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Semiconducting oxide nanocomposites of ZnO/SnO2 with different weight ratio, i.e. (i) ZnO:SnO2 = 100:0 (ZnO0), (ii) ZnO:SnO2 = 75:25 (ZnO25), and (iii) ZnO:SnO2 = 50:50 (ZnO50), were prepared by sol–gel method. X-ray diffraction (XRD) measurement reveals a rutile type tetragonal structure of SnO2 whereas hexagonal wurtzite structure of ZnO. Transmission electron microscopy (TEM) measurement suggests an effective role of SnO2 addition on the particle size of studied nanocomposites. Energy dispersive X-ray analysis (EDAX), carried out for elemental analysis for the studied nanocomposites, reveals the Sn deficiency in ZnO50 nanocomposite sample. Frequency dependent dielectric behavior recorded at different temperatures has been understood in the context of cole–cole plots for all the nanocomposites where variations in relaxation time and relaxation time distribution have been discussed in detail. Variation in ac conductivity has been discussed on the basis of Jonscher's universal power law and crossover from correlated barrier hopping (CBH) mechanism to Maxwell–Wagner (M–W) relaxation has been identified for the studies nanocomposites. Overall electrical properties have been discussed in the context of oxygen vacancies, defects, disorder, and thermal energy in details. Highlights: Cost effective synthesis of ZnO and SnO2 based nanocomposites. Strong effect of addition of SnO2 on electrical properties nanocomposites. Effective role of SnO2 nanoparticles in governing polarization mechanisms. Efficient role of SnO2 nanoparticles in governing charge hopping mechanisms. [ABSTRACT FROM AUTHOR]

The magnetoelectric (ME) properties of sol-gel grown BiFeCoO3 (BFCO) nanoceramics, with different sizes, were investigated at room-temperature. X-ray diffraction (XRD) measurement was performed to investigate structural properties of the samples understudy. Magnetic field-dependent dielectric permittivity has been systematically investigated in the frequency range of 20 Hz to 1 MHz. To ensure the origin of magnetodielectric response, the magnetoimpedance (MI) spectroscopy was adopted using equivalent circuit model. The a.c. conductivity was found to obey the Jonscher's universal power law. The modifications in spiral spin structure in the BFCO nanoparticles with size less than 62 nm significantly affect the ME coupling parameters. [ABSTRACT FROM AUTHOR]