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The characterization of magnetic susceptibility (MS) has become an accepted technique in soil science. This review examines the concept of volume and mass-specific MS, magnetism, frequency dependence, and thermal behavior of MS, as they pertain to soil material. A comparison is presented of the two types of instrumentation for measuring soil MS, based on magnetic field and electromagnetic induction (EMI). These are discussed with respect to applications including magnetic granulometry, detection of pollutants, identification of organic matter, the delineation of drainage class, paleo-environmental studies, archaeology, as well as soil erosion and degradation. Instruments that use magnetic fields can precisely measure the MS of small amounts of soil, thinly deposited layers or soil exposures, but cannot effectively measure materials at distances ≥10 cm from the sensor. EMI instruments, instead, are capable of quickly measuring apparent MS of a finite volume of the soil, and are utilized in mapping of soil MS in agricultural and archaeological investigations; however, the measured apparent MS values need to be further processed to give the real volume MS values of soil layers/segments. Although both kinds of instruments are widely used in soil science, their measured data are not interchangeable. Future work should be conducted to increase the understanding of the comparability of these instruments to find better utility among soil scientists.

Development of polymeric magnetic adsorbents is a promising approach to obtain efficient treatment of contaminated water. However, the synthesis of magnetic composites involving multiple components frequently involves tedious preparation steps. In the present study, a magnetic chitosan-palygorskite (MCP) nanocomposite was prepared through a straight-forward one pot synthesis approach to evaluate its lead (Pb2+) removal capacity from aqueous solution. The nano-architectural and physicochemical properties of the newly-developed MCP composite were described via micro- and nano-morphological analyses, and crystallinity, surface porosity and magnetic susceptibility measurements. The MCP nanocomposite was capable to remove up to 58.5 mg Pb2+ g−1 of MCP from water with a good agreement of experimental data to the Langmuir isotherm model (R2 = 0.98). The Pb2+ adsorption process on MCP was a multistep diffusion-controlled phenomenon evidenced by the well-fitting of kinetic adsorption data to the intra-particle diffusion model (R2 = 0.96). Thermodynamic analysis suggested that the adsorption process at low Pb2+ concentration was controlled by chemisorption, whereas that at high Pb2+ concentration was dominated by physical adsorption. X-ray photoelectron and Fourier transform infrared spectroscopy results suggested that the Pb adsorption on MCP was governed by surface complexation and chemical reduction mechanisms. During regeneration, the MCP retained 82% Pb2+ adsorption capacity following four adsorption–desorption cycles with ease to recover the adsorbent using its strong magnetic property. These findings highlight the enhanced structural properties of the easily-prepared nanocomposite which holds outstanding potential to be used as an inexpensive and green adsorbent for remediating Pb2+ contaminated water. Refereed/Peer-reviewed

Spin-crossover (SCO) molecules have been proposed for applications in molecular spintronic devices due to their bistability which can be reversibly switched by an external stimulus. Here, we report the synthesis, structure and characterization of an Fe(II) complex, FeL2 (L = N′-(pyridin-2-ylmethylene)-4-(undec-10-en-1-yloxy)benzohydrazide), having long aliphatic chains with terminal CC bonds. Variable-temperature Single Crystal X-ray Diffraction (SCXRD) and magnetic susceptibility measurements reveal that the SCO behavior with a thermal hysteresis loop originates from the combination of the change of the Fe(II) center coordination environment and the thermal motion of long aliphatic chains. Differential Scanning Calorimetry (DSC), variable-temperature Powder X-ray Diffraction (PXRD) and Polarized Optical Microscopy (POM) measurements suggest that the latter is also associated with a crystal–liquid crystal (LC) phase transition at high temperatures. Together, these results provide the prerequisites for potential applications of bistable SCO molecules in spintronic devices and liquid crystal displays.

The layered manganese oxide cathode materials suffer from the Jahn-Teller effect of the octahedral Mn3+ ions at low potentials and the anionic oxidation triggered structural degradation at high potentials. Introduction of vacancies in the transition metal layer has proved effective in stabilizing the structure at both the high and low potentials. Herein we specially designed vacancy-containing P2-Na2/3[Zn1/9Mn7/9□1/9]O2 (NZMO-Vac) and vacancy-free P2-Na2/3[Zn2/9Mn7/9]O2 (NZMO) to clarify how the vacancies tailor the spinning states of the Mn3+ ions and benefit the structural stability and kinetic performances. The temperature-dependent magnetic susceptibility demonstrates the increase of the Jahn-Teller inactive low-spin Mn3+ ions in NZMO-Vac at low potentials. Density functional theory calculations and advanced physical characterizations further indicate that the TM vacancies facilitate the generation of the low-spin Mn3+ ions by decreasing the Mn-O bond length during discharging. These findings provide new ideas on designing cathode materials with higher specific capacities and robust structures.

