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Graphical abstract The reductive coupling of a chelated diimine ligand, Me 2 C(CH NCH 2 (2-py)) 2 (dmp(PM) 2), by (TMEDA)TiCl 2 afforded a Ti(IV) cyclopropanated species, Me 2 cPr(cis -2,3-NCH 2 (2-py) 2 TiCl 2 (1), while di-azaallyl precursors were used to generate 7-membered ring chelates [{DBM(PI− )(PI2−)}CrIII] 2 (4) and [{DBM(PI)(PI′)}Fe] 2 (5). Abstract The reductive coupling of a chelated diimine ligand, Me 2 C(CH NCH 2 (2-py)) 2 (dmp(PM) 2), by (TMEDA)TiCl 2 afforded a Ti(IV) species containing a cyclopropane ring, Me 2 cPr(cis -2,3-NCH 2 (2-py)) 2 TiCl 2 (1). Dimeric [{Me 2 C(CH 2 N CH(2-py)(CH 2 (µ-N)CH 2 (2-py)}Mg] 2 (3) was generated in the magnesium reduction of Me 2 C(CH 2 N CH(2-py)) 2 (dmp(PI) 2) as its reduction incurred HAT. A di-azaallyl precursor was used to generate 7-membered ring chelates [{DBM(PI− )(PI2−)}CrIII] 2 (4) and [{DBM(PI)(PI′)}Fe] 2 (5). Structural studies of 1 , 3 and 4 are included, as are electronic assessments of the reductive coupling to afford 1 , and the paramagnetism of 3. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The observed unusual co-existence of AFM with GP in nanometric SCCMO sample is rare in nature. • The glassy behavior in bulk SCCMO is attributed to the antisite disorders (∼7.12%) along with magnetic frustration. • Magnetic spin dynamics and aging effect are suggesting different spin relaxation processes. Abstract Griffiths phase like behavior has been investigated in details in size modulated Sm 1.5 Ca 0.5 CoMnO 6 double perovskite, having ferromagnetic entities in the paramagnetic matrix. Temperature dependent real and imaginary part of ac susceptibility confirms that Sm 1.5 Ca 0.5 CoMnO 6 -1150 °C bulk-sample has spin-glass like ordering below T g ∼ 34.88(3) K. This glassy behavior is attributed to the antisite disorders (∼7.12%) along with and magnetic frustration in the system. However, the ground state of Sm 1.5 Ca 0.5 CoMnO 6 -600 °C nanometric-sample is observed to be antiferromagnetic in nature due to the presence of large antisite disorder (∼53.58%). The observed unusual co-existence of antiferromagnetism with Griffiths-like phase in Sm 1.5 Ca 0.5 CoMnO 6 -600 °C sample is rare in nature. Interesting magnetic spin dynamics and aging effect are also observed in both the compounds suggesting different spin relaxation processes in low temperature regime. The observed magnetism in these compounds can be tuned by nearest neighbor Co-O-Mn and/or Co-O-Co/Mn-O-Mn exchange interactions as well as the next nearest neighbor Co-O-O-Co/Mn-O-O-Mn interactions. [ABSTRACT FROM AUTHOR]

Abstract Herein, we report a prospective strategy to synthesize ZnFe 2 O 4 hierarchical structures assembled by nanoparticles to obtain different morphology like spheres, rods, and flowers. The morphological influence on physicochemical and magnetic properties has been extensively explored. Phase purity of samples was determined by X-ray diffraction (XRD) and morphological and structural features were elucidated with the help of field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) with energy dispersive spectroscopy (EDX) tool was used for elemental analysis. FESEM and HRTEM confirmed the formation of ZnFe 2 O 4 with different morphologies. Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy gave the insight of bonding mechanism associated with the synthesized materials. Meanwhile, the material chemistry of obtained products was investigated by X-ray photoelectron spectroscopy (XPS). The surface area of samples with different morphologies have also been found to vary from 19 to 55.8 m2/g while the optical band gap study confirmed that nanorods have smaller band gap having value 2.86 eV when compared to sphere and flower structures with band gap 4 eV and 3.47 eV respectively. Magnetic measurements performed on vibrating sample magnetometer (VSM) ascertains the superparamagnetic behavior of synthesized materials. [ABSTRACT FROM AUTHOR]

Abstract Molecular bridges covalently bonded to two ferromagnetic electrodes can transform ferromagnetic materials and produce intriguing spin transport characteristics. Previously, we theoretically and experimentally studied the impact of paramagnetic molecules on the magnetic properties of the magnetic tunnel junctions (Tyagi et al. Nanotechnology, Vol.26, p.305602, 2015). In this follow up paper we have investigated the impact of previously demonstrated molecule induced strong coupling on the spin transport. To study molecular coupling effect experimentally we attached paramagnetic molecules between two ferromagnetic electrodes of a magnetic tunnel junction along the exposed side edges. The strong molecule coupling between two ferromagnetic electrodes caused the drastic changes in transport properties of the magnetic tunnel junction testbed. Molecular transport channels along the tunnel junction edges decreased the tunneling current as compared to the leakage current of the bare tunnel junction at room temperature. The current magnitude on the paramagnetic molecule treated magnetic tunnel junction tended to settle in the suppressed state at room temperature. Graphical abstract Image 1 Highlights • Covalently bonded molecules created experimentally-observed strong antiferromagnetic coupling between ferromagnets of MTJ. • Upto ~ 7 orders of current reduction below leakage current of MTJ occurred on MTJMSD due to molecular bridges at RT. • In the transient state MTJ+molecules (aka MTJMSD) showed irreproducible magnetoresistance change by >1000 folds at RT. • In the transient state forcing current through MTJMSD showed irreproducible resistance change by >1000 folds at RT. • MTJMSD approach may allow mass production of molecular quantum properties based future computing and memory devices. [ABSTRACT FROM AUTHOR]

