Topological phases in (Na$_{2}$O)$_{x}$(P$_{2}$O$_{5})_{100-x}$ glasses.

We have synthesized titled glasses in the 0 \textless x \textless 0.50 range of soda paying special attention to their dryness. Pure P$_{2}$O$_{5}$ glass was synthesized by flash evaporation of bulk powder in a quartz tube as it was pumped in several attempts, and the variation of T$_{g}$ and enthalpy of relaxation ($\Delta $H$_{nr})$ measured for each attempt. These data show that as the glass got drier, T$_{g}$ increased to 431\textdegree C and $\Delta $H$_{nr}$ became miniscule. At higher soda content (x \textgreater 20{\%}), T$_{g}$(x) increased steadily, but with appearance of a local maximum near x $=$ 37.5{\%}. On the other hand $\Delta $H$_{nr}$ term, revealed a Trapezoidal-like minimum in the 32.5 {\%} \textless x \textless 42.5{\%} range, suggestive of a reversibility window or the isostatically rigid Intermediate Phase, with glasses at x \textgreater 42.5{\%} in the flexible phase while those in the 20{\%} \textless x \textless 32.5{\%} range in the stressed rigid phase. We have also obtained Raman scattering, IR reflectance and fragility index measurements on the present glasses, and these will discussed with recent$^{1}$ results in the field. \begin{enumerate} \item D.L. Sidebottom J. Chem. Phys. \textbf{140}, 154501(2014). \end{enumerate}