Purpose Magnetic resonance imaging (MRI) devices are frequently used in image-based diagnosis. In the case of large artifacts, which are generated in magnetic resonance (MR) images when magnetic materials, such as metals, are present in the body, these devices are less useful. This study aimed to develop a dual-phase Au-Pt alloy that does not generate artifacts in MR images and has high workability to prepare medical devices. Materials and methods A processing method to produce a dual-phase Au-Pt alloy was established, and the magnetic susceptibility and artifacts of different alloy compositions were determined using a SQUID (superconducting quantum interference device) flux meter and a 1.5 T-MRI system. The crystallographic phases of the prepared alloy samples were identified using X-ray diffraction. Sample cross-sections were observed using a metallurgical microscope. Furthermore, a thinning test was conducted to examine alloy workability. Results Dual-phase Au-Pt alloys Au70Pt30 and Au67Pt33—the former heat-treated at 800 and 850 °C and the latter heat-treated at 900 °C—generated minimal artifacts when imaged in a 1.5 T-MRI system. Their volume magnetic susceptibility increased as the heat-treatment temperature decreased. The alloy surfaces were observed to be uniform. Moreover, the workability of the dual-phase alloy was considerably better than that of the single-phase alloy. Conclusion Volume magnetic susceptibility could be controlled by changing the composition and processing temperature of the Au-Pt alloys. Dual-phase Au-Pt alloys those do not generate magnetic susceptibility artifacts in MRI images and have good workability could be prepared. The alloys are expected to be used in the preparation of various implantable medical devices.

Measurements of the variations of spin-locking relaxation rates (R1ρ) with locking field amplitude allow the derivation of quantitative parameters that describe different dynamic processes, such as slow molecular motions, chemical exchange and diffusion. In some samples, changes in R1ρ values between locking frequency 0 and 200 Hz may be dominated mainly by diffusion of water in intrinsic field gradients, while those at higher locking fields are due to exchange processes. The exchange and diffusion effects act independently of each other, as confirmed by simulation and experimentally. In tissues, the relevant intrinsic field gradients may arise from the magnetic inhomogeneities caused by microvascular blood so that R1ρ dispersion over weak locking field amplitudes (≤ 200 Hz) is affected by changes in capillary density and geometry. Here we first review the theoretical and experimental background to the interpretation of R1ρ dispersions caused by intrinsic magnetic susceptibility variations within the tissue. We then provide new empirical results of R1ρ dispersion imaging of the human brain and skeletal muscle at low locking field amplitudes for the first time and identify potential applications of R1ρ dispersion imaging in clinical studies.

Pancake bonding between partially oxidized tetramethyltetrathiafulvalene (TMTTF) moieties was examined via X-ray structural, spectral, and magnetic susceptibility measurements of the salts comprisi...

The crystal structure of Sc3Ir4Si13+x (x = 0.22) [space group P m 3 ‾ n $Pm\bar{3}n$ , a = 8.4651(1) Å] is found to be a new disordered variant of the primitive cubic Yb3Rh4Sn13 Remeika prototype. The silicide is stable in the narrow temperature range of 1283–1397 °C and reveals metallic properties. The crystal structure of Sc4Ir7Ge6 [U4Re7Si6 type, space group I m 3 ‾ m $Im\bar{3}m$ , a = 8.1397(8) Å] is refined for the first time. The electronic band structure calculations reveal that the properties of this germanide can be explained based on the free electron gas model. Both compounds reveal close structural relationships to the simple perovskite structure.

Tetragonal distorted spinel of CuMn2-xTixO4 (x = 0, 0.25 and 0.50) was prepared by solid state reaction method followed by neutron diffraction, FTIR spectroscopy, dielectric spectroscopy and magnetization measurements. The neutron diffraction and FTIR spectroscopy provide the information regarding phase formation. But, the magnetic susceptibility clearly shows the ferri-magnetic order below 76K associated with meta-magnetic state which turns to spin-glass behaviour upon Ti-substitution for Mn in CuMn2O4. In addition, the room temperature M(H) of all the spinels are described by the Arrott's plot for weak ferromagnetism. Further, the room temperature dielectric measurement provides the electronic property of CuMn2O4 dominated by grain boundary effect that is significantly increased upon Ti-substitution for Mn in CuMn2O4., Comment: 16-pages, 02-tables, 12-figures

The crystalline structures and magnetic and thermodynamic properties of a Gd4Ga2O9 single crystal grown with the optical floating zone technique have been investigated. Gd4Ga2O9 crystallizes in a monoclinic structure with the space group P21/c at room temperature. Temperature-dependent magnetic susceptibility measurements along the three crystallographic axes reveal a paramagnetic (PM) behavior between 2 and 300 K. A Curie–Weiss (CW) law fit was carried out and the CW temperature θCW and magnetic frustration parameter f were calculated; these suggest antiferromagnetic (AFM) interactions between Gd3+ spins and a strong magnetic frustration. The field dependence of the magnetization at 2 K further confirms the magnetic frustration characteristics. A distinct λ-shaped peak at 1.4 K in the heat capacity curves suggests a transition from the PM to AFM phase. The magnetic entropy is contributed solely by Gd3+ ions.

Summary Lanthanoid chelating tags (LCTs) are widely used for advanced paramagnetic NMR of biomacromolecules. The magnitude of their induced pseudocontact shifts (PCSs) and residual dipolar couplings (RDCs) depends critically on the anisotropy of the magnetic susceptibility tensor, which is usually determined by the resonances of the conjugated protein, inevitably reducing the effect by motional averaging. Here, for the first time, we present the intrinsic anisotropy parameters for the full lanthanoid series determined experimentally from resonances on the ligand itself. The strongly shifted proton spectra could only be assigned by extensive, site-specific isotope labeling. The extremely large anisotropies obtained deliver an upper limit for future PCS applications. To our great surprise, at least at room temperature, we observed an unprecedented correlation between the oblate or prolate f-electron distribution of the lanthanoid and the orientation of the main magnetic axis as well as the size of the magnetic anisotropy.