Abstract Magnetic drug targeting (MDT) is a drug delivery method which implements a high gradient magnetic field in order to enhance the deposition of drugs, containing magnetic materials, in a target area. In this study, we investigated drug delivery to the anterior side of human trachea by means of the MDT method. The drug delivery process was studied numerically in a realistic model of human airway and the drug deposition due to the presence of magnetic field was analyzed. The human airway model used, consists of nasal cavity, oral cavity, pharynx, larynx and trachea. A steady incompressible laminar flow regime was considered for modeling the inhalation of air into the respiratory tract. Microsphere drug particles were injected orally into the airway model. The particles were assumed to have a core-shell structure with aggregated superparamagnetic magnetite nanoparticles in the core and nanomedicine stored in the shell. A permanent magnet with a stationary magnetic field was placed near the trachea in order to enhance the particle deposition in this region. Also, a human mannequin model was employed for determining the exact location of the magnet with respect to the airway. Simulations were performed for various airflow rates, particle sizes and drug compositions in the presence and absence of the magnetic field. In addition, two different air breathing conditions were examined. Furthermore, the effects of magnetic source strength, magnetic source placement angle and gravity, as well as volume packing fraction of the aggregate core, on the drug deposition were explored. The simulation results showed marked improvement in the drug deposition in the presence of magnetic field. Finally, the appropriate conditions for the efficient application of MDT were evaluated. It was shown that the optimal drug delivery results were obtained for low airflow rates (~ 5 l/min), midsize particle diameters (~ 8 µm) and high fractions of magnetic material in the particle composition (75% volume fraction). For the optimum particle diameter, the oral inhalation was shown to lead to a more successful drug delivery relative to the oronasal inhalation. Also, increasing the strength of the magnetic source, placing the magnetic source with an angle of 0° and having the patient lie on his/her back had positive impact on the MDT outcome. Moreover, increasing the volume packing fraction improved the efficieny of drug delivery for low and moderate particle sizes (≤ 8 µm). Highlights • A realistic model containing airway, magnetic source and body was developed. • Effects of various physical parameters on magnetic drug delivery were investigated. • New parameters affecting magnetic drug delivery were introduced. [ABSTRACT FROM AUTHOR]

Graphical abstract The graphical abstract depicting the mechanism of Nanometal Surface Energy Transfer (NSET) of the quenching of fluorescence of fluorescein by gold nanoparticle and its turn on by fenitrothion. Highlights • The fluorescence of fluorescein dye is quenched by gold nanoparticle. • The quenching of fluorescence of fluorescein occurs through nanometal surface energy transfer (NSET). • The gold nanoparticle quenched fluorescein undergoes fluorescence turn on in the presence of fenitrothion. Abstract In this work, a simple and sensitive determination of fenitrothion is developed on the basis of Nanometal Surface Energy Transfer (NSET) of gold nanoparticle on the fluorescence of fluorescein. The developed gold nanoparticle quenched fluorescein system exhibits high sensitivity and selectivity towards fenitrothion in the presence of different pesticides, anions and cations. The fluorescence turn on response of the gold nanoparticle quenched fluorescein probe towards fenitrothion is successfully demonstrated on a paper strip. The real sample analysis was carried out using water samples from different sources and has limit of detection of 6.05 nM, 9.41 nM and 7.84 nM for well water, tap water and river water respectively. However, attempt to simultaneously separate and sense fenitrothion using gold nanoparticle enveloped over superparamagnetic iron oxide nanoparticle was not successful due to the irreversible quenching of fluorescence of fluorescein by Fe3+ ion present in iron oxide nanoparticle, which inhibits the requisite turn-on fluorescence of the probe. Furthermore, we successfully employed superparamagnetic iron oxide to magnetically separate fenitrothion attached to gold nanoparticle from the contaminated water. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract We report the fabrication of magnetic carbon nanotubes (MCNTs) through one-step modification with a paramagnetic cationic surfactant for migration of DNA and proteins. DNA and proteins can effectively bind to the surfactant-coated MCNTs through electrostatic interaction. Targeted transport platform of DNA and proteins as delivery agents can be constructed upon application of an external magnetic field. The native conformation of these biomacromolecules can be suitably maintained without denaturation during the migration process. We expect it will find MCNTs potential applications in gene delivery, gene transfection, protein delivery and separation. [ABSTRACT FROM AUTHOR]

