Complex Dielectric and Impedance Spectroscopic Studies in a Multiferroic Composite of Bi2Fe4O9-BiFeO3

Abstract

Complex dielectric and impedance spectroscopic studies have been carried out in a detailed manner on the system comprising of Bi2Fe4O9-BiFeO3 composite particles dispersed in a α-Fe2O3 matrix as prepared using ball milling and controlled annealing treatments. This multiferroic composite is observed to exhibit a giant dielectric constant associated with a low tangent loss. A non-Debye type of relaxation has been deduced based on complex modulus analysis. Based on these studies, the important role played by bismuth ferrite nanoshell in the core-shell composite of Bi2Fe4O9-BiFeO3 is elucidated for the observed complex impedance spectroscopic properties of the system. Electron hopping across Fe2+/Fe3+ and oxygen vacancies are deduced to be playing an important role in conduction mechanisms based on activation energy analysis of the complex impedance spectroscopy results.

Enhanced gas-sensing performance at room temperature and electrical properties of polyaniline–Ni0.6Zn0.4Fe2O4 nanocomposites

“…34 It's challenging to generate two semicircles matching the grain and grain boundary only on a single scale because the grain and grain boundary have distinct magnitudes. 56,57 The ϵ' and ϵ" decrease as the frequency increases, as shown in Figures 5(a change in ϵ' with frequency, which confirms Koop's phenomenological theory. 58 According to this model, a dielectric medium has been assumed to be made up of well-conducting grains separated by poorly conducting grain boundaries.…”

“…34 It's challenging to generate two semicircles matching the grain and grain boundary only on a single scale because the grain and grain boundary have distinct magnitudes. 56,57…”

Characterization of Na_0.5Bi_0.5TiO₃ Single Crystals by X-ray Diffraction, Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy, Optical Absorption, Electric and Thermoelectric Properties Studies

“…However, the curves from various temperatures converged to a nearly plateau region at higher frequencies (above 100 kHz) (the archlike region progressively shrinks with increasing temperature for the temperature interval above 300°C and for high frequencies the creep-like region becomes predominant, insert in Figure 13a). This phenomenon can be attributed to release of point defects (space charge) [51]. The distinguishing features are the emerging modes (maxima) in the region of intermediate frequencies involved by the electrode-sample interface.…”

“…The most probably relaxation time τ is estimated from the position of M''max. as a function of frequency, according to the relationship [51]:…”