Thermomagnetic Studies Research Articles

Lanthanum-doped Bi5Fe0.5Co0.5Ti3O15 multiferroic Aurivillius phase with improved magnetization

Bi4.2La0.8Fe0.5Co0.5Ti3O15 multiferroic ceramic system was obtained by conventional solid-state reaction method. Structural characterization from X-ray diffraction has revealed a reduction of the unit-cell volume after the incorporation of lanthanum into the structure. Raman spectroscopy exhibits local structural distortions for BO6 octahedrons in correspondence with the orthorhombic symmetry, related to the lanthanum incorporation and the partial substitution of Fe3+ by Co3+. An improved magnetization (1.1 emu/g at 15 kOe) has been obtained from the magnetic hysteresis measurements at room temperature, and in spite of the presence of magnetic secondary phases, the observed improvement can be attributed to the main Aurivillius phase. It can be explained from the influence of the La3+ doping over the Fe3+-O-Co3+ magnetic coupling. The change in slope for the real dielectric permittivity around 102 °C is associated to a magnetic transition of the Aurivillius phase. The reduction of this temperature could be related with the increase of the lanthanum content. The ferroelectric and ferromagnetic phase transitions temperatures were obtained from the differential scanning calorimetry and the thermomagnetic study.

Exchange bias effect and inhomogeneous magnetism in 6H Ba3CoFeRuO9: Role of structural site disorder

Structural, magnetic, electrical and thermal investigations on ternary barium ruthenate Ba3CoFeRuO9 (BCFRO) reveal the role of the two different octahedral B-site in creating locally varying competing antiferromagnetic and ferromagnetic interactions. BCFRO forms in 6H hexagonal structure in the P63/mmc space group. Neutron diffraction and specific heat capacity measurements affirmed the absence of any long-range ordering and structural transition in the compound. DC thermomagnetic studies evidences spin glass magnetism with Tg ∼ 50 K. A large exchange bias (EB) field of 3.48 kOe is obtained at 3 K under a cooling field of 50 kOe. Careful analysis indicates, EB in our system stems from inhomogeneous magnetism owing to spatially varying chemical composition. Competing ferromagnetic and antiferromagnetic phases giving rise to spin glass behaviour is the manifestation of site disorder induced by mixed valences of magnetic ions. The exchange bias training effect in our system follows spin relaxation model of rotatable and frozen spins which are exchange coupled at the interface. Strong electron localisation occurs by virtue of the specific 6H structure with corner shared octahedral 2a site and face shared octahedral 4f site. The electrical and thermal transport in BCFRO follows Efros-Shklovskii variable range hopping (ES VRH) model below 150 K. The high resistivity of BCFRO at low temperatures is also reflected in the low thermal conductivity and huge Seebeck coefficient.

Evolution of microstructure, magneto-structural transformation, and magnetocaloric effect in (Fe72-0.9xNi8-0.1xCo8)Zr7B4Cu1Gax (0 ≤ x ≤ 6 at.%) alloys

We report the evolution of microstructure, magnetic properties, and magnetocaloric effects in a series of (Fe72-0.9xNi8-0.1xCo8)Zr7B4Cu1Gax (0 ≤ x ≤ 6 at.%) alloys. The high temperature X-ray diffraction, calorimetric, and thermomagnetic studies revealed that the α-Fe → γ-Fe transformation occurred in the range of 691–733 K in arc-melted ingots (AMIs), whereas the same occurred at 660–723 K in as-spun ribbons (ASRs). The Curie temperature of γ phase lies in the range of 1126–1140 K and 1106–1126 K for AMIs and ASRs, respectively. Addition of Ga reduces the saturation magnetization and induce nanocrystallization in ASRs. A second-order magnetic transition has been identified in x = 0 ASR using Arrott plot exhibiting magnetic entropy change (|ΔSM|) of 0.973 J/kg.K at TCγ under magnetic field of 0.976 T. The refrigeration capacity of x = 0 and x = 6 ASRs has been estimated to be 12.78 J/kg and 22.98 J/kg, respectively, at 0.976 T.

