SPECIFIC HEAT OF TIN AND GALLIUM IN THEIR STABLE AND UNDERCOOLED PURE LIQUID STATES

The specific heats, Cp, of tin and gallium in their pure liquid state over the temperature range from 632 for tin and 611 for gallium to 425 and 245°K, corresponding to undercoolings of 80 and 58°K respectively have been measured. Over the entire temperature range, the Cp for both tin and gallium falls continuously with increasing temperature through their melting point with no singular behavior there. The excess specific heat, ΔCp, of the liquid over the corresponding crystal diverges with falling tempera ture from -0.38 for tin and 0.56 for gallium at their melting point to +0.27 and 1.04 cal/g-atm-°K at the lowest temperature to which the particular specimen could be undercooled. For both tin and gallium, the specific heat at constant volume, Cv, of the liquids at their melting point exceeds the Dulong Petit limit value of 3R, and rises with decreasing temperature. The excess specific heat, ΔCp, as well as ΔCv, of liquid over the corresponding crystal in the undercooled region is attributed to the taking up of configurational entropy with rising temperature. © 1968.