Presentation Information
[17p-W8E_307-10]Surface melting of biphenyl crystals
〇Harutoshi Asakawa1, Nakatsubo Shunichi5, Terada Tatsuji6, Ueda Masahiro6, Ito Nozomu6, Katsuno Hiroyasu2, Tsukamoto Katsuo7, Yanagiya Shin-ichiro4, Hondoh Hironari3 (1.Yamaguchi Univ., 2.Kanazawa Univ., 3.Univ. of Shizuoka, 4.Tokushima Univ., 5.JAXA-isas, 6.Advanced Technology Institute, Yamaguchi Univ., 7.Tohoku Univ.)
Keywords:
organic crystals,surface melting,advanced optical microscopy
Many studies has so far believed that surface melting is a precursory phenomonon of melting, and a liquid film covers the crystal surface just below the melting point. It was thought that the existence of the liquid film is the starting point for melting. In this study, we attempted to visualize the surface melting of biphenyl crystals (melting point: 69.4°C) by advanced optical microscopy, and verify the long-held thermodynamic theory of surface melting. At 69.2°C, just below the melting point, droplets were generated from the edge of elementary steps on the biphenyl crystal surface. Furthermore, when the temperature was increased to 69.7°C, above the melting point, the generated droplets acted as nuclei to erode the crystal surface, resulting in complete melting. Thus, we demonstrated that surface melting of biphenyl is a precursory phenomenon of melting.