Probing the dynamics of B₂O₃ across the glass transition: an X-ray photon correlation spectroscopy study

ABSTRACT

X-ray photon correlation spectroscopy is used to study the dynamics of the glass former ${\text{B}}_2{\text{O}}_3$ across the glass transition temperature, $T_g$. The obtained data confirm that while the structural relaxation drives the density rearrangements in the liquid phase, a beam-induced dynamics is the dominant effect around and below $T_g$. The use of a hybrid photon counting detector allows us to obtain high-quality correlation functions with a characteristic decay time down to a second. The characteristic time of the induced dynamics displays a linear dependence on the inverse of the absorbed X-ray power over the whole observed range, i.e. up to powers of 0.2 eV/atom/s. Up to these values, then, an X-ray irradiated ${\text{B}}_2{\text{O}}_3$ glass sample explores structurally equivalent configurations on a timescale dictated by the absorbed power.

KEYWORDS:

• Glass transition
• synchrotron radiation
• oxide glasses
• X-ray photon correlation spectroscopy
• beam-induced dynamics

Disclosure statement

No potential conflict of interest was reported by the author(s).