Two-step relaxation decay in a strong glass former

The dynamics around the liquid-glass transition in ${\mathrm{B}}_2$ ${\mathrm{O}}_3$ have been investigated by photon correlation spectroscopy. A two-step relaxation is for the first time observed in a ‘‘strong’’ network forming glass. The behavior is similar to the fast β and slower α relaxations observed for ‘‘fragile’’ glasses and proposed in mode coupling theory (MCT) for simple glass forming systems. We find that the time decays of the two processes obey power laws consistent with MCT. It seems that a two-step relaxation is a more general relaxation pattern than has been discussed so far.