CN101113946B - Device for Mechatronic Performance Testing of Nanowires under In-Situ Compression in Transmission Electron Microscopy - Google Patents

Abstract

The invention relates to a device for testing mechanical and electrical properties under in-situ compression of nanowires in a transmission electron microscope, which belongs to the field of in-situ detection of properties of nanometer materials. The design of the invention realizes the in-situ compression of single nanowires and other one-dimensional nanomaterials in the transmission electron microscope through the piezoelectric ceramic stretching unit, the mechanical detection system of the micro-cantilever beam and the electrical measurement system, and can use the transmission electron microscope during the compression process. The imaging system of the electron microscope can obtain deformation information at the nanometer scale or even at the atomic scale, and can also realize the quantitative measurement of the mechanical properties of elasticity, plasticity, bending and fracture. At the same time, it can also measure the electrical properties of one-dimensional nanomaterials. A study of the charge transport properties in . The invention has the advantages of simple structure, convenient operation, wide application range, intuitive and quantitative detection characteristics, and is convenient for explaining and discovering the excellent mechanical/electrical comprehensive properties of nanometer materials.

Description

Device for Mechatronic Performance Testing of Nanowires under In-Situ Compression in Transmission Electron Microscopy

Technical field:

The invention relates to a device for testing electromechanical properties under in-situ compression of nanowires in a transmission electron microscope, which belongs to the field of in-situ detection of properties of nanometer materials.

Background technique:

Realizing the manipulation and in-situ performance measurement of monomeric nanostructures is a key scientific and technological issue that is the bottleneck in the research of new nanostructures, new properties and new devices, especially in the transmission electron microscope, due to its narrow space, people It is more difficult to realize the test of the single nanostructure.

It should be pointed out that although people have conducted in-depth studies on the mechanical and electrical properties of monomeric nanomaterials in recent years, due to their difficulty and complexity, no accepted conclusions have been formed so far. One-dimensional nanomaterials are used as interconnect lines or basic functional units of micro-electromechanical systems and nano-electromechanical systems. Therefore, fully understanding the mechanical and electrical properties of a single one-dimensional nanomaterial and the electrical/mechanical coupling performance under stress is the key to designing nanometers. Basic guidelines for devices.

At present, the testing methods for the mechanical properties of single one-dimensional nanomaterials can be roughly divided into the following three types.

First, the testing method based on atomic force microscope or scanning tunneling microscope. Due to the high mechanical and displacement resolution of these devices, one of the methods is "Elastic modulus of ordered and disordered multi-walled elastic nanotubes" reported in "Advanced Materials" 1999, vol.11, pp. 161-165 "(Elastic modulus of ordered and disordered multiwalled carbon nanotubes), discloses a carbon nanotube straddling a hole, using the atomic force microscope tip to press and bend the nanotube, using the high mechanical and displacement sensing characteristics of the atomic force microscope, tested The elastic modulus of nanotubes, followed by similar methods have been reported for testing the mechanical properties of other nanowires. Another method reported in "Nano Letters" 2005, vol.5, 1954-1958, "elastic property of vertically aligned nanowires" (elastic property of vertically aligned nanowires), also uses the atomic force microscope to bend and grow vertically Zinc oxide nanowires, using the relationship between bending displacement and force, calculated the elastic modulus of zinc oxide nanowires. Due to the superior mechanical and displacement resolution, the mechanical testing method based on atomic force microscopy is very suitable for measuring the mechanical properties of a single nanowire, but it cannot monitor the structural changes of the nanowire during deformation in situ, and it is difficult to explain the deformation mechanism and Fracture process.

Second, develop methods for measuring the properties of single 1D nanomaterials in scanning electron microscopy. In 2000, "Strength and breaking mechanism of multiwalled carbon nanotubes under tensile load" (Strength and breaking mechanism of multiwalled carbon nanotubes under tensile load) on "Science" vol. A set of atomic force probe system is installed in the electron microscope, and two atomic force probes are used to realize the stretching of carbon nanotubes. Also in the scanning electron microscope, the article "Mechanical properties of ultrahigh-strength gold nanowires" (Mechanical properties of ultrahigh-strength gold nanowires) on "Nature materials", vol.4, 525-529 in 2005 reported the use of a single atomic force probe A device and method for needle-pressing gold nanowires, so as to realize the test of the mechanical properties of the nanowires. Although the combination of scanning microscope and atomic force probe can provide measurement data and in-situ deformation process, its resolution is at the nanometer level and cannot provide atomic-scale information, so the study of deformation mechanism is limited.

