Infrared reflectance spectra of lithium borate glasses

The infrared reflectance spectra of lithium borate glasses (0–73 mol% Li 2O) have been measured over a broad and continuous spectral range (30–4000 cm −1) in an attempt to study systematically their structure. The reflectance data have been analyzed by Kramers-Krönig inversion to obtain the optical and dielectric properties of the materials. The study of the deconvoluted mid-infrared spectra has revealed a glass network built up of various boron-oxygen groups, with structure and concentration strongly dependent on the Li 2O content. Of particular interest was the far-infrared asymmetric absorption profile, which could be well simulated by two broad bands attributed to vibrations of lithium cations in two distinct network environments. The presence of these two Li +-host site distributions was found to be independent of the details of the borate network structure and has been taken to imply a more general characteristics of ionic conducting oxide glasses.