Hardness and modulus of RuSr2RECu2O8 (RE=Eu, Gd) by nanoindentations and AFM

A nanoindenting atomic force microscope (NI-AFM) was used to study the elastic and plastic deformation properties of RuSr2RECu2O8 (RE = Eu, Gd) prepared by using the ammonium nitrate melt technique. The nanoindentation hardness and elastic modulus values of RuSr2RECu2O8 (RE = Eu, Gd) were measured in the peak load range from 10 to 400 mN. The experimental results revealed that, for each material, the measured hardness and elastic modulus values exhibit a peak-load- dependence, i.e., indentation size effect (ISE). This behaviour was then analyzed using the Meyer's law, Kick law, Hays-Kendall model, the proportional specimen resistance (PSR) model, the elastic recovery model, and the modified PSR model in order to calculate the elastic modulus and true hardness values for each material.