Mechanical characterization of YBCO thin films using nanoindentation and finite element method

Abstract

Abstract The mechanical properties of YBCO thin film deposited on SrTiO3 (100) substrates by magnetron sputtering were determined using Berkovich nanoindentation and scanning electron microscopy. Hardness and elastic modulus were determined via the Oliver–Pharr method from indentation load–depth curves. The hardness values of the YBCO thin film show depth dependence, i. e., indentation size effect, which arose from the surface roughness as detected by scanning electron microscopy. Multiple pop-in events were observed on the loading curves, however, no obvious pop-out takes place during the elastic recovery. In addition, an effective analytical method accommodating the indenter imperfection was proposed and validated against experimental data in terms of elastic modulus, yield stress and friction angle using the Drucker–Prager yield criterion for the YBCO thin film.