Third, use the transmission electron microscope as the basic test method to realize the test of the mechanical properties of a single one-dimensional nanomaterial. The mechanical resonance method is also a method for testing the mechanical properties of a single nanowire. The earliest literature report was "Electrostatic deflection and resonance of carbon nanotubes" on pages 1513-1516 of "Science" 1999, vol.283. Electromechanical resonances of carbon nanotubes), this experiment is carried out in situ in a transmission electron microscope, using an alternating electric field applied to a nanotube fixed at one end to induce the resonance of the nanotube, and measuring the bending modulus of the nanotube using the change in resonance frequency. Several research groups then used this method to measure the elastic modulus of different nanowires in transmission electron microscopy and scanning electron microscopy. This method avoids the difficulty of direct manipulation of nanowires, and at the same time, the structural information of nanotubes/wires can be obtained in situ using transmission electron microscopy, but this method is limited to the range of elastic deformation of nanowires, and cannot measure the plastic deformation of nanowires. Other important mechanical properties such as breaking strength. 2007, "Nano Letter", vol.7, 452-457 "Low temperature in situ large strain plasticity of ceramic SiC nanowires and its atomic-scale mechanism" ) reported the use of electron beams to irradiate a special support film in high-resolution transmission electron microscopy to bend a single nanowire, found the large-strain plastic behavior of SiC nanowires, and gave the atomic-scale deformation process and mechanism. Although this method can effectively give information on the atomic scale, it cannot quantify the elastic coefficient of a single one-dimensional nanomaterial.

None of the above methods can measure the electrical properties of a single one-dimensional nanomaterial under stress, and can no longer meet the current requirements for testing the mechanical properties, electrical properties, and mechanical-electrical coupling performance of nanomaterials on the microscopic scale. Transmission electron microscopy is one of the most important tools people rely on to directly reveal information at the nanometer or even atomic scale. Taking the transmission electron microscope as a platform for testing the performance of single one-dimensional nanomaterials, the most important thing is that it can give real-time atomic-scale information, and give the most direct evidence corresponding to the changes in mechanical properties and electrical properties under stress. Help us reveal the essence of things more effectively and truly.

In situ measurement of elastic modulus, plastic deformation, yield strength and fracture strength of a single one-dimensional nanomaterial in a transmission electron microscope is the most direct test method, and its recording function can be used to record one-dimensional nanomaterials in situ The details of the atomic-scale changes during the deformation process provide direct experimental evidence for revealing the deformation mechanism of one-dimensional nanomaterials. For the electrical performance test of a single one-dimensional nanomaterial in a transmission electron microscope, revealing the electrical properties and structural changes under the action of current and voltage are also the basic performance parameters and important basis for the application of one-dimensional nanomaterials, and in the stress state Testing the electrical properties of one-dimensional nanomaterials is an important problem that needs to be solved in the actual working environment of one-dimensional nanomaterials as basic devices and functional units, and it can also measure the changes in charge transport properties of one-dimensional nanomaterials under stress in real time. Combined with high-resolution images of their structures, they play a crucial role in our understanding of how structures relate to their electrical properties.

Invention content:

Aiming at the problems existing in the prior art, the present invention provides a device for testing the mechanical and electrical properties of nanowires under in-situ compression in a transmission electron microscope. Measurement, as well as the device for electrical measurement under the action of compressive stress, use the transmission electron microscope imaging system to record in situ and real-time the elastoplastic deformation process, fracture failure mode and charge transport characteristics of one-dimensional nanomaterials under the action of compressive stress field and electric field, The mechanical properties, electrical properties, mechanical and electrical coupling properties, and microstructure changes of one-dimensional nanomaterials are directly matched, and the comprehensive properties of one-dimensional nanomaterials are revealed from the atomic scale.

