The study of structural and dynamic aspects of ionic conducting glasses and their correlation with macroscopic properties presents a fascinating challenge in condensed matter physics and chemistry. Such investigations are of fundamental interest because of technological applications of these materials in electrochemical, optical and electronic devices. Therefore, understanding the dependence of physical properties on glass structure and dynamics is critical for the design of new materials for specific applications.
Structural properties of ionic glasses are investigated at TPCI by Raman and infrared spectroscopy. The analysis of Raman and mid-infrared spectra allows for the detailed mapping of the short-range order structure of the glassy network, while the corresponding far-infrared profiles provide useful information for the nature and distribution of sites hosting the charge-carrier metal cations.
Dynamic properties of ionic glasses are studied experimentally by complex impedance spectroscopy in the frequency range 5Hz-10MHz and at temperatures from 20 to 500°C. The analysis of dielectric spectra leads to the evaluation of physical quantities related to diffusive properties of ions in the glassy network including complex conductivity and the modulus function.
The experimental investigations of ionic glasses are complemented by molecular dynamics simulations, aiming at the evaluation of structural and dynamic properties at the microscopic level and their correlation with experimental findings.
A snapshot of the atomic structure of a lithium-borate glass as resulted from computer simulations. The tendency of lithium ions and non-bridging oxygen (NBO) atoms to aggregate in micro-channels (highlighted in blue) contributes to the enhancement of ionic conductivity.
Current activities at TPCI in the field of ionic glasses involve:
. Thin film electrolytes
. Mixed cation glasses
. Optical glasses
Otto-Schott Institut, Friedrich-Schiller University, Jena, Germany: D. Ehrt
Institut de Chimie de la Matiere Condensee de Bordeaux, CNRS, University of Bordeaux 1, France: P. Vinatier
Applied Physics Department, Chalmers University, Sweden: A. Matic
International Materials Institute for New Functionality in Glass, Lehigh University, USA: H. Jain
EC Grants No. ICA3-CT-2002-10018 and No. NMP3-CT-2005-516975
E.I. Kamitsos and C.P.E. Varsamis
Theoretical and Physical Chemistry Institute,
National Hellenic Research Foundation,
48 Vassileos Constantinou Ave.,
Athens 11635, Greece