Yuko Inatomi

An experimental verification of a criterion for forming metastable phases in containerless solidification

On the thermodynamic condition for forming a metastable phase from undercooled melt in a containerless state, we had proposed a criterion that crystals will preferentially form if they have a smaller entropy of fusion than the entropy of fusion of equilibrium crystals (Kuribayashi et al., Mater. Sci. Eng., A 449–451, 675 (2007)). This criterion is proposed for being applied to materials that exhibit a faceted interface, such as semiconductors and oxides. However, no experimental data that support this criterion have been obtained. From this point, we used an aerodynamic levitator as a tool for forming metastable phases from undercooled melt and verified the above-mentioned criterion using LnFeO3 (Ln: lanthanide and Y) as the model material. In addition, the condition for double recalescence, which corresponds to forming metastable phases and stable phases, was discussed in terms of competitive 2D isomorphic nucleation of the metastable phase and 3D polymorphic nucleation of the stable phase.

Dissolution Rate of GaP Crystal on a Centrifuge

The acceleration of gravity is often an important factor influencing a processing procedure, in addition to thermodynamic parameters such as temperature and pressure, especially when a fluid phase is involved. Accordingly, the control of acceleration is important to obtain high quality materials, and to understand the heat and mass transport phenomena during the process. In recent years, materials processing experiments have been performed not only in microgravity but also in hypergravity environments. Utilization of a centrifuge is used to generate hypergravity acceleration on earth. Most centrifugal crystal growth experiments were employed to study the relationship between acceleration and 1) composition and defect distributions in the resulting crystal,e. g,1,22) sedimentation during growth,3 3) morphological instability of the solid/liquid (S/L) interface,4,5 4) growth striations,6,7 5) temperature oscillations in the liquid phase, 8,9 and 6) heat transmission.10