E. C. Passamani

• Professor (Full) at Federal University of Espírito Santo

Maghemite nanoparticles (NPs) were successfully developed using phenolic-rich extracts (cyanidin) from Citrus reticulata peel residues. The 11 nm maghemite NPs, obtained at 3% w/v and at 353 K, presented the optimal synthesis conditions. To improve dye adsorption performance, the synergetic adsorption behavior between these 11 nm NPs and multiwall...

The use of natural organic extracts in nanoparticle synthesis can reduce environmental impacts and reagent costs. With that purpose in mind, a novel biosynthesis procedure for the formation of magnetic iron-oxide nanoparticles (IONPs) using Eucalyptus globulus extract in an aqueous medium has been systematically carried out. First, the biosynthesis...

Highly ordered Co2FeGa thin films were successfully prepared using direct current magnetron sputtering by adjusting the film growth conditions. This involved making modifications to substrate and annealing temperatures. Structural, chemical, and magnetic properties were systematically studied using global and surface techniques. The results showed...

In this study, we achieved the biosynthesis of novel 7–8 nm iron-oxide nanoparticles in the presence of different concentrations (5 to 50% w/v) of commercial white quinoa extract. Initially, quinoa extract was prepared at various concentrations by a purification route. The biosynthesis optimization was systematically monitored by X-ray diffraction,...

The aim of this research was to show that the absorption of divalent cadmium ions (Cd2+) in Theobroma cacao L. seedlings can be controlled and adjusted by remediation with maghemite (γ-Fe2O3) nanoparticles (NPs), i.e., leading to the low tolerance limits established by the European Union (EU) in 2014 for Cd in products made from cocoa. The research...

Using a modified co-precipitation method, 11(2) nm γ-Fe2O3 nanoparticles functionalized with PSSNa [Poly(sodium 4-styrenesulfonate)] saloplastic polymer were successfully synthesized, and their structural, vibrational, electronic, thermal, colloidal, hyperfine, and magnetic properties were systematically studied using various analytic techniques. T...

Nb/Pt and Nb/Cu nanohybrids were sputtered on Si(100) substrate and systematically studied by transmission electron microscopy and magneto-transport measurements. Our experimental findings show that the colossal spin-valve effect measured in a hybrid formed by thick Pt layers deposited on Nb films is absent in equivalent Nb/Cu nanohybrids. In the l...

Featured Application The findings presented in this work will allow the calculation of the electronic density states as well as the electrical and optical properties of complex one-dimensional coupled periodic potential wells without using expensive licensed software. Abstract The analytical generalization for N periodic potential wells coupled to...

A novel magnetic composite made of Peruvian pyroclastic dust material decorated with maghemite nanoparticles was synthesized and characterized using a variety of analytic techniques. The 13 nm maghemite nanoparticles were grown on the pyroclastic dust using the conventional coprecipitation chemical route. A short-term acute assay was developed to s...

The effect of the YBCO superconducting (SC) state on the magnetic properties of as-grown YBCO/Co/IrMn heterostructures has been systematically studied using magnetometry and ferromagnetic resonance. The obtained data showed that the superconductivity of the YBCO substrate strongly affects the ferromagnetic properties of the deposited Co layer deepe...

The effect of the YBCO superconducting (SC) state on the magnetic properties of as-grown YBCO/Co/IrMn heterostructures has been systematically studied using magnetometry and ferromagnetic resonance. The obtained data showed that the superconductivity of the YBCO substrate strongly affects the ferromagnetic properties of the deposited Co layer deepe...

Magnetic nanoremediation is quite advantageous due to its fast kinetic adsorption response, high specific surface area, catalytic response, and multifaceted surface adsorption mechanism [1]. However, their industrial application will require the spread of magnetic nanohybrids into the environment. Specifically, water effluents are the main target f...

A novel magnetic composite of zeolite 5A and maghemite nanoparticles has been synthesized at 300 K and its lead removal properties from the Peruvian river Cumbaza were systematically studied. Its kinetic adsorption properties were investigated, and a fast equilibrium time of 15 min was achieved with 97% of removal and an adsorbent dose of 0.5 g L−1...

