Topological phases in Ba-Borate glasses

Twelve compositions in the (BaO)$_{x}$(B$_{2}$O$_{3})_{100-x}$ pseudo binary, in the 15{\%} \textless x \textless 40{\%} range, were synthesized by induction melting Boric acid and anhydrous BaCO$_{3}$, taking care to handle the materials in a dry ambient environment. Modulated- DSC and Raman scattering experiments were undertaken systematically as function of BaO content (x). Calorimetric measurements reveal T$_{g}$(x) to show a broad maximum and the non-reversing enthalpy to show a Gaussian-like reversibility window$^{2}$, both centered near x $=$ 28{\%}. Raman scattering displays rich lineshapes with modes similar to those observed in Na-Borates$^{2}$. Modes near 808 cm$^{-1}$, 770 cm$^{-1}$, 740 cm$^{-1}$ and 705 cm$^{-1}$ are observed, and identified with breathing modes of pure and mixed rings from characteristic structural groupings$^{2}$. These preliminary results suggest that glasses at x \textless 24{\%} are in the stressed-rigid phase, in the 24{\%} \textless x \textless 30{\%} in the Intermediate Phase and at x \textgreater 30{\%} in the flexible phase.