Micro-mechanical properties of single high aspect ratio crystals

This work describes a new method to measure breakage strength and elastic modulus of single crystal cantilevers using atomic force microscopy. Crystal breakage is an important but poorly understood factor in mechanical processing of organic crystals. In this study, 300μm long beta glutamic acid, needle-shaped crystal cantilevers are bend and broken in an Atomic Force Microscope. We report the first directly measured distribution of breakage strength and Young’s modules of an organic crystal material. The distribution follows a Weibull distribution; 50% of the crystals break at less than 22.4MPa and have a Young’s modulus below 1.90GPa and we observed that stronger crystals are stiffer, and thicker crystals break easier. The data generated from the single crystal cantilever method provides fundamental material properties essential for understanding undesirable crystal fracture due to forces exerted on crystals in manufacturing processes such as crystallisation, filtration and drying.