H-BOND AND GLASSY STATE FORMATION - A STRUCTURAL AND DYNAMIC STUDY APPLIED TO AQUEOUS-SOLUTIONS

Aqueous electrolytic solutions MX.RH2O, especially with LiCl as solute , are good at forming a glass. At some specific concentrations, compou nd formation can be bypassed on cooling the system. This occurs when t he hydration number is such that the solution has lost the characteris tic behaviour of water. Structural relaxation can be analysed easily i n the three thermodynamic states: liquid, metastable (supercooled liqu id) and out of equilibrium (glass). The local structural relaxation is given by neutron spin echo spectroscopy. The structural evolution can be followed efficiently also using neutron scattering. Indeed using i sotopic substitution on nearly all the elements of the material Li, Cl and D we can derive the evolution of the short, medium and long range order in the three thermodynamic states. Correlated to the strong slo wing down of the structural relaxation, is the ability of the supercoo led and glassy states to construct characteristic H-bonded local confi gurations.