In order to achieve the above purpose, a device for testing electromechanical properties of nanowires under in-situ compression in a transmission electron microscope in the present invention is characterized in that the piezoelectric ceramic sheet 2 is placed in the sealed tube 1 of the sample rod, and the piezoelectric One end of the ceramic sheet 2 close to the handle 3 of the sample rod is fixed on the sealing tube 1 of the sample rod, one end of the two driving wires 19 is connected to the positive and negative poles of the piezoelectric ceramic sheet 2 , and the other end is connected to the drive power supply 20 . The connecting rod 5 is placed in the groove of the bearing base 4, one end of the connecting rod 5 is fixedly connected with the outer end of the piezoelectric ceramic sheet 2, and the other end of the connecting rod 5 is connected with the metal slider on the integrated block 6 through screws. 13 phase connections. The structure of the integrated block 6 is as follows: the rectangular parallelepiped shell 7 is fixedly connected to the bearing base 4 by screws, and the integrated block 6 can be separated from the bearing base 4 by loosening the screws to realize independent operation and processing. The first insulating spacer 8 and the second insulating spacer 9 are horizontally placed in the cuboid shell and fixed thereto, the second insulating spacer 9 is placed near the open end of the cuboid shell 7, and the first insulating spacer 8 is placed on Close to the closed end of the cuboid shell 7 , wherein the first insulating gasket 8 is close to the bearing base 4 , and the second insulating gasket 9 is away from the bearing base 4 . A 30-50 micron slit is provided between the first insulating spacer 8 and the second insulating spacer 9 to facilitate the passage of electron beams. A rectangular metal-coated silicon wafer 10 is fixed in parallel on the first insulating spacer 8 , and a cantilever beam 11 is etched by an etching method at one side near the slit. A slide rail 12 is fixed on the second insulating spacer 9 in a direction perpendicular to the cantilever beam 11. A bump is arranged on the end of the slide rail 12 away from the cantilever arm 11, and a metal slide block 13 is installed on the slide rail 12. The side of metal slide block 13 can be fixed with slide rail 12 with fastening screw 14. The upper surface of the cantilever beam 11 and the metal slider 13 are on the same level, and the gap width between the cantilever beam 11 and the metal slider 13 can be changed by adjusting the metal slider 13 with the fine adjustment knob 15 . The fine adjustment knob 15 is installed in the projection on the slide block 12 .

The piezoelectric ceramic sheet 2 is driven by the drive power supply 20 externally connected to the drive wire 19 to cause a slight displacement in the axial direction. Since the inner end of the piezoelectric ceramic sheet 2 is fixed, the piezoelectric ceramic sheet 2 can only be displaced outward. Therefore, it will drive the linkage rod 5 and the metal slider 13 connected with it (the fine-tuning knob 15 and the fastening screw 14 were loosened before), so that the metal slider 13 will be close to the cantilever arm 11, thereby realizing the fixing of both ends Uniaxial compression of nanowires 21 . The compression of the nanowire 21 will drive the deformation of the cantilever beam 11. Through the real-time recording function in the transmission electron microscope, the offset of the cantilever beam 11 can be calculated. According to its known elastic constant, the cantilever beam 11 can be calculated. 21 on the size of the pressure.

The electrical measurement system 16 is connected to the gold-plated silicon chip 10 and the metal slider 13 through the loading wire 17, the signal wire 18, the loading wire 17 is connected to the control power supply of the electrical measurement system, and the signal wire 18 is connected to the field generation test instrument of the electrical measurement system. connect. The electrical measurement system includes controllable power supply, current, voltage, resistance, capacitance, and field generation test instruments. Electrical properties can be measured without an applied stress field or with both an applied electric field and a stress field.

