Nitrogen Doping of Carbon Nanotubes Synthesized in Flowing Acetylene and Ammonia
- PDF / 1,130,848 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 67 Downloads / 195 Views
ogen Doping of Carbon Nanotubes Synthesized in Flowing Acetylene and Ammonia S. V. Bulyarskiya, V. S. Gorelikb, c, *, and R. M. Ryazanova, d aInstitute
of Nanotechnology of Microelectronics, Russian Academy of Sciences, Moscow, 115487 Russia Lebedev Physical Institute, Russian Academy of Sciences, Moscow, 119991 Russia c Bauman Moscow State Technical University, Moscow, 105005 Russia dTechnological Centre Scientific–Manufacturing Complex, Zelenograd, Moscow, 124498 Russia *e-mail: [email protected] bP.N.
Received January 16, 2020; revised May 11, 2020; accepted May 18, 2020
Abstract—A method has been demonstrated for doping carbon nanotubes (CNTs) with nitrogen during synthesis in an acetylene + ammonia atmosphere at different temperatures in the range 550–750°C, and conditions have been found for effective nitrogen doping of CNTs depending on synthesis temperature. The concentrations of various elements in the synthesized CNTs have been determined by X-ray photoelectron spectroscopy. Raman measurements with the use of a Raman microscope have made it possible to follow variations in the relative intensities of the G and D bands as functions of nitrogen dopant concentration in the CNTs. We have detected strong Raman overtone combination satellites whose parameters depend on the structural perfection of the synthesized CNTs. Keywords: nanotube, laser, synthesis, defects, Raman scattering, doping, structure, concentration DOI: 10.1134/S0020168520100027
INTRODUCTION Carbon nanotubes (CNTs) are unique physical objects attracting researchers’ attention in the context of both basic science and the development of new devices for microelectronics, hydrogen energy technology, and nonlinear optics. The physical properties of as-prepared CNTs can be modified via doping with and adsorption of various components: oxygen, boron, hydrogen, nitrogen [1–8], and other elements. Nitrogen doping of CNTs is of interest primarily from the viewpoint of controlling their electrical conductivity owing to the generation of additional electrons, which are detached from pentavalent nitrogen atoms substituting for tetravalent carbon in the cylindrical graphene shell of CNTs. Several types of defects related to the incorporation or adsorption of nitrogen are known to be possible in multiwalled CNTs [1–3, 7, 8]. Note that nitrogen can be incorporated into the graphene lattice in several ways. In most cases, nitrogen incorporated into carbon structures acts as a donor, raising the electron concentration up to the level of metallic conduction [1]. The incorporation of nitrogen distorts the graphene structure because C–N chemical bonds are shorter than C–C bonds. This gives rise to additional stress in the structure, reducing the diameter of the nanotubes and changing their morphology, for example, leading to the formation of a so-called bamboo structure [1, 9].
At present, Raman spectroscopy is widely used to probe the dynamics of structures and phase states in condensed media, including nitrogen-doped CNTs grown by chemical vapor depositio
Data Loading...
