The short series of the oxygen-poor lanthanide oxide selenides M10OSe14 with M = La-Nd

Abstract

Single crystals and phase pure samples of oxygen-poor ternary lanthanide oxide selenides with the composition M10OSe14 (M = La-Nd; tetragonal, I41/acd; a = 1592.0-1559.8 pm, c = 2106.5-2062.9 pm) could be obtained by reacting the corresponding metals, selenium and selenium dioxide as oxygen source. Their crystal structures are isotypic with Pr10OS14 and thus contain isolated [OM4]10+ tetrahedra (d(O2--M3+) = 243-248 pm) embedded in a complex anionic 3∞{[M6Se14]10-} lanthanide selenide matrix (d(M3+-Se2-) = 288-358 pm). All three crystallographically independent M3+ cations exhibit eight contacts to chalcogenide anions (O2- and/or Se2-) resulting in the formation of bicapped trigonal prismatic coordination polyhedra. The optical band gaps of the oxide selenides M10OSe14 amount to values between 1.89 and 2.04 eV indicating wide band-gap semiconductors. © 2011 by the authors; licensee MDPI, Basel, Switzerland.