CaFeFeNbO6 – an iron-based double double perovskite

Ordering of cations is important for controlling properties of ABO3 perovskites, and CaFeFeNbO6 is the first example of an Fe-based AA’BB’O6 double double perovskite, with Ca2+/Fe2+ ordered on A-site columns, and Fe3+/Nb5+ at the octahedral B-sites. Substantial (37%) antisite disorder of the latter cations leads to spin glassy magnetism below a freezing transition at 12 K. The CaMnFeNbO6 analogue also shows substantial cation disorder and spin glassy behaviour. Comparison of synthesis pressures for ordered materials based on different A-site transition metals, suggests that pressures of at least 14-18 GPa will be required to discover the expected plethora of double double perovskites based on A’ cations smaller than Mn2+Files are magnetic and powder neutron diffraction data for the two samples shown in the publication Ji, K., Bedward, J.R., Li, Q., Manuel, P., Ritterc, C. and Attfield, J.P. (2023), "CaFeFeNbO6 – an iron-based double double perovskite", Chemical Communications 59, 6371 - 6374 ( https://doi.org/10.1039/D3CC01115A ).