On Poisson's ratio of glass and liquid vitrification characteristics

The apparent activation energy for viscous flow of a glass-forming liquid, Ea, and its ratio to temperature T-f, m(f) (E-a/2.3T(f)), are seen as a measure of the viscosity's departure from the Arrhenius equation. As the viscosity, eta, increases on cooling, Ea and mf increase. On slow cooling, a liquid vitrifies at a lower T, higher eta and higher mf, and on rapid cooling it vitrifies at a higher T, lower eta and lower mf. It is argued that Poisson's ratio, upsilon(Poisson), and the instantaneous bulk modulus to shear modulus ratio, K-infinity/G(infinity), of a liquid ( and glass) would decrease as it departs from Arrhenius behaviour or mf increases. Available data on structural relaxation of metal alloy glasses confirm it. Therefore, as a glass spontaneously becomes denser with time, mf increases and its state becomes dilationally stiffer. This finding is opposite to the correlation that, amongst glass-forming liquids of different chemical compositions, upsilon(Poisson) and K-infinity/G(infinity) increase when departing from Arrhenius behaviour at T-g or m increases (V.N. Novikov and A. P. Sokolov, Nature 431 961 (2004)). Further analysis shows that a liquid's structure has a predominant effect on its elastic constants.