The invention provides a device for testing electromechanical properties of nanowires under in-situ compression in a transmission electron microscope, which can realize in-situ uniaxial compression of a single one-dimensional nanomaterial in a transmission electron microscope, and can characterize its elastic properties, plastic properties and fracture process , information can be obtained at the atomic scale. At the same time, it can also test the change of the charge transport performance of a single one-dimensional nanomaterial under the state of compressive stress, and realize the test of the electromechanical coupling performance of a single one-dimensional nanomaterial, which is characterized in that the method is carried out as follows:

1. Remove the integrated block 6 from the sample rod, loosen the fastening screw 14, adjust the fine-tuning knob 15 to the required slit width under the optical microscope, and then tighten the fastening screw 14.

2. Put the one-dimensional nanomaterials into an organic solvent (for example, ethanol, acetone, etc.) that does not react with the sample, disperse them by ultrasonic waves for 10-60 minutes, and drop the suspension on the metal slider of the sample and the micro-cantilever beam. upper surface.

3. Use a micromanipulator to arrange a single one-dimensional nanomaterial in a scanning electron microscope, and then use a focused ion beam to fix the one-dimensional nanomaterial on a metal slider and a cantilever beam.

4. Connect the integrated block 6 with the sample rod, then fix the linkage rod 5 and the metal slider 13, and fix the integrated block 6 and the bearing base with screws. Put the sample rod into the transmission electron microscope and draw a good vacuum.

5. Connect the driving wire 19, the loading wire 17, and the signal wire 18 to the piezoelectric ceramic driving power supply 20, the control power supply of the electrical measurement system, and the field generation testing instrument respectively. By controlling the driving power of the piezoelectric ceramics, the piezoelectric ceramics are driven to stretch along the axial direction, so that the one-dimensional nanomaterials fixed on the sample stage can be compressed uniaxially, and the compression process can be recorded in real time through the imaging function of the transmission electron microscope to obtain a one-dimensional Sequence images of compressive deformation of nanomaterials.

6. While the one-dimensional nanomaterial is being compressed, use a transmission electron microscope to record the deformation of the cantilever beam, and obtain the tensile force on the one-dimensional nanomaterial through the formula reported in the literature and the known elastic coefficient. At the same time, the electrical measurement system can also be used to monitor the changes in the electrical properties of one-dimensional nanomaterials during compression in real time.

Compared with the prior art, the present invention has the following advantages and outstanding effects: the one-dimensional nanomaterial mechanical and electrical testing system in the transmission electron microscope of the present invention has simple structure, reliable performance, easy installation, easy operation and wide application range The characteristics of can be applied to all one-dimensional nanomaterials with a length greater than 5 microns. The invention utilizes the sensitive mechanical sensing performance of the micro-cantilever beam and the precise displacement sensing characteristic of piezoelectric ceramics to realize displacement resolution at the nanometer level and mechanical resolution at the nanonew level. Compared with the existing atomic force or scanning tunneling microscope one-dimensional nanomaterial mechanical testing device, the present invention utilizes transmission electron microscope to record one-dimensional The microstructural change of nanomaterial deformation directly corresponds to the mechanical properties and microstructure of one-dimensional nanomaterials. Compared with the technical method of testing one-dimensional nanomaterials in the transmission electron microscope, the present invention can realize all measurements of the elasticity, plasticity and fracture process of the one-dimensional nanomaterials, can provide information on the deformation process on the atomic scale, and can obtain The stress-strain curve of one-dimensional nanomaterials under uniaxial compression can fully explain the mechanical properties of one-dimensional nanomaterials. In addition, the device of the present invention can also be used to test the change of charge transport performance of one-dimensional nanomaterials under the action of tensile stress in situ, and the change of electrical properties can be directly corresponding to the change of its atomic scale structure, which can Reveal the rich physical properties of one-dimensional nanomaterials, and provide reliable data for the development and design of one-dimensional nanomaterials in many fields such as micro-electromechanical systems, semiconductor devices, and sensors.

Description of drawings:

Fig. 1 is a top view of a device for testing electromechanical properties of nanowires under in-situ compression in a transmission electron microscope of the present invention.

FIG. 2 is a top view of an integrated block 6 that realizes the function of compressing nanowires.

FIG. 3 is an AB cross-sectional view of the integrated block 6 that realizes the function of compressing nanowires.

