Enhancing absorption dominated microwave shielding in Co@C-PVDF nanocomposites through improved magnetization and graphitization of the Co@C-nanoparticles

Choudhary, Harish Kumar and Kumar, Rajeev and Pawar, Shital Patangrao and Sundararaj, Uttandaraman and Sahoo, Balaram (2019) Enhancing absorption dominated microwave shielding in Co@C-PVDF nanocomposites through improved magnetization and graphitization of the Co@C-nanoparticles. In: PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 21 (28). pp. 15595-15608.

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Abstract

Using composites of polyvinylidene fluoride (PVDF) and carbon nanostructures embedded with Co-nanoparticles we demonstrate that electromagnetic shielding effectiveness depends strongly on the graphitic carbon concentration and the magnetic properties of Co-particles. Cobalt nanoparticles encapsulated by graphitic carbon embedded in an amorphous carbon-matrix were synthesized by a one-pot pyrolysis method at two different synthesis temperatures, T-S = 800 degrees C (Co-800) and 1000 degrees C (Co-1000). We demonstrate that T-S plays an important role in determining the structure, morphology and magnetic properties of the carbonaceous matrix, the graphite layer and the Co nanoparticles. Higher amounts of graphitic carbon and high saturation magnetization were observed for the Co-1000 sample than that for the Co-800 sample. We observed that the electromagnetic interference (EMI) shielding behavior of the PVDF-Co-1000 nanocomposite shows higher shielding effectiveness than that of the PVDF-Co-800 specimen. A more inhomogeneous dielectric medium in the PVDF-Co-1000 composite results in higher dielectric loss and impedance mismatch. A direct correlation between the shielding effectiveness with dielectric permittivity and magnetic permeability is demonstrated. The synergy between the multiple reflections at the interfaces and absorption of the microwave radiation in the conducting species confirms that a higher degree of graphitization and highly magnetic particles in nanocomposites are effectively superior for EMI shielding of microwave radiation.

Item Type:	Journal Article
Publication:	PHYSICAL CHEMISTRY CHEMICAL PHYSICS
Publisher:	ROYAL SOC CHEMISTRY
Additional Information:	copyright for this article belongs to ROYAL SOC CHEMISTRY
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	12 Sep 2019 11:42
Last Modified:	12 Sep 2019 11:42
URI:	http://eprints.iisc.ac.in/id/eprint/63404

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