Correlation between the magnetic-microstructure and microwave mitigation ability of MxCo(1−x)Fe2O4 based ferrite–carbon black/PVA composites. Issue 41 (11th October 2018)

• Record Type: Journal Article
• Authors: Datt, Gopal; Kotabage, Chetan; Datar, Suwarna; Abhyankar, Ashutosh C.
• Is Part Of: Physical chemistry chemical physics. Volume 20:Issue 41(2018)
• Page Start: 26431
• Page End: 26442
• Publication Date: 2018-10-11
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c8cp05235b
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : This work reports on the correlation between the magnetic-domain structure and microwave mitigation properties of ferrite–Carbon black/PVA Composites. Distorted co-ordination of Fe 3+ along with unique single axis oriented magnetic domains plays a crucial role in magnetic losses and hence, in mitigation of microwaves. Abstract : A study of controlling the microwave mitigation properties of ferrite–carbon black/PVA composites by tuning the magnetic microstructure and spin arrangement of the ferrite particles is presented. M x Co(1− x ) Fe2 O4 (M: Ni 2+, Mn 2+ & Zn 2+ ) nano-ferrites (NFs) were synthesized by a solvothermal method and these NFs were used to fabricate NF–CB hybrids and flexible NF–CB/PVA composite films. The magnetic force microscopy studies of the NFs reveal a unique single axis oriented domain structure for Zn-NFs and multi-domain magnetic microstructures for Mn-NFs and Ni-NFs. Mössbauer analysis of the NFs reveals highly distorted co-ordination of Fe 3+ cations in Zn-NFs, whereas sub-lattice spins are canted in Mn-NFs and Ni-NFs. Despite the distorted magnetic lattice and broken coordination, the largest microwave shielding effectiveness (SE) of 32 dB is observed, over a bandwidth of 8 to 18 GHz, for Zn-NF–CB/PVA with a major contribution from absorption (SEA ∼ 25 dB). The dielectric properties and Cole–Cole plots indicate enhanced interfacial polarization in Zn-NF–CB/PVA, which is attributed to the motion of polarons across multiple heterogeneous interfaces. These polarons are thought to be generated by distorted co-ordination of Fe 3+, and d–d electron transition between Co 2+ ⇋ Fe 3+ cations at the B-site of Zn-NF. Distorted co-ordination of Fe 3+ in Zn-NF along with unique single axis oriented magnetic domains play a crucial role in magnetic losses, as μ ′′ is almost double in Zn-NF based composites as compared to other composites. Due to their excellent and tunable microwave absorption properties, NF–CB/PVA composites could be employed for next generation stealth applications.