On the determination of spinodal temperature by electron microscopy

In a previous publication we reported that equilibrium composition fluctuations in the supercritical region of a multicomponent inorganic glass can be observed by replica electron microscopy and that the mean linear intercept length l(T, Xo) measured from the electron micrographs varies with temperature T according to a law of the type l(T, Xo) ∼ [T − To(Xo)]−ν; ν = 0.50. In the present paper we report measurements of the equilibrium volume fractions of the minor phase as a function of temperature and use them to estimate the spinodal temperature TSp(Xo). Our results suggest that TSp(Xo) = To(Xo); a result in agreement with the classical theories of phase separation.