Atomic and electronic structures of an extremely fragile liquid

The structure of high-temperature liquids is an important topic for understanding the fragility of liquids. Here we report the structure of a high-temperature non-glass-forming oxide liquid, ZrO(2), at an atomistic and electronic level. The Bhatia–Thornton number–number structure factor of ZrO(2) does not show a first sharp diffraction peak. The atomic structure comprises ZrO(5), ZrO(6) and ZrO(7) polyhedra with a significant contribution of edge sharing of oxygen in addition to corner sharing. The variety of large oxygen coordination and polyhedral connections with short Zr–O bond lifetimes, induced by the relatively large ionic radius of zirconium, disturbs the evolution of intermediate-range ordering, which leads to a reduced electronic band gap and increased delocalization in the ionic Zr–O bonding. The details of the chemical bonding explain the extremely low viscosity of the liquid and the absence of a first sharp diffraction peak, and indicate that liquid ZrO(2) is an extremely fragile liquid.