Phase Stability and Magnetic Properties of Compositionally Complex n=2 Ruddlesden-Popper Perovskites

Four new compositionally complex perovskites with multiple (four or more) cations on the B site of the perovskites have been studied. The materials have the general formula La0.5Sr2.5(M)(2)O7-delta (M = Ti, Mn, Fe, Co, and Ni) and have been synthesized via conventional solid-state synthesis. The compounds are the first reported examples of compositionally complex n = 2 Ruddlesden-Popper perovskites. The structure and properties of the materials have been determined using powder X-ray diffraction, neutron diffraction, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and magnetometry. The materials are isostructural and adopt the archetypal I4/mmm space group with the following unit cell parameters: a similar to 3.84 & Aring;, and c similar to 20.1 & Aring;. The measured compositions from energy dispersive X-ray spectroscopy were La0.51(2)Sr2.57(7)Ti0.41(2)Mn0.41(2)Fe0.39(2)Co0.38(1)Ni0.34(1)O7-delta, La0.59(4)Sr2.29(23)Mn0.58(5)Fe0.56(6)Co0.55(6)Ni0.42(4)O7-delta, La0.54(2)Sr2.49(13)Mn0.41(2)Fe0.81(5)Co0.39(3)Ni0.36(3)O7-delta, and La0.53(4)Sr2.55(19)Mn0.67(6)Fe0.64(5)Co0.31(2)Ni0.30(3)O7-delta. No magnetic contribution is observed in the neutron diffraction data, and magnetometry indicates a spin glass transition at low temperatures.