title: Tunable Twin Matching Frequency (fm1/fm2) Behavior of Ni1-xZnxFe2O4/NBR Composites over 2-12.4 GHz: A Strategic Material System for Stealth Applications.
abstract: The gel to carbonate precipitate route has been used for the synthesis of Ni1-xZnxFe2O4(x = 0, 0.25, 0.5 and 0.75) bulk inverse spinel ferrite powder samples. The optimal zinc (50%) substitution has shown the maximum saturation magnetic moment and resulted into the maximum magnetic loss tangent (tanδm) > -1.2 over the entire 2-10 GHz frequency range with an optimum value ~-1.75 at 6 GHz. Ni0.5Zn0.5Fe2O4- Acrylo-Nitrile Butadiene Rubber (NBR) composite samples are prepared at different weight percentage (wt%) of ferrite loading fractions in rubber for microwave absorption evaluation. The 80 wt% loaded Ni0.5Zn0.5Fe2O4/NBR composite (FMAR80) sample has shown two reflection loss (RL) peaks at 5 and 10 GHz. Interestingly, a single peak at 10 GHz for 3.25 mm thickness, can be scaled down to 5 GHz by increasing the thickness up to 4.6 mm. The onset of such twin matching frequencies in FMAR80 composite sample is attributed to the spin resonance relaxation at ~5 GHz (fm1) and destructive interference at λm/4 matched thickness near ~10 GHz (fm2) in these composite systems. These studies suggest the potential of tuning the twin frequencies in Ni0.5Zn0.5Fe2O4/NBR composite samples for possible microwave absorption applications.
authors.affiliation: Camouglage Division, Defence Laboratory, Ratanada Palace, Jodhpur-342011, India.|Department of Physics &Center for Solar Energy, Indian Institute of Technology Jodhpur, Old Residency Road, Jodhpur-342011, India.
authors.forename: Lokesh
authors.initials: L
authors.lastname: Saini
authors.affiliation: Camouglage Division, Defence Laboratory, Ratanada Palace, Jodhpur-342011, India.
authors.forename: Manoj Kumar
authors.initials: MK
authors.lastname: Patra
authors.affiliation: Camouglage Division, Defence Laboratory, Ratanada Palace, Jodhpur-342011, India.
authors.forename: Raj Kumar
authors.initials: RK
authors.lastname: Jani
authors.affiliation: Department of Physics &Center for Solar Energy, Indian Institute of Technology Jodhpur, Old Residency Road, Jodhpur-342011, India.
authors.forename: Goutam Kumar
authors.initials: GK
authors.lastname: Gupta
authors.affiliation: Department of Physics &Center for Solar Energy, Indian Institute of Technology Jodhpur, Old Residency Road, Jodhpur-342011, India.
authors.forename: Ambesh
authors.initials: A
authors.lastname: Dixit
authors.affiliation: Camouglage Division, Defence Laboratory, Ratanada Palace, Jodhpur-342011, India.
authors.forename: Sampat Raj
authors.initials: SR
authors.lastname: Vadera