Special Issue "Multifunctional Magnetic Nanocomposites: Innovative Processing and Applications"

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Nanocomposite Materials".

Deadline for manuscript submissions: 31 December 2021.

Special Issue Editor

Dr. Victor Kuncser
E-Mail Website
Guest Editor
National Institute of Materials Physics, Atomistilor 405A, Magurele 077125, Romania
Interests: Magnetic interactions and local electronic phenomena in intermetallics and oxides, molecular magnets, metal-organic compounds and catalysts, nanomagnetism and magnetic interactions and spin structure at the surface/interface of bilayer thin films with different magnetic anisotropies, exchange bias and exchange spring systems, multilayers, spintronics and spin-valves, magnetic nanopowders, magnetic nanoparticles dispersed in various solid state matrices, diluted magnetic semiconductors, magnetic fluids, magnetic nanocomposites, magnetofunctional materials

Special Issue Information

Dear Colleagues,

The main advantage of heterogeneous nanosystems is the possibility of combining and inter-influencing the electronic properties of constituent interfaced nanophases. Unique physicochemical properties of the hybrid material of interest in various applications can be obtained. The functionality of such systems can be provided by the possibility to actuate the most sensitive nanophase and to exploit the proper response of another nanophase which is directly or indirectly influenced by the actuated phase.

Multifunctional magnetic nanocomposites are among such heterogeneous nanosized systems where at least one phase component is magnetic and can act as an intermediate of either the actuation or the response of the system. As compared to the heterogeneous layered systems with at least one magnetic layer of nanometer thickness, also of high technological impact, multifunctional magnetic nanocomposites can be obtained by less expensive processing technologies. In addition, they present much extended specific surfaces and active interfaces which allow additional engineering of the application-oriented parameters through tunable morphologies of the nanosized components.

This Special Issue of Nanomaterials will report on the innovative processing, characterization, and applications of multifunctional magnetic nanocomposites consisting of different matrices (polymer-like, carbon-based, oxides, or intermetallics) embedded or decorated by different magnetic nanostructures (magnetic nanoparticles and nanowires of different organizations and of different structures from monophase to core–shell).

Dr. Victor Kuncser
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 papers will be 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. Nanomaterials 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

  • nanosized magnetic structures
  • nanocomposites
  • surface and interface interactions
  • magnetic-driven functionality and multifunctionality
  • magnetic sensors and actuators

Published Papers (8 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

Article
Micron-Scale Anomalous Hall Sensors Based on FexPt1−x Thin Films with a Large Hall Angle and near the Spin-Reorientation Transition
Nanomaterials 2021, 11(4), 854; https://doi.org/10.3390/nano11040854 - 27 Mar 2021
Viewed by 509
Abstract
In this work, we fabricate and characterize an energy-efficient anomalous Hall sensor based on soft-magnetic FexPt1−x thin films with a large anomalous Hall angle. By varying the composition of the FexPt1−x alloy, its layer thickness [...] Read more.
In this work, we fabricate and characterize an energy-efficient anomalous Hall sensor based on soft-magnetic FexPt1−x thin films with a large anomalous Hall angle. By varying the composition of the FexPt1−x alloy, its layer thickness and interfacial materials, the magnetization is tuned to be near the spin transition between the perpendicular and in-plane reorientations. We performed magneto-transport and noise characterizations on anomalous Hall sensors with a small sensing area of 20 × 20 µm2 in the 180 to 350 K temperature range. We found the best performance in a 1.25-nm-thick Fe0.48Pt0.52 sandwiched by two 1.6-nm-thick MgO layers at room temperature. The sensor has a large anomalous Hall angle of 1.95%. Moreover, it has the best field detectability of 237.5 nT/√Hz at 1 Hz and 15.3 nT/√Hz at 10 kHz, as well as a high dynamic reserve of 112.0 dB. These results suggest that the FexPt1−x alloy system is suitable for energy-efficient anomalous Hall sensors, particularly in micro-sensing applications. Full article
Show Figures

