Investigations of atomic structure and bonding at domain boundaries in bulk La 0.5 Eu 0.2 Sr 0.3 MnO 3

Perovskite ceramic samples of bulk La 0.7 Sr 0.3 MnO 3 doped with Eu are prepared by usual thermal decomposition and grinding procedure. Besides La 0.7 Sr 0.3 MnO 3 rhombohedral phase, with the substitution of Eu 3+ for La 3+ , another perovskite‐based structure with orthorhombic symmetry and space group Pnma can be identified by means of electron diffraction patterns (EDP) and energy‐dispersive X‐ray spectroscopy (EDX). Many 120° large‐angle orientation domains with a three‐fold rotational symmetry relationship are observed in the orthorhombic grain. According to group theory of phase transformation and matrix analyses, the 120° orientation domain originates from the three‐fold symmetry axis of pseudo‐cubic parent phase. Meanwhile, a projected model of the domain boundary is constructed based on their orientation relationships. The distortions and arrangements of MnO 6 octahedra on the domain boundary are discussed particularly. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)