Evidence of anomalous intermediate-range ordering in superionic borate glasses from neutron diffraction

Evidence of intermediate-range ordering in a superionic (AgI)x(${\mathrm{Ag}}_2$O+2${\mathrm{B}}_2$ ${\mathrm{O}}_3$ ${)}_{1\mathrm{-}\mathit{x}}$ glass is presented. Comparative neutron-diffraction measurements were performed in a low (x=0.1) and a high (x=0.6) -AgI-concentration glass. A strong and sharp diffraction peak at an anomalously low Q value of 0.8 A${̊}^{\mathrm{-}1}$ is observed for the x=0.6 glass, which is not present in the x=0.1 glass. The phenomenon is attributed to an ordering of the intermediate-range structure, due either to formations of AgI clusters or to density deficits in the boron-oxygen network.