Abstract

Stoichiometric n = 2 members of the Ruddlesden–Popper (RP) family have been synthesized. These oxides, Ln₂BaIn₂O₇ (Ln = La, Nd), crystallize in a tetragonal cell with a = 5.9141(3) Å, c = 20.8231(2) Å for La and a = 5.8940(3) Å, c = 20.467(1) Å for Nd. The crystal structure determination of the La oxide shows three remarkable structural features: (i) ordering of the La³⁺ and Ba²⁺ cations which sit in the rock salt and octahedral layers respectively; (ii) buckling of the octahedral layers; (iii) strong distortion of the rock salt layers forming an island like configuration. A comparison with the oxygen deficient n = 2 member Ba₃In₂O₆ is made.