelluride, which specifically includes the following steps:

S1. Place 1.19g of tungsten hexachloride in a 50ml beaker, add 15ml of ethylenediamine dropwise to the beaker, stir for 30min, mix well to obtain a tungsten raw material solution; add 15ml of ethylenediamine dropwise to the beaker containing 1.952 In a beaker of g tellurium powder, stir for 30 minutes, and mix well to obtain a tellurium raw material solution.

S2. Mix the tungsten raw material solution and the tellurium raw material solution in step S1 evenly (the raw material molar ratio of tungsten and tellurium is 1:2.55), stir for 30 min, transfer to a 50 ml centrifuge tube, centrifuge at 4000 rpm for 5 min, and put into vacuum drying Dry in a box at 30°C for 7h.

S3. Transfer the dried reaction mixture in step S2 to a corundum crucible, cover it, put it into a tube furnace, pass 400SCCM nitrogen to clean the furnace tube, evacuate to 0.10MPa, pass 80SCCM nitrogen, and the pressure is normal At atmospheric pressure, after sealing the furnace tube, stop feeding nitrogen, raise the temperature to 150 °C, continue feeding nitrogen and open the gas outlet, then close the furnace tube, close the gas valve, heat up to 360 °C, pass nitrogen, and open the furnace tube, Continue to introduce nitrogen gas and seal the furnace tube, raise the temperature to 800°C, keep the temperature for 12 hours, stop heating, turn off nitrogen, and cool the crucible to room temperature with the furnace, thus preparing the powder material of tungsten ditelluride with giant magnetoresistive properties.

Example 2

The embodiment of the present invention provides a preparation method of tungsten ditelluride, which specifically includes the following steps:

S1. Place 1.19g of tungsten hexachloride in a 50ml beaker, add 15ml of ethylenediamine dropwise to the beaker, stir for 30min, and mix well to obtain a tungsten raw material solution; add 15ml of ethylenediamine dropwise to the beaker containing 2.297 In a beaker of g tellurium powder, stir for 30 minutes, and mix well to obtain a tellurium raw material solution.

S2. Mix the tungsten raw material solution and the tellurium raw material solution in step S1 evenly (the raw material molar ratio of tungsten and tellurium is 1:3.00), stir for 30min, transfer to a 50ml centrifuge tube, centrifuge at 3500rpm for 5min, put into vacuum drying Dry in a box at 30°C for 7h.

S3. Transfer the dried reaction mixture in step S2 to a corundum crucible, cover it, put it into a tube furnace, pass 400SCCM nitrogen to clean the furnace tube, evacuate to 0.10MPa, pass 80SCCM nitrogen, and the pressure is normal At atmospheric pressure, after sealing the furnace tube, stop feeding nitrogen, raise the temperature to 150 °C, continue feeding nitrogen and open the gas outlet, then close the furnace tube, close the gas valve, heat up to 360 °C, pass nitrogen, and open the furnace tube, Continue to introduce nitrogen gas and seal the furnace tube, heat up to 800°C, keep the temperature for 12 hours, stop heating, turn off nitrogen, and cool the crucible to room temperature with the furnace to prepare the powder material of tungsten ditelluride with giant magnetoresistive properties.

Example 3

The embodiment of the present invention provides a preparation method of tungsten ditelluride, which specifically includes the following steps:

S1. Place 1.19g of tungsten hexachloride in a 50ml beaker, add 15ml of ethylenediamine dropwise to the beaker, stir for 30min, and mix well to obtain a tungsten raw material solution; add 15ml of ethylenediamine dropwise to the beaker containing 2.641 In a beaker of g tellurium powder, stir for 30 minutes, and mix well to obtain a tellurium raw material solution.

S2, mix the tungsten raw material liquid and the tellurium raw material liquid in step S1 evenly (the raw material molar ratio of tungsten and tellurium is 1:3.45), stir for 30min, transfer to a 50ml centrifuge tube, centrifuge at 4200rpm for 5min, put into vacuum drying Dry in a box at 30°C for 7h.

