Influence of γ Radiation on the Crystal Structure of BiFeO3
С. А. Иванов, A.I. Stash, А. А. Буш, Аlexander А. Korlyukov, V. M. Boyko, V. S. Ermakov
Abstract
—Perfect single crystals of BiFeO3 have been grown by the solution-melt method. Chemical analysis has confirmed their cationic and anionic stoichiometry. Precision X-ray diffraction analysis has provided more accurate structural data for BiFeO3 before and after γ-irradiation with a dose of 1.0 × 106 rad. It has been established that the indicated structural characteristics of the BiFeO3 crystal are in satisfactory agreement with the available literature data, although in our case a significant increase in their accuracy is observed (the R values (F > 2σ(F)) range from 0.017 to 0.023). For the first time, difference maps of the residual electron density have been constructed and possible positions of lone pairs of electrons for Bi3+ cations have been determined, which is important for establishing the structural conditionality of the ferroelectric properties in BiFeO3. The effect of lone electron pairs on the specific features of the structural framework has been studied. The characteristic features of cationic polyhedra in the structure have been analyzed, including the calculation of their distortions and the valence state of cations. It has been shown that the structure of BiFeO3 is resistant to irradiation with a given dose.