A method for inducing superconducting-insulator phase transition in two-dimensional Mo2C by rare earth element doping

Abstract

The application discloses a method for inducing two-dimensional Mo2C to occur superconductor-insulator phase transition by doping rare earth elements, and the method comprises the following steps: 1, weighing Mo2C powder and hydrated nitrate containing rare earth elements in a glove box under the protection of inert atmosphere; 2, putting the Mo2C powder and the hydrated nitrate containing rare earth elements into a polytetrafluoroethylene lining of a hydrothermal reaction kettle, and adding deionized water to form a mixed solution; 3, carrying out hydrothermal reaction after sealing; 4, separating the reaction product, and obtaining the rare earth element doped Mo2C material through washing and vacuum drying. The hydrothermal synthesis method is adopted, in-situ ion exchange and doping are carried out in the hydrothermal reaction process, the rare earth elements enter the Mo2C crystal lattice uniformly at the atomic level, the Mo2C material doped with the rare earth elements uniformly is prepared, the phase transition of the Mo2C material from a superconductor to an insulator is realized, and the method is simple in operation, mild in condition and low in cost.

Description

Technical Field

[0001] This invention belongs to the field of two-dimensional material interlayer spacing control technology, specifically relating to a method for inducing a superconducting-insulator phase transition in two-dimensional Mo2C by rare earth element doping. Background Technology

[0002] Two-dimensional transition metal carbides (TMCs) have shown broad application prospects in hard coatings, catalysis, and energy storage due to their high hardness, high melting point, and excellent chemical stability. Among them, molybdenum carbide (Mo2C), a typical TMC, has recently been found to possess superconducting properties at low temperatures, making it a potential research material in superconducting electronic devices and quantum computing. Effectively controlling the electrical properties of these materials is key to expanding their application range and achieving functionalization.

[0003] Currently, methods for modifying the electrical properties of Mo2C materials mainly include elemental doping, morphology control, and defect engineering. Elemental doping is an effective means of inducing changes in the electronic structure of materials, thereby altering their electrical transport behavior. However, existing methods for doping modification of Mo2C are mostly limited to physical mixing, high-temperature solid-state reactions, or chemical vapor deposition. These methods typically suffer from problems such as complex processes, high equipment requirements, high energy consumption, and difficulty in controlling doping uniformity. In particular, achieving a continuous and controllable phase transition from a superconducting state to an insulating state is often difficult to achieve using conventional methods. Therefore, achieving precise and efficient control of the superconducting properties of Mo2C through a simple and mild chemical method remains a challenge for those skilled in the art.

[0004] Hydrothermal synthesis, as a liquid-phase chemical synthesis technique, has advantages such as low reaction temperature, simple operation, and good product uniformity, and has been widely used in the preparation of various nanomaterials. However, research on in-situ doping of synthesized Mo2C using hydrothermal methods to induce a significant superconductor-to-insulator transformation has not been reported. Therefore, developing a novel doping method that is simple, low-cost, produces uniform doping, and can effectively control the superconducting properties of Mo2C has significant scientific and practical application value. Summary of the Invention

[0005] The technical problem this invention aims to solve is to address the shortcomings of the prior art by providing a method for inducing a superconducting-insulator phase transition in two-dimensional Mo2C through rare-earth element doping. This method employs a hydrothermal synthesis approach, utilizing in-situ ion exchange and doping during the hydrothermal reaction process to allow rare-earth elements to uniformly enter the Mo2C lattice at the atomic level, thus preparing a uniformly doped Mo2C material. This achieves a phase transition from superconductor to insulator in Mo2C, solving the problem in existing technologies where it is difficult to induce a significant superconductor-insulator transformation in Mo2C. To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a method for inducing a superconducting-insulator phase transition in two-dimensional Mo2C by rare earth element doping, characterized in that the method includes the following steps: Step 1: Weigh Mo2C powder and hydrated nitrate containing rare earth elements separately in a glove box under an inert atmosphere according to the designed molar ratio. Step 2: Place the Mo2C powder weighed in Step 1 and the hydrated nitrate containing rare earth elements into the polytetrafluoroethylene liner of the hydrothermal reactor, add deionized water and stir continuously until the hydrated nitrate is completely dissolved to form a mixed solution. Step 3: After sealing the hydrothermal reactor containing the mixed solution from Step 2, place it in an oven to carry out the hydrothermal reaction. Step 4: After the hydrothermal reaction in Step 3 is completed, the reaction products are separated, washed with deionized water until neutral, and then vacuum dried to obtain rare earth element-doped Mo2C material.