Phosphorous removal from water by two novel adsorbents was achieved with competitive efficiency. The adsorbents were synthesized using a Sol–Gel method by mixing both magnesium and iron chlorides in two proportions: (i) in a stoichiometric (S-MgFeO) ratio, yielding 90% of the MgFe2O4 plus 10% of hematite and (ii) with an excess of Mg that favored a...

Real water remediation is an important issue that requires the development of novel adsorbents with remarkable adsorption properties, permitting reusability. In this work, the surface and adsorption properties of bare magnetic iron oxide nanoparticles were systematically studied, before and after the application of a maghemite nanoadsorbent in two...

Two different magnetic core–shell nanohybrids, i) single coated magnetic nanoparticles (NPs) with polyacrylonitrile (PAN) and ii) doubly coated with SiO2 and polyaniline (PANI), were synthesized by a modified chemical co-precipitation method and their structural, vibrational, colloidal, and magnetic properties were systematically studied. XRD and R...

Multiwall carbon nanotubes functionalized with 13.8(6) nm maghemite nanoparticles (NPs) have been synthesized by a modified co-precipitation chemical route and characterized using N2 physisorption and in-field 57Fe Mössbauer studies. Textural and hyperfine magnetic properties indicated that this nanohybrid has a strong potential to be applied in ma...

Fe-substituted YFexCr1-xO3 crystalline compounds show promising magnetic and multiferroic properties. Here we report the synthesis and characterization of several compositions from this series. Using the autocombustion route, various compositions (x = 0.25, 0.50, 0.6, 0.75, 0.9, and 1) were synthesized as high-quality crystalline powders. In order...

We studied the influence of the superconducting state on the magnetic properties in a thick IrMn(100 nm)/NiFe(100 nm) bilayer deposited by magnetron sputtering onto an yttrium–barium–copper–oxide (YBCO) substrate that was previously synthesized by the acetate method. The results from magnetization experiments showed that the sign of the effective e...

The purpose of this research is to have a quantitative analysis on the temperature dependence magnetization of ferromagnetic nanoparticles (NPs), i.e., the Curie temperature (Tc), was systematically studied. The atomistic simulations were carried out using the VAMPIRE 5.0 software based on the Landau-Lifshitz-Gilbert-Heun method. The variable param...

Novel magnetic nanohybrids composed of nanomaghemite covered by organic molecules were successfully synthesized at room temperature with different functionalization agents (sodium polystyrene sulfonate, oxalic acid, and cetyltrimethylammonium bromide) in low and high concentrations. Structural, vibrational, morphological, electron energy-loss spect...

A ternary nanocomposite made of nanomaghemite, nanoanatase, and graphene oxide has been successfully synthesized using an inorganic coprecipitation approach, and it has been systematically investigated by X-ray diffraction, transmission electron microscopy, and different spectrocopic techniques (electron energy loss, µ-Raman, and 57Fe Mössbauer) af...

Using a coprecipitation route in aqueous medium with different precipitating agents (NH4OH and NaOH), iron-oxide nanostructures were prepared with distinct structural and magnetic properties. X-ray diffraction (XRD), ⁵⁷Fe Mossbauer spectroscopy and N2 sorption experiments indicated that the sample synthesized with NaOH had nanocrystalline goethite...

Maghemite nanoparticles functionalized with type 5A zeolite were prepared by co-precipitation to produce three different nanohybrid materials with potential for application in water remediation process. Raman and in-field ⁵⁷Fe Mössbauer spectroscopies were used to bring information about structural and magnetic properties of these materials, while...

Ultrathin Si(100)/Ta/Ni80Fe20/Ir20Mn80/Ta heterostructure deposited by oblique incidence in a confocal magnetron sputtering exhibits an unexpected exchange bias effect, despite the rotation of the sample holder and absence of external magnetic field during the deposition. Its magnetic loops have anomalous shifts along the field axis, whose features...

