Young’s Modulus and Tensile Strength of Ti₃C₂ MXene Nanosheets As Revealed by <i>In Situ</i> TEM Probing, AFM Nanomechanical Mapping, and Theoretical Calculations

Two-dimensional transition metal carbides, that is, MXenes and especially Ti₃C₂, attract attention due to their excellent combination of properties. Ti₃C₂ nanosheets could be the material of choice for future flexible electronics, energy storage, and electromechanical nanodevices. There has been limited information available on the mechanical properties of Ti₃C₂, which is essential for their utilization. We have fabricated Ti₃C₂ nanosheets and studied their mechanical properties using direct <i>in situ</i> tensile tests inside a transmission electron microscope, quantitative nanomechanical mapping, and theoretical calculations employing machine-learning derived potentials. Young's modulus in the direction perpendicular to the Ti₃C₂ basal plane was found to be 80-100 GPa. The tensile strength of Ti₃C₂ nanosheets reached up to 670 MPa for ∼40 nm thin nanoflakes, while a strong dependence of tensile strength on nanosheet thickness was demonstrated. Theoretical calculations allowed us to study mechanical characteristics of Ti₃C₂ as a function of nanosheet geometrical parameters and structural defect concentration.