Graphical abstract

Article
Improvement of Magnetic Particle Hyperthermia: Healthy Tissues Sparing by Reduction in Eddy Currents
Nanomaterials 2021, 11(2), 556; https://doi.org/10.3390/nano11020556 - 23 Feb 2021
Viewed by 794
Abstract
Attenuation of the unwanted heating of normal tissues due to eddy currents presents a major challenge in magnetic particle hyperthermia for cancer treatment. Eddy currents are a direct consequence of the applied alternating magnetic field, which is used to excite the nanoparticles in [...] Read more.
Attenuation of the unwanted heating of normal tissues due to eddy currents presents a major challenge in magnetic particle hyperthermia for cancer treatment. Eddy currents are a direct consequence of the applied alternating magnetic field, which is used to excite the nanoparticles in the tumor and have been shown to limit treatment efficacy in clinical trials. To overcome these challenges, this paper presents simple, clinically applicable, numerical approaches which reduce the temperature increase due to eddy currents in normal tissue and simultaneously retain magnetic nanoparticles heating efficiency within the tumor. More specifically, two protocols are examined which involve moving the heating source, an electromagnetic coil, relative to a tumor-bearing phantom tissue during the exposure. In the first protocol, the linear motion of the coil on one side with respect to the hypothesized tumor location inside the phantom is simulated. The estimated maximum temperature increase in the healthy tissue and tumor is reduced by 12% and 9%, respectively, compared to a non-moving coil, which is the control protocol. The second technique involves a symmetrical variation of the first one, where the coil is moving left and right of the phantom in a bidirectional fashion. This protocol is considered as the optimum one, since the estimated maximum temperature rise of the healthy tissue and tumor is reduced by 25% and 1%, respectively, compared to the control protocol. Thus, the advantages of a linearly moving coil are assessed through tissue sparing, rendering this technique suitable for magnetic particle hyperthermia treatment. Full article
Show Figures

Figure 1

Article
Multifunctional GaFeO3 Obtained via Mechanochemical Activation Followed by Calcination of Equimolar Nano-System Ga2O3–Fe2O3
Nanomaterials 2021, 11(1), 57; https://doi.org/10.3390/nano11010057 - 29 Dec 2020
Viewed by 600
Abstract
The equimolar oxide mixture β-Ga2O3—α-Fe2O3 was subjected to high-energy ball milling (HEBM) with the aim to obtain the nanoscaled GaFeO3 ortho-ferrite. X-ray diffraction, 57Fe Mössbauer spectroscopy, and transmission electron microscopy were used to evidence [...] Read more.
The equimolar oxide mixture β-Ga2O3—α-Fe2O3 was subjected to high-energy ball milling (HEBM) with the aim to obtain the nanoscaled GaFeO3 ortho-ferrite. X-ray diffraction, 57Fe Mössbauer spectroscopy, and transmission electron microscopy were used to evidence the phase structure and evolution of the equimolar nano-system β-Ga2O3—α-Fe2O3 under mechanochemical activation, either as-prepared or followed by subsequent calcination. The mechanical activation was performed for 2 h to 12 h in normal atmosphere. After 12 h of HEBM, only nanoscaled (~20 nm) gallium-doped α-Fe2O3 was obtained. The GaFeO3 structure was obtained as single phase, merely after calcination at 950 °C for a couple of hours, of the sample being subjected to HEBM for 12 h. This temperature is 450 °C lower than used in the conventional solid phase reaction to obtain gallium orthoferrite. The optical and magnetic properties of representative nanoscaled samples, revealing their multifunctional character, were presented. Full article
Show Figures

