Multiple Glass Transitions in Bismuth and Tin beyond Melting Temperatures

Abstract

Liquid-liquid transitions were discovered above the melting temperature (Tm) in Bi and Sn up to 2 Tm, viewed as glass transitions at Tg = Tn+ > Tm of composites nucleated at Tx < Tm and fully melted at Tn+. A glassy fraction (f) disappeared at 784 K in Sn. (Tn+) increases with singular values of (f) depending on Tx with (f) attaining 100% at Tg = Tn+ = 2 Tm. The nonclassical model of homogeneous nucleation is used to predict Tx, Tn+ and the specific heat. The singular values of (f) leading to (Tn+) correspond to percolation thresholds of configurons in glassy phases. A phase diagram of glassy fractions occurring in molten elements is proposed. The same value of (Tx) can lead to multiple (Tg). Values of (Tg = Tn+) can be higher than (2 Tm) for Tx/Tm < 0.7069. A specific heat equal to zero is predicted after cooling from T ≤ 2 Tm and would correspond to a glassy phase. Weak glassy fractions are nucleated near (Tn+) after full melting at (Tm) without transition at (Tx). Resistivity decreases were observed after thermal cycling between solid and liquid states with weak and successive values of (f) due to Tx/Tm < 0.7069.