Exploring the physical properties of Eu2SrCo1.5Mn0.5O7, a new n = 2 member of the Ruddlesden–Popper series (Eu,Sr)n+1(Co,Mn)nO3n+1
A new oxide of the Ruddlesden–Popper series has been isolated and structurally characterized in the Eu–Sr–Co–Mn–O system. X-ray diffraction and electron microscopy show that polycrystalline Eu2SrCo1.5Mn0.5O7 constitutes the n = 2 member of a homologous series, the essential feature of which is the existence of two connected Co/Mn octahedral layers, separated by Eu atoms. Electrochemical studies show that the area-specific resistance of this compound is 0.15 Ω cm2 at 700 °C in air, a performance which is comparable to that of the best state-of-the-art materials used as cathodes in intermediate temperature solid oxide fuel cells. Below 150 K the title material presents two different magnetic phenomena. The first one corresponds to the formation of ferromagnetic nanoclusters (TC ∼ 121 K) within an ordered Co2+/Mn4+ atomic configuration, whereas at lower temperature (∼21 K) a spin glass state occurs.