Sputter-deposited network glasses

Abstract

Thin films of lithium borate, sodium borate, rubidium borate, and lithium silicate glasses are prepared by ion beam sputter deposition in a thickness range between 70 and 1,400 nm. The chemical, structural, and electrical properties of the films are determined by transmission electron microscopy and impedance spectroscopy. A comparison between the thin glass layers and the corresponding bulk glasses, prepared from the melt, shows that both have similar chemical compositions and atomic short range orders. In contrast, the ionic conductivities of the borate glass films are found to be significantly increased compared to the corresponding bulk materials, while the increase depends on the chemical composition of the glasses and is not observed in the case of the silicate system. We propose a modified network structure of the sputter-deposited glass layers, namely, an increased nonbridging oxygen concentration, to be responsible for the elevated ionic conductivity.