地震発生についての相転移論

第1部 フッ化アンモニウムの相転移音の観測

抄録

When a crystal structure of ammonium fluoride, NH₄F, reversibly transforms from Wurtzite structure to NaCl structure at ca. 4kb, a number of small elastic shocks are accompanied with the volume change by the rapid phase transition for polycrystalline specimen. These shocks are also generated during the lowering pressure run, where NaCl structure transforms to Wurtzite structure. If we assume that each of the shocks corresponds to a phase transition in a small volume in the specimen, the amount of the reactant is given by the accumulated number of shocks. Fitting the bulk rate of the phase transition by the equation of the rate theory; dX/dt=K(1-X)^p, where X is the mole fraction of the reactant at the time t, we obtain p≈1 and K≈10^-1sec^-1. The present result shows that the phase transition is the first order reaction and the bulk rate of the phase transition is in the order of 10^-1sec^-1, although the process of the phase transition is not continuous but is the superposition of very rapid ones with elastic wave radiation.