Internal oxidation of laminated Nb–Ru coatings

A direct current magnetron cosputtering system was used to deposit Nb–Ru coatings with various chemical compositions onto silicon wafers. The Nb–Ru coatings exhibited distinct nanolaminated structures because of the cyclical gradient concentration deposition. The oxidized Nb–Ru coatings formed oxide and metal multilayers when they experienced internal oxidation at 400–600 °C in a 1% O₂–99% Ar atmosphere. A two-stage parabolic-rate law was obeyed for the Nb_0.49Ru_0.51 coatings oxidized at 350–550 °C in 1% O₂–99% Ar. The activation energies in the two-stage oxidation, dominated by oxygen dissolution and oxide formation, were calculated at 88 and 127 kJ/mol, respectively.