Figure 1

Article
Unidirectional Magnetic Anisotropy in Dense Vertically-Standing Arrays of Passivated Nickel Nanotubes
Nanomaterials 2020, 10(12), 2444; https://doi.org/10.3390/nano10122444 - 07 Dec 2020
Viewed by 708
Abstract
We report the facile and low-cost preparation as well as detailed characterization of dense arrays of passivated ferromagnetic nickel (Ni) nanotubes (NTs) vertically-supported onto solid Au-coated Si substrates. The proposed fabrication method relies on electrochemical synthesis within the nanopores of a supported anodic [...] Read more.
We report the facile and low-cost preparation as well as detailed characterization of dense arrays of passivated ferromagnetic nickel (Ni) nanotubes (NTs) vertically-supported onto solid Au-coated Si substrates. The proposed fabrication method relies on electrochemical synthesis within the nanopores of a supported anodic aluminum oxide (AAO) template and allows for fine tuning of the NTs ferromagnetic walls just by changing the cathodic reduction potential during the nanostructures’ electrochemical growth. Subsequently, the experimental platform allowed further passivation of the Ni NTs with the formation of ultra-thin antiferromagnetic layers of nickel oxide (NiO). Using adequately adapted magnetic measurements, we afterwards demonstrated that the thickness of the NT walls and of the thin antiferromagneticNiO layer, strongly influences the magnetic behavior of the dense array of exchange-coupled Ni/NiO NTs. The specific magnetic properties of these hybrid ferromagnetic/antiferromagnetic nanosystems were then correlated with the morpho-structural and geometrical parameters of the NTs, as well as ultimately strengthened by additionally-implemented micromagnetic simulations. The effect of the unidirectional anisotropy strongly amplified by the cylindrical geometry of the ferromagnetic/antiferromagnetic interfaces has been investigated with the magnetic field applied both parallel and perpendicular to the NTs axis. Full article
Show Figures

Graphical abstract

Article
Controlling the Oxidation of Magnetic and Electrically Conductive Solid-Solution Iron-Rhodium Nanoparticles Synthesized by Laser Ablation in Liquids
Nanomaterials 2020, 10(12), 2362; https://doi.org/10.3390/nano10122362 - 27 Nov 2020
Cited by 7 | Viewed by 1168
Abstract
This study focuses on the synthesis of FeRh nanoparticles via pulsed laser ablation in liquid and on controlling the oxidation of the synthesized nanoparticles. Formation of monomodal γ-FeRh nanoparticles was confirmed by transmission electron microscopy (TEM) and their composition confirmed by atom probe [...] Read more.
This study focuses on the synthesis of FeRh nanoparticles via pulsed laser ablation in liquid and on controlling the oxidation of the synthesized nanoparticles. Formation of monomodal γ-FeRh nanoparticles was confirmed by transmission electron microscopy (TEM) and their composition confirmed by atom probe tomography (APT). For these particles, three major contributors to oxidation were analysed: (1) dissolved oxygen in the organic solvents, (2) the bound oxygen in the solvent and (3) oxygen in the atmosphere above the solvent. The decrease of oxidation for optimized ablation conditions was confirmed through energy-dispersive X-ray (EDX) and Mössbauer spectroscopy. Furthermore, the time dependence of oxidation was monitored for dried FeRh nanoparticles powders using ferromagnetic resonance spectroscopy (FMR). By magnetophoretic separation, B2-FeRh nanoparticles could be extracted from the solution and characteristic differences of nanostrand formation between γ-FeRh and B2-FeRh nanoparticles were observed. Full article
Show Figures

Figure 1

Article
A New Zinc Phosphate-Tellurite Glass for Magneto-Optical Applications
Nanomaterials 2020, 10(9), 1875; https://doi.org/10.3390/nano10091875 - 18 Sep 2020
Cited by 1 | Viewed by 885
Abstract
This work investigates the structural, magnetic and magneto-optical properties of a new zinc phosphate-tellurite glass belonging to the 45ZnO-10Al2O3-40P2O5-5TeO2 system. The glass was prepared by a wet method of processing the starting reagents followed [...] Read more.
This work investigates the structural, magnetic and magneto-optical properties of a new zinc phosphate-tellurite glass belonging to the 45ZnO-10Al2O3-40P2O5-5TeO2 system. The glass was prepared by a wet method of processing the starting reagents followed by suitable melting–stirring–quenching–annealing steps. Specific parameters such as density, average molecular mass, molar volume, oxygen packaging density, refractive index, molar refractivity, electronic polarizability, reflection loss, optical transmission, band gap and optical basicity have been reported together with thermal, magnetic and magneto-optical characteristics. Absorption bands appear in the blue and red visible region, while over 600 nm the glass becomes more transparent. FTIR and Raman spectra evidenced phosphate-tellurite vibration modes proving the P2O5 and TeO2 network forming role. Magnetic measurements reveal the diamagnetic character of the Te-doped glass with an additional weak ferromagnetic signal, specific to diluted ferromagnetic oxides. Positive Faraday rotation angle with monotonous decreasing value at increasing wavelength was evidenced from magneto-optical measurements. The final product is a composite material comprising of a non-crystalline vitreous phase and Te-based nanoclusters accompanied by oxygen vacancies. The metallic-like Te colloids are responsible for the dark reddish color of the glass whereas the accompanying oxygen vacancies might be responsible for the weak ferromagnetic signal persisting up to room temperature. Full article
Show Figures

