Preparation method of 1T '-MoTe2 single crystal
The preparation of 1T'-MoTe2 single crystals by chemical vapor transport method solves the problems of complex preparation, serious pollution and high cost in the existing technology, and realizes the preparation of high-quality single crystals with high efficiency and low cost.
Patent Information
- Application Number
- CN202511925903.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-19
- Publication Date
- 2026-02-24
AI Technical Summary
Existing technologies are difficult to efficiently prepare high-quality 1T'-MoTe2 single crystals, and the preparation process is complex, polluting, costly, and yields few samples.
The chemical vapor transport method was adopted. The molybdenum powder and tellurium powder were weighed and mixed and ground in stoichiometric ratio. The mixture was then sealed in a quartz tube under vacuum and inert atmosphere, heated with an oxyhydrogen flame torch and sintered in a high-temperature box furnace. Subsequently, the mixture was transported in a multi-temperature zone tube furnace to obtain 1T'-MoTe2 single crystal.
The preparation process was simplified, the cycle was shortened, pollution was reduced, sample quality and yield were improved, costs were reduced, and high-purity 1T'-MoTe2 single crystals were obtained.
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Figure CN121556149A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of single crystal material preparation methods, specifically relating to a method for preparing 1T'-MoTe2 single crystal. Background Technology
[0002] MoTe2 commonly has three structures: 2H structure, 1T' structure, and T... d Structure. The most common structure of MoTe2 is 2H, which is a semiconductor phase and belongs to the hexagonal crystal system, with Mo and Te atoms coordinated in a trigonal prism configuration. T stands for Trigonal, and the 1T' structure represents a structural distortion within the atomic stacking of a single layer. The originally regular octahedral coordination is slightly distorted, forming a mixed coordination of distorted octahedral or trigonal prisms. Under high temperatures, the 2H structure of MoTe2 transforms into the 1T' structure. The 1T' structure of MoTe2 is monoclinic and remains stable above 900°C. It can be stabilized at room temperature through rapid cooling, controlling the tellurization rate of the Mo film, or relying on film stress stretching, exhibiting a half-metallic phase. Using a standard 1:2 ratio of molybdenum powder to tellurium powder for chemical vapor transport growth, it is difficult to directly grow 1T' structure MoTe2 single crystals, resulting in poor quality and a small number of single crystal samples. Summary of the Invention
[0003] Objective: In view of the above problems, this invention provides a method for preparing 1T'-MoTe2 single crystals. This method simplifies the preparation process, shortens the preparation cycle, reduces pollution generated during preparation, improves preparation efficiency, enhances sample quality, and is also low in cost and uses safe and non-toxic raw materials.
[0004] Technical Solution: To achieve the above-mentioned objectives, this invention proposes a method for preparing 1T'-MoTe2 single crystals, which includes the following steps:
[0005] A. Weigh the molybdenum powder and tellurium powder according to a stoichiometric ratio of 1:(0.8-1.2);
[0006] B. Pour the powder weighed in step A into a mortar and mix and grind it evenly for 20 to 30 minutes.
[0007] C. Pour the alloy powder that has been ground in step B into the corundum crucible;
[0008] D. Place the corundum crucible from step C into the S1 quartz glass tube;
[0009] E. Seal the S1 quartz glass tube in step D with a quartz glass stopper;
[0010] F. Use a mechanical vacuum pump to evacuate the S1 quartz glass tube, then fill it with inert argon gas, and evacuate it again to make the gas pressure inside the S1 quartz tube lower than the predetermined value. Repeat the gas purging step three times and then evacuate it again to make the gas pressure inside the S1 quartz tube lower than the predetermined value.
[0011] G. Use an oxyhydrogen flame torch to heat the S1 quartz glass tube wall and the quartz glass stopper together, then cool and solidify them into a whole to complete the vacuum seal;
[0012] H. Place the quartz glass tube from step G into a high-temperature box furnace. After sintering through a heating process, remove it and place it in water for cooling and quenching. Then, remove the corundum crucible from the S1 quartz tube to obtain polycrystalline solids.
