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Nanocomposites consisting of nanoparticles of iron oxide (Fe3O4) and iron carbide (Fe3C) with a core-shell structure (Fe core, Fe3O4 and/or Fe3C shells) coated with additional graphite-like carbon layer dispersed in carbon matrix have been synthesized by solid-phase pyrolysis of iron-phthalocyanine (FePc) and iron-porphyrin (FePr) with a pyrolysis temperature of 900°C, and post-annealing conducted at temperatures ranging from 150°C to 550°C under controlled oxygen- and/or nitrogen-rich environments. A comprehensive analysis of the samples’ morphology, composition, structure, size, and magnetic characteristics was performed by utilizing scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-STEM) with elemental mapping, X-ray diffraction analysis (XRD), and magnetic measurements by utilizing vibrating sample magnetometry (VSM). The effect of the annealing process on magnetic performance and efficient control of the hysteresis loop and specific absorption rate (SAR) are discussed.
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This content will become publicly available on March 17, 2026
Synthesis of magnetic nanostructures in different carbon matrices and post annealing with oxygen, nitrogen and argon
This study explores the innovative use of carbon matrices in the synthesis of magnetic nanographite, layered graphene stacks and graphene coated magnetic nanoparticles, with a focus on their morphological, structural, and magnetic prop-erties. To obtain a deeper insight into the influences of impurities in the graphene matrices on the magnetic properties of synthesized by pyrolysis, the two different metal free modifications of porphyrin such as tetraphenyl porphyrin (TPP) and tetra(4-carboxyphenyl) porphyrin (TCPP) with oxygen content (radical) were synthesized by subsequential post annealing with oxygen, argon and nitrogen, to characterize and investigate the role of oxygen and nitrogen content in graphene environment. The research highlights the significance of porphyrin and phthalocyanine metal free precursors and their metal counterparts for use as carbon matrices, examining their unique characteristics and applications in nanoparticle synthesis by sequential annealing. For example, the magnetization figure below for TPP indicates that the samples are diamagnetic at relatively high temperatures and large magnetic fields. Annealing at 150 °C for 180 min, specifically, for oxygen, it increases paramagnetic behavior and saturation. As for nitrogen, it increases coercivity. Employing advanced characterization techniques such as powder x-ray diffraction (PXRD), we analyzed the graphitization and porosity effects and layer sizes of nanographite and their impact on magnetic properties. A novel algorithm, integrating node extraction and 2D Gaussian mapping, is developed to enhance the accuracy of morphological analysis. Our findings reveal the critical role of graphene, and role of oxygen and nitrogen impurities in influencing the magnetic behavior of metal free carbon matrices and embedded nanoparticles, providing valuable insights into the design and development of advanced magnetic nanomaterials.
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- Award ID(s):
- 2112554
- PAR ID:
- 10609936
- Publisher / Repository:
- AIP Publishing
- Date Published:
- Journal Name:
- AIP Advances
- Volume:
- 15
- Issue:
- 3
- ISSN:
- 2158-3226
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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