Mechanical characterization of MgB₂ thin films using nanoindentation technique

Highlights: • MgB₂ thin films deposited via single composite Mg + B target by RF magnetron sputtering. • Samples were heat treated at 590 °C in a vacuum oven at 2 × 10⁻⁶ Torr base pressure. • Several measures were implemented to reduce the oxygen in the deposition chamber. • Structural properties were characterized by grazing incident XRD and SEM. • Mechanical properties have been investigated by using nanoindentation method. - Abstract: Mechanical properties of MgB₂ thin films deposited by RF magnetron sputtering technique have been studied. MgB₂ thin films were deposited approximately 300 nm on Si substrate above room temperature, and the thin films were subsequently annealed. Great care has been taken to reduce O₂ in the chamber during deposition. Structural and mechanical properties of MgB₂ thin films were investigated using the Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and nanoindentation techniques. Unloading segments of nanoindentation curves analyzed using Oliver–Pharr method. Both reduced elastic modulus and nanohardness values show load dependence, i.e., indentation size effect (ISE). Proportional specimen resistance (PSR) model was used to calculate the load independent nanohardness value. Load-independent hardness value was calculated using the proportional specimen resistance (PSR) model. XRD and SEM results show that the MgB₂ thin films have fine grain size. Nanoindentation results show that hardness and elastic modulus values were 11.72 GPa and 178.13 GPa, respectively