The reversible electrochemical insertion of multivalent ions into materials has promising applications in many fi elds, including batteries, seawater desalination, element purifi cation, and wastewater treatment. However, fi nding materials that allow for the insertion of multivalent ions with fast kinetics and stable cycling has proven diffi cult because of strong electrostatic interactions between the highly charged insertion ions and atoms in the host framework.Here, an open framework nanomaterial, copper hexacyanoferrate, in the Prussian Blue family is presented that allows for the reversible insertion of a wide variety of monovalent, divalent, and trivalent ions (such as Rb + , Pb 2+ , Al 3+ , and Y 3+ ) in aqueous solution beyond that achieved in previous studies. Electrochemical measurements demonstrate the unprecedented kinetics of multivalent ion insertion associated with this material. Synchrotron X-ray diffraction experiments point toward a novel vacancy-mediated ion insertion mechanism that reduces electrostatic repulsion and helps to facilitate the observed rapid ion insertion. The results suggest a new approach to multi valent ion insertion that may help to advance the understanding of this complex phenomenon.

Na 2 S was prepared from stoichiometric Na (Acros Organics, rod, 99.8%, mechanically cleaned prior to use) and S (see main text) in separate alumina crucibles (Almath) in an evacuated silica ampoule. The reactants were heated at 1°C min −1 to 300°C for 48 h and cooled ambiently to room temperature. The ground product was a fine powder of a slightly tan-color. The product was determined to be phase pure by XRD.

Laser powder bed fusion additive manufacturing is an emerging 3D printing technique for the fabrication of advanced metal components. Widespread adoption of it and similar additive technologies is hampered by poor understanding of laser-metal interactions under such extreme thermal regimes. Here, we elucidate the mechanism of pore formation and liquid-solid interface dynamics during typical laser powder bed fusion conditions using in situ X-ray imaging and multi-physics simulations. Pores are revealed to form during changes in laser scan velocity due to the rapid formation then collapse of deep keyhole depressions in the surface which traps inert shielding gas in the solidifying metal. We develop a universal mitigation strategy which eliminates this pore formation process and improves the geometric quality of melt tracks. Our results provide insight into the physics of laser-metal interaction and demonstrate the potential for science-based approaches to improve confidence in components produced by laser powder bed fusion.