Eric Faulques (DR)
Achieving confined crystal growth in one dimension (1D) of semiconducting and insulating materials inside small diameter carbon nanotubes is a topic of great physical interest which has been successfully realized by several groups in the world using various synthesis methods. These tiny 1D crystals have no analogues in the 3D realm and their bulk physical properties can be profoundly changed by encapsulation. British scientists at the University of Warwick have coined these crystalline structures “extreme nanowires” since they are ultimately thin (one or two-atom thick for the smallest diameters). Furthermore, filled carbon nanotubes can have their own electronic properties drastically modified due to the charge transfer induced by electron-donor or electron-acceptor fillers. Aside from molecular species, clusters, fullerenes, graphene nanoribbons, and elemental forms, a wide variety of binary crystals have been encapsulated in carbon nanotubes like oxides/hydroxides, metal halides, and chalcogenides.
In collaboration with the Warwick team we have carried out the filling of single-walled carbon nanotubes (SWNTs) with binary crystals of KI and HgTe by melt infiltration. High-resolution transmission electron microscopy reveals that the crystal structure of these objects belongs to the rod symmetry group #29 (p42/m).
Raman experiments performed at University of Southampton and at IMN on the filled nanotubes show the appearance of new vibrational modes in the low-frequency region and changes of the G-band position. These modifications can be ascribed to specific vibrations of the encapsulated linear crystals and to their interaction with the nanotube walls. The equilibrium structures of the isolated 1D nanocrystals (~ 1 nm diameter) have been determined by periodic DFT calculations at IMN. For HgTe@SWNT, electronic calculations show the opening of an energy gap of ~1.35 eV in contrast to the gapless band structure of the 3D HgTe topological insulator. Furthermore, the DFT-calculated frequencies are in fair correspondence with the experimental Raman spectra.
The studies demonstrate that stable 1D crystalline nanowires with remarkable electronic and vibrational properties can be grown inside small diameter SWNTs. Such nanocomposites are extremely promising for nanoelectronics applications like p-n junctions with encapsulated donor and acceptor moieties, and spintronics. Experimental and theoretical investigations are planned for other binary chalcogenides in collaboration with the Department of Condensed Matter Physics, University of Sofia (Bulgaria).
|Figure 1. Left panel: Ball-and-stick model of an HgTe extreme nanowire encapsulated in a SWNT of 1 nm diameter. The 1D crystal can be detected with Raman spectroscopy and gives two experimental Raman modes at 47 and 51 cm-1 stemming from radial vibrations (lexc = 1.76 eV). Right panel: DFT calculations of the HgTe nanowire: optimized structure (top), absorption spectra, and electronic band structure using CASTEP.|
two-year joint Project Hubert Curien RILA 2017-2018, #38661ZF “Electronic and optical properties of extreme nanowires” funded by French Ministry of Foreign Affairs and International Development (MAEDI), French MENESR, and the Bulgarian Ministry of Education and Science.
Eric Faulques (DR)
- Prof. Victor Genchev Ivanov, Prof. Miroslav Abrashev, Dr. Neno Todorov, Department of Condensed Matter Physics, University of Sofia (Bulgaria)
- Prof. Jeremy Sloan, Team Leader, Department of Physics, University of Warwick (UK)
- Prof. D. C. Smith, School of Physics and Astronomy, University of Southampton (UK)
Students (2017) : M. Nicolas, V. Villory
High-precision imaging of an encapsulated Lindqvist Ion and correlation of its structure and symmetry with quantum chemical calculations
E.Bichoutskaia, Z. Liu, N. Kuganathan, E. Faulques, K.Suenaga, I.J. Shannon, J. Sloan, Nanoscale 4, 1190 (2012).
Aberration corrected imaging of a carbon nanotube encapsulated Lindqvist Ion and correlation with Density Functional Theory
J Sloan, E Bichoutskaia, Z Liu, N Kuganathan1, E Faulques, K Suenaga, I J Shannon, J of Phys.:Conf. Ser. 371, 012018 (2012).
Raman spectroscopy of optical transitions and vibrational energies of 1nm HgTe extreme nanowires within single walled carbon nanotubes
J.H. Spencer, J. M. Nesbitt, H. Trewhitt, R. J. Kashtiban, G. Bell, V. G. Ivanov, E. Faulques, J. Sloan, D. C. Smith, ACS Nano 9, 9044-9052 (2014).
A new method for controlling the quantized growth of dendritic nanoscale point contacts via switchover and shell effects
A. P. Pospelov, A. I. Pilipenko, G. V. Kamarchuk, V. V. Fisun, I. K. Yanson, and E. Faulques, J. Phys.Chem. C 119, 632-639 (2015).
Dynamics of charge migration in poly(para phenylene vinylene) films and nanocomposites with single walled carbon nanotubes
E. Mulazzi, D. E. Galli, F. Massuyeau, S. Lefrant, J. Wéry, E. Faulques, J. Phys. Cond. Mat. 28, 045304, (2016).
Resonance Raman Spectroscopy of Extreme Nanowires and other 1D systems
Smith, D. C; Spencer, J.H ; Sloan, J.; McDonnell,L. P; Faulques, E., J. Vis. Exp. 110, e53434 (2016). DOI: 10.3791/53434 Open.
- Key note lecture: E. Faulques, University of Warwick, September 2017, UK
- Invited: E. Faulques, Functional nanowires, Global Congress & Expo on Materials Science & Nanoscience, October 24-26, 2016 Dubai, UAE
- Invited : J. Sloan et al, E. Faulques, Extreme nanowires: the smallest crystals in the smallest nanotubes, European Microscopy Congress 2016, Lyon
- Invited : V. G. Ivanov, D. C. Smith, J. Sloan and E. Faulques, Crystallography and Raman-Spectroscopy Markers for 1-D Nanorods Encapsulated in Single-Wall Carbon Nanotubes, INERA Conference 2015: Light in Nanoscience and Nanotechnology (LNN 2015), 20-22 October, Hissar, Bulgaria.
- Invited: E. Faulques, Studies of crystalline nanowires grown inside carbon nanotubes, ISSMD-3, 5-7 February 2015, Chennai, India
- Invited:E. Faulques, Modelling carbon-nanotube confined nanomaterials, NanoTec14, Bruxelles, 20-23 August 2014, Brussels, Belgium
- Invited : E. Faulques, Hybrid nanowires and nanofibrils, Nanobiophysics : Fundamental and Applied Aspects, 7-10 October 2013, Kharkov, Ukraine
- Invited : E. Faulques, Functional hybrid nanofibers based on carbon nanotubes, International Conference on Optoelectronic Materials and Devices, Qingdao University, 26-28 October 2012, Qingdao, China
- Oral talk:E. Faulques, Modelling the encapsulation of alkali iodides in single-walled carbon nanotubes, International Conference on Nanoscience + Technology 2012, 23-27 July 2012, Paris