Temperature and magnetic field dependences of the magnetic susceptibility and dielectric permittivity of the α-MnS single crystal with NaCl structure are first investigated at around Neel temperature and at 4.2 K and H up to 70 kOe. A relation between the investigated properties was established. The founded phenomena can be due to the magnetostriction or magnetoelastic mechanism and the spin-dependent dipole moment.

A series of Lu3+, Tb3+: CeF3 nanoparticles were successfully prepared via the hydrothermal method. The results show that the nanoparticles exhibit obvious green emission after being effectively doped with Tb3+ ions, and the luminous intensity further increases with the increase of Lu3+ doping concentration. Hysteresis loops show that the magnetic susceptibility of Lu3+, Tb3+: CeF3 nanoparticles is 0.1310 emu/g under a magnetic field of 10,000 Oe. These proof-of-concept results show that Lu3+, Tb3+: CeF3 nanoparticles can be widely used in many important fields. It provides a theoretical basis for the combination of luminescent and magnetic properties of nanoparticles.

In the plasma of pulsed high-voltage discharge, initiated between nickel electrodes in air, when the fluoroplastic is placed in the discharge gap, powder nanocomposite material has been synthesized. The nanocomposite contains NiF2 nanoparticles less than 5 nm in size, dispersed in a matrix consisting of carbon and fluorocarbon substances. The carbonaceous substance contains nanoscale disordered graphite-like regions. The fluorocarbon component of the composite contains fragments of PTFE molecules and fluorocarbon molecular fragments that differ in structure from PTFE molecule’s structure. After annealing the composite in air at 773 K, the initial nanocomposite is transformed into a nanocomposite containing nanosized PTFE and nanoparticles of NiF2 less than 5 nm in size, scattered in a matrix composed of nanographite and low-layer nanosized graphene, after aneling at 1173 K into a material containing NiO nanoparticles less than 10 nm in size. After annealing of the initial nanocomposite in argon atmosphere at 1073 K, the obtained nanocomposite contains Ni nanoparticles with sizes less than 5 nm and carbon and fluorocarbon components. The magnetic susceptibility of the unannealed nanocomposite is investigated. A transition to the antiferromagnetic phase at 73 K was detected. At T = 4K, exchange bias interaction of the AFM / FM type takes place in the composite. There is divergence of the FC and ZFC curves, which can be explained by the presence of a superparamagnetic phase or a spin glass phase in the sample. The field dependences of the magnetic susceptibility measured at T = 300 K show sharp changes that occur at certain values of the magnetic field. Elucidation of the nature of these changes requires additional research.

In the present study, Fe3O4 (FO) nanoparticles and Au-Fe3O4 (AFO) nanocomposite have been synthesised by using sedimentary method. The samples have been characterised by different techniques including X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), EDX, magnetisation vs applied field (M-H), AC magnetic susceptibility, vibrating sample magnetometer and photo-thermal activity. Structural study showed that both samples formed in spinel cubic structure with Fd-3 m space group and composite form was also observed in Au-Fe3O4. FTIR spectral analysis showed the spinel belonging two vibrational stretching modes and Au attached over the Fe3O4 core. TEM images revealed the nano-metric morphology for both samples. The chemical composition of the samples was determined by EDX analysis. Magnetic results indicated that the samples have a superparamagnetic behavior, and a frequency dependence of AC susceptibility. Conclusively, this research has demonstrated that the samples are the most promising candidates in cancer therapy using hyperthermia. Superparamagnetic Au-Fe3O4 bifunctional nanocomposite have been detected in magnetic and hyperthermia activities.

SUMMARY Cyclic loading at elevated temperatures occurs either naturally during tectonic or volcanic-induced earthquakes or can be human-induced due to various geological engineering activities. The aim of this study is to test if mechanical fatigue in rocks can be monitored by magnetic methods. For this purpose, the effect of cyclic-mechanical loading (150 ± 30 MPa) on the magnetic susceptibility and its anisotropy of a magnetite-bearing ore with varying temperatures (400 and 500 °C) and environment (air and vacuum) was investigated. Our study shows that magnetic susceptibility decreases significantly (up to 23 per cent) under air conditions and in vacuum (up to 4 per cent) within the first ca. 1000 cycles. Further loading does not significantly affect the magnetic susceptibility which then remains more or less constant. The decrease of susceptibility parameters is stronger at 500 °C compared to 400 °C under both experimental conditions. Magnetic susceptibility was always measured after decompression of the loaded sample at room temperature so that magnetostriction can be excluded as a reason for these changes. The higher the temperature at which samples were loaded the more pronounced is the oxidation of magnetite to haematite. The transformation of magnetite into haematite under ambient conditions is the most important mechanism influencing bulk magnetic properties. The weak changes in magnetic susceptibility after vacuum loadings are probably caused by intragranular microcracks formed on the surface of magnetite grains. These surface deformation structures are accompanied by the refinement of magnetic domains, which is observed by magnetic force microscopy. Bulk magnetic grain size modifications are also confirmed by hysteresis parameters as well as by the increasing Hopkinson peak ratios determined from magnetic susceptibility measurements over Curie point. The degree of magnetic anisotropy and shape factor only change for the air-treated samples and are therefore related to the haematite formation and not to irreversible ductile deformation in magnetite. Our experimental study shows that cyclic loading can change significantly the magnetic properties of a rock due to mineral transformation below

