Synthesis, crystal structure, and microstructure analysis of perovskite-type compounds LnCo(0.95)Ni(0.05)O(3) (Ln = La, Pr, Nd, Sm, Gd, and Dy)

摘要

The crystal structure and the microstructure of LnCo(0.95)Ni(0.05)O(3) compounds, synthesized by a soft chemistry process, were studied. Synchrotron and laboratory X-ray diffraction data of LnCo(0.95)Ni(0.05)O(3) (Ln = Pr, Nd, Sm, Gd, and Dy) can be refined in the Pbnm space group (SG). The orthorhombic symmetry has been confirmed by transmission electron microscopy. The X-ray diffraction data of LaCo0.95Ni0.05O3 can be fitted with rhombohedral R (3) over barc and monoclinic I2/a SG. The comparison of experimental electron diffraction with theoretical simulation showed the monoclinic symmetry for the La compound has a better match than that of the rhombohedral symmetry. The Pr compound has shown to have a three-dimensional microdomain texture in which the orientation of the real unit cell, i.e., similar to root 2a(p) x root 2a(p) x 2a(p) (where a(p) is the lattice parameter of the aristotype Pm (3) over barm perovskite, noted with a "p" subscript), alternates in each domain in one of the three space directions.