In situ precipitation synthesis of FeNi/ZnO nanocomposites with high microwave absorption properties

• Published in: Materials chemistry and physics Vol. 266; p. 124508
• Main Authors: Entezari, H., Almasi Kashi, M., Alikhanzadeh-Arani, S., Montazer, A.H., Zavašnik, J.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.07.2021; Elsevier BV
• Subjects: Absorbers; Coercivity; Eddy currents; Electromagnetic radiation; FeNi/ZnO nanoparticle Composite; In situ precipitation; Intermetallic compounds; Magnetic alloys; Magnetic properties; Magnetic saturation; Magnetic shielding; Microwave absorption; Morphology; Nanocomposites; Nanoparticles; Optimum thickness; Particulate composites; Particulates; Radar equipment; Reflection loss; Synthesis; Zinc oxide; Nanoparticles; FeNi/ZnO nanoparticle Composite; In situ precipitation; high-resolution transmission electron microscopy; Microwave absorption; Reflection loss; field-emission scanning electron microscopy; NP composites; Optimum thickness; Magnetic properties
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2021.124508

Novel synthetic methods and materials tuned for high-efficiency absorbers are increasingly being used for shielding environments from microwaves with frequencies of gigahertz range emitted from cell phones and radar systems. Here, an in situ precipitation route in the synthesis of nanocomposites consisting of magnetic alloy FeNi and semiconductor ZnO nanoparticles (NPs) with different FeNi/ZnO ratios (1:1, 1:2, and 2:1) is presented. The resulting nanocomposites were employed as electromagnetic wave absorbers in the microwave range, and their structural and magnetic properties were investigated. Scanning and transmission electron microscopic analyses of FeNi/ZnO NP composites (NPCs) revealed crystalline particulates with spherical and conical morphology. Saturation magnetization and coercivity significantly increased to 161 Oe and 90 emu/g after performing an annealing process, starting from 77 Oe and 26 emu/g for as-synthesized (FeNi)2/(ZnO)1 NPC. In this case, a high reflection loss of −37.3 dB at 11.8 GHz was obtained for the NPC with an optimum thickness of 1.6 mm. Our calculations indicate that the eddy current effect plays a crucial role in the electromagnetic loss of magnetic alloy/semiconductor NPCs. [Display omitted] •FeNi/ZnO NPCs with different ratios were synthesized by an in situ precipitation route.•FESEM, EDS, XRD, HRTEM, HAADF-STEM, SAED, VSM and VNA were used to characterize NPCs.•Hc and Ms showed significant increase of 110% and 245% for annealed (FeNi)2/(ZnO)1 NPC.•RL = −37.3 dB was obtained at 11.8 GHz for (FeNi)2/(ZnO)1 NPC with a thickness of 1.6 mm.•Eddy current was responsible for magnetic loss in as-synthesized and annealed NPCs.