Transmission electron microscopy investigation of domains and boundaries in bulk La_2/3Ca_1/3MnO₃

The microstructure of domains and boundaries in a bulk orthorhombic La_2/3Ca_1/3MnO₃ material is analysed by applying symmetry group theory. Group theory predicts that the 120° and 90° orientation domains occur in bulk La_{1− x} Ca _x MnO₃ (LCMO) when the cubic LCMO transforms into the orthorhombic LCMO by means of a structural phase transition. The orientation domains are observed and characterized by means of electron diffraction and high-resolution electron microscopy. Antiphase boundaries due to the loss of translation operations have displacement vectors of 1/2[010]o, 1/2[101]o and 1/2[111]0, according to the group theory. Diffraction contrast technique reveals that the displacive vector of most antiphase boundaries is 1/2[111]o, which is also confirmed by means of high-resolution electron microscopy.