Fe-doped Na0.47Bi0.47Ba0.06Ti0.98-xV0.02FexO3: Structure correlated vibrational, optical and electrical properties

Abstract

Structural, optical, and electrical properties of rhombohedral (R3c) Fe-doped Na0.47Bi0.47Ba0.06Ti0.98-xV0.02FexO3 (x = 0, 0.005 and 0.01) are reported. The bond-lengths and bond angles were studied and were correlated with the vibrational, optical, and electrical properties of the materials. Oxygen displacement, Ti off-centering and tilting of octahedra are discussed and correlated with the optical/electronic properties. The theoretical phonon modes of NBT calculated from DFT analysis were correlated with the experimentally observed phonon modes for the three samples. The dielectric properties were explored along with the ferroelectric properties. High temperature phase transitions were analyzed leading from a ferroelectric phase at room temperature to an antiferroelectric phase at ∼200 °C and further to a paraelectric phase at ∼400 °C. The phase transition temperatures vary from sample to sample and can be the disorderness of the A/B site cations. The energy storage efficiency varied with the structural changes and was found to be maximum for the 0.5% doped Fe(S2).