S3. Transfer the dried reaction mixture in step S2 to a corundum crucible, cover it, put it into a tube furnace, pass 400SCCM nitrogen to clean the furnace tube, evacuate to 0.10MPa, pass 80SCCM nitrogen, and the pressure is normal At atmospheric pressure, after sealing the furnace tube, stop feeding nitrogen, raise the temperature to 150 °C, continue feeding nitrogen and open the gas outlet, then close the furnace tube, close the gas valve, heat up to 360 °C, pass nitrogen, and open the furnace tube, Continue to introduce nitrogen gas and seal the furnace tube, raise the temperature to 800°C, keep the temperature for 12 hours, stop heating, turn off nitrogen, and cool the crucible to room temperature with the furnace, thus preparing the powder material of tungsten ditelluride with giant magnetoresistive properties.

Example 4

The embodiment of the present invention provides a preparation method of tungsten ditelluride, which specifically includes the following steps:

S1. Place 2.38g of tungsten hexachloride in a 50ml beaker, add 20ml of ethylenediamine dropwise to the beaker, stir for 60min, and mix evenly to obtain a tungsten raw material solution; In a beaker of g tellurium powder, stir for 60 min, and mix evenly to obtain a tellurium raw material solution.

S2. Mix the tungsten raw material solution and the tellurium raw material solution in step S1 evenly, stir for 60 min, transfer to a 100 ml centrifuge tube, centrifuge at 4000 rpm for 5 min, and put it into a vacuum drying box for drying at 50° C. for 6 h.

S3. Transfer the dried reaction mixture in step S2 to a corundum crucible, cover it, put it into a tube furnace, pass 400SCCM argon to clean the furnace tube, evacuate to 0.10MPa, pass 80SCCM argon, pressure When it is at normal atmospheric pressure, after sealing the furnace tube, stop feeding argon gas, heat up to 160 °C, continue feeding argon gas and open the gas outlet, then close the furnace tube, close the gas valve, heat up to 400 °C, and pass argon gas, After opening the furnace tube, continue to pass argon gas and seal the furnace tube, heat up to 800 ° C, keep the temperature for 16 hours, stop heating, turn off the argon gas, and cool the crucible to room temperature with the furnace, that is, tungsten ditelluride with giant magnetoresistance properties is prepared. powder material.

Example 5

The embodiment of the present invention provides a preparation method of tungsten ditelluride, which specifically includes the following steps:

S1. Place 3.97g of tungsten powder in a 50ml beaker, add 20ml of ethylenediamine dropwise to the beaker, stir for 75min, and mix evenly to obtain a tungsten raw material solution; add 20ml of ethylenediamine dropwise to the beaker containing 4.79g In the beaker of tellurium oxide, stir for 75 minutes, and mix well to obtain the tellurium raw material solution.

S2. Mix the tungsten raw material solution and the tellurium raw material solution in step S1 evenly, stir for 75 min, transfer to a 100 ml centrifuge tube, centrifuge at 4000 rpm for 5 min, and put it into a vacuum drying box for drying at 55° C. for 4.5 h.

S3. Transfer the dried reaction mixture in step S2 to a corundum crucible, cover it, put it into a tube furnace, pass 400SCCM argon to clean the furnace tube, evacuate to 0.10MPa, pass 80SCCM argon, pressure When it is normal atmospheric pressure, after sealing the furnace tube, stop feeding argon gas, raise the temperature to 180 °C, continue feeding argon gas and open the gas outlet, then close the furnace tube, close the gas valve, heat up to 410 °C, and pass argon gas, After opening the furnace tube, continue to pass argon gas and seal the furnace tube, heat up to 800 ° C, keep the temperature for 16 hours, stop heating, turn off the argon gas, and cool the crucible to room temperature with the furnace, that is, tungsten ditelluride with giant magnetoresistance properties is prepared. powder material.

In the present invention, the tungsten ditelluride powder material is a transition group metal compound formed by tungsten and tellurium in a chemical element ratio of 1:2, wherein tungsten has a valence of +4, and tellurium has a valence of -2.

