Home > Public Relations > Events > 2018 > The 124th AMCP Open Seminar

The 124th AMCP Open Seminar

In-situ experiments on low-dimensional materials inside the transmission electron microscope

Schedules 2018.05.10 Finished


Date & Time

Thursday, May 10, 2018 15:00-16:00

Venue

National Institute for Materials Science (NIMS)
Sengen Main Bldg. 8F Middle Seminar Room  → access

Registration

Pre-registration is not required.
For inquiries, please contact the Administrative Office.
This lecture is open to the public. Your participation is strongly encouraged.

Speaker

Dr. Ovidiu Cretu (ICYS Researcher)

Title

In-situ experiments on low-dimensional materials inside the transmission electron microscope

Abstract

In this talk I will show some results which have been obtained by performing in-situ experiments on 2D monolayered nanosheets and 1D individual nanotubes and nanowires inside a transmission electron microscope (TEM).

The first part of the talk discusses the idea of electron irradiation damage in a very beam-sensitive material - hexagonal boron nitride. I will show that the interplay between electron irradiation and sample temperature allows us to obtain a wide range of new structures. This includes well-known defects with triangular symmetry, but also completely new configurations, such as hexagonal-shaped and boron-terminated vacancies or - in more extreme cases - boron nitride atomic chains. Due to the nature of the experiments, these structures can be immediately characterized. The data is discussed in relation to various damage mechanisms, showing that the transformations are determined by an interplay between electron irradiation and thermally-enhanced reconstructions. In support of these findings, I will show that electron beam damage in this material can be completely avoided by overlapping the sample with a monolayer of graphene.

The second part of the talk shows data acquired on carbon nanotubes and CdS nanowires inside the TEM, using a combination of commercial and custom-made instrumentation. This approach is centered on sample holders which allow for an optical fiber and/or a metallic probe to be positioned close to the region of interest of the sample, via a piezoelectric mechanism, with nanometer precision. Firstly, I will show the possibility of mapping the luminescence centers in CdS nanowires through cathodoluminescence. The results reveal the distribution of centers with nanometer-precision, and then associate them to various intrinsic defects in CdS. Subsequent experiments improve on the previous method and describe optoelectronic measurements. CdS nanowires are probed before, during and after mechanical bending, revealing details such as their optical ON/OFF ratios and wavelength-dependent photocurrent generation. Lastly, I will introduce the idea of carbon nanotube telescoping and highlight the stability of these structures, which remain electrical conductive while extended and recover their initial properties once retracted, over the course of several cycles.


Summary

Event Title
The 124th AMCP Open Seminar
In-situ experiments on low-dimensional materials inside the transmission electron microscope
Venue
National Institute for Materials Science (NIMS)
Sengen Main Bldg. 8F Middle Seminar Room
Schedules Hours
2018.05.10
15:00~16:00
Registration Fee
Free

Contact

Research Center for Advanced Measurement and Characterization Administrative Office
National Institute for Materials Science
1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan
Tel:81-29-859-2643/2839
Fax:81-29-859-2801
E-Mail: amc=ml.nims.go.jp(Please change "=" to "@")
2018.08
Sun Mon Tue Wed Thu Fri Sat
1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

National Institute for Materials Science (NIMS)
1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, JAPAN
TEL.+81-(0)-29-859-2000
FAX.+81-(0)-29-859-2029