[0013] I. Weigh out the polycrystalline powder block, grind it, and put it into the S2 quartz glass tube along with the iodine particles. Repeat step F to complete the sealing.
[0014] J. Place the S2 quartz glass tube into a tube furnace with multiple temperature zones for heating and cooling treatment using a preset temperature gradient.
[0015] K. Obtain the desired 1T'-MoTe2 single crystal sample from the S2 quartz tube.
[0016] Furthermore, steps A, B, C, D, and E are all carried out in a glove box filled with an inert argon atmosphere.
[0017] Furthermore, in step F, the predetermined value is 10. -2 Pa.
[0018] Furthermore, the melting temperature in step G is 2000-3000°C.
[0019] Furthermore, the heating procedure in step H is as follows: raise the temperature from room temperature to 350°C in 5 hours and hold for 6 hours; raise the temperature from 350°C to 1100°C in 11 hours and hold for 12 hours.
[0020] Furthermore, the cooling process in step H is as follows: after 18 hours, the temperature drops from 1100 degrees to 900 degrees.
[0021] Furthermore, step H yields a MoTe2 polycrystalline block.
[0022] Furthermore, in step I, the polycrystalline block is 2-3g and the iodine particles are 0.1-0.3g.
[0023] Furthermore, in step J, the high-temperature zone program is as follows: the temperature is raised from room temperature to 1000°C over 16 hours and maintained for 168 hours; the low-temperature zone program is as follows: the temperature is raised from room temperature to 950°C over 16 hours and maintained for 168 hours.
[0024] Furthermore, the cooling procedure after heating in step J is as follows: the temperature in both temperature zones is simultaneously reduced to 725°C over 5 hours, then further reduced to 450°C over another 5 hours, held at that temperature for 24 hours, and the program ends.
[0025] Beneficial effects: Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:
[0026] (1) The present invention eliminates the need for quenching when transporting and growing 1T'-MoTe2, which is simpler and safer than the previous quenching scheme.
[0027] (2) When preparing 1T'-MoTe2 single crystals, the sample yield obtained by the present invention is higher than that obtained by the traditional method.
[0028] (3) When preparing 1T'-MoTe2 single crystals, the purity of the samples obtained by the present invention is higher than that obtained by traditional methods, and high-purity samples that are difficult to obtain in the past can be obtained. Attached Figure Description
[0029] Figure 1 The XRD pattern of this sample corresponds to the standard PDF card #15-0658. The 2-Theta angles of 12.54°, 25.25°, 39.13°, 53.03°, and 67.84° correspond to the (002), (004), (006), (008), and (0010) crystal planes of MoTe2, which belong to the same zone axis
[002] diffraction peaks. Therefore, it can be confirmed that the grown MoTe2 single crystal is a single crystal.
[0030] Figure 2 The Raman characterization diagram of this sample is shown in the figure at 108 cm⁻¹. -1 The location is in Bg vibration mode, 112cm. -1 The location is in Ag vibration mode, 130cm. -1 The location is in Ag vibration mode, 164cm. -1 The location is in Ag vibration mode, 193cm. -1 The location is in Bg vibration mode, 261cm. -1 The location is in Ag vibration mode, which proves 1T'-MoTe2. Detailed Implementation
[0031] This invention proposes a method for preparing 1T'-MoTe2 single crystals, which includes the following steps:
[0032] A. Weigh the molybdenum powder and tellurium powder according to a stoichiometric ratio of 1:(0.8-1.2);
[0033] B. Pour the powder weighed in step A into a mortar and mix and grind it evenly for 20 to 30 minutes.
