Structure and magnetic properties of cation-disordered perovskites SrLaCrSnO6 and Ca2CeCr2TiO9

Abstract Polycrystalline samples of the new perovskites SrLaCrSnO 6 and Ca 2 CeCr 2 TiO 9 have been synthesised using the ceramic method and characterized by x-ray diffraction, neutron diffraction and magnetometry. Both crystallise in the space group Pbnm , with a disordered distribution of B-site cations, and both exhibit G z -type antiferromagnetism at low temperatures. The antiferromagnetic order develops over a large temperature range. It is proposed that isolated antiferromagnetic clusters grow in size upon cooling to form a long-range antiferromagnetically-ordered backbone running through the structure. Cations with few magnetic nearest-neighbours remain decoupled from the backbone down to 2 K. More decoupled clusters are present in Ca 2 CeCr 2 TiO 9 than in SrLaCrSnO 6 . This is attributed to the increase in frustration that accompanies the increase in strength of the next-nearest-neighbour interactions that occurs when d 10 :Sn 4+ is replaced by d 0 :Ti 4+ .