Chlorine insertion promoting iron reduction in Ba-Fe hexagonal perovskites: effect on the structural and magnetic properties

Abstract

BaFeClO has been synthesized and studied. A proper tuning of the synthetic route has been designed to stabilize this compound as a single phase. The thermal stability and evolution, along with the magnetic and structural properties are reported here. The crystal structure has been refined from neutron powder diffraction data, and it is of the type (hhchc)-10H. It is stable up to a temperature of 900 °C, where the composition reads BaFeClO. The study by electron microscopy shows that the crystal structure suffers no changes in the whole BaFeClO (2.34 ≤ 3-y ≤ 2.48) compositional range. Refinement of the magnetic structure shows that the Fe is antiferromagneticaly ordered, with the magnetic moment parallel to the ab plane of the hexagonal structure. At higher temperature, a nonreversible phase transition into a (hchc)-4H structure type takes place with overall composition BaFeClO. Microstructural characterization shows that, in some crystals, this phase intergrows with a seemingly cubic related phase. Differences between these two crystalline phases reside in the chlorine content, which keeps constant through the phase transition for the former and disappears for the latter.