Abstract Published magnon dispersion data are discussed, showing that magnon dispersions of bulk magnets are essentially as for linear spin chains, i.e. one-dimensional. This applies to all propagation directions in cubic magnets, in layered two-dimensional magnets and in axial magnets. Propagation of magnons seems to be restricted to the individual magnetic domain. Within each domain the spin structure is collinear (one-dimensional). Perfect collinear spin structures up to ordering temperature, in spite of local exchange anisotropies, cannot be understood on the basis of atomistic models. As we have argued earlier, collinear spin structures are caused by a one-dimensional boson field. The bosons are essentially magnetic dipole radiation emitted by the precessing spins. Since emission is by stimulated emission, perfect one-dimensional boson fields result. The one-dimensional boson fields are considered as responsible for the magnon dispersions of linear chain type. However, magnon dispersions follow sine function of wave vector (for antiferromagnets) and sine function squared (for ferromagnets) not perfectly. At low q-values, magnon dispersions often deflect from sine function (or from sine function squared) towards a magnon gap at q≡0. This part of the magnon dispersion is excellently described by gap energy plus qx power function of wave vector. The two analytically different sections of wave vector have different temperature dependencies. The gap closes for T→T c , while the sine function persists nearly unperturbed into the paramagnetic phase. In contrast to the sine functions, the qx term is universal that is, independent of spin structure but depends on whether the spin is integer or half-integer. It is concluded, that for all q-values, the functional wave-vector dependence of the magnon dispersions (not their absolute energies) is determined by boson fields with well defined dimensionalities. [ABSTRACT FROM AUTHOR]

Abstract Magnetization measurements on antiferromagnetic iron storage protein ferritin are reported. The magnetization as a function of applied magnetic field data in superparamagnetic region are analyzed considering a distribution in particle size. The estimated particle size distribution is compared with that determined from transmission electron micrograph. Effect of magnetic anisotropy on magnetization process of this nanoparticle system is also discussed. Highlights • Iron storage protein ferritin is a model superparamagnet. • Its magnetization data in superparamagnetic region are analyzed. • Magnetization is affected by particle size distribution and anisotropy. • This work is also found to be useful in estimation of particle size distribution. [ABSTRACT FROM AUTHOR]

Abstract The corrosion inhibitive effects of new polyvinylpyrrolidone stabilized crystalline super-paramagnetic nanoparticles (5–20 nm) were investigated. Several characterization techniques confirmed the high stability of the prepared stabilized nanoparticles in solution. The polarization and EIS measurements showed that the inhibition efficiency increased with increasing concentration of the magnetite nanoparticles. The results obtained from EIS and electrochemical polarization curves are in reasonably good agreement. The obtained results suggest that the prepared stabilized system is an excellent inhibitor for carbon steel corrosion in 1 M HCl solution. [ABSTRACT FROM AUTHOR]

Highlights • Cobalt ferrite (CFO) nanoparticles were synthesized by a facile, simple method. • High quality and cubic symmetry of CFO NPs is demonstrated in all the studies. • Surface/interface controlled structure induces giant magnetic parameters. • Co NPs exhibit the mild anti-proliferative character with no cytotoxicity. • Biocompatibility and safety towards the normal cells is demonstrated. Abstract High quality, crystalline, well-dispersed, and stable magnetic oxide nanoparticles (NPs) of inverse spinel cobalt ferrite (CoFe 2 O 4 ; CFO) were prepared by a facile, reproducible, and simple hydrothermal route. The transmission electron microscopy, small-angle scattering and X-ray diffraction analyses demonstrate the structural quality of CFO NPs with a controlled size of ∼12 nm. Small-angle scattering experiments demonstrate that the pristine CFO NPs have the individual size ∼8.5 nm and spherical shape. The Raman and infrared spectroscopic measurements further confirm their high chemical quality and cubic symmetry. CFO NPs exhibit a remarkable, maximum coercivity (H C) value of 18.92 kOe, which is the highest value achieved to date. Surface spins and spins canting along with a weak dipolar interaction accounts for the giant H C and large effective anisotropy (11.45 × 106 erg/cm3) of these CFO NPs. The magnetic grain size of NPs reveals that the canted surface spins exist around the magnetic particles. Reorientation of surface spins and interparticle interaction causes the jumping behaviour in M-H hysteresis loops at H = 0. The cell viability of CFO NPs against the cancer (cisplatin resistant ovarian cancer – A2780/CP70) was evaluated to determine their potential application in biomedicine and health science. The mild response of CFO NPs in terms of their anti-proliferative nature against cancer cells and negligible cytotoxicity suggests their human-safe-and-friendly nature which makes them suitable for biomedical/health-related applications. Assessment of toxicity toward human red blood cells (RBC) revealed that hemolysis is less than 5% compared to the positive control confirming the potential applications of CFO NPs targeting human cells and making relevant for adopting them in biomedicine. [ABSTRACT FROM AUTHOR]