[0006] The above-mentioned method for inducing a superconducting-insulator phase transition in two-dimensional Mo2C by rare earth element doping is characterized in that the rare earth element in step one is one or more of lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium and holmium.

[0007] The above-mentioned method for inducing a superconducting-insulator phase transition in two-dimensional Mo2C by rare earth element doping is characterized in that the molar ratio of Mo2C powder and hydrated nitrate containing rare earth elements in step one is 1:0.05~0.4.

[0008] The above-mentioned method for inducing a superconducting-insulator phase transition in two-dimensional Mo2C by rare earth element doping is characterized in that the hydrothermal reaction in step three is carried out at a temperature of 160℃~200℃ for 12h~24h.

[0009] The above-mentioned method for inducing a superconducting-insulator phase transition in two-dimensional Mo2C by rare earth element doping is characterized in that the vacuum drying temperature in step four is 60℃~100℃ and the time is 6h~12h.

[0010] Compared with the prior art, the present invention has the following advantages: 1. This invention employs a hydrothermal synthesis method, in which Mo2C powder is mixed with hydrated nitrates containing rare earth elements to form a solution and reacted under high temperature and high pressure. Through in-situ ion exchange and doping during the hydrothermal reaction, rare earth elements are uniformly introduced into the Mo2C lattice at the atomic level, thereby preparing a Mo2C material uniformly doped with rare earth elements. This achieves effective control over the superconducting properties of Mo2C, causing it to transform from a superconductor to an insulator.

[0011] 2. By precisely controlling the molar ratio of Mo2C powder and rare earth elements, this invention can continuously and controllably adjust the electrical properties of the material over a wide range, successfully inducing a dramatic phase transition from superconducting to insulating state in Mo2C material, thus overcoming the bottleneck of traditional methods in achieving phase transition control.

[0012] 3. This invention adopts a one-step hydrothermal synthesis method, which has a simple process route and does not require complex equipment or harsh vacuum and high temperature environments. Moreover, the entire reaction process is carried out in the aqueous phase, which is green and environmentally friendly. The reaction products only need to be washed and dried at low temperature in a vacuum to obtain high-purity products, avoiding side reactions or structural damage that may be caused by high-temperature annealing. The process is safe and simple.

[0013] 4. The method of the present invention is simple to operate, has mild conditions, low cost, and can achieve uniform doping of rare earth elements, which provides important assistance for studying the electronic properties of Mo2C materials and expanding their applications.

[0014] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0015] Figure 1 La prepared in Example 2 of this invention 3+ MT spectrum of doped Mo2C material.

[0016] Figure 2 La prepared in Example 4 of this invention 3+ XRD pattern of doped Mo2C material.

[0017] Figure 3 La prepared in Example 4 of this invention 3+ SEM images of doped Mo2C materials.

[0018] Figure 4 La prepared in Example 4 of this invention 3+ Elemental mapping of doped Mo2C materials.

[0019] Figure 5 La prepared in Example 4 of this invention 3+ RT spectrum of doped Mo2C material. Detailed Implementation

[0020] Example 1 This embodiment includes the following steps: Step 1: Weigh Mo2C powder and La(NO3)3 separately in a glove box under argon atmosphere protection at a molar ratio of 1:0.05. 6H2O; Step 2: Combine the Mo2C powder and La(NO3)3 weighed in Step 1. 6H2O was placed in the polytetrafluoroethylene liner of the hydrothermal reactor, and 40 mL of deionized water was added. The mixture was stirred continuously until La(NO3)3 was obtained. 6H2O completely dissolves, forming a mixed solution; Step 3: After sealing the hydrothermal reactor containing the mixed solution from Step 2, place it in an oven and carry out the hydrothermal reaction at 160°C for 24 hours. Step 4: After the hydrothermal reaction in Step 3 is completed, the reaction products are separated, washed with deionized water until neutral, and dried under vacuum at 100℃ for 6 hours to obtain La. 3+ Doped Mo2C material.

