Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
3.9
2.6
Journals
Magnetochemistry
Special Issues
Magnetic Properties of Nanomaterials
share announcement

Magnetic Properties of Nanomaterials

A special issue of Magnetochemistry (ISSN 2312-7481). This special issue belongs to the section "Magnetic Nanospecies".

Deadline for manuscript submissions: closed (31 October 2021) | Viewed by 12711
Related Special Issue: Magnetic Properties of Nanomaterials

Special Issue Editor

Prof. Dr. Lotfi Bessais

E-Mail Website
Guest Editor
Institut de Chimie et des Matériaux Paris-Est, ICMPE–CNRS, 94320 Thiais, France
Interests: solid state physics; magnetic nanomatrials; magnetocaloric materials; multifunctional magnetic materials; permanent magnets; intermetallic compounds; superparamagnetism
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The aim of this special issue is to give the opportunity to researchers working in different fields related to the "Magnetic Properties of Nanomaterials" to submit manuscripts: review papers, full articles and short communications.

New magnetic materials are emerging, and their various applications demonstrate that they are essential in our everyday lives. Hard, semi-hard and soft magnetic nanomaterials allow a significant improvement in energy conversion. Thus, these nanomaterials play a key role in addressing today's challenges and particularly those concerning the reduction of fossil fuel consumption and climate change.

Nanomaterials offer a wide range of possibilities in terms of both synthesis and characterization. The changes in properties that occur at such a small scale allow the discovery of innovative and promising properties. In the field of magnetism, several characteristic dimensions are found at the nanoscale, such as the domain wall thickness and the exchange length in hard magnetic phases. In the case of magnetic recording media, nanoscaling allows the increasing of the surface density of the data storage. As for permanent magnets, the energy product has been successfully improved through using nanocomposite phases.

This special issue focuses on many areas of magnetic nanomaterial applications (giant magnetoresistance, automotive applications, high density recording media, magnetic refrigeration, biomedicine...). Contributions may cover topics such as theoretical work and ab initio calculations, the characterization of magnetic compounds, spintronic materials, magnetic nanoparticles for recording media, shape memory effects, hard magnetic single and nanocomposite phases, and magnetocaloric effects.

You may choose our Joint Special Issue in Applied Sciences.

Prof. Dr. Lotfi Bessais
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Magnetochemistry is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Rare earth based intermetallic compounds
  • Soft magnetic materials
  • Hard magnetic materials
  • Nanocomposites
  • Permanent magnets
  • Magnetic recording
  • Magnetocaloric materials
  • Shape reconfigurable materials
  • Magnetic imaging
  • Magnetic hyperthermia
  • Magnetoelectric materials

Benefits of Publishing in a Special Issue

  • Ease of navigation: Grouping papers by topic helps scholars navigate broad scope journals more efficiently.
  • Greater discoverability: Special Issues support the reach and impact of scientific research. Articles in Special Issues are more discoverable and cited more frequently.
  • Expansion of research network: Special Issues facilitate connections among authors, fostering scientific collaborations.
  • External promotion: Articles in Special Issues are often promoted through the journal's social media, increasing their visibility.
  • e-Book format: Special Issues with more than 10 articles can be published as dedicated e-books, ensuring wide and rapid dissemination.

Further information on MDPI's Special Issue polices can be found here.

Published Papers (4 papers)

Download All Papers
Order results
Result details
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:

Research

Jump to: Review

12 pages, 3424 KiB  
Article
AC Susceptibility Studies under DC Fields in Superspinglass Nanomaghemite-Multiwall Carbon Nanotube Hybrid
by Juan A. Ramos-Guivar, F. Jochen Litterst and Edson C. Passamani
Magnetochemistry 2021, 7(4), 52; https://doi.org/10.3390/magnetochemistry7040052 - 12 Apr 2021
Cited by 7 | Viewed by 2360
Abstract
Magnetic properties of maghemite (γ-Fe2O3) nanoparticles grown on activated multiwall carbon nanotubes have been studied by alternating current (AC) magnetic susceptibility experiments performed under different temperatures, frequencies, and applied magnetic fields. Transmission electron images have suggested that the γ-Fe [...] Read more.
Magnetic properties of maghemite (γ-Fe2O3) nanoparticles grown on activated multiwall carbon nanotubes have been studied by alternating current (AC) magnetic susceptibility experiments performed under different temperatures, frequencies, and applied magnetic fields. Transmission electron images have suggested that the γ-Fe2O3 nanoparticles are not isolated and have an average size of 9 nm, but with a relatively broad size distribution. The activation energies of these 9 nm γ-Fe2O3 nanoparticles, determined from the generalized Vogel–Fulcher relation, are reduced upon increasing the direct current (DC) field magnitude. The large activation energy values have indicated the formation of a superspinglass state in the γ-Fe2O3 nanoparticle ensemble, which were not observed for pure γ-Fe2O3 nanoparticles, concluding that the multiwall carbon nanotubes favored the appearance of highly concentrated magnetic regions and hence the formation of superspinglass state. Magnetic relaxation studies, using Argand diagrams recorded for DC probe fields (<20 kOe) below the magnetic blocking temperature at 100 and 10 K, have revealed the presence of more than one relaxation process. The behavior of the ensemble of γ-Fe2O3 nanoparticles can be related to the superspinglass state and is also supported by Almeida–Thouless plots. Full article
(This article belongs to the Special Issue Magnetic Properties of Nanomaterials)
►▼ Show Figures

