Structural and mechanical properties of Zr1−x Mox thin films: From the nano-crystalline to the amorphous state

Abstract

Zr1−xMox thin films were synthesized on glass substrates by co-sputtering molybdenum and zirconium targets in the presence of argon with x in the 0.32–0.95 range. From X-ray diffraction analyses and transmission electron microscopy images it was possible to observe an evolution of the samples structure from a nano-crystalline solid solution of Zr in the bcc lattice of Mo to clusters of Zr(Mo) nano-crystalline in an amorphous matrix. The coherence length deduced from X-ray diffractograms was around 1 nm–8 nm depending on the composition. Mechanical measurements show that the films exhibited high hardness H, low Young's modulus E and therefore high H∕E ratio compared with the bulk of Zr and Mo. We also found a low friction coefficient values for all the samples. Finally, an inverse Hall-Petch effect was observed for coherence length lower than 6 nm.