Concentration-dependent structural transition in the La0.70Sr0.30MnO3-δ system

The crystal structure of anion-deficient La0.70Sr0.30MnO3-delta manganites (delta = 0, 0.10, 0.15, and 0.20) has been studied by powder neutron diffraction at room temperature. The crystal structures of the stoichiometric La0.70Sr0.30MnO3 and anion-deficient La0.70Sr0.30MnO2.90 samples are satisfactorily described by the rhombohedral R (3) over barc space group. The anion-deficient La0.70Sr0.30MnO2.85 sample separates into two perovskite phases with the R (3) over barc and I4/mcm space groups. The crystal structure of La0.70Sr0.30MnO2.80 cannot be described by a single perovskite phase in the I4/mcm space group. It is found that the clustering of oxygen vacancies is the cause of structural phase separation at 293 K in anion-deficient La0.70Sr0.30MnO3-delta manganites.