A press model combined with tem and a method for preparing nanoparticles

Abstract

The application provides a press model combined with a TEM and a preparation method of nanoparticles, and the press model comprises a transmission electron microscope, a press mechanism arranged in the transmission electron microscope, a long-side vibration crystal resonator and a support, a first tungsten needle arranged on the support, a second tungsten needle arranged on the long-side vibration crystal resonator, free ends of the first tungsten needle and the second tungsten needle are oppositely arranged and are on the same straight line, the free ends of the first tungsten needle and the second tungsten needle are both fixed with diamond pressure heads, the long-side vibration crystal resonator is connected with a phase-locked loop and a piezoelectric ceramic respectively, the piezoelectric ceramic is connected with a voltage controller, the phase-locked loop and the voltage controller are both connected with an intelligent control end, and the intelligent control end is connected with the transmission electron microscope. The application can obtain nanodiamonds without functional groups on the surface, can observe the preparation process and structural information of the nanodiamonds in real time, and can also measure the mechanical properties of the initial sample.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nanoparticle preparation, in particular to a press model combined with TEM and a preparation method of nanoparticles. BACKGROUND

[0002] Diamond can be widely used in the industrial development of electronic and optoelectronic materials due to its super-high thermal conductivity, dielectric breakdown strength, carrier mobility and super-wide band gap.

[0003] The current press for synthesizing diamond using high temperature and high pressure technology mainly includes two-sided top and six-sided top. The two-sided top press forms a closed space through the upper and lower press hammers and the two-sided top mold, and applies pressure to the sample from the upper and lower directions, so as to achieve the synthesis condition. The two-sided top press has the characteristics of good pressure stability and large pressure cavity volume, and is suitable for synthesizing large block materials, such as large block diamond, with a diameter of microns to millimeters.

[0004] The six-sided top press applies force to the middle from different directions through six oil cylinders to achieve the synthesis condition. Since the longer the time, the greater the pressure drop in the cavity, which is not conducive to the stable growth of diamond, the particle size quality of the diamond synthesized by the six-sided top press is not good.

[0005] However, the existing technology is mainly used for synthesizing large block materials, and it is not easy to obtain nanoparticles such as nanodiamonds. Studies have shown that nanodiamonds with a diameter of 2-10 nanometers can be synthesized by explosion method, but the synthesized diamond has poor crystallinity and has many defects, and the surface has many functional groups, which limits the application of nanodiamonds. SUMMARY

[0006] The present application provides a press model combined with TEM and a preparation method of nanoparticles, which can obtain nanodiamonds without functional groups on the surface, observe the preparation process and structure information in real time, and measure the mechanical properties of the sample.

[0007] The technical scheme of the present application is as follows: a press model combined with TEM, comprising a transmission electron microscope, a press mechanism arranged in the transmission electron microscope, the press mechanism comprising a long-side vibration crystal resonator and a support, a first tungsten needle arranged on the support, a second tungsten needle arranged on the long-side vibration crystal resonator, the free ends of the first tungsten needle and the second tungsten needle being oppositely arranged and on the same straight line, a diamond press head fixed to the free end of each of the first tungsten needle and the second tungsten needle, the long-side vibration crystal resonator being connected with a phase-locked loop and a piezoelectric ceramic respectively, the piezoelectric ceramic being connected with a voltage controller, the phase-locked loop and the voltage controller being connected with an intelligent control end, and the intelligent control end being connected with the transmission electron microscope.

[0008] A preparation method of nanoparticles, using the press model, comprising the following steps:

[0009] (1) placing the sample on the diamond indenter of the first tungsten needle or the second tungsten needle, and then placing the press mechanism in the transmission electron microscope;

[0010] (2) applying a set voltage to the piezoelectric ceramic through the intelligent control end and the voltage controller, the piezoelectric ceramic drives the long-side vibrating crystal resonator and the second tungsten needle to move towards the first tungsten needle, thereby extruding the sample with the two diamond indenters until the sample is crushed to obtain nanoparticles, and observing the preparation process and structural information of the nanoparticles through the transmission electron microscope;

[0011] (3) during the extrusion of the sample in step (2), measuring the mechanical properties of the sample through the long-side vibrating crystal resonator and the phase-locked loop.

[0012] Further, in step (1), the diameter of the sample is > 5 nm.

[0013] The beneficial effects of the present application are:

[0014] The present application combines the press model of TEM, which can be used to prepare nanoparticles without functional groups on the surface, such as nanodiamonds, and through the TEM image, the preparation process and structural information can be observed in real time; during the extrusion of the nanoparticles, the mechanical properties of the sample can also be measured. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description, and obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0016] Figure 1 The schematic diagram of the measurement system used for research;

[0017] Figure 2 For Figure 1 Enlarged view of the dashed box;

[0018] Figure 3 TEM image of the diamond sample before extrusion;

[0019] Figure 4 TEM image of the diamond sample after extrusion.