Fig. 4 is a CD sectional view of the metal slider 13 and its guide rail 12

Detailed ways:

As shown in Figure 1, the piezoelectric ceramic sheet 2 is placed in the sealed tube 1 of the sample rod, and its inner end is fixed on the sealed tube 1 of the sample rod, and one end of the two driving wires 19 is connected to the piezoelectric ceramic sheet 2 positive and negative poles, and the other end is externally connected to the driving power supply 20. The connecting rod 5 is a rigid material, placed in the groove of the bearing base 4, one end of the connecting rod 5 is fixedly connected with the outer end of the piezoelectric ceramic sheet 2, and the other end of the connecting rod 5 is connected to the integrated block 6 by screws. The metal slider 13 is connected. The ends of the two loading wires 17 and the two signal wires 18 are connected to the gold-plated silicon chip 10 and the metal slider 13 on the integrated block 6 and are detachable. The other end of the driving wire 19, the loading wire 17 and the signal wire 18 are drawn from the outer end of the handle 3 of the sample rod, so as to be convenient to connect with the external piezoelectric ceramic driving power supply 20 and the control power supply of the electrical measurement system 16, and the field generation testing instrument. connect. And ensure the tightness of the sample rod.

The structure of the integrated block 6 is shown in Figure 2: the rectangular parallelepiped shell 7 can be fixedly connected to the bearing base 4 by screws, and the integrated block 6 can be separated from the bearing base 4 by loosening the screws to realize independent operation and processing. The top and bottom of the cuboid housing 7 and the side close to the bearing base 4 are not closed, and the other parts are closed. The size of the cuboid shell 7 is designed according to the specification of the original sample rod. The first insulating spacer 8 and the second insulating spacer 9 are placed in parallel in the cuboid shell, and are fixed with it, and the second insulating spacer 9 is placed on one side near the bearing base 4, and the first insulating spacer is placed 8 is close to the closed end of the cuboid shell 7. A narrow slit with a width of 30-50 microns is provided between the first insulating spacer 8 and the second insulating spacer 9 to facilitate the passage of electron beams. A metal-plated silicon chip 10 is fixed on the first insulating spacer 8 , and a cantilever beam 11 is etched by an etching method at a side close to the slit. Two electrodes are drawn out from the upper surface of the metal-plated silicon wafer 10 for easy connection with two loading wires 17 and two signal wires 18 . The length of the cantilever beam 11 is 0.3 cm, the width is 600 nm, and the thickness is 800 nm. The gap between it and the gold-plated silicon chip is 5 microns. A slide rail 12 is fixed on the second insulating gasket 9, and a metal slide block 13 is installed on the slide rail 12. The metal slide block 13 can be fixed with the slide rail 12 by fastening screws 14, and the slide rail 12 is away from the cantilever arm 11. One end is provided with a protrusion, and the cross section of the slide rail 12 can be designed as a trapezoid. The upper surface of the cantilever beam 11 and the metal slider 13 are on the same level. A fine-tuning knob 15 is set in the projection on the slide rail 12, so that one end of the fine-tuning knob 15 can contact the metal slider 13, like this, the distance between the cantilever beam 11 and the metal slider 13 can be changed by adjusting the fine-tuning knob 15. gap. In order to show the relative position of each component more clearly, we have given two sectional views, Fig. 3 is a sectional view along the AB plane, Fig. 4 shows the second insulating gasket 9, slide rail 12, metal slider 13 and Cross-sectional view of the fastening screw 14 along the CD plane.

