IR, UV–vis spectroscopic and DSC investigations of europium doped tellurite glasses obtained by sol–gel synthesis Original Research Article

FTIR, UV–vis spectroscopy and DSC studies were utilized in order to study structural changes produced by the variation of the Eu(NO3)3 content in binary europium–tellurite glasses obtained using the sol–gel method. Our results show that the europium ions can be considered as modifiers because they will produce the transformation of [TeO4] and [TeO6] structural units into [TeO3] trigonal pyramidal units and the formation of a significant number of non-bridging oxygen ions. UV–vis studies show that the higher Eu(NO3)3 concentrations (24 mol%) in the host matrix induce a growth of the number of 4f–4f electronic transitions of the Eu+3 ions and a increase of the number of non-bridging oxygen ions in the regions between 325 and 600 nm. In brief, partial replacement of TeO bonds by EuO ionic bonds induces a global weakening of the network explaining the decrease of the glass transition temperature and crystallization temperature by gradually increasing of europium ions in the matrix network.