Abstract
Gold doped ruby glasses are classical examples of metal-glass nanocomposites that have been investigated for their striking optical properties. For the example of weakly Au doped lithium-borate glasses these materials are shown to exhibit a transition from ionic to electronic conduction within the same sample. It is achieved via appropriate heat treatment, presumably by introducing polarons formed from the trapping of electrons at partially ionized gold atoms. This unique electrical response is expected to introduce new functionality to this class of nanocomposites. (C) 2009 American Institute of Physics. [doi:10.1063/1.3242416]