Double Crystal Symmetries in Morphotropic Phase Boundary of Substituted BiFeO3 Ceramics.

The compositional driven crystallographic phase transition and its effect on the dielectric constant have been investigated on Nd and Mn Co-substituted BiFeO3 Ceramics. The distinct changes in phonon modes of Raman spectra and transmission band of FT-IR show the evidence for structural transition (rhombohederal (R3c) to orthorhombic orthorhombic (Pbnm)) with the increase in the substitution concentration. The dielectric constant was found to increase by significant magnitude with the increase in substitution concentration of Nd and Mn around morphotropic phase Boundary (7.5 % of co-substitution) due to increase in the off-centre movement of Fe3+ ions and Bi3+ in the oxygen octahedra and cuboctahedra respectively. [ABSTRACT FROM AUTHOR]