Graphical abstract The synthesis and crystal structure of seven-, six- and eight-coordinated MnII complexes is reported. Electron Paramagnetic Resonance Spectroscopy in combination with Density Functional Theory calculations is performed in order to determine the Zero Field Splitting (ZFS) parameters. We verify that the ZFS parameters in seven- and six-coordinated complexes are comparable. Abstract The reactions of Mn(NO 3) 2 ·4H 2 O with the heterocyclic aromatic ligands 2,3,5,6-tetrakis(2-pyridyl)pyrazine (tppz), 2,4,6-tri(2-pyridyl)-1,3,5-triazine (tptz) and 2,6-bis(pyrazol-1-yl)pyridine (bppy) in MeOH gave the cationic complexes [Mn(L)(NO 3)(MeOH) 2 ](NO 3) (L = tppz (1), tptz (3), bppy (5)) and the neutral complexes [Mn(L)(NO 3) 2 (S)] (L = tppz, S = H 2 O (2); L = tptz, S = MeOH (4); L = bppy, S = MeOH (6)), all of which contain the MnII ion in the rare seven-coordinate pentagonal bipyramidal geometry (the crystal structure of 6 contains also a MnII complex showing the rare eight-coordinate triangular dodecahedron geometry). The reactions of Mn(ClO 4) 2 ·6H 2 O with tptz and bppy in MeCN gave [Mn(tptz)(H 2 O) 2 (MeCN)](ClO 4) 2 (7) and [Mn(bppy) 2 ](ClO 4) 2 (8), in which the MnII ion exhibits six-coordination. Electron Paramagnetic Resonance spectroscopy at X- and Q-band on powder samples was used in order to determine the zero field splitting (ZFS) parameters for 1 – 4 and 7 , 8. All complexes exhibit ZFS parameter, | D | in the range 0.08–0.11 cm−1. The experimentally determined values are in agreement with theoretical calculations which reveal the contribution of each mechanism responsible for the ZFS interaction. The present results add further evidence that for seven-coordinated MnII complexes comprising N/O ligands ZFS is comparable to this found in six-coordinated MnII complexes. [ABSTRACT FROM AUTHOR]

Abstract This article comprises of the structural, magnetic, magneto-caloric and critical behavior study of single phase perovskite manganite LaMnO 3+δ sample synthesized by traditional Solid State route. X-ray powder diffraction (XRD) at room temperature indicates the single phase trigonal crystalline structure of LaMnO 3+δ with hexagonal setting R 3 ‾ c. Magnetic, magnetocaloric and critical behavior are studied using temperature dependent magnetization (M−T) and applied magnetic field dependent magnetization (M−H) data probed by Physical Property Measurement System (PPMS). The second order ferromagnetic to paramagnetic (FM-PM) phase transition is observe at Curie temperature (T C ∼ 180 K). This phase transition is responsible for maximum entropy change (Δ S M max ) of 0.451(1) J/kg K at applied magnetic field of 6 Tesla with relative cooling power (RCP) of 54.293(5) J/kg. At T C , the order of magnetic phase transition is examined by employing Modified Arrott plots (MAP), Kouvel Fisher (KF) and simple isotherm analysis technique. The obtained values of critical exponent’s β ≈ 0.365 ± 0.06, γ ≈ 1.14 ± 0.04 and δ ≈ 4.16 ± 0.10 elaborate that the magnetic phase transition coordinated well with the 3D-Heisenberg model at T C ≈ 180 K and are confirmed by scaling equations of state. Similarly the change in magnetic entropy (ΔS M) versus applied magnetic field recorded complies with the power law ΔS = (H)n with n = 0.64 at T C = 180 K. [ABSTRACT FROM AUTHOR]

Abstract Bulk cobalt ferrite, being a hard ferrite, shows high magnetization, high resistivity and high coercivity. If thin films of cobalt ferrite can be deposited at a low enough temperature and if its coercivity can be reduced, cobalt ferrite will make a very good candidate for use as a magnetic core of an integrated inductor in RF-CMOS ICs. Though polycrystalline and epitaxial thin films of cobalt ferrite have been made by various techniques, there are no reports of thin films of superparamagnetic cobalt ferrite. In this work, nanocrystalline cobalt ferrite thin films, which are superparamagnetic as deposited, have been prepared in the solution medium at ∼190 °C, using microwave irradiation. The as-prepared films have a saturation magnetization (M S) of 401 emu/cc and coercivity (H C) of 19 Oe at room temperature for a crystallite size of 2 nm. The cobalt ferrite powder obtained as a by-product during the same process has M S of 50 emu/g and H C of 5 Oe at room temperature, making it superparamagnetic. The as-prepared films were annealed in air at 300 °C for 5 min and 10 min. Annealing for 10 min results in an increase in crystallite size to 36 nm, M S increases from 401 emu/cc to 545 emu/cc, and H C increases from 19 Oe to 860 Oe. The change in magnetic properties can be directly associated with change in the crystallite size and degree of crystallographic inversion, as determined by neutron diffraction and deduced from X-ray photoelectron spectroscopy. [ABSTRACT FROM AUTHOR]

Highlights • A series of Ni 1.5 [Fe(CN) 6 ] x [Cr(CN) 6 ] 1-x ·nH 2 O (x = 0, 0.25, 0.5, 0.75, 1) is studied. • The properties of the materials change in the regular way with the change of x. • The values of MCE varies between 2.4 J·mol−1K−1 and 3.5 J·mol−1K−1 at Δ H = 50 kOe. • MCE and a RPC are comparable to those of the intermetallic materials. • Scaling behaviour of the magnetocaloric effect is discussed. Abstract A comprehensive study of structural, magnetic and magnetocaloric properties in the ternary Prussian blue analogue (PBA) Ni 1.5 [Fe(CN) 6 ] x [Cr(CN) 6 ] 1-x ·nH 2 O (x = 0, 0.25, 0.5, 0.75 and 1) is presented. For all compounds the second-order magnetic phase transition from high temperature paramagnetic to the low temperature ferromagnetic state at the Curie temperature (T c) is observed. We show the possibility of tuning the magnetic and magneto-caloric properties of PBA materials by changing the compositional factor of the metal centres involved in the cyano-bridging. An increase in Fe content leads to increase in the coercive field, whereas the critical temperature decreases from 60 to 22 K. The magnetic entropy change Δ S , as well as the related Relative Cooling Power (RCP), vary with x parameter in the regular way. The highest value of Δ S was observed for sample with x = 1 and was equal to 3.49 J mol−1K−1 under a magnetic field of 50 kOe, whereas the RCP varied from 62 J mol−1 (145.35 J kg−1) to 118 J mol−1 (273.33 J kg−1), when x decreased from 1 to 0. [ABSTRACT FROM AUTHOR]

