High-temperature annealing effects on multiwalled carbon nanotubes: electronic structure, field emission and magnetic behaviors.
This work elucidates the effects of high-temperature annealing on the microscopic and electronic structure of multiwalled carbon nanotubes (MWCNTs) using high-resolution transmission electron microscopy, micro-Raman spectroscopy, X-ray diffraction, X-ray absorption near-edge structure (XANES) and valence-band photoemission spectroscopy (VBPES), respectively. The field emission and magnetization behaviors are also presented. The results of annealing are as follows: (1) MWCNTs tend to align in the form of small fringes along their length, promote graphitization and be stable in air, (2) XANES indicates an enhancement in oxygen content on the sample, implying that it can be adopted for sensing and storing oxygen gas, (3) the electron field emission current density (J) is enhanced and the turn-on electric field (E(TOE)) reduced, suggesting potential use in field emission displays and as electron sources in microwave tube amplifiers and (4) as-grown MWCNTs with embedded iron nanoparticles exhibits significantly higher coercivity approximately 750 Oe than its bulk counterpart (Fe(bulk) approximately 0.9 Oe), suggesting its potential use as low-dimensional high-density magnetic recording media.
Ray
Sekhar Chandra
SC
Department of Physics, Tamkang University, Tamsui 251, Taiwan.
Pao
Chih-Wen
CW
Tsai
Huang-Ming
HM
Chen
Huang-Chin
HC
Chen
Yu-Shin
YS
Wu
Shang-Lun
SL
Ling
Dah-Chin
DC
Lin
I-Nan
IN
Pong
Way-Faung
WF
Gupta
Sanju
S
Giorcelli
Mauro
M
Bianco
Stefano
S
Musso
Simone
S
Tagliaferro
Alberto
A