[0020] Long-side vibrating crystal resonator 1, support 2, first tungsten needle 3, second tungsten needle 4, diamond indenter 5, phase-locked loop 6, intelligent control end 7, piezoelectric ceramic 8, voltage controller 9, sample 10. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1

[0023] like Figure 1 and 2 As shown, a press model combined with TEM includes a transmission electron microscope (TEM). A press mechanism is placed within the sample chamber of the TEM. The press mechanism includes a long-side vibrating crystal resonator 1 and a support 2. The support 2 can be directly adopted from the sample holder of the TEM. A first tungsten needle 3 is mounted on the support 2, and a second tungsten needle 4 is mounted on the long-side vibrating crystal resonator 1. The free ends of the first tungsten needle 3 and the second tungsten needle 4 are arranged facing each other and on the same straight line. Diamond indenters 5 are fixed to the free ends of both the first tungsten needle 3 and the second tungsten needle 4 using silver paste. The long-side vibrating crystal resonator 1 is connected to a phase-locked loop (PLL) 6 and a piezoelectric ceramic 8, respectively. The piezoelectric ceramic 8 is connected to a voltage controller 9, and the PLL 6 and the voltage controller 9 are connected to an intelligent control terminal 7, which is connected to the TEM. The intelligent control terminal 7 can be a computer control terminal, etc. The TEM, the long-side vibrating crystal resonator 1, the PLL 6 and the intelligent control terminal 7, the piezoelectric ceramic 8, and the voltage controller 9 are all existing equipment.

[0024] Example 2

[0025] A method for preparing nanoparticles, using the press model described in Example 1, includes the following steps:

[0026] (1) If the diameter of sample 10 is >5nm, place sample 10 on the diamond indenter 5 of the first tungsten needle 3 or the second tungsten needle 4. If the diameter of sample 10 is in the nanometer range, it can be directly adsorbed on the diamond indenter 5. If the diameter of sample 10 exceeds the nanometer range, such as micrometer range or above, sample 10 can be bonded to a diamond indenter 5.

[0027] Then the press mechanism is placed inside a transmission electron microscope; the diameters of the first tungsten needle 3 and the second tungsten needle 4 vary from tens of nanometers to hundreds of nanometers, and can be set according to needs.

[0028] (2) Set the voltage, ultra-high vacuum and the density of strong electron beam in the transmission electron microscope, which is the function of the transmission electron microscope, clean the sample 10, such as voltage 200 kV, ultra-high vacuum 10-7Pa, avoid the sample 10 being contaminated, and the density of strong electron beam is 100A / cm2 2 Clean the sample 10 and obtain the TEM image;

[0029] The piezoelectric ceramic 8 is applied with a set voltage through the intelligent control end 7 and the voltage controller 9, the set voltage is 0.01-10V, which can be set according to the need, the piezoelectric ceramic 8 drives the long-side vibration crystal resonator 1 and the second tungsten needle 4 to move to the direction of the first tungsten needle 3, and then the two diamond anvil 5 extrude the sample 10, until the sample 10 is broken, and the nano-particle with smaller particle size is obtained, and the preparation process of the nano-particle and the structure information of the nano-particle are observed through the transmission electron microscope;

[0030] (3) In the extrusion process of the sample 10 in step (2), the mechanical properties of the sample 10 are measured through the long-side vibration crystal resonator 1 and the phase-locked loop 6, and the method for measuring the mechanical properties is the prior art.

[0031] As shown in Figure 3 , the sample 10 is a diamond sample with a particle size of 6.9nm, and the nano-diamond prepared by the method of embodiment 2 is as shown in Figure 4 .

[0032] The above only describes the preferred embodiments of the present application and is not used to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing nanoparticles by using a press model, the press model comprising a transmission electron microscope, a press mechanism arranged in the transmission electron microscope, the press mechanism comprising a long-side vibration crystal resonator and a support, a first tungsten needle arranged on the support, a second tungsten needle arranged on the long-side vibration crystal resonator, the free ends of the first tungsten needle and the second tungsten needle being oppositely arranged and on the same straight line, a diamond press head fixed on each of the free ends of the first tungsten needle and the second tungsten needle, the long-side vibration crystal resonator being connected with a phase-locked loop and a piezoelectric ceramic respectively, the piezoelectric ceramic being connected with a voltage controller, the phase-locked loop and the voltage controller being connected with an intelligent control end respectively, the intelligent control end being connected with the transmission electron microscope, characterized in that, The method comprises the following steps: (1) placing a sample on a diamond indenter of a first tungsten needle or a second tungsten needle, and then placing a press mechanism in a transmission electron microscope; the sample is a diamond sample with a diameter > 5 nm; (2) applying a set voltage to a piezoelectric ceramic through an intelligent control end and a voltage controller, so that the piezoelectric ceramic drives a long-side vibrating crystal resonator and the second tungsten needle to move towards the first tungsten needle, thereby causing the two diamond indenters to extrude the sample until the sample is crushed to obtain nanoparticles, and observing the preparation process and structural information of the nanoparticles through a transmission electron microscope; (3) measuring the mechanical properties of the sample through the long-side vibrating crystal resonator and a phase-locked loop during the extrusion of the sample in step (2); the nanoparticles are nanodiamonds without functional groups on the surface.

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