The nature of synthetic basic ferric arsenate sulfate (Fe(AsO4)1−x(SO4)x(OH)x) and basic ferric sulfate (FeOHSO4): their crystallographic, molecular and electronic structure with applications in the environment and energy

In this study we investigate a new family of arsenate-bearing phases belonging to one set of structures (Basic Ferric Sulfate-BFS: monoclinic-orthorhombic FeOHSO4) that are significant as an industrial arsenic control material in the environment or a cathodic material in rechargeable Li-ion battery cells. We determine for the first time (after two decades of its known existence in the processing industry) the average crystallographic structure of Basic Ferric Arsenate Sulfate-BFAS: Fe(AsO 4)1-x(SO4)x(OH)x· (1-x)H2O) that is a member of this family of phases and how it relates to its parent BFS structure. Moreover, we demonstrate how the substitution of AsO4 ↔ SO4 affects the crystallographic structure of these phases, the phase(s) that are formed and their material properties as environmentally stable arsenic controls or Li-ion battery cathodes. © The Royal Society of Chemistry 2013.