Graphical abstract

Article
Magnetic Phase Coexistence and Hard–Soft Exchange Coupling in FePt Nanocomposite Magnets
Nanomaterials 2020, 10(8), 1618; https://doi.org/10.3390/nano10081618 - 18 Aug 2020
Cited by 1 | Viewed by 713
Abstract
With the aim of demonstrating phase coexistence of two magnetic phases in an intermediate annealing regime and obtaining highly coercive FePt nanocomposite magnets, two alloys of slightly off-equiatomic composition of a binary Fe-Pt system were prepared by dynamic rotation switching and ball milling. [...] Read more.
With the aim of demonstrating phase coexistence of two magnetic phases in an intermediate annealing regime and obtaining highly coercive FePt nanocomposite magnets, two alloys of slightly off-equiatomic composition of a binary Fe-Pt system were prepared by dynamic rotation switching and ball milling. The alloys, with a composition Fe53Pt47 and Fe55Pt45, were subsequently annealed at 400 °C and 550 °C and structurally and magnetically characterized by means of X-ray diffraction, 57Fe Mössbauer spectrometry and Superconducting Quantum Interference Device (SQUID) magnetometry measurements. Gradual disorder–order phase transformation and temperature-dependent evolution of the phase structure were monitored using X-ray diffraction of synchrotron radiation. It was shown that for annealing temperatures as low as 400 °C, a predominant, highly ordered L10 phase is formed in both alloys, coexisting with a cubic L12 soft magnetic FePt phase. The coexistence of the two phases is evidenced through all the investigating techniques that we employed. SQUID magnetometry hysteresis loops of samples annealed at 400 °C exhibit inflection points that witness the coexistence of the soft and hard magnetic phases and high values of coercivity and remanence are obtained. For the samples annealed at 500 °C, the hysteresis loops are continuous, without inflection points, witnessing complete exchange coupling of the hard and soft magnetic phases and further enhancement of the coercive field. Maximum energy products comparable with values of current permanent magnets are found for both samples for annealing temperatures as low as 500 °C. These findings demonstrate an interesting method to obtain rare earth-free permanent nanocomposite magnets with hard–soft exchange-coupled magnetic phases. Full article
Show Figures

Figure 1

Article
Magnetic Properties of SmCo5 + 10 wt% Fe Exchange-Coupled Nanocomposites Produced from Recycled SmCo5
Nanomaterials 2020, 10(7), 1308; https://doi.org/10.3390/nano10071308 - 03 Jul 2020
Cited by 4 | Viewed by 792
Abstract
Nanostructured alloy powders of SmCo5 + 10 wt% Fe obtained using recycled material were studied for the first time. The SmCo5 precursor was obtained from commercial magnets recycled by hydrogen decrepitation. The results were compared with identically processed samples obtained using [...] Read more.
Nanostructured alloy powders of SmCo5 + 10 wt% Fe obtained using recycled material were studied for the first time. The SmCo5 precursor was obtained from commercial magnets recycled by hydrogen decrepitation. The results were compared with identically processed samples obtained using virgin SmCo5 raw material. The samples were synthesized by dry high-energy ball-milling and subsequent heat treatment. Robust soft/hard exchange coupling was observed—with large coercivity, which is essential for commercial permanent magnets. The obtained energy products for the recycled material fall between 80% and 95% of those obtained when using virgin SmCo5, depending on milling and annealing times. These results further offer viability of recycling and sustainability in production. These powders and processes are therefore candidates for the next generation of specialized and nanostructured exchange-coupled bulk industrial magnets. Full article
Show Figures

