| Abstract [eng] |
The purpose of this work is to investigate the resistivity, charge transfer mechanisms and low-frequency noise characteristics of hybrid composites with single-wall (SWCNT) and multi-wall (MWCNT) carbon nanotubes. Investigated composite materials were prepared by combining polydimethylsiloxane (PDMS) and different concentrations of CNTs. Measurements of specific resistivity and low-frequency (10 Hz – 20 kHz) electric noise voltage fluctuation characteristics were carried out at room temperature in a voltage range of (4.5–55) V, as well as under fixed voltage in a temperature range of (75–355) K. The specific resistance of the investigated composites relates to the filler concentration; composites with higher filler concentrations exhibit lower specific resistance. SWCNT composites exhibit lower specific resistance than hybrid SWCNT/MWCNT composites with equivalent total filler concentrations. At low temperatures ((75–175) K), the temperature dependence of specific resistance is well-fitted by Arrhenius’ thermal activation and fluctuation-induced tunneling models. The dominant charge transfer mechanism in this temperature range is said to be thermal activation of charge carriers with activation energies of (4.67–5.27) meV. After being heated at temperatures above 350 K, the specific resistance of the composites exhibits irreversible change upon cooling due to the changes in the percolation network induced by the thermal expansion and constriction of the polymer matrix. Voltage fluctuations of the investigated composites consist largely of 1/f and 1/fα type noise. Generative–recombinative components with characteristic times of 1 ms are identifiable at low temperatures ((75–100) K) At room temperature, the low-frequency voltage noise spectra are proportional to the voltage square. |
