ZrCuSiAs type layered oxypnictides: A birdʹs eye view of LnMPnO compositions

This work presents a survey of LnMPnO materials crystallizing in the ZrCuSiAs structural archetype. Tabulated lattice parameter values for a number of LnMPnO compositions are presented along with atomic positions and bond lengths. Using this information a bond valence sum (BVS) analysis is carried out for these compositions. The lanthanoid BVS values agree quite well with Ln3+ in all cases, however the BVS values for the M cations deviate considerably from the expected value of M2+ if only ionic bonding were present. This deviation clearly indicates the covalent nature of M–Pn bonding in these materials and the significance of M–M interactions. The reported physical properties for these materials are also surveyed and arranged according to compositional M cation.