Is it possible to develop a new strategy to modify the physical properties of glasses? A research team led byUniversity of Padua seems to have found an answer to this stimulating question, as evidenced by the study published in "PNAS". The research, entitled “Stochastic atomic acceleration during the X-ray-induced fluidization of a silica glass”, shows how the atoms of some glasses, exposed to X-rays, move through a series of sudden accelerations.
in glassy state, the atoms are placed in a disordered form, but with an almost fixed configuration, which keeps them bound to their equilibrium position, with the possibility of displacements within the material linked to decidedly long times.
The exposure of the glass to a beam of X-rays can instead modify this 'stiffness', causing one rapid movement of atoms within matter, which becomes fluid.
The study, product of the collaboration between the Physics and Astronomy Department of the University of Padua, the Physics Institute of the University of Amsterdam, the DESY research center in Hamburg and the Physics Department of the University of Trento, investigates the movements of the atoms, exposed in X-rays. Thanks to the correlation spectroscopy of X photons it is possible to trace this change of position.
The dynamics analyzed follow the hypertransport laws, a type of motion where the distance traveled by the atoms increases over time more rapidly than in a common diffusion process.
Glasses and Lévy's distribution
Reporting the explanation of Giulio Monaco, Professor of the Department of Physics and Astronomy of the University of Padua, X-rays "induce force fields that behave like compressed springs, which, in turn, displace nearby atoms up to of the order of hundreds or thousands of angstroms (= ten-millionth of a millimeter)”. The atoms of the glass therefore they move with a series of sudden accelerations: short displacements are interspersed with long jumps, according to a probability distribution known as Levy distribution.
This dynamic has been examined in a number of fascinating phenomena, including animal migrations andacceleration of interstellar mattercaused by randomly distributed magnetic fields.
However, it is the first time that this type of displacement distribution has been observed in a compact system, such as glass, due to the effect of interatomic forces. And the enthusiasm is well justified. Indeed, this research introduces a new strategy for controlling the physical properties of glass.
All that remains is to ask what the future applications of this discovery will be.
Source: unipd.it
