Effect of La/Cr co-doping on dielectric dispersion of phase pure BiFeO3 nanoparticles for high frequency applications

Energy storage materials play a vital role in modern technology. A single device can perform multifunctions if fabricated using a multifunctional material like BiFeO3. For this purpose, a series of La and Cr doped BiFeO3 was synthesized using sol‒gel auto-combustion technique. A single phase rhombohedral distorted perovskite crystal structure related to bismuth ferrite with space group R3c (161) was confirmed from the X-ray diffraction patterns. Doping of La/Cr at Bi/Fe lattice sites in BiFeO3 did not affect the crystal symmetry of the parent compound. Morphological analysis exhibited homogeneous micro structures showing uniform distribution of multi-shaped grains with decreasing porosity and grain sizes with increasing Cr contents. These materials exhibited the conventional ferrite-like dielectric response, which gradually decreased with increasing frequency and lastly became constant in the high frequency regime. Impedance spectroscopy revealed the contribution of grains, grain boundaries and interfaces in electrical response of the samples. Frequency dependent electric modulus analysis confirmed the non-Debye type relaxation.