Spectroscopic analysis of multi-walled carbon nanotube–alumina composite films: Optimization of temperature coefficient of resistance and thermal hysteresis for thermal sensor applications

In this paper, we report a novel approach to study the potential use of multi-walled carbon naotubes (MWCNTs)–alumina (Al2O3) composite for heat sensing applications. This is achieved by optimizing the temperature coefficient of resistance (TCR) and thermal hysteresis of the composite. The composites were developed by uniform dispersion of MWCNTs in alumina in different concentrations following sol‐gel route. MWCNT loading in the alumina was found to be very effective to control the TCR as well as the hysteresis loss. The room temperature TCR versus MWCNTs concentration plot first shows an increasing trend with increase of MWCNTs concentration in the composite and reaches a threshold followed by drop in TCR. The maximum value of TCR that has been achieved is −0.56%/°C for 4 wt% MWCNTs content and is found to be ~1.5 times higher than the conventional metals and semiconductors. The hysteresis loss was found to decrease gradually to almost zero from 5 wt% onwards. The TCR and hysteresis variation is correlated with MWCNTs concentration dependent Raman, FESEM, EDS studies in the composite and there is a fair agreement in support of the observations.