Variation of crystal structure,magnetization, and dielectric properties of Nd and Ba co-doped BiFeO3 multiferroics

Multiferroics having composition Bi_0.80Nd_0.20-xBa_xFeO₃ were prepared to investigate the effect of doping on crystal structure, magnetic, and dielectric properties. The Rietveld refinement deduces the formation of mixed structural symmetry. With larger content of Nd, crystal structure consisting of major rhombohedral R3c and minor orthorhombic Pnma has been accomplished. The fraction of rhombohedral phase has been found to increase with doping of Ba up to x = 0.10. At composition x = 0.15, the orthorhombic phase Pnma disappears, and there is evolution of triclinic phase P1 in place of it. The mixed structure now accomplished contains ≈61% rhombohedral R3c and rest 39% triclinic P1. In solely Ba-doped sample (ie, at x = 0.20), the fraction of rhombohedral R3c phase again rises and attains ≈92% fraction of the structure along with rest triclinic P1 phase. The M-H loops depict enormous enhancement in magnetic properties with increasing doping of Ba. Dielectric constant (ε′) and dielectric loss (tan δ) both were found to increase with doping of Ba. The anomalies present in the dielectric constant and dielectric loss with temperature may be regarded to the hopping conduction of e⁻ between Fe³⁺ and Fe²⁺ and their interaction with oxygen vacancies.