Dalian University of Technology

Junfeng Cui

Zhenyu Zhang

Dongming Guo

Bo Wang

Leilei Chen

Dongdong Liu

Yuefeng Du

A TEM electromechanical in-situ testing method of one-dimensional materials is provided. A multi-function sample stage which can compress, buckle and bend samples is designed and manufactured. A carbon film on a TEM grid of Cu is eliminated, and the TEM grid of Cu is cut in half through the center of the circle. The samples are dispersed ultrasonically in alcohol and dropped on the edge of the semicircular grid of Cu with a pipette. A single sample is fixed on the edge of a substrate of the sample stage with conductive silver epoxy by using a micromechanical device under an optical microscope, and conductive silver paint is applied to the surface of the substrate of the sample stage; and an electromechanical in-situ testing is conducted in a TEM. This provides a simple and efficient sample preparation and testing method for a TEM electromechanical in-situ observing experiment.

TEM electromechanical in-situ testing method of one-dimensional materials

A method of in-situ TEM nanoindentation for a damaged layer of silicon is disclosed. Wet etching and ion beam lithography are used for preparing a silicon wedge sample. An etched silicon wedge is thinned and trimmed by a focused ion beam; thinning uses ion beam of 30 kV: 50-80 nA, and trimming uses ion beam of 5 kV: 1-6 pA; and the top width of the silicon wedge is 80-100 nm. The sample is fixed on a sample holder of an in-situ TEM nanomechanical system by using a conductive silver adhesive. The sample is indented with a tip in the TEM, so that the thickness of the damaged layer of the sample is 2-200 nm; and an in-situ nanoindentation experiment is conducted on the damaged layer of the sample in the TEM.

Method of in-situ TEM nanoindentation for damaged layer of silicon

A self-healing method for fractured single crystal SiC nanowires. A hair in a Chinese brush pen of yellow weasel's hair moves and transfers nanowires, which are placed on an in-situ TEM mechanical microtest apparatus. An in-situ nanomechanical tension test is realized. The nanowires are loaded. Displacement is 0-200 nm. Fracture strength of the single crystal nanowires is 12-15 GPa. After the nanowires are fractured, unloading causes slight contact between the fractured end surfaces, electron beam is shut off, and self-healing of the nanowires is conducted in a vacuum chamber. Partial recrystallization is found at a fracture after self-healing through in-situ TEM representation. A fracture strength test is conducted again after self-healing. A fractured position after healing is the same as the position before healing. The fracture strength of the single crystal nanowires after self-healing is 1-2.5 GPa. The recovery ratio of the fracture strength is 10-20%.

Self-healing method for fractured SiC single crystal nanowires

The present invention provides a self-healing method for fractured SiC amorphous nanowires. A goat hair in a Chinese brush pen of goat hair moves and transfers single crystal nanowires under an optical microscope. On an in-situ nanomechanical test system of a TEM, local single crystal nanowires are irradiated with an electron beam for conducting amorphization transformation. Amorphous length of a single crystal after transformation is 60-100 nm. A fracture strength test is conducted on the amorphous nanowires in the single crystal after transformation in the TEM; and fracture strength of the amorphous nanowires is 9-11 GPa. After the amorphous nanowires are fractured, unloading causes a slight contact between the fractured end surfaces; and self-healing of the nanowires is conducted after waiting for 16-25 min in a vacuum chamber of the TEM. Atom diffusion is found at a healed fracture through in-situ TEM representation; and recrystallization is found in the amorphous nanowires. The present invention provides a method for realizing self-healing for fractured SiC amorphous nanowires without external intervention.

Self-healing method for fractured SiC amorphous nanowires

The present invention provides a method for moving and transferring nanowires using tapered hair of diameter in micron range. The nanowires have a diameter of 60-150 nm. The tapered hair has a diameter of 1-100 &#x3bc;m, a tip curvature radius of 0.8-3 &#x3bc;m and a length of 4-10 mm. A plastic film on a copper grid used for a TEM is removed, the copper grid is reserved, and holes have a diameter of 50-100 &#x3bc;m. The copper grid after ultrasonic cleaning gains the nanowires from the acetone liquid with ultrasonic dispersed nanowires. The copper grid with distributed nanowires and the tapered hair are respectively placed on mobile platforms of two different optical microscopes. Millimeter movement and micron movement of the tapered hair are realized, thereby realizing movement and transfer operation for the nanowires. The tip of the tapered hair is dipped in a small drop of conductive silver epoxy, and the conductive silver epoxy is respectively dropped on both ends of the nanowires; and the radius of the dropped conductive silver epoxy is 4-8 &#x3bc;m. The present invention realizes a method for moving and transferring nanowires using tapered hair through the mobile platforms of the two optical microscopes.

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Dalian, China

Junfeng Cui