Investigation of dielectric, impedance, and magnetodielectric behavior in Bi5Ti3FeO15–Bi2Fe4O9 composites prepared by sol–gel modified method

Abstract

Abstract We report detailed studies of the dielectric, impedance, and magnetodielectric properties of sol–gel synthesized (1−x)Bi5Ti3FeO15–(x)Bi2Fe4O9, x = 0.1 composites. The Rietveld refinement of X-ray diffraction data confirms the presence of mixed phases Bi5Ti3FeO15 (A21 am) and Bi2Fe4O9 (Pbam) with the orthorhombic crystal structure. The average grain size of the sample is calculated from scanning electron microscopy and found to be 0.74 µm and 0.80 µm for BTFO and BFO samples, respectively. The room temperature dielectric behavior of the prepared composite is demonstrated over a frequency range (102 Hz to 106 Hz) and at different fixed magnetic fields (0 T to 1.3 T). The decreasing trend of dielectric dispersion and loss signifies the presence of negative magnetodielectric and magneto-loss in the composite. Frequency-dependent magnetoresistance through impedance spectroscopy has been carried out to analyze the origin of the observed MD effect. The magnetic field-dependent MD and ML exhibit maximum coupling of about −0.19% and −0.36% at 50 kHz, respectively. The obtained MD response in this composite is due to the grain (capacitive) effect. These results establish a relation between the electric and magnetic order in the composites and extend their application in the field of magnetic memory and sensor devices.