Rock magnetism and AMS studies in Kondapalle-Pangidi layered complex, Eastern Ghats Belt, India: Remanence carriers and tectonic implications

The present study is an integrated approach towards the rock magnetism and Anisotropy of Magnetic Susceptibility (AMS) of the high-grade metamorphic rocks in the Kondapalle Pangidi Layered Complex (KPLC), Eastern Ghats Belt (EGB), India. Our study aims at determining the petrography, rock magnetic properties and the magnetic fabrics. The rock magnetic properties and the magnetic fabrics from AMS studies are used to determine their tectonic implications. Petrography reveals that the chief remanence carrier mineral is Ti-magnetite. Rock magnetic studies including Isothermal Remanent Magnetization (IRM), back-field IRM, hysteresis loop studies, and thermo-magnetic studies reveals the same. The magnetic hysteresis parameters (remanence and coercivity) are used to determine the magnetic domains from a modified Day plot. The magnetic domains lie within Stable Single Domain and Pseudo Single Domain ranges, thereby explaining their potential to record an ancient magnetic field. Besides the ferrimagnetic remanence carriers, paramagnetic silicates are also dominant which controlled the development of magnetic fabric. The magnetic fabric bears analogy with the regional structures and bear tectonic implications related to the post-rifting closure of the ocean followed by subduction of the ocean basin, accretionary orogeny and felsic magmatism in the Indo-Antarctic continental blocks.

On the structural and thermo-magnetic study of the magnetocaloric Heusler alloy Ni2Mn1-x Cu x Ga0.8Al0.2

Full Heusler alloys present martensitic transition and shape memory effect related phenomena and several technological applications can be envisaged. One promising area is the magnetocaloric effect (MCE) as the magnetic and structural transitions combine to produce a large isothermal entropy and adiabatic temperature change useful for heating and cooling applications. In this work, we study a Ni–(Mn, Cu)–(Ga, Al) Heusler alloy family which has a giant MCE when the chemical composition is fine-tuned to bring the temperature of the second-order magnetic transition close the first-order structural one. Our results show that, for a certain range of copper concentration, the samples show interesting physical properties captured by calorimetric, microscopy imaging, and magnetization measurements, leading to a high MCE with minimized hysteresis.

Structure and Magnetic Properties of Pulsed Electrodeposited Nickel–Indium Alloy

A nickel–indium (Ni–In) ferromagnetic alloy is successfully synthesized through a facile pulsed electrodeposition method. The composition, structure, and morphology are analyzed through atomic absorption spectroscopy (AAS), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and electron microscopy. The composition and structural analysis indicate fcc phase for the Ni43In57 and Ni63In37 alloys. The Ni–In alloy shows mixed phases when the Ni content is increased from 63 to 66 at%. Thermal analysis of the Ni63In37 results in an activation energy of 46 and 557 kJ mol−1 that can arise from the grain growth phenomena and phase transformation, respectively. Thermomagnetic studies show a Curie temperature of 340 °C for the Ni–In alloy with 63 at% Ni that also exhibits a saturation magnetization of 36 emu g−1.

Metallic Iron in Basalts of the Malyi Yenisei Lava River: Results of Thermomagnetic Study

Thermomagnetic analysis of samples from two sections of lava layers of the Late Cenozoic basalt lava river in the Malyi Yenisei valley is carried out. The main magnetization carrier in the studied basalts is titanomagnetite with the Curie points of 100–120°C which is frequently substantially oxidized both single-phase and heterophase up to magnetite. It is likely that some part of metallic iron in the studied samples has also been oxidized and even disintegrated, which resulted in the significant scatter of iron concentration across the flow against which, however, the increasing trend of iron concentration in the lava flow from the top downwards is observed. The relative magnitude of this increase (iron concentration gradient along the vertical of the lava flow) is almost constant for all flows of the lava sequence probably indicating the decisive role of gravity in iron particle precipitation in the lava. Based on the synthesis of iron particle data from different objects and different regions of the world, this correlation with gravity also follows from the very similar shapes of particle size histograms of iron. This is most clearly seen from the same particle size modes (10–20 μm). Another important finding is that this constant mode of iron particle size does not depend on age and origin of rock as well as on the type of particle source (terrestrial or extraterrestrial).