A ternary magnetic nanohybrid, composed of maghemite, titanium dioxide (anatase phase), and graphene oxide as synthetized by co-precipitation method and initially applied with success to arsenic removal from contaminated synthetic effluent, has its main magnetic properties (the thermal dependence of the coercive field, the saturation magnetization,...

Hybrid Nb(20)/Cu(5)/Py(2), Nb(20)/Cu(5)/Co(40) and Nb(20)/Cu(d\(_{Cu}\))/Py(2)/Cu(5)/Co(40) heterostructures (values in nanometers and d\(_{Cu}\) = 0, 2.5 and 5.0) were fabricated using a confocal DC magnetron sputtering setup. Performing magnetotransport measurements and using the anisotropic Ginzburg–Landau approach, the stray field values in zer...

Nanostructured (Fe0.5Ni0.5)92Zr5B3 alloy was prepared by milling a blend of pre-alloyed Fe50Ni50 precursor and high purity chemical elemental powders of Zr and B in a high-energy ball mill setup. Rietveld refinement of the X-ray diffraction pattern of the final sample (30 h of milling) revealed presence of two Fe–Ni rich phases [disordered fcc γ–(F...

Morphological, structural and magnetic properties of Co nanowire/IrMn film heterostructures are studied by atomic force microscopy, non-coplanar X-ray diffraction and magnetization measurements, the latter performed with magnetic field parallel and perpendicular to the nanowire length direction and using remnant (as-grown) and field-cooling protoco...

In this work, a new magnetic composite, with good performance in the adsorption of boron from aqueous solutions, is proposed. The composite was prepared from CoFe2O4 and MgO precursors, which were produced by the sol-gel method using orange juice residues. X-ray diffraction, scanning electron microscopy, infrared spectroscopy, ⁵⁷Fe Mössbauer spectr...

Arsenic and lead heavy metals are polluting agents still present in water bodies, including surface (lake, river) and underground waters; consequently, the development of new adsorbents is necessary to uptake these metals with high efficiency, quick and clean removal procedures. Magnetic nanoparticles, prepared with iron-oxides, are excellent candi...

The novel A-doped Co3O2BO3 (A⁴⁺=Zr, Hf) ludwigites have been synthetized by the first time and investigated by X-ray diffraction, magnetization and specific heat experiments. The non-magnetic ions place mainly at sites 4 of the structure. This doping strengthens the magnetic interactions rising the magnetic transition temperatures from 42 K, for th...

Aleaciones cristalinas desordenadas Fe50Mn25+xSn25-x, con x = -1.25, 0.0, 2.5, 5.0, 7.5, cercanas a las composiciones de Heusler-211, fueron preparadas por fusión en atmósfera inerte, subsecuentemente, sometidas a recocido térmico durante 4 días a 1173 K y, finalmente, enfriadas en agua helada. Todas las aleaciones han sido sistemáticamente analiza...

Magnetic properties of ferromagnetic nanostructures were studied by atomistic simulations following Monte Carlo and Landau–Lifshitz–Gilbert approaches. First, we investigated the influence of particle size and shape on the temperature dependence of magnetization for single cobalt and gadolinium nanoparticles and also in bi-magnetic Co@Gd core–shell...

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...

Applying a modified coprecipitation method, maghemite and anatase nanoparticles embedded in graphene oxide and multiwall carbon nanotube frameworks were prepared, and a detailed structural characterization is presented. Transmission electron images have revealed that the multiwall carbon nanotubes and graphene oxide act as substrates to reduce the...

The structural, vibrational, and magnetic properties of maghemite nanoparticles functionalized with zeolite type 5A and synthesized by coprecipitation were studied in detail. Crystallite and particle sizes were determined and discussed based on the polydispersity index. Its value of 0.4 has suggested the presence of a broad particle distribution wi...

The magnetic properties of site-disordered Ni5Sn(O2BO3)2 ludwigite have carefully been studied using local probes and bulk experimental methods in temperatures down to 1.6 K and magnetic fields up to 9 T. Our results have clearly shown the role of the effect of order/disorder site occupancy in these complex compounds with spin moments S=1. Differen...

