A method for preparing ZrS2 monoclinic P21 / m phase by high-pressure shearing

Abstract

This invention discloses a method for preparing the ZrS2 monoclinic P21 / m phase via high-pressure shearing, belonging to the field of semiconductor material synthesis and preparation. ZrS2 exists as a trigonal P3m1 phase under normal temperature and pressure. An appropriate amount of ZrS2 P3m1 phase is weighed and placed at the center of the anvil of a double-sided rotating hydraulic press. The original sample is pressurized until the target pressure is reached. Then, the anvil is rotated by a certain angle, applying pressure and shear stress simultaneously. The sample removed after depressurization is the monoclinic P21 / m phase ZrS2. This invention uses high-pressure, high-shear treatment to prepare the ZrS2 monoclinic P21 / m phase while maintaining the same composition. The process can be carried out at room temperature without adding any external additives, and is simple and easy to operate.

Description

Technical Field

[0001] This invention relates to the field of semiconductor materials, specifically to a method for preparing a high-pressure phase of ZrS2 semiconductor material. Background Technology

[0002] Transition metal chalcogenides (TMDs) (such as MoS2, WS2, ZrS2, MoSe2, TaS2, etc.) have become alternatives to graphene, and their rich physical properties, such as charge density wave (CDW), superconductivity, and optoelectronic properties, have inspired research enthusiasm in the field of materials physics in recent decades.

[0003] ZrS2 is a high-performance semiconductor material. In its bulk form, it exhibits an indirect bandgap of 1.08 eV. When transformed into a monolayer two-dimensional material, although it still exhibits an indirect bandgap, its bandgap width increases to 1.4 eV. Upon application of strain, such as enhanced thermoelectric properties, conductivity, and strain-driven transitions, it transitions from an indirect bandgap to a direct bandgap, expanding the bandgap range to 1.8 eV–2.2 eV. ZrS2 also possesses a high phonon-confined mobility limit (1200 cm⁻¹). 2 / V·s) is also a TMDs-containing MoS2 (340cm) 2 ZrS2 has a density three times that of V·s. Therefore, ZrS2 is an excellent material for manufacturing semiconductor devices and can be well-suited for photodetectors and field-effect transistors.

[0004] High-pressure shearing is a process that combines pressure and shear stress. As a processing technique that does not introduce other impurities at room temperature, the large plastic strain generated by it has a series of effects on the microstructure, phase transition mechanism, thermodynamics, and kinetics of the material. The phase transition pressure point induced by shear stress or plastic strain is 3 to 5 times lower than that induced by single pressure. This is mainly because shear stress is limited by the yield strength, and its contribution to the thermodynamic driving force of phase transition is smaller compared to hydrostatic pressure. Phase transitions induced by pressure and stress begin with pre-existing crystal defects in the material and when the stress has not reached the yield limit. These defects (such as various dislocation structures or grain boundaries) generate stress concentrations and serve as nucleation sites for phase transitions. Plastic strain-induced phase transitions, on the other hand, occur through nucleation and limited growth at new defects generated during plastic strain, forming dislocation stacks and generating extremely high stress concentrations. Local stresses can be very large, and these stresses can be increased by continuing to increase plastic deformation at relatively low pressures, thereby driving the phase transition. Summary of the Invention

[0005] This invention discloses a method for treating ZrS2 trigonal structures using high-pressure, high-shear processes. Method for preparing ZrS2 monoclinic P21 / m phase:

[0006] To achieve the above objectives, the technical solution disclosed in this invention is as follows:

[0007] A method for preparing ZrS2 monoclinic P21 / m phase by high-pressure shearing specifically includes the following steps:

[0008] Step a, weigh 300-400 mg of the trigonal structure ZrS2 powder of the phase is placed at the center of the anvil; the anvil is frustum-shaped with a diameter of 3cm and is made of hard alloy material. The two anvils are installed opposite each other in the middle of the hydraulic cylinder of the double-sided rotary hydraulic press, and the rotation of the anvil is achieved by rotating one of the anvils.

[0009] Step b, for The ZrS2 phase is slowly pressurized until the target pressure is reached, which is 50-2000 kN.

[0010] Step c: While keeping the pressure constant, the double-sided rotary hydraulic press drives the anvil to rotate 10° to 720° to apply shear stress to the sample;

[0011] Step d: After depressurization, the product is removed, and sample preparation is complete. ZrS2 has a trigonal structure. The phase transitions to a monoclinic structure P21 / m phase.

