Electrical and optical properties of MWNTs/HDPE composites in Terahertz region

Electrical and optical properties of MWNTs/HDPE composites in Terahertz region 1 2 first-author 3 2 corresp Corresponding author. E-mail address: zhuzhiyong@sinap.ac.cn Corresponding author. E-mail address: zhuzhiyong@sinap.ac.cn zhuzhiyong@sinap.ac.cn Yellow River Conservancy Technical Institute, Kaifeng 475004, China Yellow River Conservancy Technical Institute, Kaifeng 475004, China Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China Optical and electrical properties of composites, prepared by filling of high density polyethylene (HDPE) with two kinds of multi-walled carbon nanotubes (MWNTs) differing in diameters, were explored by terahertz time-domain spectroscopy (THz-TDS) in the frequency range from 0.2 to 1.6 THz. It is found that composite with larger-diameter MWNTs possesses larger absorption coefficient and conductivity at the same concentration. The real part of the ac conductivity of the composites follows a power law dependence on frequency. And the power index is around 0.75 regardless of the MWNT concentration and diameter. The experimental data were analyzed with Cole-Cole equation under the assumption that the conductive clusters dispersed in the polymer matrix behave like dipoles and contribute mainly to the dielectric loss. It is found that both of the composites have similar values of relaxation time and distribution parameter. With increase of the MWNTs concentration, the relaxation time increases and tends to saturate at 0.7 ps after passing through the percolation threshold. Carbon nanotubes Transport properties Terahertz time-domain spectroscopy Cole-Cole equation References Han P Y , Tani M , Usami M , et al . J Appl Phys , 2001 , 89 : 2357 - 2359 . J Appl Phys Popov V N . Mat Sci Eng R , 2004 , 43 : 61 - 102 . Mat Sci Eng R Kymakis E , Amaratunga G A J . Appl Phys Lett , 2002 , 80 : 112 - 114 Appl Phys Lett Seo M A , Lee J W , Kim D S . J Appl Phys , 2006 , 99 : 066103 - 066106 . J Appl Phys Hecht D , Hu L B , Grüner G . Appl Phys Lett , 2006 , 89 : 133112 - 133114 . Appl Phys Lett Jeon T I , Son J H , An G H , et al . J Appl Phys , 2005 , 98 : 034316 - 4 . J Appl Phys Jeon T I , Son J H , An G H , et al . J Korean Phys Soc , 2001 , 39 : S185 - S188 . J Korean Phys Soc Chen X L , Ma M W , Yang X M , et al . Nucl Sci Tech , 2009 , 20 : 265 - 270 . Nucl Sci Tech Chen X L , Ma M W , Song Y F , et al . Spectrosc Spect Anal , 2011 , 31 : 906 - 910 . Spectrosc Spect Anal Chen X L , Ma M W , Yang X M , et al . Acta Phys Chim Sin , 2008 , 24 : 1969 - 1974 . Acta Phys Chim Sin Duvillaret L , Garet F , Coutaz J L . IEEE J Sel Top Quantum Electron , 1996 , 2 : 739 - 746 . IEEE J Sel Top Quantum Electron Adriaanse L J , Reedijk J A , Teunissen P A A , et al . Phys Rev Lett , 1997 , 78 : 1755 - 1758 . Phys Rev Lett Song Y , Noh T W , Lee S I , et al . Phys Rev B , 1986 , 33 : 904 - 909 . Phys Rev B Gefen Y , Aharony A , Alexander S . Phys Rev Lett , 1983 , 50 : 77 - 80 . Phys Rev Lett Hu L , Hecht D S , Gruner G . Nano Lett , 2004 , 4 : 2513 - 2517 . Nano Lett Durkop T , Getty S A , Cobas E , et al . Nano Lett , 2004 , 4 : 35 - 39 . Nano Lett Calame J P . J Appl Phys , 2003 , 94 : 5945 - 5957 . J Appl Phys Yamanaka S , Fukuda T , Sawa G , et al . IEEE Trns Electr Insul , 1992 , 27 : 1073 - 1082 . IEEE Trns Electr Insul 10.13538/j.1001-8042/nst.23.156-162 Supported by National Natural Science Foundation of China (10675157) and (10875161) and by the National Basic Research Program of China (Grant No. 2010CB832903) 2011-10-09 2012-06-20 2021-01-19 2012 Nuclear Science and Techniques 03 23