[0021] La prepared from this embodiment 3+ The XRD pattern of the doped Mo2C material shows obvious (002) diffraction peaks, indicating that La 3+ Doping does not change the crystal structure of two-dimensional Mo2C; its SEM images show that the morphology of doped Mo2C still maintains a two-dimensional sheet structure, and no significant structural change has occurred; its MT test results show that when Mo2C reacts with La... 3+ When the molar ratio of doping is 1:0.05, La 3+ The superconducting transition temperature of the doped Mo2C material is 4.9K.

[0022] In this embodiment, the rare earth element may also be one or more of the following, excluding lanthanum: lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, and holmium.

[0023] Example 2 This embodiment includes the following steps: Step 1: Weigh Mo2C powder and La(NO3)3 separately in a glove box under argon atmosphere protection at a molar ratio of 1:0.1. 6H2O; Step 2: Combine the Mo2C powder and La(NO3)3 weighed in Step 1. 6H2O was placed in the polytetrafluoroethylene liner of the hydrothermal reactor, and 40 mL of deionized water was added. The mixture was stirred continuously until La(NO3)3 was obtained. 6H2O completely dissolves, forming a mixed solution; Step 3: After sealing the hydrothermal reactor containing the mixed solution from Step 2, place it in an oven and carry out the hydrothermal reaction at 160°C for 24 hours. Step 4: After the hydrothermal reaction in Step 3 is completed, the reaction products are separated, washed with deionized water until neutral, and dried under vacuum at 100℃ for 6 hours to obtain La. 3+ Doped Mo2C material.

[0024] La prepared from this embodiment 3+ The XRD pattern of the doped Mo2C material shows obvious (002) diffraction peaks, indicating that La 3+ Doping does not alter the crystal structure of two-dimensional Mo2C; its SEM images show that the morphology of doped Mo2C still maintains a two-dimensional lamellar structure, but some lamellars are broken, and small particles appear on the lamellar surface; its elemental mapping results show that the elemental distribution is uniform at this time, achieving La 3+ Uniform doping; its MT test results are... Figure 1 This indicates that when Mo2C reacts with La... 3+ When the molar ratio of doping is 1:0.1, La 3+ The superconducting transition temperature of the doped Mo2C material is 4.5 K, indicating that with the increase of La... 3+ Increasing the doping concentration inhibited the superconducting properties of Mo2C.

[0025] Example 3 This embodiment includes the following steps: Step 1: Weigh Mo2C powder and La(NO3)3 separately in a glove box under argon atmosphere protection at a molar ratio of 1:0.3. 6H2O; Step 2: Combine the Mo2C powder and La(NO3)3 weighed in Step 1. 6H2O was placed in the polytetrafluoroethylene liner of the hydrothermal reactor, and 40 mL of deionized water was added. The mixture was stirred continuously until La(NO3)3 was obtained. 6H2O completely dissolves, forming a mixed solution; Step 3: After sealing the hydrothermal reactor containing the mixed solution from Step 2, place it in an oven and carry out the hydrothermal reaction at 160°C for 24 hours. Step 4: After the hydrothermal reaction in Step 3 is completed, the reaction products are separated, washed with deionized water until neutral, and dried under vacuum at 100℃ for 6 hours to obtain La. 3+ Doped Mo2C material.

[0026] La prepared from this embodiment 3+ The (002) diffraction peak remains unchanged in the XRD pattern of the doped Mo2C material, indicating that La3+ Doping does not change the crystal structure of two-dimensional Mo2C, but the appearance of many La2O3 peaks in the XRD indicates that La... 3+ Excessive doping leads to the formation of a second phase, La₂O₃. SEM images show that the morphology of the doped Mo₂C still maintains a two-dimensional lamellar structure, but lamellar fragmentation is intensified, with numerous particles appearing on the lamellar surface, and the particle size is non-uniform. Elemental mapping results show that the elemental distribution is uniform at this point, indicating that La₂O₃... 3+ It can still be uniformly doped; its RT test results show that when Mo2C and La 3+ When the molar ratio of doping is 1:0.3, La 3+ The doped Mo2C material has undergone an insulating phase transition and lost its superconducting properties.