After adjusting the slit width between the cantilever beam 11 and the metal slider 13 to the desired width, tighten the fastening screw 14, and then place a single one-dimensional nanomaterial 21 on the gold-plated silicon wafer 10 and the on the metal slider 13, and then use focused electron beams to fix it on the cantilever beam 11 and the metal slider. Further fix the rectangular parallelepiped shell 7 and the metal slider 13 on the integrated block 6 with the bearing base 4 and the linkage rod 5 respectively. Put the whole sample rod into the transmission electron microscope and draw a good vacuum. Lead the other end of the driving wire 19, the loading wire 17 and the signal wire 18 to the outside of the sample rod, connect with the external piezoelectric ceramic driving power supply 20 and the control power supply of the electrical measurement system 16, and connect the field generation testing instrument, and then control the piezoelectric ceramic The driving power of the piezoelectric ceramic sheet 2 realizes the lateral displacement of the piezoelectric ceramic sheet 2. Since the inner end of the piezoelectric ceramic sheet 2 is fixed, the displacement is only carried out to the outside, which drives the linkage rod 5 and the metal slider 13 to move, and makes the metal slider 13 close to the cantilever Beam 11, thereby realizing uniaxial compression of one-dimensional nanomaterials. Further, the in-situ observation and recording system of the transmission electron microscope is used to record the deformation of the one-dimensional nanomaterial and the deformation of the cantilever beam 11, and the elastic modulus of the one-dimensional nanomaterial is calculated according to the deformation amount of the cantilever beam 11. At the same time, it can also be energized during the compression process of one-dimensional nanomaterials, so that the change of electrical properties can be measured while being compressed.

Claims (3)

1. force and electrical behavior testing device under Nanometer lines in-situ compressing in the transmission electron microscope, it is characterized in that: piezoelectric ceramic piece (2) is positioned in the sealed tube (1) of sample for use in transmitted electron microscope bar, piezoelectric ceramic piece (2) one ends are fixed, external two of stiff end drives lead (19), drive the external driving power of the other end (20) of lead (19), the other end of piezoelectric ceramic piece (2) joins with the trace (5) that is positioned in the groove that carries base (4), the other end of trace (5) joins by the metal slide block (13) in screw and the integrated package (6), carrying base (4) is terminated at the sealed tube (1) of sample for use in transmitted electron microscope bar, and the other end of carrying base (4) is connected to integrated package (6);

Being constructed as follows of described integrated package (6) is described: rectangular parallelepiped shell (7) top, bottom and a side are not sealed, claim that the side of not sealing is an openend, be called blind end with the corresponding side of openend, the openend of rectangular parallelepiped shell (7) is fixedly connected by screw and carrying base (4), first insulation spacer (8) is in to be placed horizontally on the same surface level in the rectangular parallelepiped shell (7) with second insulation spacer (9) and also fixes with it, second insulation spacer (9) is placed on the openend near rectangular parallelepiped shell (7), first insulation spacer (8) is placed on the blind end near rectangular parallelepiped shell (7), wherein the centre of first insulation spacer (8) and second insulation spacer (9) keeps the slit of a 30-50 micron, make the slit parallel with the openend of rectangular parallelepiped shell (7), secured in parallel one plating silicon chip (10) on first insulation spacer (8), it carves a semi-girder (11) near a side of second insulation spacer (9) by etching method, and makes overarm arm (11) also be parallel to the openend of rectangular parallelepiped shell (7).Fixing a slide rail (12) on the direction perpendicular to overarm arm (11) on second insulation spacer (9), slide rail (12) is provided with a projection away from an end of overarm arm (11), metal slide block (13) is installed on slide rail (12), it is fixing with slide rail (12) at the upper surface of metal slide block (13) trip bolt (14) to be installed, the upper surface of semi-girder (11) with metal slide block (13) is arranged on the same surface level, gap width between semi-girder (11) and the metal slide block (13) can be adjusted metal slide block (13) by vernier adjustment knob (15) and change, and vernier adjustment knob (15) is installed in the projection on the slide rail (12).

2. force and electrical behavior testing device under Nanometer lines in-situ compressing in a kind of transmission electron microscope according to claim 1, it is characterized in that: also comprise electrical measurement system (16), this electrical measurement system (16) loads lead (17) by two and two signal conductors (18) are connected with integrated package (6), load an end of lead (17) and the control power supply of electrical measurement system and join, the other end that loads lead (17) joins with semi-girder (11) and metal slide block (13) respectively; The field generation testing tool of signal conductor (18) one ends and electrical measurement system joins, and the other end of signal conductor (18) also joins with semi-girder (11) and metal slide block (13) respectively.

3. force and electrical behavior testing device under Nanometer lines in-situ compressing in a kind of transmission electron microscope according to claim 2 is characterized in that: described electrical measurement system comprises the control power supply, resistance, electric capacity, a generation testing tool.

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