Study of frequency dependent dielectric response and ferroelectric behaviour of (Nd,Ni) co-doped BiFeO3

Abstract

Nanocrystalline samples of pristine BiFeO3(BFO) and (Nd,Ni) co-doped BFO (Bi0.9Nd0.1Fe0.9Ni0.1O3) have been synthesized through the sol-gel auto combustion process and characterized to probe the influence of doping on its dielectric and ferroelectric properties. The frequency dependent dielectric measurements carried out at room temperature reveal dispersive nature of dielectric constant within low frequency regime which further becomes constant at higher frequencies. The real and imaginary parts of the dielectric constant exhibit significant rise with the Nd and Ni doping, which is attributed to the occurrence of greater space charge polarization due to dopant ions. The ac conductivity follows the Jonscher’s universal dynamic law and accordingly increases with frequency as well as with doping. It is inferred that the enhancement in small polaron hopping due to Ni2+ ion is responsible for the conduction mechanism. Both the pristine and (Nd,Ni) co-doped samples are found to exhibit Universal Dielectric Response (UDR) phenomena for the entire frequency range of 75kHz-5MHz. The polarization-field measured at room-temperature manifests enhanced remnant polarization and lower breakdown fields due to the structural distortion and uniformity in grain boundaries induced upon Nd doping. The creation of oxygen vacancies due to charge imbalance instigated by Ni substitution is responsible for higher leakage current and formation of unsaturated, lossy ferroelectric loops. Thus, from the enhanced dielectric characteristics and polarization values, it is established that the co-doping of (Nd,Ni) in BiFeO3 can find exceptional applications in microelectronic industries.