Figure 1

13 pages, 4772 KiB  
Article
Core Size and Interface Impact on the Exchange Bias of Cobalt/Cobalt Oxide Nanostructures
by Maral Ghoshani, Morteza Mozaafari, Peter S. Normile, Jose A. De Toro and Abdulrahman Al-Nabhani
Magnetochemistry 2021, 7(3), 40; https://doi.org/10.3390/magnetochemistry7030040 - 16 Mar 2021
Cited by 11 | Viewed by 2388
Abstract
Two series of Co/Co-oxide nanostructures have been synthesized by the co-precipitation method followed by different reduction and oxidation processes in an attempt to optimize their exchange bias (EB) properties. The samples are characterized by X-ray diffraction, scanning and transmission electron microscopy, and SQUID [...] Read more.
Two series of Co/Co-oxide nanostructures have been synthesized by the co-precipitation method followed by different reduction and oxidation processes in an attempt to optimize their exchange bias (EB) properties. The samples are characterized by X-ray diffraction, scanning and transmission electron microscopy, and SQUID (superconducting quantum interference device) magnetometry. The two series differ with respect to their average Co core grain sizes: in one (the l-series), the size is ≈100 nm, and in the other (the s-series, obtained using lower synthesis temperatures than the l-series), it is ≈10 nm. In the l-series, progressive oxidation yields an increase in the EB field together with a reduction in Co core size. In contrast, progressive oxidation in the s-series results in growth of the Co-oxide fraction at the expense of the Co core upon oxidation, which is accompanied by a decrease in the EB effect that is attributed to an ordering of the ferromagnetic–antiferromagnetic interface and therefore a reduction of uncompensated spins density. These results illustrate how the interface details become relevant only for small enough ferromagnetic cores. Full article
(This article belongs to the Special Issue Magnetic Properties of Nanomaterials)
►▼ Show Figures

