Temperature-Dependent Electrical and Thermal Conductivity of Glassy Carbon Wires

Glassy carbon nanowires show potential as nano-gap electrode devices and gas sensors; however, its properties have not been fully explored. After previously reporting the size-dependent electrical and thermal conductivities of electrospun glassy carbon wires, here, we report how these properties change with temperature. We measured the electrical and thermal conductivities using the 4-probe technique from room temperature to 600 K. The resulting linear increase of both properties with the temperature indicates that the electrons and phonons are being thermally activated and that the lattice disorder dominates the scattering of the carriers. We find the electron activation energy to be between 8.5 and 14 meV, depending on the sample. In addition, we use local Joule heating to study the effect of high temperatures up to the sublimation point, including the mean change in electrical and thermal conductivity and the mechanical stability of the structure. Wires shorter than 40 mu m preserved its shape and all samples undergo an annealing process when the maximum temperature surpasses 800 K. Moreover, we explored how non-uniformities in the wire diameter change the temperature profile. The outcomes of this work will enable precise understanding of temperature dependent processes in glassy carbon and promote the development of glassy carbon-based sensors.