Role of Ni-Co co-substitution in improving electrical and dielectric properties of La-based multiferroics nanomaterials

The synthesis of a material having ferroelectric and ferromagnetic properties in the same phase is a challenging task. In the present work, lanthanum based multiferroic materials, with composition La1−xCoxFe1−yNiyO3 (where, x=0.0-0.5 and y=0.0-1.0), have been synthesized via sol-gel auto-combustion method. The phase of the synthesized materials was confirmed by the X-ray diffraction (XRD) analysis, while the surface morphology and particle size were determined by the scanning electron microscopy (SEM) analysis. The DC electrical resistivity and activation energy were observed to increase from 2.14×107 to 3.04×1010 Ω cm and 0.64 to 0.77 eV, respectively with the increase in concentration of substituents. The drift mobility decreases from 3.27×10−13 to 2.80×10−16 cm2 V−1 S−1. The dielectric constant, dielectric loss and dielectric loss factor decrease with the increase in frequency (1 MHz to 3 GHz) and Ni-Co content as well. The electrical and dielectric results are in good agreement with each other. The increase in electrical resistivity and decrease in dielectric parameters make these materials suitable for applications in microwave devices.