Figure 1

Review

Jump to: Research

23 pages, 4286 KiB  
Review
Influence of Chemical Substitution and Light Element Insertion on the Magnetic Properties of Nanocrystalline Pr2Co7 Compound
by Riadh Fersi, Najeh Mliki and Lotfi Bessais
Magnetochemistry 2022, 8(2), 20; https://doi.org/10.3390/magnetochemistry8020020 - 27 Jan 2022
Cited by 6 | Viewed by 2863
Abstract
It is well recognized that intermetallics based on rare-earth (R) and transition metals (T) display numerous interesting magnetic properties, leading to potential applications in different fields. The latest progress regarding magnetic properties and the magnetocaloric effect (MCE) in the nanostructured Pr2Co [...] Read more.
It is well recognized that intermetallics based on rare-earth (R) and transition metals (T) display numerous interesting magnetic properties, leading to potential applications in different fields. The latest progress regarding magnetic properties and the magnetocaloric effect (MCE) in the nanostructured Pr2Co7 compound, as well as its carbides and hydrides, is reviewed in this paper. Some of this progress reveals remarkable MCE performance, which makes it attractive in the field of magnetic refrigeration at high temperatures. With the purpose of understanding the magnetic and magnetocaloric characteristics of these compounds, the crystal structure, microstructure, and magnetism are also brought into focus. The Pr2Co7 compound has interesting magnetic properties, such as a high Curie temperature TC and uniaxial magnetocrystalline anisotropy. It crystallizes in a hexagonal structure (2:7 H) of the Ce2Ni7 type and is stable at relatively low temperatures (Ta ≤ 1023 K), or it has a rhombohedral structure (2:7 R) of the Gd2Co7 type and is stable at high temperatures (Ta ≥ 1223 K). Studies of the magnetocaloric properties of the nanocrystalline Pr2Co7 compound have shown the existence of a large reversible magnetic entropy change (ΔSM) with a second-order magnetic transition. After its substitution, we showed that nanocrystalline Pr2Co7−xFex compounds that were annealed at Ta = 973 K crystallized in the 2:7 H structure similarly to the parent compound. The extended X-ray absorption fine-structure (EXAFS) spectra adjustments showed that Fe atoms preferably occupy the 12k site for x ≤ 1. The study of the magnetic properties of nanocrystalline Pr2Co7−xFex compounds revealed an increase in TC of about 26% for x = 0.5, as well as an improvement in the coercivity, Hc (12 kOe), and the (BH)max (9 MGOe) product. On the other hand, the insertion of C atoms into the Pr2Co7 cell led to a marked improvement in the TC value of 21.6%. The best magnetic properties were found for the Pr2Co7C0.25 compound annealed at 973 K, Hc = 10.3 kOe, and (BH)max = 11.5 MGOe. We studied the microstructure, hydrogenation, and magnetic properties of nanocrystalline Pr2Co7Hx hydrides. The crystal structure of the Pr2Co7 compound transformed from a hexagonal (P63/mmc) into an orthorhombic (Pbcn) and monoclinic (C2/c) structure during hydrogenation. The absorption of H by the Pr2Co7 compound led to an increase in the TC value from 600 K at x = 0 to 691 K at x = 3.75. The Pr2Co7H0.25 hydride had optimal magnetic properties: Hc = 6.1 KOe, (BH)max = 5.8 MGOe, and TC = 607 K. We tailored the mean field theory (MFT) and random magnetic anisotropy (RMA) methods to investigate the magnetic moments, exchange interactions, and magnetic anisotropy properties. The relationship between the microstructure and magnetic properties is discussed. The obtained results provide a fundamental reference for adapting the magnetic properties of the Pr2Co7, Pr2Co6.5Fe0.5, Pr2Co7C0.25, and Pr2Co7H0.25 compounds for potential permanent nanomagnets, high-density magnetic recording, and magnetic refrigeration applications. Full article
(This article belongs to the Special Issue Magnetic Properties of Nanomaterials)
►▼ Show Figures

Figure 1

22 pages, 11067 KiB  
Review
Magnetic Nanomaterials as Biocatalyst Carriers for Biomass Processing: Immobilization Strategies, Reusability, and Applications
by Mayra A. Mariño, Stephanie Fulaz and Ljubica Tasic
Magnetochemistry 2021, 7(10), 133; https://doi.org/10.3390/magnetochemistry7100133 - 23 Sep 2021
Cited by 25 | Viewed by 4000
Abstract
Environmental concerns, along with oil shortages, have increased industrial interest in biomass conversion to produce biofuels and other valuable chemicals. A green option in biomass processing is the use of enzymes, such as cellulases, hemicellulases, and ligninolytic (laccase and peroxidases), which have outstanding [...] Read more.
Environmental concerns, along with oil shortages, have increased industrial interest in biomass conversion to produce biofuels and other valuable chemicals. A green option in biomass processing is the use of enzymes, such as cellulases, hemicellulases, and ligninolytic (laccase and peroxidases), which have outstanding specificity toward their substrates and can be reused if immobilized onto magnetic nanocarriers. Numerous studies report the biocatalysts’ performance after covalent binding or adsorption on differently functionalized magnetic nanoparticles (MNPs). Functionalization strategies of MNPs include silica-based surfaces obtained through a sol–gel process, graphene oxide-based nanocomposites, polymer-coated surfaces, grafting polymer brushes, and others, which have been emphasized in this review of the immobilization and co-immobilization of enzymes used for biomass conversion. Careful analysis of the parameters affecting the performance of enzyme immobilization for new hybrid matrices has enabled us to achieve wider tolerance to thermal or chemical stress by these biosystems during saccharification. Additionally, it has enabled the application of immobilized laccase to remove toxic organic compounds from lignin, among other recent advances addressed here related to the use of reusable magnetic carriers for bioderived chemical manufacturing. Full article
(This article belongs to the Special Issue Magnetic Properties of Nanomaterials)
►▼ Show Figures

Graphical abstract

Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying articles 1-4
Back to TopTop