Cooperative structural effects in relaxing Pd-Er-H and Fe-C systems

The dynamics of oscillating structural changes in nonequilibrium Fe-C and P d-Er-H systems is studied. For Fe-C it is established that the Fourier spec trum of the time dependence of its Mossbauer spectra is similar to the Four ier transform of systems in a state of dynamic chaos on which several long- wavelength modes are superposed. The structural-oscillatory effects for Pd- Er-H consist of a combination of oscillatory processes, corresponding to th e appearance and partial dissipation of H-D-M complexes, vibrational change s in the ratio of the fractions of the erbium-rich and -poor phases, and th e difference of the compositions of these phases. The oscillations have a m ultimode character with periods increasing with time. Thus, cooperative eff ects associated with collective interactions of the matrix atoms, defects, and "perturbing" impurities such as hydrogen and oxygen atoms are clearly s een in the processes studied. It is shown that the synergetic concept in th e spirit of the system of nonlinear Lorentz equations is useful for giving a macroscopic description of the observed defects. (C) 1999 American Instit ute of Physics. [S1063-7834(99)00209-9].