Maximum Entropy Method Applied in the Experimental Visualization of Electron Density Distributions in BiFeO₃

Abstract

The BiFeO₃ is a largely studied compound with magnetoeletric coupling at room temperature. This is due its potential technological applications that can be directly used in advanced technologies. BiFeO₃ is an oxide with perovskite structure and R3c space group (rhombohedral symmetry). In this work, synchrotron radiation X-ray powder diffraction data was used to obtain a detailed description of BiFeO₃ crystal structure. Thereafter, experimental electron density distribution calculations were obtained using by the maximum entropy method (MEM) statistical approach. The ionic/covalent nature of the bonding and the interaction between the ions are clearly revealed by constructing electron density maps. The Fe³⁺-O²⁻ and Bi³⁺-O²⁻ bonding were studied in 1 and 2 dimensional electron density distributions. Due the high resolution of the obtained maps, it can be regarded as the most precise electron density distributions seen inside the material.

Keywords:

• BiFeO₃
• electron density maps
• maximum entropy method