Revealing the structural and magnetic susceptibility aspects of Sr2+ substituted Y2−xSrxNiMnO6 (0 ≤ x ≤ 0.1) compounds

We have investigated the structural and magnetic properties of strontium (Sr2+) substituted polycrystalline doubly-ordered perovskite Y2−xSrxNiMnO6 (x = 0, 0.05, 0.1), characterized with X-ray diffraction, X-ray photoelectron spectroscopy, dc-magnetization, and frequency-dependent linear ac-susceptibility measurements. The undoped Y2NiMnO6 is observed with traces of YMnO3 and NiO as secondary phases, whereas the phase purity improved with Sr2+ substitution. The XRD patterns of Y2−xSrxNiMnO6 (x = 0, 0.05, 0.1) are fitted with the Rietveld refinement in a monoclinic (P21/n) space-group symmetry and the secondary phases YMnO3 and NiO are fitted in hexagonal (P63cm) and cubic (Fm3m) space groups, respectively. The structural modifications observed with Sr2+ substitution manifest in octahedral distortion, altered lattice parameters, average bond-length, bond angles, tolerance factor, and corresponding electron bandwidths. The XPS study confirms the presence of Jahn-Teller (JT-active) species (Ni3+, Mn3+) along with Ni2+, Mn4+ ions. Increasing Sr2+ concentration triggers the paramagnetic (PM) to ferromagnetic (FM) transition spontaneously, along with increased transition temperature (Tc). The thermomagnetic study in field cooled/zero-field cooled modes and linear ac-susceptibility measurements suggest that the investigated compounds exhibit nonspontaneous and cumulative magnetic domain-wall dynamics to attain FM-state with glassy-type behavior toward lower temperatures.

Detection of metallic iron in urban dust by using high-temperature measurements supplemented with microscopic observations and Mössbauer spectra

This paper presents a thermomagnetic study of fresh, unheated indoor dust, outdoor dust, street dust and dust from the cabin air filters of cars. Detailed analysis of thermomagnetic curves clearly indicated the presence of two magnetic transitions: the first identified at the Curie temperature TC ~ 585 °C for magnetite; the second TC detected at about ~765 °C, indicating the presence of metallic iron and/or iron-based alloys. The ‘tail,’ i.e., the substantial decreasing of κ visible on the heating curves of κ(T) between 600 °C and 700 °C, was attributed to the metallic iron or iron-based alloys. The presence of a high-temperature Fe-phase is not dependent on the types of urban dust or the sampling method, as variable amounts of metallic iron were detected in material collected from different environments: both indoor dust and outdoor dust, and dust gathered by sweeping indoor floor surfaces as well as dust collected with a vacuum cleaner.The presence of metallic iron in different types of dust was confirmed by non-magnetic methods. Electron microscopic observations with Energy-Dispersive X-ray Spectroscopy revealed elongated shaving-like particles comprised of metallic iron. A component with a magnetic hyperfine field of Bhf ~ 33 T and an almost zero value for isomeric shift as well as zero quadrupole splitting typical of metallic α-Fe at micrometer size or Fe-based alloys was recognized in all the Mössbauer spectra.Additional measurements of hysteresis properties at high temperatures (up to 750 °C) and after step-wise annealing indicated the process of oxidation of iron to magnetite. This has a strong effect on the run of κ(T) and M(T) curves during heating and cooling because M and κ are strongly dependent on the apparent concentration of both ferromagnetic phases (magnetite and metallic iron).

Biogenic synthesis and thermo-magnetic study of highly porous carbon nanotubes.

Nanomaterials synthesis using natural sources is the technology to up come with advanced materials through extracts of plant, microorganisms, poultry waste etc. In this study, the authors report the synthesis of porous carbon nanotubes using high-temperature decomposition technique facilitated by cobalt salt using chicken fats, a poultry waste as a precursor. Since chicken fats contain fatty acids which can decompose into short hydrocarbon chains and cobalt can act as the catalyst. The formation of carbon nanotubes was confirmed by Raman spectra, peaks at 1580 and 1350.46 cm-1 confirmed the graphite mode G-band and structural imperfections defect mode D-band, respectively. Transmission electron microscopy showed the formation of tube-like structures. Nitrogen adsorption-desorption studies showed the high-surface area of 418.1 m2g-1 with an estimated pore diameter of 8.1 nm. Thermogravimetry analysis-derivative thermogravimetric analysis-differential thermal analysis showed the instant weight loss at 517°C attributed to the rapid combustion of nanotubes. A vibrating-sample magnetometer showed the paramagnetic nature of the so-formed carbon nanotubes formed.