[0034] C. Pour the alloy powder that has been ground in step B into the corundum crucible;
[0035] D. Place the corundum crucible from step C into the S1 quartz glass tube;
[0036] E. Seal the S1 quartz glass tube in step D with a quartz glass stopper;
[0037] F. Use a mechanical vacuum pump to evacuate the S1 quartz glass tube, then fill it with inert argon gas, and evacuate it again to make the gas pressure inside the S1 quartz tube lower than the predetermined value. Repeat the gas purging step three times and then evacuate it again to make the gas pressure inside the S1 quartz tube lower than the predetermined value.
[0038] G. Use an oxyhydrogen flame torch to heat the S1 quartz glass tube wall and the quartz glass stopper together, then cool and solidify them into a whole to complete the vacuum seal;
[0039] H. Place the quartz glass tube from step G into a high-temperature box furnace. After sintering through a heating process, remove it and place it in water for cooling and quenching. Then, remove the corundum crucible from the S1 quartz tube to obtain polycrystalline solids.
[0040] I. Weigh out the polycrystalline powder block, grind it, and put it into the S2 quartz glass tube along with the iodine particles. Repeat step F to complete the sealing.
[0041] J. Place the S2 quartz glass tube into a tube furnace with multiple temperature zones for heating and cooling treatment using a preset temperature gradient.
[0042] K. Obtain the required 1T'-MoTe2 single crystal sample from the S2 quartz tube.
[0043] Furthermore, steps A, B, C, D, and E must be performed in a glove box under an argon atmosphere.
[0044] The corundum crucible in step C has a length of 57 mm, an outer diameter of 15.4 mm, and an inner diameter of 12.5 mm.
[0045] The S1 quartz glass tube in step D has a length of 200mm, an outer diameter of 30.3mm, and an inner diameter of 26mm.
[0046] The quartz glass stopper in step E has a height of 20 mm and a diameter of 25 mm.
[0047] The gas purging process in step F involves purging the S2 quartz tube three times with argon gas to remove air; finally, it is evacuated to 10°C. -2 Below Pa;
[0048] In step G, when heating and fusing the S1 quartz glass tube wall and the quartz glass plug with an oxyhydrogen flame torch, the S1 quartz tube is kept rotating at a certain speed.
[0049] In step H, the heating process involves raising the temperature from room temperature to 350°C over 5 hours and holding it at that temperature for 6 hours; then raising the temperature from 350°C to 1100°C over 11 hours and holding it at that temperature for 12 hours.
[0050] In step H, the cooling process involves reducing the temperature from 1100°C to 900°C over 18 hours.
[0051] The final sample obtained in step H is a polycrystalline bulk MoTe2.
[0052] In step I, the mass of the polycrystalline powder is 2.0 g, and the mass of iodine is 0.28358 g.
[0053] The S2 quartz glass tube in step I has a length of 340 mm, an outer diameter of 20 mm, and an inner diameter of 17 mm.
[0054] In step J, when placing the S2 quartz glass tube into the dual-temperature zone tube furnace, the low-temperature zone section needs to be slightly raised to facilitate gas phase transport. The top of the quartz tube is located in the low-temperature zone, and the bottom is located in the high-temperature zone. Furthermore, the sintering process in step J is divided into a high-temperature zone and a low-temperature zone. The high-temperature zone program is as follows: the temperature is raised from room temperature to 1000°C over 16 hours and held for 168 hours. The low-temperature zone program is as follows: the temperature is raised from room temperature to 950°C over 16 hours and held for 168 hours.
[0055] The cooling procedure in step J is as follows: the temperature in both temperature zones is simultaneously reduced to 725°C over 5 hours, then further reduced to 450°C over another 5 hours, held at that temperature for 24 hours, and then the procedure is terminated.
[0056] As shown in Table 1 below, the elemental composition of the target material consists of Mo and Te elements. The mass percentage of Mo is 27.37% and the atomic percentage is 33.39%, while the mass percentage of Te is 72.63% and the atomic percentage is 66.61%. The total mass percentage of the elements is 100.00%, which reflects the elemental composition ratio of the material.
