Mixed-valent iron niobate (Fe0.35Nb0.65)3O6 polymorphs for lithium battery anodes
A di-rutile (Fe0.35Nb0.65)3O6, FNO-r, is prepared under mild hydrothermal conditions at 240 °C that subsequently transforms to a columbite-type, orthorhombic polymorph, FNO-o, at 900 °C under a N2 atmosphere. The two polymorphs are structurally characterised using high-resolution powder X-ray diffraction, X-ray absorpt...