Highlights • This study investigates the magnetic properties of rutile TiO 2 implanted with cobalt ions. • SPM behavior here is highly anisotropic coupled with magneto-crystalline anisotropy of the Ti 1−x Co x O 2. • The Co nanoclusters possess an easy and hard axis of magnetization. • The M-T variation reveals the prominent role of dipole and inter-cluster exchange interaction. • Highly anisotropic nature of the SPM presents applications in magnetic switching devices. Abstract The present study investigates the magnetic properties of single crystal rutile TiO 2 (110) implanted with cobalt ions for fluences between 5 × 1016 and 1 × 1017 ions/cm2 with energy of 200 keV. The temperature and field dependent magnetization for magnetic fields along [0 0 1] and [ 1 1 ¯ 0 ] directions of the as implanted TiO 2 crystals show anisotropic super-paramagnetic behaviour due to formation of Co (hcp) nano-clusters unlike the complete ferromagnetic behaviour from previous reports. The ZFC and FC magnetization curves show a much higher blocking temperature ( T B ) along [ 1 1 ¯ 0 ] with values ranging from 30 to 150 K, while for field along [0 0 1] shows a lower T B ranging from 8 to 70 K. The magnetization isotherms above T B show a sharper rise and universal scaling behaviour, for field along [ 1 1 ¯ 0 ] direction. At 2 K, M - H curves show hysteresis behaviour similar of easy and hard axis of a ferromagnet. The magnetic anisotropy of Co nano clusters are coupled by the magneto crystalline anisotropy of secondary phases of cobalt with TiO 2 , thus indicating the highly oriented nature of the Co clusters. Role of dipole interactions and inter cluster exchange interactions have also been discussed. [ABSTRACT FROM AUTHOR]

Graphical abstract Four tetracoordinate Ni(II) complexes have been prepared, structurally characterized, and subjected to magnetometric studies. The complexes [Ni(PPh 3) 2 (NCS) 2 ], [Ni(dppp)(NCS) 2 ], and [Ni(dppm)Br 2 ] are planar and thus diamagnetic. The complex [Ni(biqu)Br 2 ] is pseudotetrahedral, with the geometry close to C 2v symmetry, and paramagnetic. Highlights • Four tetracoordinate Ni(II) complexes have been prepared. • Three complexes are planar and diamagnetic. • One complex is pseudotetrahedral and paramagnetic. • It exhibits a ZFS of the ground term described by D and E parameters. • The GCFT and ab initio calculations confirm this interpretation. Abstract Four tetracoordinate Ni(II) complexes have been prepared, structurally characterized, and subjected to magnetometric studies. The complexes [Ni(PPh 3) 2 (NCS) 2 ], [Ni(dppp)(NCS) 2 ], and [Ni(dppm)Br 2 ] are planar and thus diamagnetic. The complex [Ni(biqu)Br 2 ] is quasi-tetrahedral, with the geometry close to C 2v symmetry, and paramagnetic. While on one side it resembles a prolate bisphenoid (the angle N-Ni-N = 83 deg), on the second side it mimics an oblate bisphenoid (Br-Ni-Br = 126 deg). It exhibits a zero-field splitting of the ground term 3A 2 into three crystal-field multiplets that can be described by D and E parameters within the spin Hamiltonian formalism. The ab initio calculations confirm this interpretation; however, the evaluation of the spin-Hamiltonian parameters meets difficulties owing to the quasi-degeneracy of the electronic terms. [ABSTRACT FROM AUTHOR]

Abstract Cobalt ferrite particles with homogeneous microstructure have been prepared encased in MCM-41 (Mobil Composition Matter) and SBA-15 (Santa Barbara Amorphous) silica mesoporous structures. In addition, it was possible to obtain ferrite nanowires once the silica matrix was dissolved. The variety of samples prepared has allowed to deeply analyze the matrix effect in the magnetic behavior of these particles that behave as superparamagnetic at room temperature. It was found at 5 K, a drastic magnetic hardening of the encased ferrite particles due to the employment of such matrices, while no matrix effect was observed at 250 K. Highlights • Cobalt ferrite nanoparticles encased in silica matrix. • Cobalt ferrite nanowires obtained by dissolving the silica matrix. • Magnetic behavior depending on the surrounding medium. • Superparamagnetism above room temperature. [ABSTRACT FROM AUTHOR]

