Tuning the conduction mechanism in niobium-doped titania nanoparticle networks

0361372 - FZÚ 2012 RIV US eng J - Journal Article
Němec, Hynek - Mics, Zoltan - Kempa, Martin - Kužel, Petr - Hayden, O. - Liu, Y. - Bein, T. - Fattakhova-Rohlfing, D.
Tuning the conduction mechanism in niobium-doped titania nanoparticle networks.
Journal of Physical Chemistry C. Roč. 115, č. 14 (2011), s. 6968-6974. ISSN 1932-7447. E-ISSN 1932-7455
R&D Projects: GA ČR(CZ) GP202/09/P099; GA AV ČR(CZ) IAA100100902
Institutional research plan: CEZ:AV0Z10100520
Keywords : time-domain terahertz spectroscopy * electron transport * transparent conductors * doped TiO₂
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 4.805, year: 2011

Networks of niobium-doped TiO2 anatase nanoparticles with variable doping concentrations were investigated by time-domain terahertz spectroscopy and microwave impedance spectroscopy. A detailed description of their electromagnetic response is proposed; the model takes into account the depolarization fields of inhomogeneous samples and allows us to understand the conductive and dielectric response of individual nanoparticles. We find that electron hopping is the dominating contribution to the conductivity at terahertz frequencies and that the dielectric losses of TiO2 nanoparticles are enhanced in comparison with bulk anatase. The conductive properties of nanoparticles can be tuned via synthesis conditions and thermal posttreatment. In particular, annealing at elevated temperatures improves the nanoparticle crystallinity, reduces the density of structural defects, and enhances the conductive percolation of the network.
Permanent Link: http://hdl.handle.net/11104/0198695