Structural and magnetic properties of Nb substituted Zr-Co-Si-B nanocrystalline ribbons

The effect of large atomic radii Nb substitution on the structural and hard magnetic properties of Zr16Co78-xNbxSi3B3 nanocrystalline ribbons has been investigated. Structural and thermo-magnetic studies revealed that the substitution of Nb restrains the formation of both Co and orthorhombic Zr2Co11 phases in Zr-Co-Nb-Si-B which is essential for developing high coercivity. As a result, coercivity increases from 2.9 to 4.8 kOe as the Nb content increase from 0 to 3 at.%, while the magnetization decrease from 61 to 42 emu/g. The rhombohedral Zr2Co11 phase is responsible for the coercivity development in these materials. Substitution of Nb is found to decrease the Curie temperature from 440 to 390 °C as the Nb content increases from x = 0 to 3. Transmission electron microscopy studies demonstrate the grain refinement in the samples with substitution of Nb, where the grain size decreases from 150 to 50 nm as the Nb content increases from x = 0 to 3.

Modulation in magnetic exchange interaction, core shell structure and Hopkinson’s peak with chromium substitution into Ni0.75Co0.25Fe2O4 nano particles

The ever growing applications and ever evolving challenges of magnetic nano particles has been motivating the researchers from various disciplines towards this area of magnetic nano particles. Cation substitutional effect on the magnetic structure of the nanoparticles forms a crucial aspect in their applications. Here the environmentally benign auto combustion method was employed to synthesize chromium substituted nickel cobalt ferrite (Ni0.75Co0.25Fe2-xCrxO4; x = 0, 0.10, 0.15) nano particles, from aqueous metal nitrate solutions. Chromium substitution has shown its effect on the structural, magnetic and electrical properties of Ni0.75Co0.25Fe2O4. Structural and phase analysis of the prepared samples show increased phase purity of ferrite sample with increasing Cr substitution. The TEM (Transmission Electron Microscope) image confirms the nano size of the particles, EDS (Energy dispersive X-ray Spectroscopy) has supported the stoichiometry of the prepared samples and FTIR (Fourier-transform infrared spectroscopic) analysis confirms the spinel structure and also suggests cation redistributions with chromium substitution. VSM (Vibrational Sample Magnetometer) is used to study the magnetic properties through magnetic hysteresis (M−H) loop and magnetic Hopkinson effect. All samples show hysteresis and show reduction in magnetic properties with increase in chromium content. The thermo magnetic study shows Hopkinson peak(s) in the magnetization vs. temperature (M−T) graph and also shows variation in the nature of Hopkinson peak with chromium substitution. Possible reasons for the changes in the nature of the peak are discussed.

Temperature dependent and applied field strength dependent magnetic study of cobalt nickel ferrite nano particles: Synthesized by an environmentally benign method

Spinel ferrites have come a long way in their versatile applications. The ever growing applications of these materials demand detailed study of material properties and environmental considerations in their synthesis. In this article, we report the effect of temperature and applied magnetic field strength on the magnetic behavior of the cobalt nickel ferrite nano powder samples. Basic structural properties of spinel ferrite nano particles, that are synthesized by an environmentally benign method of auto combustion, are characterized through XRD, TEM, RAMAN spectroscopy. Diffuse Reflectance Spectroscopy (DRS) is done to understand the nickel substitution effect on the optical properties of cobalt ferrite nano particles. Thermo magnetic studies using SQUID in the temperature range 5 K to 400 K and room temperature (300 K) VSM studies are performed on these samples. Fields of 0Oe (no applied field: ZF), 1 kOe (for ZFC and FC curves), 5 kOe (0.5 T), 50 kOe (5T) (for M-H loop study) are used to study the magnetic behavior of these nano particles. The XRD,TEM analysis suggest 40 nm crystallites that show changes in the cation distribution and phase changes in the spinel structure with nickel substitution. Raman micrographs support phase purity changes and cation redistributions with nickel substitution. Diffuse reflectance study on powder samples suggests two band gap values for nickel rich compounds. The Magnetic study of these sample nano particles show varied magnetic properties from that of hard magnetic, positive multi axial anisotropy and single-magnetic-domain structures at 5 K temperature to soft magnetic core shell like structures at 300 K temperature. Nickel substitution effect is non monotonous. Blocking temperature of all the samples is found to be higher than the values suggested in the literature.

