Temperature-Reliant Dynamic Properties and Elasto-Plastic to Plastic Crystal (Rotator) Phase Transition in a Metal Oxyacid Salt

Although, dynamic crystals are attractive for use in many technologies, molecular level mechanisms of various solid-state dynamic processes and their interdependence, remain poorly understood. Here, we report a rare example of a dynamic crystal (1), involving a heavy transition metal, rhenium, with an initial two-face elasticity (within approximate to 1 % strain), followed by elasto-plastic deformation, at room temperature. Further, these crystals transform to a rotator (plastic) crystal phase at approximate to 105 degrees C, displaying exceptional malleability. Qualitative and quantitative mechanical tests, X-ray diffraction, mu-Raman and polarized light microscopy experiments reveal that the elasto-plastic deformation involves both partial molecular rotations and slip, while malleability in the rotator phase is facilitated by reorientational motions and increased symmetry (slip planes). Our work, connecting the plastically bendable (1D or 2D) crystals with the rotator phases (3D), is important for designing multi-functional dynamic crystals.

Automated summary

This study presents a rare example of a dynamic crystal involving the heavy transition metal rhenium, displaying initial two-face elasticity and elasto-plastic deformation at room temperature, followed by transformation into a rotator crystal phase at approximately 105 degrees C. The mechanical tests, X-ray diffraction, mu-Raman, and polarized light microscopy experiments reveal that the elasto-plastic deformation involves molecular rotations and slip, while malleability in the rotator phase is facilitated by reorientational motions and increased symmetry. Connecting plastically bendable crystals with rotator phases is important for designing multi-functional dynamic crystals.