Abstract The MAB phases are ternary, atomically laminated compounds that crystallize with orthorhombic structures and consist of transition metal (M) boride sublattices interleaved with single or double layers of Al. To date, the magnetic properties of ferromagnetic Fe 2 AlB 2 have been well-studied experimentally, but those of most end member MAB phases with other transition metals remain poorly understood. Herein, predominantly single-phase Cr 3 AlB 4 and Cr 2 AlB 2 powders, with minor amounts of CrB impurities, were synthesized by heating mixtures of chromium monoboride (CrB), aluminum (Al), and boron or CrB and Al under flowing Ar. These reactants were found to substantially suppress the formation of undesired phases in the Cr-Al-B system. The magnetic properties of Cr 3 AlB 4 , Cr 2 AlB 2 and CrB powders were characterized. All compounds exhibit paramagnetic behavior down to 4 K, with susceptibilities that are quite weakly temperature dependent at higher temperatures and a Curie-Weiss-like component prominent at low temperatures. Magnetization isotherms of the three compounds, showed approximately linear behavior above 5 kOe and no saturation of the magnetic moment up to 40 kOe, which is consistent with paramagnetism. The magnitude of the magnetic moments showed little variation with composition, on a per Cr atom basis. While the exact nature of the Curie-Weiss component is not entirely clear, we tentatively attribute it to dilute extrinsic impurities. Highlights • Cr 2 AlB 2 and Cr 3 AlB 4 are synthesized as predominantly single-phase powders. • Magnetization and heat capacity studies suggest Pauli-like paramagnetic behavior. • STEM imaging shows atomic structure and defects in Cr 3 AlB 4 for the first time. [ABSTRACT FROM AUTHOR]

Permanent magnet materials based on the MM 2 Fe 14 B (MM = Misch-metal) are widely noted. However, as a room temperature paramagnetic phase, the existence of CeFe 2 phase in MM 2 Fe 14 B alloy is unavoidable. In order to eliminate the CeFe 2 phase, the La substitution on MM in MM 2 Fe 14 B alloys was described. Alloys with nominal composition of (La x MM 1−x ) 33 Fe 66 B (x = 0, 0.025, 0.05, 0.075, 0.1, 0.15) were prepared, and the crystal structure and magnetization of the (La x MM 1−x ) 33 Fe 66 B alloys were investigated. XRD results reveal that the lattice parameter a, c, unit-cell volume V, and c/a ratio of (La x MM 1−x ) 33 Fe 66 B alloys increase linearly with the La increase, indicating that La atoms enter into the main phase. Key to this study is the finding that CeFe 2 phase disappears with the La content above 0.075. It is therefore concluded that La substitution could inhibit formation of CeFe 2 phase. This is consistent with the observation from SEM-EDS. Another interesting finding is that La substitution would cause the change of Nd, Pr, La and Ce ratio in main phase, which means the ratios of four rare earth elements change with the La substitution. With the increase of x, the (Pr + Nd)/(La + Ce) ratio in main phase of (La x MM 1−x ) 33 Fe 66 B alloys decreases first, showing the lowest point at x = 0.075, and then increases. As a result, the saturation magnetization (M s ) of (La x MM 1−x ) 33 Fe 66 B alloys has the same tendency, which decreases from 11.78 kG (x = 0) to 11.35 kG (x = 0.075) first, and then increases to 11.96 kG (x = 0.15). And the Curie temperature (T c ) displays the same trend compared to the M s . These facts show that the MM has a great potential to prepare the low cost sintered permanent magnets. [ABSTRACT FROM AUTHOR]

Using an efficient first-principles computational scheme, we calculate the intrinsic stacking fault energy ( γ i s f ) and the unstable stacking fault energy ( γ u s f ) of paramagnetic γ -Fe as a function of temperature. The formation energies are derived from free energies accounting for thermal longitudinal spin fluctuations (LSFs). LSFs are demonstrated to be important for the accurate description of the temperature-dependent magnetism, intrinsic and unstable stacking fault energies, and have a comparatively large effect on γ i s f of γ -Fe. Dominated by the magneto-volume coupling at thermal excitations, γ i s f of γ -Fe exhibits a positive correlation with temperature, while γ u s f declines with increasing temperature. The predicted stacking fault energy of γ -Fe is negative at static condition, crosses zero around 540 K, and reaches 71.0 mJ m −2  at 1373 K, which is in good agreement with the experimental value. According to the plasticity theory formulated in terms of the intrinsic and unstable stacking fault energies, twinning remains a possible deformation mode even at elevated temperatures. Both the large positive temperature slope of γ i s f and the predicted high-temperature twinning are observed in the case of austenitic stainless steels. [ABSTRACT FROM AUTHOR]

