Microstructure and magnetic properties of MFe 2 O 4 (M = Co, Ni, and Mn) ferrite nanocrystals prepared using colloid mill and hydrothermal method Journal of Applied Physics 117, 17A328 (2015) Nickel substituted cobalt ferrite nanoparticles with composition Co 1−x Ni x Fe 2 O 4 (0.0≤x≤1.0) was synthesized using simple, low temperature auto combustion method. The X-ray diffraction patterns reveal the formation of cubic phase spinel structure. The crystallite size varies from 30-44 nm with the nickel content. Porous and agglomerated morphology of the bulk sample was displayed in the scanning electron microscopy. Micro Raman spectroscopy reveals continuous shift of E g and E g (2) stokes line up to 0.8 Ni substitution. The dispersion behavior of the dielectric constant with frequency and the semicircle nature of the impedance spectra show the cobalt nickel ferrite to have high resistance. The ferromagnetic nature is observed in all the samples, however, the maximum saturation magnetization was achieved by the 0.4 Ni substituted cobalt ferrite, which is up to the 92.87 emu/gm at 30K. C 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License. [http://dx

No abstract

In this study, coral cauliflower‐like polypyrrole (PPy) hemispheres are synthesized on an alumina substrate via a simple chemical oxidative polymerization route. The stony coral‐like morphology of PPy hemispheres acts as a conducting trap in absorbing electromagnetic (EM) radiation via multiple internal reflections. A PPy thin film deposited at 0.2 M pyrrole concentration shows a minimum reflection loss (RL) of −30.80 dB (99.9% microwave absorption) at the frequency of 14.2 GHz, and the highest total shielding effectiveness achieved is −18.3 dB at 16.8 GHz at 4.38 μm film thickness. The thin films exhibit excellent microwave absorption ability at low thicknesses, and the effective absorption bandwidth (RL < –10 dB) attains a high value of 2.2 GHz in the frequency range of 13–15.2 GHz. These findings can help researchers to enhance the EM wave absorption characteristics in a broad frequency region using lightweight intrinsically conducting polymers.

No abstract

No abstract