Electron Microscopy and Electron Energy-Loss Spectroscopy Study of Nd_1−xSr_xCoO_3−δ (0≤x≤1) System

Abstract

A solid solution of Nd 1-x Sr x CoO 3-δ (with x=0, 1/3, 2/3, and 1) has been prepared and characterized by a combination of X-ray diffraction, electron microscopy, and electron energy-loss spectroscopy (EELS). The structural characterization indicates that Nd-doped materials present an orthorhombic symmetry with a=√2xa p, b=√2xa p, and c=2xa p (a p refers to lattice parameter of simple cubic perovskite), while SrCoO2.5 has an orthorhombic symmetry with a=√2xa p, b=4xa p, and c=√2xa p. EELS analysis revealed that Co are in 3+ oxidation states but in different spin configurations.