[0012] The beneficial effects of this invention are:

[0013] This invention is prepared by adjusting pressure and shear stress without introducing other impurities. It can be carried out at room temperature without adding any external additives. The process is simple and easy to operate. Attached Figure Description

[0014] Figure 1 A schematic diagram illustrating the high pressure and high shear stress generated by a double-sided rotary hydraulic press.

[0015] Figure 2 The image shows the XRD pattern of the monoclinic P21 / m phase ZrS2 prepared by the preparation method described in this invention. Detailed Implementation

[0016] The technical solution of the present invention will be further explained and described below with reference to specific embodiments.

[0017] The device used in this invention to generate high pressure and high shear stress is a double-sided rotary hydraulic press, and the applied pressure ranges from 0.8 to 3 GPa. For example... Figure 1As shown, the opposing anvil is frustum-shaped with an anvil surface diameter of 3cm and is made of hard alloy. The two opposing anvil surfaces are installed opposite each other in the middle of the hydraulic cylinder of the double-sided rotary hydraulic press. The rotation of the anvil is achieved by rotating one of the anvils, and the rotation angle range is 10° to 720°.

[0018] Example 1

[0019] This embodiment describes a method for preparing the ZrS2 monoclinic P21 / m phase by high-pressure shearing, which specifically includes the following steps:

[0020] Step a, weigh 300 mg of the trigonal structure The ZrS2 powder (JCPDS: 11-0679) of the phase was placed in the center of the anvil. The purpose of placing the sample in the center as much as possible is to prevent the sample from overflowing and pressing the anvil after receiving shear force.

[0021] Step b, for The ZrS2 phase is slowly pressurized until the target pressure of 200kN is reached;

[0022] Step c: While keeping the pressure constant, the double-sided rotary hydraulic press drives the anvil to rotate 360° to apply shear stress to the sample;

[0023] Step d: After depressurization, the product is removed, and the sample preparation is complete.

[0024] Example 2

[0025] This embodiment uses the same method as Embodiment 1, except that in step a, 400mg of [the substance] is weighed. For ZrS2 phase, the target pressure in step b is 600kN, and the rotation is 180° in step c.

[0026] Figure 2 The image shows the XRD pattern of the monoclinic P21 / m phase ZrS2 prepared by the preparation method described in this invention, with the initial structure... The diffraction peaks of the phase almost completely disappeared, and the XRD diffraction peaks of the obtained new structure were consistent with those of the monoclinic P21 / m phase of ZrS2. The cell parameters of the obtained new structure were: α=β=90°, γ=108.73(86)°, Furthermore, the particle size of the ZrS2 monoclinic P21 / m phase prepared by this invention is significantly smaller than that of the raw material.

[0027] In other embodiments of the present invention, the target pressure is set to 50-2000 kN and the anvil is rotated 10°-720°.

Claims

1. A method for preparing ZrS2 monoclinic P21 / m phase by high-pressure shearing, characterized in that, The method specifically includes the following steps: Step a: Weigh 300-400 mg of ZrS2 powder with a trigonal structure P3m1 phase and place it at the center of the anvil; the anvil is frustum-shaped with a diameter of 3 cm and is made of hard alloy material. The two anvils are installed opposite each other in the middle of the hydraulic cylinder of the double-sided rotary hydraulic press, and the rotation of the anvil is achieved by rotating one of the anvils. Step b: Slowly pressurize the ZrS2 in the P3m1 phase until the target pressure is reached, which is 50-2000 kN. Step c: While keeping the pressure constant, the double-sided rotary hydraulic press drives the anvil to rotate 10° to 720° to apply shear stress to the sample; Step d: After depressurization, the product is removed, and the sample preparation is complete. ZrS2 changes from the trigonal P3m1 phase to the monoclinic P21 / m phase.

2. The method for preparing ZrS2 monoclinic P21 / m phase by high-pressure shearing according to claim 1, characterized in that, In step a, 300 mg of ZrS2 powder with a trigonal P3m1 phase is weighed; in step b, the target pressure is 200 kN; in step c, the anvil is rotated 360°.

3. The method for preparing ZrS2 monoclinic P21 / m phase by high-pressure shearing according to claim 1, characterized in that, In step a, 400 mg of ZrS2 powder with a trigonal P3m1 phase is weighed; in step b, the target pressure is 600 kN; in step c, the anvil is rotated 180°.

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