Nuclear magnetic resonance, resistance and acoustic studies of the melting-freezing phase transition of gallium in Vycor glass

The melting-freezing phase transition of gallium confined within Vycor glass was studied by NMR, resistance and acoustic techniques. A single although broadened Ga-71 NMR line corresponding to melted gallium was observed in contrast to lineshapes found until now for liquid gallium in porous matrices. A difference between results obtained using the three methods was explained by formation of various confined solid gallium modifications. A depression of the freezing and melting phase transition temperatures and a pronounced hysteresis in the melting-freezing processes were found and are discussed. Heterogeneous nucleation was suggested to explain the dependence of crystallization on temperatures of pre-warming.. Irreversible melting was observed for the second gallium modification.