Kinetic processes of stage transitions and critical behaviors of intercalant melting

Abstract

We present the kinetic processes of stage transitions from stage ni to nf between which some intermediate stages are included; | ni - nf| ≧ 2 . Even in a non-equilibrium process successive stage transitions, ni → (ni + 1) → (ni + 2) → … → nf, occur and each intermediate stage exists as a single-staged metastable state in a short period. The results are interpreted by the rapid diffusion of intercalants(K) along graphite galleries. We also present nearly continuous melting transitions in stage 1 Rb-GIC. Rubidium atoms in liquid phase have strong positional correlations with the symmetry of the solid (σβ) phase which grow significantly near Tm, the melting temperature, and shows no discontinuous change at Tm in the interatomic distance and atomic density. The solid phase (αβ) shows a continuous growth of the ordering parameter and also a remarkable positional fluctuation close below Tm in solid phase, which are characteristics of the 2nd order transition. The critical behaviours of melting in the quasi-two-dimensional system will be discussed.