Ambi-polar anomalous Nernst effect in a magnetic topological insulator

We report electromagnetic and thermomagnetic transport studies on a magnetic topological insulator thin film Cr0.15(Bi0.1Sb0.9)1.85Te3 grown by molecular beam epitaxy. The temperature and gate voltage dependence of the anomalous Hall effect exhibits the typical behavior of a quantum anomalous Hall insulator. The anomalous Nernst effect (ANE) shows a sign reversal when the Fermi level is tuned across the charge neutrality point of the surface Dirac cone. We show that the ambi-polar behavior of the ANE can be explained by the semiclassical Mott relation, in conjunction with the ambi-polar Dirac band structure.

Structural and magnetic properties of multiferroic Y2NiMnO6 double perovskite

ABSTRACTThe double perovskite Y2NiMnO6 is prepared by a citrate-gel combustion method. The structural, magnetic and dc transport properties of Y2NiMnO6 are investigated systematically. A monoclinic crystal structure having space group P21/n is identified for the material from XRD. Magnetic structure is characterized by isothermal and thermomagnetic studies. The material possesses a ferromagnetic transition at 88 K. The dynamic magnetic structure of the material is analyzed using the ac susceptibility data. Resistivity data suggests the semiconducting behavior of the material. The work provides well advancement in researchers on potential material for spintronic applications.

Native iron in the Earth and space

Thermomagnetic and microprobe studies of native iron in the terrestrial upper-mantle hyperbasites (xenoliths in basalts), Siberian traps, and oceanic basalts are carried out. The results are compared to the previous data on native iron in sediments and meteorites. It is established that in terms of the composition and grain size and shape, the particles of native iron in the terrestrial rocks are close to each other and to the extraterrestrial iron particles from sediments and meteorites. This suggests that the sources of the origin of these particles were similar; i.e., the formation conditions in the Earth were close to the conditions in the meteorites’ parent bodies. This similarity is likely to be due to the homogeneity of the gas and dust cloud at the early stage of the solar system. The predominance of pure native iron in the sediments can probably be accounted for by the fact that interstellar dust is mostly contributed by the upper-mantle material of the planets, whereas the lower-mantle and core material falls on the Earth mainly in the form of meteorites. A model describing the structure of the planets in the solar system from the standpoint of the distribution of native iron and FeNi alloys is proposed.

Contrasting Pan-African structural styles at the NW margin of the Congo Shield in Cameroon

Field, microstructural, and anisotropy of magnetic susceptibility (AMS, magnetic fabrics) studies assessed the Pan-African deformational history and strain geometry at the southern margin of the Central African Fold Belt (CAFB) against the older, cratonic basement of the Congo Shield (CS). Reflected light microscopy and thermomagnetic studies supported the identification of magnetic minerals. Data cover a low angle thrust margin (Mbengis-Sangmelima area) in the east and high angle shear zones cutting the margin (Kribi area) in the west, at the Atlantic coast. In the CS basement units, magnetic anisotropy is generally higher than in the low grade Pan-African units. In the latter, early D1/D2 shortening produced a flat-lying magnetic foliation parallel with the regional trend of the belt, a shallow magnetic lineation, and mostly oblate fabrics. Subsequent D3 deformation is only of local importance in the Mbengis-Sangmelima area. The magnetic lineation shows distinct maxima in NNE-SSW direction, parallel with the low angle tectonic transport direction.In the Kribi area, the NNE-SSW trending Kribi-Campo shear zone (KCSZ) affected both older rocks and Pan-African high grade metapelites of the Yaoundé unit together with their basal thrust. The early planar fabric (S1) was overprinted during D2 folding under relatively high T conditions, and subsequent D3 wrenching. Magnetic fabrics document a progressive change from oblate towards prolate ellipsoids towards the KCSZ. Magnetic foliations with medium to steep dips curve into the N-S to NE-SW orientation of the KCSZ, lineations follow the same trend with shallow to medium plunges. This fabric implies that the KCSZ is a Pan-African strike-slip shear zone with a subordinate component of compression.Strike-slip tectonics in the west (KCSZ) and thrusting in the east imply N-S to NE-SW convergence during Pan-African terrane assembly against the present northern margin of the CS. In addition, the KCSZ may separate the CS from the São Francisco Craton in Brazil and thus be the northern part of a link connecting the CAFB to the West Congo Belt in the south. This putative Pan-African link separated the São Francisco Craton from the Congo Shield prior to Mesozoic Gondwana break-up.

