CONICET | Buscador de Institutos y Recursos Humanos

Most alkali-containing oxide glasses exhibit non-additive variations of certain properties when one alkali ion is substituted by another one. This phenomenon is known as the ?mixed alkali effect? and is one of the most intriguing unsolved phenomena in glass science. The mixed alkali effect especially manifests itself in non-additive discrepancies in transport properties, such as diffusion, conductivity, and viscosity. These properties are commonly referred to as dynamic properties, in contrast to static properties such as density, refractive index, and molar volume, all of which exhibit relatively small deviations from linearity. The mixed alkali effect has been known for decades, yet over the past few years it is still drawing significant attention. In contrast, the mixed alkaline earth effect has received relatively little attention. The mixed alkaline earth effect is phenomenologically analogous to the mixed alkali effect, i.e., it concerns substitution of one alkaline earth ion by another one. The influence of the mixed alkaline earth effect on glass properties is also analogous to that of the mixed alkali effect, i.e., deviations from linearity are observed for certain glass properties upon substitution of alkaline earth ions. Since the mixed alkaline earth effect can affect the glass properties in a non-predictive manner, it is important to study this effect from both scientific and technological points of views. The aim of this work is to study the ?Mixed Alkaline?Earth Effect? in a new family of glasses of general formula: 0.8[xBaO(1-x)MgO]0.2TM.2TeO2with TM(transition metal)=Nb2O5, V2O5, MoO3and WO3. These new materials will be characterized by impedance spectroscopy, Raman spectroscopy, AFM, density measurements, etc. We are interested in finding out how are affected the material properties mainly with the partial change in the ratio Ba/Mg and which is the influence of transition metals (Nb, V, Mo and W) in the glass matrix.