Acoustic study of the melting and solidification of gallium incorporated in an opal matrix

An acoustic study is reported of the crystallization and melting of gallium embedded in an opal-like matrix. The variations of the velocity and absorption of longitudinal ultrasonic waves during phase transitions in the alpha and beta modifications have been found to be hysteretic in nature. It is shown that acoustic methods do not detect gallium melting and crystallization in the tetragonal phase forming in a restricted geometry. Experimental evidence for heterogeneous crystallization of gallium in pores has been obtained. (C) 2000 MAIK "Nauka/Interperiodica"