Electrical resistivity and Mossbauer studies for the structural relaxation process in Pd-Cu-Ni-P glasses

The structural relaxation process in several Pd-Cu-Ni-P glasses was investigated by the electrical resistivity and the Mossbauer experiments. The change in the resistivity, rho(300), and the corresponding slope, alpha(300) = (drho/dT)(300), at room temperature was measured after a given heat treatment. The change in rho(300) with isochronal annealing below the glass transition temperature (, 572 K), starting from room temperature, demonstrated that the rho(300) increased with temperature and decreased beyond 550 K. The isothermal annealing at 570 K exhibited that the rho(300) showed an increase, about 1%, during an initial annealing stage for 3.0 x 10(2) s and remained almost constant up to 6.0 x 10(3) s, and hereafter monotonously decreased. The change in alpha(300) showed an opposite sign to that in alpha(300). The reversible change in rho(300) due to isochronal annealing was observed in the heat treatment repeated between 350 and 550 K. The Mossbauer spectroscopy experiments were performed at room temperature to investigate the local structure change due to structural relaxation. The isomer shift and the quadrupole splitting for an annealed sample decreased in comparison with that of an as-quenched sample. Based on these results, the structural relaxation process and the structure change were discussed within the framework of the free volume model.