A local structure change of bulk Pd40Ni40P20 glass during full relaxation

The change in the amorphous structure of bulk Pd40Ni40P20 glass during structural relaxation was examined by an anomalous X-ray scattering (AXS) experiment with energies near the Ni K-absorption edge. It was confirmed by differential scanning calorimetry that the sample reached a meta-stable state (a fully relaxed state) with an equilibrium free volume concentration after annealing for about 1 × 104 s at 563 K and 4 × 104 s at 557 K just below the glass transition temperature Tg = 567 K. The structural changes on the progression toward a fully relaxed state were examined in samples annealed for 1 × 103 and 2 × 104 s at 563 K (glass A), and for 3.2 × 103, 1 × 104 and 7 × 104 s at 557 K (glass B). The structural analysis revealed that the coordination number of Ni-Ni like atom pairs increased with annealing time and that of Ni-Pd, unlike atom pairs, decreased. Meanwhile, the coordination number NPNi of P-Ni atom pairs and the nearest neighbor distance rPNi did not show a remarkable variation. However, prolonged annealing of 7 × 104 s at 557 K induced a remarkable change in NPNi and rPNi.