AC electrical properties of TiO2 and Magnéli phases, TinO2n−1

D. Regonini, V. Adamaki, C.R. Bowen, A.C.E. Dent, S.R. Pennock, John Taylor

Research output: Contribution to journalArticle

  • 25 Citations

Abstract

This paper presents a comprehensive impedance spectroscopy comparison of the AC properties of dense stoichiometric TiO2 and conductive TinO2n − 1 Magnéli phases over a broad temperature range (up to 1000 °C for TiO2 and 375 °C for TinO2n − 1). The frequency dependent conductivity and permittivity of both materials is explained in terms of “universal” power law behaviour. A deviation from the law, with a giant relative permittivity which is largely independent of frequency from 0.1 Hz to 100–200 kHz is observed in the case of TinO2n − 1, due to the presence of residual TiO2 generating an Internal Barrier Layer Capacitor (IBLC) effect. The real–imaginary impedance plots are interpreted using an RC model and allow separation of the contribution of the grain bulk and the grain boundaries to the total resistivity of the material. In the case of the TinO2n − 1 based materials this confirms that the IBLC effect is generated by insulating grain boundaries. The conduction mechanism in both TiO2 and TinO2n − 1 appears to be dominated by electronic conductivities, activated mainly through shallow donor levels up to 200 °C and over the entire band gap, which is narrower for TinO2n − 1, above 200 °C. A deeper understanding of the AC properties of Magnéli phases of Ti at different temperatures aids in the optimisation of electrical properties for a variety of sensor and electrical applications.
LanguageEnglish
Pages38-44
Number of pages7
JournalSolid State Ionics
Volume229
DOIs
StatusPublished - 14 Dec 2012

Fingerprint

barrier layers
alternating current
capacitors
Electric properties
grain boundaries
electrical properties
impedance
permittivity
conductivity
Grain boundaries
Capacitors
Permittivity
plots
deviation
conduction
electrical resistivity
optimization
temperature
sensors
Energy gap

Cite this

AC electrical properties of TiO2 and Magnéli phases, TinO2n−1. / Regonini, D.; Adamaki, V.; Bowen, C.R.; Dent, A.C.E.; Pennock, S.R.; Taylor, John.

In: Solid State Ionics, Vol. 229, 14.12.2012, p. 38-44.

Research output: Contribution to journalArticle

@article{60c71d9625d145cb8c941c2dcf2798da,
title = "AC electrical properties of TiO2 and Magn{\'e}li phases, TinO2n−1",
abstract = "This paper presents a comprehensive impedance spectroscopy comparison of the AC properties of dense stoichiometric TiO2 and conductive TinO2n − 1 Magn{\'e}li phases over a broad temperature range (up to 1000 °C for TiO2 and 375 °C for TinO2n − 1). The frequency dependent conductivity and permittivity of both materials is explained in terms of “universal” power law behaviour. A deviation from the law, with a giant relative permittivity which is largely independent of frequency from 0.1 Hz to 100–200 kHz is observed in the case of TinO2n − 1, due to the presence of residual TiO2 generating an Internal Barrier Layer Capacitor (IBLC) effect. The real–imaginary impedance plots are interpreted using an RC model and allow separation of the contribution of the grain bulk and the grain boundaries to the total resistivity of the material. In the case of the TinO2n − 1 based materials this confirms that the IBLC effect is generated by insulating grain boundaries. The conduction mechanism in both TiO2 and TinO2n − 1 appears to be dominated by electronic conductivities, activated mainly through shallow donor levels up to 200 °C and over the entire band gap, which is narrower for TinO2n − 1, above 200 °C. A deeper understanding of the AC properties of Magn{\'e}li phases of Ti at different temperatures aids in the optimisation of electrical properties for a variety of sensor and electrical applications.",
author = "D. Regonini and V. Adamaki and C.R. Bowen and A.C.E. Dent and S.R. Pennock and John Taylor",
year = "2012",
month = "12",
day = "14",
doi = "10.1016/j.ssi.2012.10.003",
language = "English",
volume = "229",
pages = "38--44",
journal = "Solid State Ionics",
issn = "0167-2738",
publisher = "Elsevier",

}

TY - JOUR

T1 - AC electrical properties of TiO2 and Magnéli phases, TinO2n−1

AU - Regonini,D.

AU - Adamaki,V.

AU - Bowen,C.R.

AU - Dent,A.C.E.

AU - Pennock,S.R.

AU - Taylor,John

PY - 2012/12/14

Y1 - 2012/12/14

N2 - This paper presents a comprehensive impedance spectroscopy comparison of the AC properties of dense stoichiometric TiO2 and conductive TinO2n − 1 Magnéli phases over a broad temperature range (up to 1000 °C for TiO2 and 375 °C for TinO2n − 1). The frequency dependent conductivity and permittivity of both materials is explained in terms of “universal” power law behaviour. A deviation from the law, with a giant relative permittivity which is largely independent of frequency from 0.1 Hz to 100–200 kHz is observed in the case of TinO2n − 1, due to the presence of residual TiO2 generating an Internal Barrier Layer Capacitor (IBLC) effect. The real–imaginary impedance plots are interpreted using an RC model and allow separation of the contribution of the grain bulk and the grain boundaries to the total resistivity of the material. In the case of the TinO2n − 1 based materials this confirms that the IBLC effect is generated by insulating grain boundaries. The conduction mechanism in both TiO2 and TinO2n − 1 appears to be dominated by electronic conductivities, activated mainly through shallow donor levels up to 200 °C and over the entire band gap, which is narrower for TinO2n − 1, above 200 °C. A deeper understanding of the AC properties of Magnéli phases of Ti at different temperatures aids in the optimisation of electrical properties for a variety of sensor and electrical applications.

AB - This paper presents a comprehensive impedance spectroscopy comparison of the AC properties of dense stoichiometric TiO2 and conductive TinO2n − 1 Magnéli phases over a broad temperature range (up to 1000 °C for TiO2 and 375 °C for TinO2n − 1). The frequency dependent conductivity and permittivity of both materials is explained in terms of “universal” power law behaviour. A deviation from the law, with a giant relative permittivity which is largely independent of frequency from 0.1 Hz to 100–200 kHz is observed in the case of TinO2n − 1, due to the presence of residual TiO2 generating an Internal Barrier Layer Capacitor (IBLC) effect. The real–imaginary impedance plots are interpreted using an RC model and allow separation of the contribution of the grain bulk and the grain boundaries to the total resistivity of the material. In the case of the TinO2n − 1 based materials this confirms that the IBLC effect is generated by insulating grain boundaries. The conduction mechanism in both TiO2 and TinO2n − 1 appears to be dominated by electronic conductivities, activated mainly through shallow donor levels up to 200 °C and over the entire band gap, which is narrower for TinO2n − 1, above 200 °C. A deeper understanding of the AC properties of Magnéli phases of Ti at different temperatures aids in the optimisation of electrical properties for a variety of sensor and electrical applications.

UR - http://www.scopus.com/inward/record.url?scp=84868451573&partnerID=8YFLogxK

UR - http://dx.doi.org/10.1016/j.ssi.2012.10.003

U2 - 10.1016/j.ssi.2012.10.003

DO - 10.1016/j.ssi.2012.10.003

M3 - Article

VL - 229

SP - 38

EP - 44

JO - Solid State Ionics

T2 - Solid State Ionics

JF - Solid State Ionics

SN - 0167-2738

ER -