In Situ Observation of Fracture along Twin Boundaries in Boron Carbide.

The observation of fracture behaviors in perfect and twinned B C crystals via in situ transmission electron microscopy (TEM) mechanical testing is reported. The crystal structure of the synthesized B C, composed of B C icosahedra connected by boron-deficient C-▫-C chains in a chemical formula of B C , is determined by state-of-the-art aberration-corrected scanning TEM. The in situ TEM observations reveal that cracking is preferentially initiated at the twin boundaries (TBs) in B C under both indentation and tension loading.

Inclined Ultrathin BiOSe Films: A Building Block for Functional van der Waals Heterostructures.

As an emerging ultrathin semiconductor material, BiOSe exhibits prominent performances in electronics, optoelectronics, ultrafast optics, However, until now, the in-plane growth of BiOSe thin films is mostly fulfilled on atomically flat mica substrates with interfacial electrostatic forces setting obstacles for BiOSe transfer to fabricate functional van der Waals heterostructures. In this work, controlled growth of inclined BiOSe ultrathin films is realized with apparently reduced interfacial contact areas upon mica flakes. Consequently, the transfer of BiOSe could be facile by overcoming weaker electrostatic interactions.