Thermoelectric investigation of structural relaxation processes of the transition-metal-based amorphous alloys

The relaxation processes in different amorphous alloys based on a transition metal (TM) have been investigated through thermopower measurements. The thermopower, E T , as a function of an annealing time, t a , at different annealing temperatures, T a (T a << T x , where T x is the crystallisation temperature) was measured in a couple containing annealed and as-quenched alloys of the same composition. The dependence of the thermopower on the annealing time t a shows a two-stage behaviour and a tendency to saturate at large t a . The temperature dependence of E T for different annealing times shows curves with a maximum. The existence of that maximum is explained by different mechanisms of structural relaxation processes in different temperature ranges. The migration of two types of atomic complexes (TM atoms and TM - metalloid complexes) has been considered. There are at least two processes that define the structural relaxation at the initial stages of this process. According to the Arrhenius law, E T depends on the annealing temperature T a . The activation energies, E a , of relaxation processes can be found in the range 0.3 - 1.6 eV. Higher values of E a correspond to alloys containing two types of metalloids.