Figure 1 shows the X-ray diffraction pattern of the self-doped non-stoichiometric tungsten ditelluride prepared in Examples 1-3 of the present invention. The stoichiometric tungsten ditelluride sample, the pure-phase tungsten ditelluride sample in Example 2, and the non-stoichiometric tellurium-doped tungsten ditelluride sample in Example 3, the non-stoichiometric tungsten-doped tungsten sample in Example 1 The small font in the XRD pattern of the tungsten ditelluride sample corresponds to the diffraction peak of tungsten, and the small font in the XRD pattern of the tellurium-doped non-stoichiometric tungsten ditelluride sample in Example 3 is marked with a small font The diffraction peaks corresponding to tellurium shown, the diffraction peaks corresponding to tungsten ditelluride marked in large fonts in the X-ray diffraction pattern, compared with the standard atlas, it is found that the prepared tungsten ditelluride is [002] orientation tungsten ditelluride material.

FIG. 2 shows the Raman spectrum of the pure phase tungsten ditelluride in the stoichiometric ratio prepared in Example 2 of the present invention when the laser is excited along the b-axis direction.

Finally, the above are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A method for preparing tungsten ditelluride, which is characterized by comprising the following steps: uniformly mixing a tungsten raw material solution consisting of a first solvent with a complexing effect and a tungsten raw material with a tellurium raw material solution consisting of a second solvent with a reducing effect and a tellurium raw material, centrifugally separating, drying at a low temperature in a vacuum drying oven, reacting for 10-20h at the temperature of 750-850 ℃ under the protection of inert gas, and cooling to obtain the complex compound;

the first solvent is ethylenediamine, the tungsten raw material is tungsten hexachloride and/or tungsten powder, the second solvent is ethylenediamine and/or hydrazine hydrate, and the tellurium raw material is tellurium powder and/or tellurium dioxide.

2. The production method according to claim 1,

the purity of the tungsten raw material is more than or equal to 99.5 percent;

and/or the purity of the tellurium raw material is more than or equal to 99.95 percent.

3. The production method according to claim 1,

the purity of the first solvent is more than or equal to 99.5%;

and/or the purity of the second solvent is greater than or equal to 99.5%.

4. The production method according to claim 1,

in the tungsten raw material liquid, the material-liquid ratio of the tungsten raw material to the first solvent is 1 g: 12-18 ml;

and/or in the tellurium raw material liquid, the material-liquid ratio of the tellurium raw material to the second solvent is 1 g: 6-15 ml.

5. The production method according to claim 1,

the inert gas is argon or nitrogen.

6. The production method according to claim 5,

the purity of the inert gas is more than or equal to 99.99 percent, and the flow rate of the inert gas is 10-400 SCCM.

7. The method for preparing the compound of claim 1, wherein the centrifugation speed is 3000-4500rpm, and the centrifugation time is 3-5 min.

8. The preparation method according to claim 1, wherein the drying temperature of the low-temperature drying is 29-55 ℃, and the drying time is 4.5-8.5 h.

9. The preparation method according to any one of claims 1 to 6, wherein the high temperature reaction process further comprises closing the furnace tube opening operation of the atmosphere furnace, specifically, introducing inert gas at 120 to 205 ℃, opening the gas outlet by loosening the rubber tube, keeping for 5 to 20min, not introducing inert gas, recovering the closing operation, introducing inert gas at 320 to 410 ℃, opening the gas outlet by loosening the rubber tube, keeping for 5 to 20min, not introducing inert gas, and recovering the closing operation.

10. The method for preparing a polymer according to any one of claims 1 to 6, comprising the steps of:

s1, dropwise adding a first solvent with a complexing effect into a tungsten raw material, uniformly mixing to obtain a tungsten raw material solution, simultaneously dropwise adding a second solvent with a reducing effect into a tellurium raw material, and uniformly mixing to obtain a tellurium raw material solution;

s2, uniformly mixing the tungsten raw material liquid and the tellurium raw material liquid in the step S1, performing centrifugal separation to obtain a reaction mixture, and then placing the reaction mixture in a vacuum drying oven for low-temperature drying;

s3, placing the dried reaction mixture in the step S2 in an atmosphere furnace, reacting at high temperature in an inert atmosphere, and cooling to obtain the catalyst.

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