Study On Conductance Calculation Of Carbon Nanotubes And Relative Experiments

Carbon Nanotubes(CNTs) are advanced materials with many potential applications. However, there is no effective and convictive method to calculate their conductance till now, which prevented its development seriously. In this paper, an optimal model was chosen to calculate CNT films'conductance after contrasting and analyzing large numbers of literature. Related experiments had been done to demonstrate the model. Stress and doped effect of CNT films were also been studied. We analyzed the data, finding good match between the calculation and experiments.Firstly, according to analyzing some regular principles and models to calculate CNTs'conductance after introducing their structures, the most optimal model-- Heterogeneous Fibrillar Model has been proposed to compute CNT films'conductance, and the formulas of resistivity and conductance for CNT films have been obtained on the base of Neugebauer-Webb Theory and triangle barrier model. the TCRs have been calculated by using these formulas. Then we measured the resistance of CNT films with different diameters under different temperature. It is found that the resistance of single-walled carbon nanotube (SWNT) film increases with increasing of temperature, indicating metal behavior, while the resistance of multi-walled carbon nanotube (MWNT) films exhibite a crossover from decreasing to increasing resistance with temperature increasing, the cross temperature ranged from 338K to 358 K, much higher than the former results. It is also showed that the TCR of MWNT films had an inverse proportion to their diameters, being consistent with our computation result.Furthermore, this paper firstly exams piezoresistive effect of CNT films with different diameters and their acceleration sensing based on piezoresistive effect. The experimental results indicate that the fractional increase in resistance increases linearly versus the increase of strain; In the case of MWNT film, the slope increases with the decrease of diameters; for SWNT film, the resistance just has very slight change when the strain vary; Piezoresistive sensitivity reduces with the accretion of the diameters for MWNT films up to 800 micro strain. The experimental results also show that centripetal acceleration of MWNT films exhibites a well linear behavior with strain under low strain (beneath 0.7×10-6). But up to 0.7×10-6, the linear behavior is weaken while the acceleration having a sharp increase of the slope. All the results above were explained, and the potential application of MWNT films for acceleration sensor is demonstrated.