[0027] Example 4 This embodiment includes the following steps: Step 1: Weigh Mo2C powder and La(NO3)3 separately in a glove box under argon atmosphere protection at a molar ratio of 1:0.4. 6H2O; Step 2: Combine the Mo2C powder and La(NO3)3 weighed in Step 1. 6H2O was placed in the polytetrafluoroethylene liner of the hydrothermal reactor, and 40 mL of deionized water was added. The mixture was stirred continuously until La(NO3)3 was obtained. 6H2O completely dissolves, forming a mixed solution; Step 3: After sealing the hydrothermal reactor containing the mixed solution from Step 2, place it in an oven and carry out the hydrothermal reaction at 160°C for 24 hours. Step 4: After the hydrothermal reaction in Step 3 is completed, the reaction products are separated, washed with deionized water until neutral, and dried under vacuum at 100℃ for 6 hours to obtain La. 3+ Doped Mo2C material.

[0028] La prepared from this embodiment 3+ XRD patterns of doped Mo2C materials Figure 2 The (002) diffraction peak was observed, indicating that the two-dimensional Mo2C crystal structure is still maintained, and the La2O3 second phase still appears in the XRD; its SEM image is... Figure 3 (Figure (a) is a low-magnification image, and Figure (b) is a high-magnification image) shows that the sheet morphology of Mo2C after doping is slightly more fragmented; its elemental mapping distribution is as follows: Figure 4 The display shows only four elements: Mo, C, O, and La, with La element evenly distributed, indicating that uniform doping has been achieved; its RT test results are... Figure 5 This indicates that when Mo2C reacts with La... 3+ When the molar ratio of doping is 1:0.4, La3+ The doped Mo2C material exhibits insulating properties.

[0029] Example 5 This embodiment includes the following steps: Step 1: Weigh Mo2C powder and La(NO3)3 in a glove box under nitrogen atmosphere protection at a molar ratio of 1:0.2. 6H2O; Step 2: Combine the Mo2C powder and La(NO3)3 weighed in Step 1. 6H2O was placed in the polytetrafluoroethylene liner of the hydrothermal reactor, and 40 mL of deionized water was added. The mixture was stirred continuously until La(NO3)3 was obtained. 6H2O completely dissolves, forming a mixed solution; Step 3: After sealing the hydrothermal reactor containing the mixed solution from Step 2, place it in an oven and carry out the hydrothermal reaction at 200°C for 12 hours. Step 4: After the hydrothermal reaction in Step 3 is completed, the reaction products are separated, washed with deionized water until neutral, and dried under vacuum at 60°C for 12 hours to obtain La. 3+ Doped Mo2C material.

[0030] The La prepared in this embodiment 3+ The XRD pattern of the doped Mo2C material is basically the same as that of Example 4, indicating that the product prepared by increasing the hydrothermal reaction temperature and shortening the reaction time is the same, and the crystal structure does not change; its RT test results show that when Mo2C and La 3+ When the molar ratio of doping is 1:0.2, La 3+ The doped Mo2C material exhibits insulating properties.

[0031] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for inducing a superconducting-insulator phase transition in two-dimensional Mo2C by rare earth element doping, characterized in that, The method includes the following steps: Step 1: Weigh Mo2C powder and hydrated nitrate containing rare earth elements in a glove box under an inert atmosphere according to the designed molar ratio; the molar ratio of Mo2C powder to hydrated nitrate containing rare earth elements is 1:0.05~0.

4. Step 2: Place the Mo2C powder weighed in Step 1 and the hydrated nitrate containing rare earth elements into the polytetrafluoroethylene liner of the hydrothermal reactor, add deionized water and stir continuously until the hydrated nitrate is completely dissolved to form a mixed solution. Step 3: After sealing the hydrothermal reactor containing the mixed solution from Step 2, place it in an oven to carry out the hydrothermal reaction. Step 4: After the hydrothermal reaction in Step 3 is completed, the reaction products are separated, washed with deionized water until neutral, and then vacuum dried to obtain rare earth element-doped Mo2C material.

2. The method for inducing a superconducting-insulator phase transition in two-dimensional Mo2C by rare earth element doping according to claim 1, characterized in that, The rare earth element mentioned in step one is one or more of lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, and holmium.

3. The method for inducing a superconducting-insulator phase transition in two-dimensional Mo2C by rare earth element doping according to claim 1, characterized in that, The hydrothermal reaction in step three is carried out at a temperature of 160℃~200℃ for 12h~24h.

4. The method for inducing a superconducting-insulator phase transition in two-dimensional Mo2C by rare earth element doping according to claim 1, characterized in that, The vacuum drying temperature in step four is 60℃~100℃, and the time is 6h~12h.

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