Figure 1

Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: New Te-based zinc aluminophosphate glass with local clustering for magneto-optical applications
Authors: M. Elisa; R. C. Stefan; I. C. Vasiliu; S. M. Iordache; A-M. Iordache; M. I. Rusu; D. Savastru; B. A. Sava; L. Boroica; M. C. Dinca; A. V. Filip; M. Eftimie; A. C. Galca; C. Bartha; N. Iacob; V. Kuncser
Affiliation: a National Institute of R & D for Optoelectronics, INOE 2000, 409 Atomistilor Str., 077125, Magurele, Jud. Ilfov, Romania b National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Str, 077125 Magurele, Jud. Ilfov, Romania c University Politehnica of Bucharest, 313 Spl. Independentei, 060042, Bucharest, Romania d National Institute of Materials Physics, Atomistilor 405A, 077125, Magurele, Ilfov, Romania
Abstract: This work investigates structural, optical, magnetic and magneto-optical properties of a special Te-zinc-aluminophosphate glass, from 45ZnO-10Al2O3-40P2O5-5TeO2 system. The glass was prepared by a wet method of processing materials, followed by melting-stirring-quenching-annealing. Various parameters as glass density, oxygen packaging density, refractive index, molar refractivity, electronic polarizability, reflection loss, optical transmission, refractive index, band gap, optical basicity, magnetization reversal and rotation of the polarization vector have been considered. Temperature dependent magnetic measurements showed shifted hysteresis loops superposed over a diamagnetic signal, providing evidence not only for a diluted ferromagnetic oxide character but also for the presence of an atypical unidirectional anisotropy due to the interaction of the diluted ferromagnetic phase with Te2 nanosized clusters of local magnetic moments. The positive Faraday rotation angle evidenced from magneto-optical measurements correlated with this atypical enhanced magnetic response open the way for new magneto-optical applications of such transparent glass-like multifunctional magnetic nanocomposites.

Title: Original Anisotropic Architecture for Magneto-Optical Surface Plasmon Resonance Biosensing
Authors: Mathias Dolci; Xiaokun Ding; Yannick Dusch; Rabah Boukherroub; Sabine Szunerits; Philippe Pernod; Nicolas Tiercelin
Affiliation: Université de Lille, CNRS, Centrale Lille, ISEN, Université de Valenciennes, UMR8520, France
Abstract: Devices based on magneto-plasmonic modulation generate a strong interest due to their use in active plasmonic and biosensing applications. The combination of ferromagnetic (FM) and plasmonic (Pl) material in metallic sandwich trilayer structure (e.g. PL/FM/PL) allows to provide a transverse magneto-optical Kerr effect (TMOKE) of p-polarized light and exhibits improved physical sensitivity over classic surface plasmon resonance measurements. Here, we present experimental and theoretical study on a new anisotropic magneto-optical surface plasmon resonance (AMOSPR) sensor. The introduction of TbCo_2 /FeCo in the ferromagnetic layer provides a magnetic uni-axial anisotropy and leads to original magneto-plasmonic behavior. The study on this system will allow in the future to exploit the detection of biomolecules as well as new active functionalities

Title: High performance magnetic nanoparticles with tailored size and shape for localized hyperthermia applications
Authors: Izabella Crăciunescu; P. Palade; N. Iacob; G. Ispas; V. Kuncser; Rodica Turcu
Affiliation: 1 National Institute for Research and Development of Isotopic and Molecular Technologies, 400293 Cluj-Napoca, Romania 2 National Institute of Materials Physics, Bucharest-Magurele, Ilfov, 077125, Romania
Abstract: Iron oxide (Fe3O4) and ferrite (MeFe2O4, Me - Mn, Zn) hydrophobic magnetic nanoparticles were synthesized with various shapes and sizes, including spherical, cubic, hexagonal and octahedral, from high temperature reaction of organic precursor’s solution. Tailoring the shapes and sizes of nanoparticles allows controlling a variety of properties that are relevant to many potential applications of magnetic nanoparticles. Structurally well-formed hydrophobic magnetic nanoparticles with high saturation magnetization values, between 85-95 emu/g were obtained. The hydrophobic oleic acid (OA) shell it is transformed by a simple and environmentally friendly oxidative scission method into Azelaic Acid (AZA), which is a di-acid with a free carboxylic group which does the magnetic nanoparticles hydrophilic. This oxidative scission of OA does not induce aggregation, obtaining a very narrow dimensional distribution of magnetic nanoparticles following this process.

