Electron diffraction evidence of charge-ordering at room-temperature in La1-xCaxMnO3 (0.55 <= x <= 0.67)

摘要

Temperature dependent electron diffraction of La1-xCaMnO3 for 0.55 <= x <= 0.67 using transmission electron microscope (TEM) has been carried out in the temperature range of 106-300 K to study the melting of chartge-ordering across the transition temperature. Clear signature of charge-ordering as evident by the presence of diffuse super-lattice spots persist even at room temperature. This has been consistently observed for four different samples with compositions within the range of 0.55 <= x <= 0.67. The results indicate emergence of some degree of itinerancy in the localized charge carriers as temperature rises. (c) 2005 Elsevier Ltd. All rights reserved.