Abstract Coulomb interactions replicates in N (N − 1)∕2 terms for interacting 3-D N − e confined quantum dots leading to non-trivial Schr ö dinger equations. For the systems having N > 3, e − e interaction reciprocating to both lateral (electrical) and transverse (magnetic) confinements in moderate fields causes acute interplay in anisotropic quantum dots. As DFT, Hartree-Fock and other perturbative methods have certain limitations, recasting Schr ö dinger equations into self-adjoint Whittaker- M functions addresses coulomb (exchange) integrals as simplest, finite and single-summed analytical Lauricella functions (F 2) via Chu-Vandermonde identity. In case of higher ′ N ′, expansion of coulomb correlations in terms of multi-pole expansion facilitates the convergences for bound states upto quadrapole and octopole terms. Although, fermionic exchange symmetry of many electron systems could be included in terms of various two-electron integrals, for the sake of brevity we have aimed to reproduce experimental results without spin. Level clustering/accidential degeneracies manifest on energy level spectra due to competitive role among anisotropic confinement strength, magnetic field, mass of the carrier and dielectric constant of the medium. It triggers orbital induced paramagnetism (T ∼ (0 − 1) K), signature of fractional quantum Hall effect (FQHE) in chemical potential cusps (μ) and formation of different ′shell structures′ in capacitive energy respectively, spanning over wide dielectric range of materials (atomic like quantum dots, ZnO , GaAs and PbSe (Lead Chalcogenide) etc). Graphical abstract Image 1 Highlights • Non-triviality of N -e (N = 2,3,4,5,…) Schr ö dinger equation is exactly elucidated by recasting the Hamiltonian of 3-D N -e anisotropic dot in Whittaker- M function. • Coulomb interaction is shaped using multipole expansion into simple nite single-summed Lauricella function for all bound states. • Level clustering manifest on energy level spectra due to anisotropy and coulombinteraction. • Orbital induced paramagnetism seen due to anisotropy. • Formation of shell structure with magic number N = 2,6,12.., is observed in spherical GaAs dot which gets deformed in presence of anisotropy in ellipsodial dot. [ABSTRACT FROM AUTHOR]

Abstract A novel method for synthesis of diamagnetic Ru(II) carborane clusters based on reduction of corresponding Ru(III) species by amines was developed. The interaction of paramagnetic 17-electron complex ( 1 ) with aliphatic amines in dichloromethane solution at 40 °C proceeds with the abstraction of chlorine atom from the ruthenium center and results in formation of corresponding 16-electron species. The latter can be stabilized by 2-electron ligands such as triphenylphosphine or acetonitrile through the formation of novel stable complexes of ruthenium (II): ( 2 : L = PPh 3 ; 4 : L = CH 3 CN). A bis( ortho- phenylene)cycloboronated complex ( 6 ) may be obtained in a similar way from corresponding precursor. The related reaction conducted with diamagnetic closo- carborane cluster of ruthenium (IV) 3,3-Ph 2 P(CH 2 ) 4 PPh 2 -3-H-3-Cl- closo -3,1,2-RuC 2 B 9 H 11 ] ( 7 ) gives 3-CH 3 CN-3,3-Ph 2 P(CH 2 ) 4 PPh 2 - closo -3,1,2-RuC 2 B 9 H 11 ] ( 8 ). The obtained complexes were characterized by means of NMR and IR spectroscopy and mass spectrometry. A single-crystal X-ray diffraction study confirmed closo- structure of the obtained complexes and the presence of acetonitrile molecule as a ligand. The performed electrochemical investigation of the obtained ruthenacarboranes testified its ability to undergo reversible oxidation to Ru(III) species. The comparison of the properties of the obtained complex 2 with its analogue with shorter alkyl fragment in diphosphine moiety shows that the slight difference in the structure leads to the decrease of stability. Graphical abstract Image 1 Highlights • Ruthenium (III) and (IV) complexes were reduced to Ru (II) species by aliphatic amines. • Stable carborane complexes of Ru(II) with nitrile ligands were obtained. • The dependence of complex stability on diphosphine bite angle is discussed. [ABSTRACT FROM AUTHOR]

Abstract We demonstrate that a ferronematic (a dilute suspension of ferromagnet nanoparticles in a nematogenic matrix) may display a direct analog of Néel superparamagnetism entailed by the orienting effect of the matrix on the embedded particles. The latter are assumed to be the objects with pronounced anisometricity; in magnetic aspect, they are single-domains with strong magnetic hardness (e.g. imposed by their rod-like shape) so that the magnetic moment is fixed inside the particle body. Above the isotropic–nematic transition point, the considered system is just a ferrofluid with random distribution of the particle axes. Below the transition, the particle–matrix coupling emerges that sets the axis of each particle (and, hence, its magnetic moment) under the same angle to the director. If this alignment is along the director, then each particle falls under the action of orientational potential with two equal wells (0° and 180°) separated by the energy barrier whose height is defined by the intensity of the surface particle–matrix interaction. Provided the thermal energy is of the order of the barrier height (the material estimates readily admit that), the Brownian motion makes the particle to randomly rotate between the orientational minima. This mechanism entails spontaneous inversions of the magnetic moment as well, thus ensuring relaxation of any initially established magnetization of the ferronematic; the reference time of this process depends exponentially on the hight of the energy barrier scaled with thermal energy. Treating the nematogenic matrix with the aid of mean field model and using the linear response theory to describe the magnetodynamics of the particles, we show that the "liquid-crystalline" superparamagnetism produces an easily identifiable signature in the dynamic magnetic susceptibility spectrum of a ferronematic. Highlights • Ferronematics are nematic matrices loaded with magnetic nanoparticles (MNPs). • Interactions at the particle–matrix interface establish their orientational coupling. • Thermal fluctuations induce spontaneous magnetic "switching" of anisometric MNPs. • This mechanism establishes in ferronematics an analog of Néel superparamagnetism. • The effect manifests itself in the frequency spectrum of the magnetic susceptibility. [ABSTRACT FROM AUTHOR]