The microstructure, mechanical and magnetic properties of Zr–x (8, 9, 10, wt.%)Nb–4Sn alloys were investigated to obtain novel Zr-based alloy with low Young’s modulus and magnetic susceptibility for biomedical implants. After homogenization annealing, hot forging and solution annealing, Zr–8Nb–4Sn, Zr–9Nb–4Sn and Zr–10Nb–4Sn alloys were composed of β+α″ phase, β+α″ phase, β+ω phase, respectively. The temperature at which the α" and ω phase were transformed into β phase during the heating process was about 200 ​°C, and the phase transformation temperature decreased with the increase of Nb element. Among all the Zr–x (x ​= ​8,9,10)Nb–4Sn(wt.%) alloys, Zr–9Nb–4Sn alloy had the lowest Young's modulus of 46.6 ​GPa and the low magnetic susceptibility of 1.294 ​× ​10−6 cm3g−1, which has a good application prospect for biomedical applications.

For the classical antiferromagnet MnF2 with TN≃67K, the pressure dependence of static magnetic susceptibility χ at T > TN was studied for the first time. The measurements of χ(P) were carried out at fixed temperatures 78, 140, and 300 K using a pendulum-type magnetometer and helium gas pressure P up to 2 kbar. The experimental data on the pressure derivative of magnetic susceptibility, d lnχ/dP, were analyzed within the Curie–Weiss law for χ(T) behavior, yielding estimate of the pressure derivative of paramagnetic Curie temperature dΘ/dP = – (0.31 ± 0.05) K/kbar and value (1/Θ)dΘ/dP = (3.5 ± 0.5) Mbar–1. The obtained experimental result is explained by the volume dependence of superexchange interaction between the magnetic moments of Mn2+ ions.

Magnetic phase coexistence in the substituted perovskite compound, La0.4Bi0.3Sr0.3MnO3, is attributed to the spontaneous moment and a step-like metamagnetic transition observed in the magnetization measurements in its magnetically order state. The magnetism of samples reduced to nanometer sizes by the “top down” approach exhibits interesting changes with respect to the bulk, thus giving a handle in influencing the physical properties by reducing the particle size. The bulk sample orders ferromagnetically at TC = 295 K, whereas in nano-sized samples with particle sizes in the range of 21–30 nm, even though TC does not change, the transitions are suppressed. The nano-sized powder samples show a broad hump in the plot of magnetic susceptibility, signifying the possible disordered antiferromagnetic state. A systematic decrease in the magnitude of magnetization in nano-sized samples shows that the reduction in magnetic interaction could be attributed to the formation of a magnetic dead layer around the magnetic core.

Inducing magnetic coupling between 4f elements is an ongoing challenge. To overcome this formidable difficulty, we incorporate highly delocalized tetrazinyl radicals, which strongly couple with f-block metallocenes to form discrete tetranuclear complexes. Synthesis, structure, and magnetic properties of two tetranuclear [(Cp*2 Ln)4 (tz. )4 ]⋅3(C6 H6 ) (Cp*=pentamethylcyclopentadienyl; tz=1,2,4,5-tetrazine; Ln=Dy, Gd) complexes are reported. An in-depth examination of their magnetic properties through magnetic susceptibility measurements as well as computational studies support a highly sought-after radical-induced "giant-spin" model. Strong exchange interactions between the LnIII ions and tz. radicals lead to a strong magnet-like behaviour in this molecular magnet with a large coercive field of 30 kOe.

Bi1 − xFexNbO4 (x = 0.25, 0.50, and 0.75) samples were synthesized by the sol–gel method and its morphologic, structural, dielectric, and magnetic properties were studied. The structure was analyzed by X-ray diffraction and the morphology by scanning electron microscopy. The dielectric characterization that was performed using impedance spectroscopy, in the frequency range of 102–106 Hz, as a function of temperature, revealed that the dielectric constant and the dielectric losses increased with the iron content. The prepared materials presented relaxation processes, with the corresponding activation energies being calculated by fitting the experimental data to the Arrhenius model. The dependence of AC conductivity on frequency was found to satisfy Jonscher’s universal power law at different temperatures. The conduction mechanisms are governed by two processes: correlated barrier hopping (CBH) and non-overlapping small polaron tunneling (NSPT). Magnetic susceptibility, for an applied magnetic field of 0.5 T, doubles when the iron concentration goes from 0.25 to 0.5 and doubles again when the iron concentration rises to 0.75. The increase in magnetization with the concentration of iron is also observed in the curves M vs. H at 7 K. The remaining magnetization and the coercive field do not exist for x = 0.25 (paramagnetic behavior); it is small for x = 0.5 and is already observed when x = 0.75.

