Application of time resolved x-ray diffraction to study the solidification of glass-forming melts
L. Hennet, I. Pozdnyakova, A. Bytchkov, J. W. E. Drewitt, J. Kozaily, M. Leydier, S. Brassamin, D. Zanghi, H. E. Fischer, G. N. Greaves and D. L. Price
Using time resolved x-ray diffraction combined with aerodynamic levitation and CO2 laser heating, we have studied the structural evolution of the fragile glass-forming liquid CaAl2O4 during supercooling from the stable liquid phase to the cold glass below Tg. In particular, we followed the evolution of the structure factor S(Q) and of the corresponding pair distribution function g(r). The results show significant structural changes around 1.25 Tg indicating an increase in the degree of both intermediate- and short-range order occurring close to the dynamical crossover temperature. Experiments were carried out at several beamlines at various synchrotron sources and we show that the potential of third generation synchrotron beamlines is limited by the lack of efficient detectors for making time resolved measurements on disordered materials. In this paper, we present an overview of the advances performed in this area over the past 10 years pointing out the limitations and expectations for the near future.
Keywords: glass transition; supercooling; time-resolved; x-ray diffraction; calcium aluminates; levitation; high-temperature liquids.