Phase Transitions in Confined Gallium Droplets

Phase transitions in submicrometric Ga droplets confined in epoxy resin are studied by combining energy-dispersive x-ray diffraction (EDXRD), x-ray absorption fine structure, and single-energy x-ray absorption. The restricted fluid is undercooled down to 150 K while the melting point is depressed down to 254 K. Melting and freezing are sharp processes occurring with temperature broadening of 1 and 10 K, respectively. EDXRD patterns are consistent with that of $\ensuremath{\beta}\ensuremath{-}\mathrm{Ga}$, while the stable phase at ambient conditions $\ensuremath{\alpha}\ensuremath{-}\mathrm{Ga}$ is not found to exist. Appearance of $\ensuremath{\gamma}\ensuremath{-}\mathrm{Ga}$ and $\ensuremath{\delta}\ensuremath{-}\mathrm{Ga}$ solid phases and relevance of present results to recent studies of Ga confined in porous glass are discussed.