We report the single crystal growth, structural and magnetic properties of honeycomb spin-lattice compounds Na2M2TeO6 (M = Co, Ni) and spin dimer compound Na2Cu2TeO6. The single crystals of Na2M2TeO6 (M = Co, Ni, Cu) have been grown by the self-flux method, which is one of the good techniques to control the magnetic impurity, different crystalline phase, crystal morphology, crystal size and the crystal surface through the selection of a suitable self-flux. Crystal structure, magnetic and thermodynamics properties are examined using X-ray diffraction (XRD), magnetic susceptibility and heat capacity measurements, respectively. The single crystal XRD studies of Na2M2TeO6 (M = Co, Ni, Cu) show the purity and the high quality of grown single crystals. The measurements of magnetic susceptibility of Na2M2TeO6 show the distinct anisotropic behaviour of the prepared single crystals. The anisotropic behaviour and the complicated magnetic phase transitions observed arise from the distinct honeycomb planes constituted by MO6 octahedra in Na2M2TeO6 (M = Co, Ni) leading to the antiferromagnetic (AFM) interaction in the honeycomb planes. In the case of Na2Cu2TeO6 broad maximum occurring at 160 K is believed to arise from short-range one-dimensional antiferromagnetic correlations. The values of (effective magnetic moment) μeff. observed for Na2Co2TeO6, Na2Ni2TeO6 and Na2Cu2TeO6 are 5.42 μB, 3.17 μB and 1.96 μB respectively.

The crystal structure and physical properties of Nb25Mo5+xRe35Ru25-xRh10 (0 ≤ x ≤ 10) and Nb5Mo35-yRe15+yRu35Rh10 (0 ≤ y ≤ 15) high-entropy alloys (HEAs) have been studied by X-ray diffraction, electrical resistivity, magnetic susceptibility, and specific heat measurements. The results show that the former HEAs with valence electron concentration (VEC) values of 6.7–6.9 crystallize in a noncentrosymmetric cubic α-Mn structure, while the latter ones with VEC values of 7.1–7.25 adopt a centrosymmetric hexagonal close-packed (hcp) structure. Despite different structures, both series of HEAs are found to be bulk superconductors with a full energy gap, and the superconducting transition temperature Tc tends to decrease with the increase of VEC. Nevertheless, the Tc values of the hcp-type HEAs are higher than those of the α-Mn-type ones, likely due to a stronger electron phonon coupling. Furthermore, we show that VEC and electronegativity difference are two key parameters to control the stability of α-Mn and hcp-type HEAs. These results not only are helpful for the design of such HEAs, but also represent the first realization of structurally different HEA superconductors without changing the constituent elements.

The experimental study of the specific heat, magnetic susceptibility, and magnetization of Gd2MoO6 powder sample was performed in the temperature range between 0.4 K and 300 K in the magnetic fields up to 9 T. Powder sample was prepared via nonconventional mechanochemical/thermal process from powdered oxide precursors. Magnetic ion Gd3+ with spin S = 7/2 is responsible for the magnetic properties. The specific heat study in zero magnetic field revealed two anomalies; a phase transition to the ordered state at TN1 ≈ 0.98 K and a smaller maximum at TN2 ≈ 0.6 K. Relatively high magnetic density 6.85 g/cm3 of Gd2MoO6 predetermines this compound as potential magnetocaloric material with a high cooling performance at cryogenic temperatures. A large conventional magnetocaloric effect was found around 3 K with magnetic entropy change −ΔSmax ≈ 44 J/(kg K) (300 mJ/(Kcm3)) for magnetic field change from 9 T down to zero with a refrigerant capacity of 464 J/kg. Maximal temperature change -ΔTad ≈ 23.8 K was found for initial temperature Tinit ≈ 29.9 K for the mentioned change of magnetic field. Alternating susceptibility measurements revealed the presence of two relaxation channels in Gd2MoO6 existing in two different time scales ≈ 10-3 s and ≈ 1 s.

We present the results of structural and magnetic properties of two types of heterostructures composed of ferroelectric BaTiO3 and dielectrics LaMnO3 or SrTiO3. By means of the first principle calculations we analyze structures of BaTiO3/LaMnO3 and BaTiO3/SrTiO3 interfaces and investigate magnetic properties and an impact of ferroelectric polarization. Experimental results of magnetic susceptibility measurements for Ba0.8Sr0.2TiO3/LaMnO3 heterostructure are presented.

The magnetic properties of oil constituents appear to be related to their key physical and chemical properties; therefore, the application of new magnetic characterization techniques for oils can make additional contributions to the field. In this study, despite the high dilution of 3d-like ions in crude oil, magnetic susceptibility measurements, recorded at different temperatures and frequencies, and electronic paramagnetic resonance measurements below room temperature were applied to detection of magnetic nanoparticles naturally found in distinctive dehydrated crude oils from the same geological reservoir, but from different oil wells. Electronic paramagnetic resonance measurements probed the presence of Fe3+ ions, with characteristics attributed to magnetite or maghemite (γ-Fe2O3) magnetic nanoparticles in super paramagnetic regime, whilst the presence of a magnetic susceptibility peak, that is visible only at 5000 Hz, has indicated a magnetically blocked regime, via Brownian relaxation, of iron-oxide magnetic nanoparticles. The magnetic susceptibility data showed that it is possible to distinguish the particle size distribution homogeneity and, with the support of the electron paramagnetic resonance technique, the relative fractions of iron-oxide magnetic nanoparticles in crude oils. Thus, these findings show that the magnetic susceptibility technique, supported by electronic paramagnetic resonance spectroscopy, can be applied for the study of magnetic nanoparticles in crude oils and can aid in determining and understanding the fundamental properties of crude oils.