ПЕРШІ РЕЗУЛЬТАТИ ЕКОМАГНІТНИХ ДОСЛІДЖЕНЬ СЛАБКОУРБАНІЗОВАНИХ МІСТ НА ПРИКЛАДІ ТРУСКАВЦЯ (УКРАЇНА) ТА МОНПЕЛЬЄ (ФРАНЦІЯ)

The objective of the present study is the assessment of the general trends for the pollution level of slightly impacted urban environment based on energy-efficient technology. The implementation of this approach is proposed on the examples of Truskavets (Ukraine) and Montpellier (France). The ultimate goal is to produce the preliminary data of the pollution with magnetic measurements. Regarding the anthropogenic pollution of the studied area the slight level of the urbanization must be accepted. The first source of the pollution is the road traffic and the second one is the railway and trams network. Non-urbanized landscape of Truskavets is presented by the forests. The soil types are gleysols. The urbanized soils of Truskavets and Montpellier are the urbozems. The magnetic susceptibility for the non-polluted soil in Truskavets is up to 8-10×10-8 m3/kg, very low values for Ukrainian soils, were registered. At the same time the polluted soils collected from the profiles and under the areal researches near the roadway and railway are characterized by a much higher MS: χ=36-162×10-8 m3/kg. The pollution of the soils were confirmed by the frequency dependence of magnetic susceptibility with the values of χfd= 2-3. The tree leaves from the Montpellier have much higher isothermal remanence along the roadway and tram line comparing with the natural area. The magnetic mineralogical analyses included thermomagnetic studies, hysteresis and remanence acquisition, ARM, and S ratio. The magnetite-like phase as the main magnetic mineral responsible for the magnetic enchantments in polluted soil was identified. At the same time non-polluted soil may contain the small amount of the single-domain (SD) particles and the high coercivity minerals such as haematite and goethite. Our results are valuable for the environmental management companies, centers of environmental monitoring, and geophysical observatories. Low cost, non-destructive and rapid magnetic techniques are promising in monitoring soil and air pollution both in highly anthropogenic impacted areas and at the slightly urbanized sites.

Newly formed minerals of the Fe–P–S system in Kolyma fulgurite

Newly obtained data from microscopic, geochemical, and thermomagnetic studies of the large Kolyma fulgurite are presented here: the fulgurite was formed in the Holocene as a result of lightning affected black shale alluvium. The composition is very close to that of glass formed from a melt. The glass has elevated concentrations of Y, Zr, Nb, and REEs. The newly formed mineral phases have been identified: those are Al–Si glass, α-cristobalite, moissanite, native iron with a phosphorus admixture, nickel-less shreibersite (?), troilite, and possibly cohenite. The formation of these minerals is related to the melt fractionation and the effects of element concentration and segregation of ore components under conditions of the rock melting caused by the effect of high-energy plasma (lightning strike).

Magnetic mapping of air pollution in Tandil city (Argentina) using the lichen Parmotrema pilosum as biomonitor

The lichen Parmotrema pilosum is sensitive to pollution and it can live accumulating airborne pollutants for long time, such characteristic allows its use as biomonitor for environmental mapping in urban areas when this epiphytic specie is available. In this work, we investigated the use of such passive collector and magnetic techniques to monitor the air pollution in Tandil, a city located in Buenos Aires province with approximately 125,000 inhabitants, 60,000 vehicles and various metallurgical factories inside the urban area. The sampling strategy was carried out following a random stratified design and measuring magnetic susceptibility, magnetic hysteresis loops, anhysteretic and isothermal remanent magnetization and thermomagnetic studies to determine the magnetic properties of airborne particles accumulated on lichen samples. Scanning electron microscopy observations show particles with different morphologies (individual particles, spherules and aggregates) and composition (Fe, Al, Ni, Cr, Ti, Cu, K and Br) produced by metallurgical factories and by gaseous/solid vehicle emissions. The magnetic mineralogy shows the predominance of pseudo-single domain magnetite-like mineral and the magnetic grain size estimations indicate the presence of fine particles (<0.1 μm) in sites with low vehicular traffic or less polluted, while sites more affected by pollution (high vehicular traffic and metallurgical industries) are characterized by coarser magnetic grain size particles, between 0.1 and 5 μm. Mass-specific magnetic susceptibility was represented in a 2-D contour map to observe in detail the distribution of magnetic particles in this urban area, giving high values (up to 1161.2 × 10−8 m3 kg−1) that are indicative of areas with high pollution loading.