Local structures of amorphous and crystalline phases of silica, SiO2, by neutron total scattering

Abstract

We quantify the relationship between the atomic structures of the amorphous and the ordered and disordered crystalline phases of silica using neutron total scattering measurements to determine the local atomic configurations. The instantaneous local atomic arrangements of HP-tridymite and β-cristobalite. both dynamically-disordered high-temperature crystalline phases, bear a striking resemblance to the quenched structure of amorphous silica, unlike those of the two phases of quartz and ordered α-cristobalite. The high-temperature phases are not domain averages of their respective low-temperature phases. Our approach has wider application for characterization of disordered crystalline structures in general. (Some figures in this article appear in colour in the electronic version; see www.iop.org).