The synthesis of phenalenyl-endcapped [5]cumulene as a cumulene-based singlet biradical and the spin correlation changes of one-dimensional aggregates are described. The high propensity for self-aggregation of phenalenyl rings and the introduction of bulky substituents into the appropriate positions led to the formation of a one-dimensional chain assembly. Single-crystal X-ray structural analysis indicated that the bond length alternation of the cumulene chain increased with decreasing temperature, along with improved overlapping of the phenalenyl rings. Variable-temperature Raman spectroscopy and magnetic susceptibility measurements revealed that a localized spin pair within the molecule decouples at low temperatures, and a continuum spin system involving intra- and intermolecular spin-spin interactions emerges in the one-dimensional chain.

We report the design, synthesis, structure, and properties of two complex layered phosphide nitrides, $Ak$Th$_2$Mn$_4$P$_4$N$_2$ ($Ak$ = Rb, Cs), which contain anti-fluorite-type [Mn$_2$P$_2$] bilayers separated by fluorite-type [Th2N2] layers as a result of the intergrowth between AkMn$_2$P$_2$ and ThMnPN. The new compounds are featured with an intrinsic hole doping associated with the interlayer charge transfer and a built-in chemical pressure from the [Th$_2$N$_2$] layers, both of which are reflected by the changes in the lattice and the atomic position of phosphorus. The measurements of magnetic susceptibility, electrical resistivity, and specific heat indicate existence of local moments as well as itinerant electrons in relation with d-p hybridizations. The expected dominant antiferromagnetic interactions with enhanced d-p hybridizations were demonstrated by the first-principles calculations only when additional Coulomb repulsions are included. The density of states at the Fermi level derived from the specific-heat analysis are 3.5 and 7.5 times of the calculated ones for Ak = Rb and Cs, respectively, suggesting strong electron correlations in the title compounds.

From a technological point of view one of the most important characteristics of magnetorheological fluids and ferrofluids is their fast (on the [Formula: see text] s time scale) response to external magnetic fields. We report response time measurements based on the time domain magnetic susceptibility response of commercially available fluids. The dynamic susceptibility is measured over time in the presence of external magnetic field by a method using an inductive resonant circuit. The response time of the fluids is extracted as the characteristic time constant from the response to ramp excitation. We investigated the influence of the slope of the ramp excitation on the response time. The macroscopic response times were correlated with the characteristic time scales of the microscopic processes behind the susceptibility response. In case of the magnetorheological fluids the overall response time have been associated with the characteristic times of structure formation. The relatively slow response of the ferrofluid corresponded to a relaxation dominated by Brownian mechanism, which indicated the presence of multi-core clusters.

We have synthesized a GaSb–Fe3Ga4 semiconducting eutectic composite. It has been characterized by X-ray diffraction at different temperatures, and we have determined the elemental composition of its matrix, metallic inclusions, and the interfacial zone. Its specific magnetization and magnetic susceptibility have been measured by a ponderomotive method in the temperature range ~80–750 K and a vibrating sample method at 4.6 and 295 K in magnetic fields of up to B = ±14 T. The GaSb–Fe3Ga4 eutectic composite has been shown to have properties of a magnetic material with a Curie temperature TC = 355 K. At liquid-nitrogen temperature, the specific magnetization of the eutectic composite is σ ≈ 1.5 A m2/kg and its average magnetic moment is µ ≈ 0.17µВ. The magnetic characteristics of the composite have been shown to be stable to thermal loads up to 750 K and insensitive to the external magnetic field up to 14 T.

The double perovskite YBaMn2O6 exhibited complex structural, magnetic, and charge/orbital ordering phase transitions. In this paper, we investigated the correlation between the temperature-dependent optical response and complex phase transitions of YBaMn2O6 single crystals through spectroscopic ellipsometry and Raman scattering spectroscopy. The room temperature optical absorption spectrum of YBaMn2O6 revealed three bands of approximately 1.50, 4.05, and 5.49 eV. The lowest optical absorption band was assigned to on-site d-d transitions in Mn ions, whereas the other two optical features were assigned to charge-transfer transitions between the 2p states of O and 3d states of Mn. The room temperature Raman scattering spectrum revealed 25 phonon modes. Notably, the MnO6 octahedral tilting and bending modes between 360 and 440 cm-1 increased in intensity at temperatures

The influence of growth impurities (oxygen and carbon) on the thermalsdefect formation in silicon single crystals has been studied. Annealing was carried out in the temperature range 700-1100°C in steps of 50°C for 5 hours at each temperature. The magnetic, micromechanical and structural properties of annealed silicon single crystals have been experimentally studied. The distribution of defects formed at different annealing temperatures has been studied. The correlation between changes of magnetic susceptibility, microhardness and rearrangement of structural defects in crystals after their heat treatment is revealed. Concentrations and sizes of magnetically ordered clusters are estimated. Interpretation of the obtained experimental results is offered.

