We have investigated the structure of a model fragile glass former ${\mathrm{Ca}}_{0.4}{\mathrm{K}}_{0.6}{(\mathrm{N}\mathrm{O}}_3{)}_{1.4}\mathrm{}\left(\mathrm{CKN}\right)\mathrm{}$ by using neutron and x-ray diffraction and reverse Monte Carlo modeling in a temperature range covering the glass transition. The results show that the structure of the glass phase contains, in addition to short-range charge ordering, intermediate-range ordering that is due to fluctuation of nitrate ion concentration in the range 3–15 Å. Furthermore, the nitrate ions are orientationally correlated and form chainlike substructures. Gradual changes of the structure factor were observed in the Q range 1–5 ${\mathrm{\AA }}^{\mathrm{-}1}$ on passing through the glass transition temperature, which can partly be attributed to changes in density. However, the orientational correlation between the planar ${\mathrm{NO}}_3^{-}$ ions present in the glass phase is lost in the liquid phase.

• Received 18 January 2001

DOI:https://doi.org/10.1103/PhysRevB.64.224207