[0057] Table 1
[0058]
[0059] The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Anyone can make changes or adjustments to the technical content and parameters mentioned in the present invention under the guidance of the present invention. Therefore, any additional changes or modifications made without departing from the essence and principle of the present invention shall fall within the protection scope of the present invention.
Claims
1. A method for preparing 1T'-MoTe2 single crystal, characterized in that, The method includes the following steps: A. Weigh the molybdenum powder and tellurium powder according to a stoichiometric ratio of 1:(0.8-1.2); B. Pour the powder weighed in step A into a mortar and mix and grind it evenly for 20 to 30 minutes. C. Pour the alloy powder that has been ground in step B into the corundum crucible; D. Place the corundum crucible from step C into the S1 quartz glass tube; E. Seal the S1 quartz glass tube in step D with a quartz glass stopper; F. Use a mechanical vacuum pump to evacuate the S1 quartz glass tube, then fill it with inert argon gas, and evacuate it again to make the gas pressure inside the S1 quartz tube lower than the predetermined value. Repeat the gas purging step three times and then evacuate it again to make the gas pressure inside the S1 quartz tube lower than the predetermined value. G. Use an oxyhydrogen flame torch to heat the S1 quartz glass tube wall and the quartz glass stopper together, then cool and solidify them into a whole to complete the vacuum seal; H. Place the quartz glass tube from step G into a high-temperature box furnace. After sintering through a heating process, remove it and place it in water for cooling and quenching. Then, remove the corundum crucible from the S1 quartz tube to obtain polycrystalline solids. I. Weigh out the polycrystalline powder block, grind it, and put it into the S2 quartz glass tube along with the iodine particles. Repeat step F to complete the sealing. J. Place the S2 quartz glass tube into a tube furnace with multiple temperature zones for heating and cooling treatment using a preset temperature gradient. K. Take out the required 1T'-MoTe2 single crystal sample from the S2 quartz tube.
2. The method for preparing 1T'-MoTe2 single crystal according to claim 1, characterized in that steps A, B, C, D, and E are all carried out in a glove box filled with an inert argon atmosphere.
3. The method for preparing 1T'-MoTe2 single crystal according to claim 1, characterized in that, In step F, the predetermined value is 10. -2 Pa.
4. The method for preparing 1T'-MoTe2 single crystal according to claim 1, characterized in that, The melting temperature in step G is 2000-3000°C.
5. The method for preparing 1T'-MoTe2 single crystal according to claim 1, characterized in that, The heating procedure in step H is as follows: raise the temperature from room temperature to 350°C in 5 hours and keep it at that temperature for 6 hours; raise the temperature from 350°C to 1100°C in 11 hours and keep it at that temperature for 12 hours.
6. The method for preparing 1T'-MoTe2 single crystal according to claim 1, characterized in that, The cooling process in step H is as follows: after 18 hours, the temperature drops from 1100 degrees to 900 degrees.
7. The method for preparing 1T'-MoTe2 single crystal according to claim 1, characterized in that, In step H, a MoTe2 polycrystalline block is obtained.
8. The method for preparing 1T'-MoTe2 single crystal according to claim 1, characterized in that, In step I, the polycrystalline block is 2-3g and the iodine particles are 0.1-0.3g.
9. The method for preparing 1T'-MoTe2 single crystal according to claim 1, characterized in that, In step J, the high-temperature zone program is as follows: the temperature is raised from room temperature to 1000°C over 16 hours and maintained for 168 hours; the low-temperature zone program is as follows: the temperature is raised from room temperature to 950°C over 16 hours and maintained for 168 hours.
10. The method for preparing 1T'-MoTe2 single crystal according to claim 1, characterized in that, The cooling procedure after heating in step J is as follows: the temperature is simultaneously reduced to 725°C in both temperature zones for 5 hours, then further reduced to 450°C for another 5 hours, held at that temperature for 24 hours, and the program ends.