Percolative conductivity in alkaline earth silicate melts and glasses

Abstract

Ion conducting $(CaO{)}_x(Si{O}_2{)}_{1-x}$ glasses and melts show a threshold behaviour in dc conductivity near $x=x_t=0.50$, with conductivities increasing linearly at $x>x_t$. We show that the behaviour can be traced to a rigid ($x<0.50$) to floppy ($x>0.50$) elastic phase transition near $x=x_t$. In the floppy phase, conductivity enhancement is traced to increased mobility or diffusion of $C{a}^{2+}$ carriers as the modified network elastically softens.

15 pages, 5 figures. Europhysics Letters (2003), in press