Phase transitions and undercooling in confined gallium

Phase transitions in submicrometre gallium droplets confined in epoxy resin are revealed by single-energy X-ray absorption spectroscopy using synchrotron radiation, a technique previously applied in high-temperature studies of solid and liquid metals. These unconventional measurements are accompanied by a detailed characterization of samples using scanning electron microscopy and adiabatic calorimetry measurements. Exceptional undercooling down to 150 K is confirmed by the present data. Specific heat measurements performed during the warming cycles confirmed the presence of three different solid phases for gallium, namely beta-Ga, gamma-Ga and delta-Ga and the absence of the alpha-Ga stable phase at ambient conditions.