Ni metal particles, with sizes ranging from 70 to 110 nm, dispersed in activated carbon produced from the babassu coconut endocarp (BAC) were successfully synthesized and evaluated by scanning electron microscopy, dispersive energy X-ray spectroscopy, flame atomic absorption spectroscopy and powder X-ray diffraction. These hybrid BACNi-X materials...

Magnetic interactions in iron nanoparticles embedded in an ytterbium metallic matrix have been systematically studied using several DC magnetic protocols (zero-field cooling ZFC and field-cooling FC). A transition from a superparamagnetic to a magnetically blocked regime was observed at 4.4 K associated with ultrafine (∼ 1.8 nm³) iron particles. Th...

EDTA functionalized γ-Fe2O3 nanoparticles, with controlled-sizes between 4 and 8 nm and specific surface areas up to 272 m2/g, were prepared using modified co-precipitation routes and systematically characterized using local, surface and global experimental methods. The functionalized nanoparticles behave as a magnetic trilayer-like system formed b...

Novel magnetic zeolite type 5A nanocomposites were synthesized by the co-precipitation method and applied to lead removal from aqueous ambient. Maghemite nanoparticles were mixed with zeolite and, by controlling its content, transmission electron microscopy results gave sizes of 5 to 15 nm and selected area electron diffraction patterns confirmed t...

The crystal structure and the magnetic properties of the Co2.5Cr0.5BO5 ludwigite have been investigated by x-ray diffraction, magnetization, and specific heat experiments. Cr ions mainly occupy sites 4 of the ludwigite lattice, substituting approximately half of the Co3+. It changes the interatomic distances and favors a high spin state for the rem...

A set of hybrid ferromagnetic/superconductor heterostructures was prepared by a confocal DC magnetron sputtering setup. The samples were systematically studied by measuring the magnetization and magneto-transport properties up to 2.5 T. The anisotropic behavior of the critical temperature, under applied magnetic fields, was investigated. For the Nb...

Anisotropic Ginzburg-Landau model was systematically tested in NbtNb and NbtNb/Cu5nm/Co40nm (tNb = 20 and 100 nm) films. A ΔTC-parameter was defined as a temperature difference between the critical temperatures determined for in-plane and out-of-film plane field configurations (ΔTC=TC⊥C−TC∥C). The ΔTC behavior for Nb(20nm) and Nb(20nm)/Co(40nm) fil...

Non-collinear exchange couplings between Py and Co layers (0∘⩽φ⩽90∘) were achieved in Py(10)/Cu(5)/Co(10)/IrMn(8) (thickness values in nm) spin valves by modifying their layer morphologies using oblique deposition in a confocal sputtering setup. Two series of spin valves were prepared by keeping the sample holder fix during the depositions, except...

Magnetic separation of oil from water by cobalt ferrite (CoFe2O4) was studied. Ferrite was produced using orange albedo and pectin extraction (PI) and commercial residue bagasse (PII – with pectin extraction and PIII - raw), as an organic ligand. X-ray diffraction and ⁵⁷Fe Mössbauer data suggest that the three procedures resulted in samples with ap...

A modified magnetron sputtering setup was used to fabricate planar nanowire (NW) arrays of Co. The structural characterization of these polycrystalline Co NW arrays confirms the coexistence of both hcp and fcc phases, in which their relative fractions depend on the Co deposition time as well as the presence (or absence) of a bcc nanowire seed layer...

Monophasic Zn1-xFexO nanoparticles with wurtzite structure were synthesized in the 0 ≤ x ≤ 0.05 concentration range using a freeze-drying process followed by heat treatment. The samples were characterized regarding their optical, structural, and magnetic properties. The analyses revealed that iron doping of the ZnO matrix induces morphological chan...