Title: High performance magnetorheological fluids: very high magnetization FeCo-Fe3O4 nanoclusters in ferrofluid carrier
Authors: Izabell Crăciunescu; Elena Chiţanu; Mirela M. Codescu; N.Iacob; A.Kuncser; V.Kuncser; V. Socoliuc; Daniela Susan-Resiga; Florica Bălănean; G. Ispas, S. Porav; Tϋnde Borbáth; I. Borbáth; L. Vékás; Rodica Turcu
Affiliation: 1-National Institute for R&D of Isotopic and Molecular Technologies (INCDTIM), Cluj-Napoca, Romania; 2-National R&D Institute for Electrical Engineering (ICPE-CA), Bucharest, Romania; 3-National Institute for R&D of Materials Physics (INCDFM), Bucharest-Magurele, Romania; 4-Romanian Academy–Timisoara Branch (RATB), Center for Fundamental and Advanced Technical Research, Timisoara, Romania; 5-ROSEAL Co., Odorheiu-Secuiesc, Romania.
Abstract: The behavior of conventional MR fluids is affected by irreversible aggregation and sedimentation, in-use thickening and abrasiveness, as well as severe redispersibility issues of the magnetizable component. In order to overcome these shortcomings recently various new formulations of MR fluids came into play. Among these, the extremely bidisperse ferrofluid based MR fluids show completely new features, such as increasing the attractive interaction force between ferromagnetic (Fe) microparticles due to the nonzero magnetic susceptivity of the ferrofluid carrier. Magnetic nanoparticles of the carrier are impeding direct contact between micrometer size ferromagnetic particles to prevent irreversible agglomeration and to provide aid to easy redispersion. The careful design of the composition and structure both at nano and micro level allows adapting the characteristics of MR fluids to the requirements of a wide range of semi-active devices, from seismic MR dampers and MR brakes to MR flow controllers for hydraulic machinery. In this paper we’ll focus on tailoring both the ferrofluid carrier and the magnetizable disperse phase in order to reduce the sedimentation rate and, at the same time, to favor intense and reversible particle structuring to provide a significant magnetorheological response. A new MR fluid was prepared using high colloidal stability polar ferrofluids and high magnetization FeCo-Fe3O4 nanoclusters. The high magnetization magnetic nanoclusters have been obtained by miniemulsion procedure using a mixture of surface passivated FeCo nanopowder and a high evaporation rate non-polar ferrofluid. The physico-chemical properties of the ferrofluid, surface passivated FeCo nanoparticles and FeCo-Fe3O4 nanoclusters investigated by different methods: TEM, SEM, HRTEM, EDAX, XPS, Mössbauer spectroscopy and VSM are reported. The evaluation of magnetorheological characteristics of the new MR fluid and a comparative analysis using previous results concerning nano-micro composite MR fluids are presented.

Title: Multifunctional GaFeO3, obtained via mechanochemical activation followed by calcination of equimolar nano-system Ga2O3-Fe2O3
Authors: L. Diamandescu; F. Tolea; M. Feder; F. Vasiliu; I. Mercioniu; M. Enculescu; T. Popescu
Affiliation: National Institute of Materials Physics, Atomistilor 405A, 077125, Magurele-Bucharest, Romania
Abstract: This work emphasizes the important role of mechanochemical activation (using High-Energy Ball Milling) in the synthesis of nano-structured multiferroic GaFeO3. X Ray Diffraction, Transmission Electron Microscopy and Mössbauer Spectroscopy were used to understand the phase evolution and mechanisms in the mechanochemical activation of the equimolar nano-system Ga2O3-Fe2O3, both as prepared or followed by subsequent calcination - to obtain the desired multifferoic nano-crystalline GaFeO3 at more friendly temperatures and with lower energy consumption. Thus, after heat treatment for 4 hours at 950 oC only the presence of GaFeO3 was evidenced, which means that the temperature for obtaining gallium ortho-ferrite was lowered by ~ 450 oC comparing to the temperatures at which this material is obtained by conventional solid phase reaction. Optical, photocatalytic and magnetic properties of representative samples highlights their multifunctional character.

Back to TopTop