A note on the different crystalline features of the EuMnO3-based solid solutions as a function of the modifying cation nature

International audienceThe structural properties of solid solutions based on EuMnO3, in which Eu has been substituted by divalent Ca2+ and Mn by the divalent cation Ni2+ or the variable valence cation Co2+-Co3+ have been studied by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). These substitutions lead to changes in the lattice parameters and the symmetry of the orthorhombic, O' perovskite-type of the pristine compound EuMnO3. The structural changes depend on several factors. Solid solutions Eu(Mn,Ni)O3 and Eu(Mn,Co)O3 change from the O'-type to O-type orthorhombic perovskite symmetry when the content of the Mn3+ cation decreases due to the progressive substitution by Ni and Co. This change occurs for a percentage of the Ni2+ cation of 20 at%, whereas for the Co cation, only 10 at% are needed for such a transition. (Eu,Ca)MnO3 solid solutions showed a different behaviour. Even at an amount as high as 50 at% Ca2+ there is no transition from O' to O-type orthorhombic perovskite symmetry. The tolerance factor, t, increases monotonically for both Eu(Mn,Ni)O3 and (Eu,Ca)MnO3, while for Eu(Mn,Co)O3 it first decreases and then increases. The increase is lower for Ni-based and Co-based samples than for the Ca-based ones