The covalent bonding interaction in the ferroelectric LuMnO(3)

Abstract

The electron density distributions of paraelectric and ferroelectric LuMnO3 are analyzed using high temperature synchrotron x-ray powder diffraction data with the Rietveld method, the maximum entropy method (MEM), and MEM-based pattern fitting. Bonding electrons due to orbital hybridization are clearly seen in the Lu1-O3 and Lu2-O4 bonds along the c-axis polarization direction. The Lu1-O3 bond was determined to be covalent due to hybridization below the ferroelectric transition temperature, and was identified as the driving force for ferroelectricity in LuMnO3. However, the Lu2-O4 bond shows covalent character in both paraelectric and ferroelectric states. Also, we suggest that the Lu2-O4 covalent bonding is responsible for large spontaneous polarization in LuMnO3, associated with the small radius of the Lu3+ ion. (C) 2011 American Institute of Physics. [doi:10.1063/1.3655986]