Variable-range electron hopping, conductivity cross-over and space-charge relaxation in C60Br6
Dielectric spectroscopy is employed to probe the frequency-dependent conductivity and dipolar dielectric response of solid C60Br6. Below approximately 215 K, charge conduction is electronic and well described by Mott's variable-range polaron hopping model, with effective hopping activation ener...
| Autores: | , , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2016 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/96734 |
| Acceso en línea: | https://hdl.handle.net/2117/96734 https://dx.doi.org/10.1016/j.synthmet.2016.03.028 |
| Access Level: | acceso abierto |
| Palabra clave: | Dielectrics--Spectra Fullerenes--Electric properties Fullerene derivatives Organic molecular solid Universal dielectric response Dielectric spectroscopy Variable range hopping Relaxation loss PHASE-TRANSITION SOLID C60 DIELECTRIC RESPONSE FULLERENE C-60 DYNAMICS DIFFUSION C61H2 FULLERIDES TRANSPORT ISOMER Ful·lerens--Propietats elèctriques Dielèctrics Àrees temàtiques de la UPC::Física::Electromagnetisme::Conductivitat |
| Sumario: | Dielectric spectroscopy is employed to probe the frequency-dependent conductivity and dipolar dielectric response of solid C60Br6. Below approximately 215 K, charge conduction is electronic and well described by Mott's variable-range polaron hopping model, with effective hopping activation energy Ea varying between 0.12 eV at 125 K and 0.16 eV at 220 K, and most probable hopping range varying between 100 and 125% of the decay length of the localized polaron's wavefunction. Above 215 K a new contribution appears in the conductivity, accompanied by a weak endothermic feature in the calorimetric thermogram, which might signal a solid-solid phase transition. A broad dielectric loss feature is observed in the imaginary part of the permittivity. Such feature stems largely from a conductivity-related frequency-dependent loss associated with polaron hopping, as confirmed by the validity of the Barton-Nakajima-Namikawa condition. (C) 2016 Elsevier B.V. All rights reserved. |
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