Ultraprecise anisotropy mapping of Young's modulus in single-crystal diamond via mechanical resonance

The exceptional stiffness of diamond is strongly anisotropic due to its crystal structure, yet experimental quantification of Young's modulus along different orientations remains limited. Here, we present a direct measurement of elastic anisotropy in microwave plasma chemical vapor deposition (MPCVD) single-crystal diamond (SCD) by analyzing the resonance frequencies of cantilevers aligned along distinct crystallographic directions. The measured Young's modulus exhibited a minimum value of 1085 ± 21 GPa along the ⟨100⟩ direction and a maximum value of 1189 ± 22 GPa along the ⟨110⟩ direction. The compliance constants derived from the MPCVD-SCD differ substantially from previously reported values for natural diamonds and are more consistent with first-principles theoretical values. This method enables precise determination of orientation-dependent stiffness, revealing significant variation in Young's modulus across crystallographic axes. These insights are critical for the design of diamond-based micro- and nano-mechanical systems as well as other high-precision devices, where directional elasticity strongly influences performance.