Periodic Spinodal Decomposition in Solid Binary Mixtures

Abstract

Phase separation is studied when the temperature is made to oscillate around a critical value near a second-order phase transition. In such a case the structure factor is calculated for a one-component system with conserved order parameter using a computational method of Langer, Bar-on and Miller. The structure factor tends to a periodic function when the average of the oscillating temperature is higher than a new critical value which is lower than the equilibrium critical temperature. However, its maximum grows without limit when the average temperature is lowered below the critical value. This is a new type of phase transition where the fluctuations are much enhanced above the thermal level. Besides solid binary mixtures the results of this paper are applicable to uniaxial ferromagnets under strong ultra-sounds in which the spin component along the easy axis is conserved.