Cathodic cage, operating in the plasma nitriding mode, has been widely applied to improve the mechanical properties of steel surfaces. This paper investigated the use of this method for the deposition of titanium nitride films on a glass substrate, demonstrating its promising application in nanostructured materials with good electrical and optical...

Chemical disorders in L21-B2-type structure, naturally occurred in ⁵⁷Fe-doped Ni50Mn36Sn14 pseudo-Heusler alloy or enhanced in milled material, were systematically investigated using local probe methods: ⁵⁷Fe Mössbauer spectroscopy (MS) and extended X-ray absorption fine structure (EXAFS). ⁵⁷Fe Mössbauer studies show two Fe configurations: paramagn...

Correlations between the photocatalytic activity and the chemical composition of carbon-supported P-Fe-based nanocomposites were found. Nanoporous carbon was prepared by chemical activation with H3PO4 of the endocarp of babassu coconut. The synthesis of the nanocomposites was conducted by aqueous impregnation of the support with Fe(NO3)39H2O and N...

γ-Fe 2 O 3 nanoparticles were dispersed in a mesoporous silica (SBA15)matrix using the co-precipitation method. While structural properties were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, micro-Raman and transmission electron microscopy, magnetic studies were performed with DC and AC magnetometry. The γ-Fe 2 O 3 nanopartic...

In this investigation, we synthesized monophasic and nanostructured (Zn 1-x-y Fe x Co y)O samples , with x + y = 0.05. These nanophases were characterized by X-ray diffraction, magneti-zation techniques, and Mössbauer spectroscopy. The analyzes revealed that doping ZnO with iron or cobalt induced a morphological change for the crystallites. The pre...

In this work, we have systematically investigated the face centered cubic (FCC) to body centered cubic (BCC) transition and its influence on hyperfine and magnetic properties of Al-substituted Fe2MnGa laminated metallic ribbons (non-annealed and annealed) prepared by arc-melting. X-ray diffraction results of non-annealed ribbons show the formation...

Fe50Ni50 alloy powder was prepared by milling the 1:1 stoichiometric mixture of Fe and Ni high purity elements using high energy vibrational ball-mill. Final powdered material was obtained directly after 30 h of milling process and the Rietveld analysis of the X-ray diffraction pattern of the sample reveals the presence of two Fe–Ni phases: the dis...

Tungsten nanowires were deposited by DC magnetron sputtering onto vicinal sapphire substrates with a specific geometry in which the entrance angle (solid angle) of the vapor beam relative to the substrate was modified. Through 2D auto-correlation function analysis, suitable conditions to obtain a nanoscale corrugated surface with a high-order corre...

This paper presents an extensive study of the structural, magnetic, and thermodynamic properties of the hulsite Ni5.15Sn0.85(O2BO3)2. The crystal structure of the hulsite has two planar substructures formed by Ni and Sn atoms: one with rectangular configuration and the other with a triangular arrangement. These substructures are linked by the boron...

Structural and magnetic properties of ZnFe2O4 nanograins, prepared by high-energy ball milling and annealed, were systematically studied by X-ray diffraction, ⁵⁷Fe Mössbauer spectroscopy and AC magnetic susceptibility measurements. Disordered spinel-like structure, with a grain size of 12 nm, is established after 200 h of milling. While the 300 K M...

Structural and magnetic properties of the disordered and ordered Fe2MnAl Heusler alloys have systematically been investigated by local and bulk experimental methods. Plastic deformation, induced by cold-work, leads to a structural phase transformation from the ordered L21 to a disordered A2-structure, concomitantly with a change from paramagnetic P...

An experimental method was developed to set the magnetization direction in ferromagnetic layers of Si(100)/Cu/NiFe/Cu/Co/IrMn/Cu morphologically modified spin valves. Large uniaxial anisotropies emerged in the NiFe and Co layers due to modifications of their morphologies induced by the shadowing effect that arises from oblique depositions. Therefor...

Nb-films (thicknesses of 20 nm, 50 nm and 100 nm), directly grown on orientated Si substrates by DC sputtering, have shown reduced superconducting critical temperatures as compared to the bulk value; an effect associated with their disordered granular character (the disorder phenomenon of the Nb-films depresses the density of states at the Fermi le...

