Synthetic analogues of Fe(ii)–Fe(iii) minerals containing a pentagonal ‘Cairo’ magnetic lattice

Abstract

Versiliaite and apuanite are two minerals containing Fe²⁺ and Fe³⁺ in a low-dimensional structure exhibiting chains of edge-linked FeO₆ octahedra. The chemistry of these minerals has not been fully examined because of their rarity. We demonstrate that chemical synthesis of these minerals is possible to allow measurement of their magnetic properties and a more complete description of their structural features using neutron powder diffraction. We also show that chemical manipulation is possible to provide isostructural phases with different chemical compositions.