Correlation between structure, dielectric and multiferroic properties of lead free Ni modified BaTiO3 solid solution

Abstract

Present study highlights the influence of Ni doping on the structural, optical, dielectric, ferroelectric and magnetic properties of nanocrystalline BaTi1-xNixO3 (0 ≤ x ≤ 0.06) ceramics synthesized by sol-gel auto combustion process. Phase identification and crystal structure are examined through Rietveld refinement analysis that ensures mono-phase nature with tetragonal crystal structure in P4mm space group. The observed variation in the structural parameters viz. lattice constants, unit cell volume, bond lengths (Ti-O) and bond angles (Ti-O-Ti) are the direct evidence of distortion produce in the unit cell under the effect of Ni doping. The FTIR studies confirm perovskite structure and presence of stretching/bending vibrations of the various bands present in the samples. The optical properties divulge a minor alteration in optical bandgap under the influence of Ni content. Dielectric studies reveal higher value of the dielectric constant for pristine sample in the low frequency region, but its value decreases on Ni doping. The dielectric response, analyzed through UDR model, exhibits deviation from linear behavior at higher frequencies. Ferroelectric measurements demonstrate that the pristine sample has higher values of remnant polarization (Pr) and maximum polarization (Pm) which decrease linearly with the increase in Ni doping. Magnetic hysteresis loops at room temperature establish a weak ferromagnetic nature of the samples that arises due to the carrier-mediated exchange interactions with smaller values of magnetic parameters. These investigations ensure that the ferromagnetism can be induced in BaTiO3 by appropriate doping of Ni ions, which may find their potential use in the field of multiferroics.