This paper presents an extensive study of the structural, magnetic, and thermodynamic properties of the heterometallic ludwigite Co4.76Al1.24(O2BO3)2. This material orders ferrimagnetically at 57 K. Despite the fact that, in Co4.76Al1.24(O2BO3)2, one quarter of the Co ions of the parent compound Co3O2BO3 is replaced by nonmagnetic Al3+ ions, the TC...

Hybrid Nb(tNb)/Co(10 nm)/IrMn(15 nm)/Nb(10 nm) heterostructured materials were prepared by DC Magnetron Sputtering and systematically studied by X-ray, magnetization and ferromagnetic resonance techniques. For thinner Nb buffer layer (≤10 nm), it was found that there is an inter-diffusion at Co/IrMn interface, which favors double-like hysteresis lo...

Bulk and local magnetic properties of the polycrystalline Fe2 MnGa compound, submitted to cold-work and annealing, have been studied using DC magnetization measurements and ⁵⁷ Fe Mössbauer spectroscopy in a broad temperature range (15–400 K). Structural characterization has shown stabilization of an ordered L12-type structure for annealed materials...

The influence of the substrate temperature TS on the superconducting properties of 100 nm sputtered Nb films, prepared directly onto orientated Si (100) substrate, was systematically investigated by measuring their structural, morphological and magnetic properties. Within the TS interval 293–373 K no significant change is observed either in the Nb...

This work describes the production and characterization of carbon-iron nanocomposites obtained from the decomposition of iron pentacarbonyl (Fe(CO)5) mixed with different carbon materials: a high surface area activated carbon (AC), powdered graphite (G), milled graphite (MG), and carbon black (CB). The nanocomposites were prepared either under argo...

Structural and magnetic properties of nanocomposite, consisting of Fe2P particles dispersed in a porous carbon matrix, have fully been investigated using X-ray diffraction, Mössbauer and ac and dc magnetization measurements. Besides production of the nanocomposite, using an activated carbon (prepared by chemical activation of a char with H3PO4), im...

We present direct measurements of the magnetocaloric effect on a Fe2P-based compound induced by a milliseconds pulsed magnetic field of 1 T to test their possible use in high frequency (up to 100 Hz) thermomagnetic cycles. The reported measurements were performed with an innovative and versatile non-contact set up based on the mirage effect. The ad...

A simple, room temperature reduction-hydrolysis of FeCl3 in water mediated by glycerol serving as an intermediate for controlling the concentration of Fe3+ ions in solution is an efficient and practical approach for preparing [small alpha]-Fe/amorphous-Fe2B nanosheets without using a template.

Carbon-based magnetic nanocomposites are of large interest for applications in catalysis, magnetic separation, water cleaning, and magnetic resonance imaging, among others. This work describes the synthesis of nanocomposites consisting of iron oxides dispersed into a char (obtained from the carbonization at 700 °C of a lignocellulosic precursor) an...

Magnetic properties of sputtered Gd thin films grown on Si (100) substrates kept at two different temperatures were investigated using X-ray diffraction, ac magnetic susceptibility, and dc magnetization measurements. The obtained Gd thin films have a mixture of hcp and fcc structures, but with their fractions depending on the substrate temperature...

Bulk and local magnetic properties of the polycrystalline -Fe2MnGa Heusler alloy have been studied using X-ray diffraction, magnetization measurements and zero-field and in-field Mössbauer spectroscopy. X-ray diffraction data indicate stabilization of a L12-type structure and no structural phase transformation in the temperature range 30–300 K. Whi...

The temperature dependence of the magnetic properties of Fe nano-sized clusters in (5.0 at. % Fe)Yb films, prepared by vapor co-deposition, has systematically been investigated using zero-field and in-field Mössbauer spectroscopy as well as AC and DC magnetization measurements. Room temperature Mössbauer spectra reveal two types of Fe clusters, wit...