Phase transition and water molecules in titanylphthalocyanine phase Y crystal

Abstract

We have performed several experiments and molecular dynamics calculations to investigate a phase transition of titanylphthalocyanine phase Y crystal and the behavior of water molecules in the crystal. We have shown that water is in the crystal as well as on its surface and the humidity dependence of the photosensitivity of the phase Y is due to the water on the surface. We propose a mechanism for the phase transition from the metastable phase Y to a stable phase I as follows. Water molecules on the surface detach as the crystal is heated to 100°C. At about 250°C water molecules in the crystal begin to jump from one space to another through channels connecting the spaces and as a result are expelled from the crystal. After the water molecules leave the spaces, the phase transition to phase I occurs by molecular rearrangement to shrink these spaces.