The superconducting magnetic separation was examined to reduce the volume of cesium contaminated soil by the Fukushima Daiichi nuclear power plant accident. By using superconducting high gradient magnetic separation, silt and clay with high radioactive concentration due to the large particle surface area per unit mass can be further separated into high-dose 2:1 type and low-dose 1:1 type clay minerals selectively. Here, we examined filter conditions to improve the magnetic separation performance in farmland soil that is rich in organic matter. The results of magnetic separation of uncontaminated soil suggested that the separation selectivity of 1:1 and 2:1 type clay minerals was larger with the filters with smaller wire diameter. On the other hand, it was found that it was difficult to magnetically separate 0–20 μm particles even with the filters with small wire diameter and high selectivity. To solve this problem, magnetic separation was performed under the same conditions on actual contaminated soil that was highly classified into 0–20 μm and 20–75 μm particles. As the result, it was found that the radioactivity can be further reduced by removed high-dose 0–20 μm particles and targeting the 20–75 μm particles.

Use of superconductors for the shielding of the magnetic field is a common solution nowadays. In case when the magnetic signature of the shielding device matters, forming a magnetic cloak by combining superconductor with ferromagnetic material is a viable option. When considering the operation in alternating magnetic fields the AC loss linked to the delay in phase of the shielding currents represents an important topic. It is well known that the coated conductor (CC) tapes represent a valid alternative to bulk superconducting material when an AC loss reduction appears as a significant requirement. However, the commercially available coated conductors are usually limited to 12 mm width, therefore finding a suitable arrangement of tapes plays a significant role in the magnetic cloak design. We made a set of experiments on two possible arrangements in the superconducting part (helically wound tapes or straight pieces of the tape) and with the total number of layers up to six. For understanding the mechanism of magnetic field penetration inside the cloak the 2D and 3D numerical models were built. Presented numerical models helped in the localization of the cloak component with high energy dissipation. Analysis of the experimental and computation results allow us to formulate some recommendations for the construction of the superconducting part of the magnetic cloak.

Purpose A phantom is presented in this study that allows for an experimental evaluation of QSM reconstruction algorithms. The phantom contains susceptibility producing particles with dia- and paramagnetic properties embedded in an MRI visible medium and is suitable to assess the performance of algorithms that attempt to separate isotropic dia- and paramagnetic susceptibility at the sub-voxel level. Methods The phantom was built from calcium carbonate (diamagnetic) and tungsten carbide particles (paramagnetic) embedded in gelatin and surrounded by agarose gel. Different mass fractions and mixing ratios of both susceptibility sources were used. Gradient echo data were acquired at 1.5 T, 3 T and 7 T. Susceptibility maps were calculated using the MEDI toolbox and relaxation rates Δ R 2 ∗ were determined using exponential fitting. Results Relaxation rates as well as susceptibility values generally coincide with the theoretical values for particles fulfilling the assumptions of the the static dephasing regime with stronger deviations for relaxation rates at higher field strength and for high susceptibility values. MRI raw data are available for free academic use as supplementary material. Conclusions In this study, a susceptibility phantom is presented that might find its application in the development and quantitative validation of current and future QSM reconstruction algorithms which aim to separate the influence of isotropic dia- and paramagnetic substructure in quantitative susceptibility mapping.

Physicochemical properties of the iron(II) 2-naphthalenesulfonate complex with 4-amino-1,2,4-triazole ([Fe(NH2trz)3](ns)2·2H2O (I)) are studied. The complex exhibits the 1A1 ↔ 5T2 spin crossover. Complex I and the initial compound for its preparation, Fe(ns)2 (II), are studied by static magnetic susceptibility, conductometry, spectrophotometry, and cyclic voltammetry methods. The μeff(T) dependence for I shows that the spin transition is abrupt both in the initial complex and in the DMF solution. Forward and inverse spin crossover temperatures are determined.

Information support of modern agriculture and ecology forms a demand for ever higher requirements for efficiency and density of the sampling network. This fact determines the spread of high-performance methods of soil research, among which are magnetometric ones. However, these methods have a number of limitations associated with the existence in soils of ferromagnets of non-pedogenic nature. The purpose of the study is to show the patterns of spatial and profile distribution of soils with high values of magnetic characteristics, inherited from parent rocks as a result of pedogenesis. The research used: determination of specific magnetic susceptibility using kappabridge KLY-2, determination of volumetric magnetic susceptibility with kappameter KT-5 and induction of magnetic field by proton magnetometer MP 203. The study was conducted at two objects located in the central part of the Ukrainian shield region. Studies have shown that soils developed on the weathering crust are characterized by certain features of their magnetic properties. First of all, it depends on the petromagnetic parameters of the source rocks. On magnetic rocks, the MS of soils is determined primarily by inherited magnetic minerals. The magnetic susceptibility of such soils has two maxima. The first is in the upper part of the profile, where it is determined by the sum of pedogenic and terrigenous magnets. The second is located in the lower part of the profile, which consists almost entirely of weathering products.

—It is shown that the size and shape of cementite inclusions in eutectoid steel determine its magnetic properties in both unstrained and plastically strained states. In the case of the unstrained state, the coercivity of steel comprising a fine pearlite is found to be the highest, whereas the coercivity of steel comprising a coarse pearlite is the lowest. Tensile plastic deformation leads to an increase in the coercivity of samples and a decrease in their remanence and maximum magnetic susceptibility. The appearance of bend or a second maximum in the field dependences of the magnetic susceptibility measured along the deformation direction indicates the formation of the “easy-plane” magnetic texture caused by residual compressive stresses. Calculated magnetic anisotropy fields of initial unstrained samples of eutectoid steel differing in pearlite morphology are from 10.4 to 19.1 A/cm. The plastically strained samples exhibit an increase in the induced magnetic anisotropy and, therefore, in the residual stresses as compared to those observed for the unstrained state.

