Crystal lattice dynamics of the substituted solid solutions in the Bi(Gd)–Fe–O and Bi(Nd)–Fe–O systems

Abstract

The substitutional solid solutions in the Bi(Gd)–Fe–O and Bi(Nd)–Fe–O systems of the Bi1-xGdxFeO3 and Bi1-xNdxFeO3 types with x up to 0.20 were synthesized by the solid-state reaction method and investigated using X-ray diffraction analysis and infrared reflective spectrometry in the wavelength range from 12.5 to 24 μm. It was determined that the Bi1-xGdxFeO3 and Bi1-xNdxFeO3 crystal structure is a distorted form of perovskite, R3c space group. Two extremums at 18.2 μm (strong extremum) and 22.5 μm (rather weak extremum) on the infrared reflection spectra of the Bi1-xGdxFeO3 and Bi1-xNdxFeO3 solid solutions were discovered. The extremum at 18.2 μm corresponds to the Fe – O stretching vibrations and the extremum at 22.5 μm corresponds to the O–Fe–O bending vibrations of the FeO6 groups. The growth of reflectivity of the Bi1-xGdxFeO3 and Bi1-xNdxFeO3 solid solutions in comparison with pure BiFeO3 and the displacement of the reflectivity band maximum into the side of the spectrum with longer wavelengths with the increase of the atomic part of the substitutive element x up to 0.20 were found.