SUPERHEATING AND SUPERCOOLING IN SINGLE SPHERES OF TIN INDIUM AND GOLD-PLATED INDIUM

An experimental study of the superheating and supercooling properties of tin, indium, and gold-plated indium spheres, typically 10 μm in diam, has been made. The results are more reliable than those obtained from experiments on powders. The effects of nucleation centers are discussed, and it is shown that in indium, at least, different nucleation centers are active in superheating and supercooling. The effect of nucleation centers vanishes as one approaches Tc, where the following values for the Ginzburg-Landau parameter κ are obtained: κSn=0.0926±0.001 and κIn=0.0620±0.001. The effect of specimen size upon superheating and supercooling is also clearly demonstrated. It is found that gold plating reduces the supercooling field near Tc by a factor of 1.70 (±2%), as predicted by theory. Gold plating affects the superheating field, as a function of temperature, in a manner which is qualitatively predicted by the Ginzburg-Landau theory. © 1969 The American Physical Society.