Heat capacity of Pd40Ni40P20 in the deeply undercooled liquid state determined by relaxation experiments in the glass transition region

An indirect method is presented which allows for the heat capacity determination of deeply undercooled melts at temperatures in the glass transition region, which are inaccessible to continuous calorimetric measurements. The method is based only on the unique relaxation behavior of glass-forming liquids in the transition region, and thus is generally applicable for vitreous systems. Here it is illustrated by measurements of the specific heat of deeply undercooled Pd₄₀Ni₄₀P₂₀, a metallic bulk-glass former, resulting in a considerable approach of the measurements towards the isentropic limit. Additionally, the consequent application of this method allowed for the determination of the dependence of the glass temperature on the cooling rate during vitrification, yielding a linear relation between the glass temperature and the logarithm of the cooling rate, as observed for several non-metallic glass-forming systems.