In this comparative study, Tb and Tm substituted Sr-hexaferrites (HFs) with the chemical compositions of SrTbxFe12−xO19 and SrTmxFe12−xO19 (x = 0.00, 0.02 and 0.04) were fabricated via citrate sol-gel approach. The AC susceptibility and FC-ZFC magnetization were investigated. The product structure and morphologies were also investigated via XRD, TEM and SEM along with EDX. Measurements of temperature dependence of magnetization M-T and AC magnetic susceptibility versus temperature were carried out. The various synthesized HFs displayed ferrimagnetic behavior within 10–325 K. At lower temperatures, super-spin glass-like behavior was noticed. Neel-Arrhenius and Vogel-Fulcher models were employed to explore the experimental data of AC susceptibility.

Three new metal–organic coordination polymers, {[Co2(TDC)2(H-3,3′-pytz)2(μ2-OH)]·4DMF}n (1), [Mn5(NDC)4(3,3′-pytz)(DMF)4(μ3-OH)2]n (2), [Co5(NDC)4(3,3′-pytz)(DMF)4(μ3-OH)2]n (3). (3,3′-pytz = 3,6-bis(3-pyridyl)-1,2,4,5-tetrazine; H-3,3′-pytz = protonated 3,6-bis(3-pyridyl)-1,2,4,5-tetrazine; H2TDC = 2,5-Thiophenedicarboxylic acid; H2NDC = 1,4-naphthalenedicarboxylic acid) were synthesized under hydro-/solvothermal conditions and characterized by techniques of single-crystal X-ray diffraction analysis, elemental analysis, infrared spectra (IR) and thermogravimetric analysis (TGA). The resulting analyses demonstrate that complex 1 displays a rare 3D 8-connected bcu framework with the point symbol of {424·64} based on dinuclear [Co2(μ2-OH)(COO)4] cluster, while complex 2 and 3 possessed a rare 3D 10-connected pentanuclear-cluster-based ile{36·434·53·62}framework. The variable-temperature magnetic susceptibility data show that the complex 1, 2 and 3 exhibit antiferromagnetic interaction.

PurposeThe purpose is to calculate the change in the total energy of a small fragment of an idealized lattice of iron (in its pure form and with impurity atoms) containing an edge dislocation during its elementary motion at one interatomic spacing, both under the influence of a constant magnetic field and without it. The introduction of a magnetic field into the system is aimed at checking the adequacy of the description of the phenomenon of magnetoplasticity by changing the total energy of the atomic system.Design/methodology/approachThe design procedure is based on a quantum-mechanical description of the switching process of the covalent bond of atoms in the dislocation core. The authors used the method of density functional theory in the Kohn-Shem version, implemented in the GAUSSIAN 09 software package. Using the perturbation theory, the authors modeled the impact of an external constant magnetic field on the energy of a system of lattice atoms.FindingsThe simulation results confirmed the effect of an external constant magnetic field on the switching energy of the covalent bond of atoms in the dislocation core, and also a change in the magnetic susceptibility of a system of atoms with a dislocation. This complements the description of the magnetoplastic effect during the deformation of metals.Originality/valueThe authors created quantum-mechanical models of the dislocation motion in the Fe crystal lattice: without impurities, with a substitutional atom Cr and with an interstitial atom C. The models take into account the influence of an external constant magnetic field.

The 57Fe doped LiMnPO4 cathode with potential applications in Li-ion batteries was prepared by solid-state reaction. The magnetic susceptibility ordered antiferromagnetically at Neel temperature (TN = 34 K). The spin reorientation temperature (TS) and effective moment were determined to be 8 K and 5.78 μB. We obtained the Mossbauer spectra at various temperatures and fitted the spectra below TN to eight absorption lines. The behavior of the magnetic hyperfine field and the quadrupole splitting change with increasing temperature above TS indicates that the quenched orbital angular moment is due to a strong crystal field at the Mn(Fe)O6 site.

We report the structural, magnetic, and magnetocaloric properties of Bismuth (Bi)-substituted manganite La0.85-xBixNa0.15MnO3 (x=0, 0.1, 0.2, 0.25, and 0.3). X-ray diffraction data implicates the rhombohedral structure with $$ R\overline{3}c $$ R 3 ¯ c space group. Bi2O3 has helped in ensuring phase pure, densified compounds even at low sintering temperature and hence avoiding the evaporation of volatile sodium. The increase in grain size and decrease in magnetic transition temperature (TC) are due to the Bi chemical activity and electronic structure. The samples have shown indirect magnetic transformation from soft ferromagnet to canted ferromagnet/antiferromagnet with Bi. Griffiths phase-like behavior in the inverse magnetic susceptibility was observed for x=0.1; with further increase in Bi, the samples are found to develop the antiferromagnetic competing phase. The phenomenological model was used to model the thermomagnetic behavior of all the samples. The sample with x=0.1 shows an increase in magnetic entropy change upon Bi substitution and the maximum of magnetic entropy change is seen at 275K emphasizing its potential in room temperature magnetic refrigeration.