BaFe9LiO15: a new layered antiferromagnetic ferrite.

The new Fe(3+) oxide BaFe9LiO15 is isostructural with the magnetically frustrated material BaV10O15, adopting a structure based on the stacking of close-packed pure oxide and BaO7 layers. Neutron diffraction and Mössbauer spectroscopy shows that BaFe9LiO15 is long-range antiferromagnetically ordered with a Néel temperature of 460 K. The magnetic ordering of antiferromagnetically coupled ferromagnetic planes is stabilized by 90° and 180° superexchange interactions between the Fe(3+) cations that supersede the frustrated in-plane direct exchange observed in t(2g)-only systems.