title: AC Conduction and Time-Temperature Superposition Scaling in a Reduced Graphene Oxide-Zinc Sulfide Nanocomposite.
abstract: We report, herein, the results of an in depth study and concomitant analysis of the AC conduction [σ'(ω): f=20 Hz to 2 MHz] mechanism in a reduced graphene oxide-zinc sulfide (RGO-ZnS) composite. The magnitude of the real part of the complex impedance decreases with increase in both frequency and temperature, whereas the imaginary part shows an asymptotic maximum that shifts to higher frequencies with increasing temperature. On the other hand, the conductivity isotherm reveals a frequency-independent conductivity at lower frequencies subsequent to a dispersive conductivity at higher frequencies, which follows a power law [σ'(ω)∝ω(s) ] within a temperature range of 297 to 393 K. Temperature-independent frequency exponent 's' indicates the occurrence of phonon-assisted simple quantum tunnelling of electrons between the defects present in RGO. Finally, this sample follows the "time-temperature superposition principle", as confirmed from the universal scaling of conductivity isotherms. These outcomes not only pave the way for increasing our elemental understanding of the transport mechanism in the RGO system, but will also motivate the investigation of the transport mechanism in other order-disorder systems.
authors: Department of Physics and Technophysics, Vidyasagar University, Midnapore, 721102, India.
authors: Koushik
authors: K
authors: Chakraborty
authors: Department of Physics, Midnapore College, Midnapore, 721101, India.
authors: Poulomi
authors: P
authors: Das
authors: Department of Physics and Technophysics, Vidyasagar University, Midnapore, 721102, India.
authors: Sankalpita
authors: S
authors: Chakrabarty
authors: Department of Physics, Midnapore College, Midnapore, 721101, India. tanusri.pal@gmail.com.
authors: Tanusri
authors: T
authors: Pal
authors: Department of Physics and Technophysics, Vidyasagar University, Midnapore, 721102, India. surajit@mail.vidyasagar.ac.in.
authors: Surajit
authors: S
authors: Ghosh
keywords: AC conductivity; conductivity scaling; electronic transport; graphene composites; quantum tunnelling