Cobalt ferrite (CF) – Graphene oxide (GO) composite was synthesized using an in-situ chemical co-precipitation method at 27 °C. The combined effect of inorganic spinnel ferrite with an organic GO enhanced the magnetodielectric (MD) properties to a greater extend. A maximum dielectric constant of 1.12 × 10 8 and a capacitance of 37.27 × 10 −6  F at a frequency of 100 Hz with an applied magnetic field of 0.9 T, was achieved. The coupling mechanism between electric polarization and intrinsic magnetisation of the composite gave rise to MD effect. The incorporation of GO in CF, reduces the particle size of it, which resulted in the transition between the ferromagnetic to superparamagnetic nature. The high MD property of CF-GO enables its potential usage not only as a superstrate material in antenna miniaturization but also in flexible memory devices, electronic systems, spintronics and data storage. [ABSTRACT FROM AUTHOR]

The search for materials that can bear the increasingly abrupt conditions imposed to electronic devices in computers and other systems has intensified. Materials that are sensitive to variations in magnetic fields and resistant to sharp variations in temperature are desirable. To achieve such materials, several sample preparation methods have been employed. Most of these methods rely on the mechanical systems of mixtures and usually require significant discharge temperatures. In particular, the sol-gel method is quite promising because it allows for direct control of the structure and morphology of the material in all stages of the synthetic procedure. In this study, we have doped a titanium oxide matrix with manganese chloride, which afforded a material with a paramagnetic phase. Results from our investigation into the relationship between magnetic susceptibility and temperature, obtained from measurements in a superconducting quantum interferometer device (SQUID), pointed to the great sensitivity of the prepared material to low-intensity magnetic fields for temperature. [ABSTRACT FROM AUTHOR]

The colloidal nanoparticles Fe m O n –SiO 2 have been obtained using the sol–gel method. Based on the data obtained with transmission electron microscopy and dynamic light scattering, a lognormal size distribution of nanoparticles with an average size of 20–30 nm have been constructed. The shape of Mössbauer spectra implies that they have the characteristic relaxation time of the order of 10 –9 –10 –10  s that corresponds to the grain size of about 10 nm. X-ray diffractometry indicates that the crystalline phase of the particles is magnetite. Hysteresis loops have been traced with a vibration sample magnetometer and the demagnetization curve of anhysteretic remanent magnetization measured with a SQUID magnetometer. Theoretical analysis of magnetization data based on a model of magnetostatically interacting superparamagnetic nanoparticles confirms the presence of both separate superparamagnetic magnetite particles (less than 20 nm in size) and those organized into clusters with an average size of about 30 nm. [ABSTRACT FROM AUTHOR]

In this work, we develop a specifically engineered variant of carbonized melamine foam (cMF) by carrying systematic structural modifications with Au nanoparticles, graphene (G), Fe 3 O 4 (IO) and poly(dimethyl siloxane) (PDMS). Our main goal is to construct a lightweight and flexible cMF composite with tailored 3D hierarchical architecture for achieving high-efficiency in electromagnetic interference (EMI) shielding. By capitalizing on the synergistic effect of the multifunctional components in the fabrication of the typical closed-cell structure, cMF-Au-G-IO/PDMS composite produced herein demonstrates superior physical properties including low density (116 mg/cm 3 ), high conductivity (81.3 S/m), large specific surface area (708 m 2 /g), proven superparamagnetism (Ms = 22.6 emu/g), and moderate compressive strength (110 KPa), collectively leading to the significant attenuation effect towards EMI. The cumulative EMI shielding effectiveness (SE) of cMF-Au-G-IO/PDMS film with a thickness of 2 mm is determined as 30.5 dB in X band (8.2–12.4 GHz). Interestingly, SE is further raised up to 52.5 dB when the film thickness is increased to 10 mm. Hence, we envision the emergence of multifunctional cMF-based composite as a promising engineering system for fulfilling the demanding applications in EMI shielding. [ABSTRACT FROM AUTHOR]

Fe 3 O 4 magnetic nanoparticles (MNPs) were prepared using the modified green synthesis method and the effects of reaction time on the structural and magnetic properties of MNPs were evaluated. For the synthesis of MNPs, green tea extract and ethylene glycol were used as a reducing agent and solvent, respectively. The MNPs were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), thermogravimetric analysis and vibrating sample magnetometer. It was observed that the reaction time strongly influenced the magnetic and structural properties. With increasing reaction time, the crystallite size was found to be increased from 7.5 to 12 nm along with improvement in saturation magnetization (M S ). The magnetic measurement study revealed that MNPs were superparamagnetic at room temperature, while at 60 K they have ferromagnetic as well as superparamagnetic contributions. The effect of an increase in particle size with reaction time was also reflected with an increase in blocking temperature, which is consistent with the Stoner–Wohlfarth theory. [ABSTRACT FROM AUTHOR]

The idea of preparing electromagnetic wave absorption cement-based composite using nano-Fe 3 O 4 magnetic fluid as electromagnetic wave absorber is proposed. Nano-Fe 3 O 4 magnetic fluid with obvious superparamagnetism is synthesized based on the co-precipitation method. When 5% nano-Fe 3 O 4 magnetic fluid is added into cement, the composite prepared shows excellent electromagnetic wave absorption properties, e.g. the absorption bandwidth with reflection loss lower than −10 dB and lower than −15 dB is about 9.5 GHz and 6.3 GHz respectively, much better than that of the composite prepared with nano-Fe 3 O 4 powder and bulk Fe 3 O 4 powder. As well, nano-Fe 3 O 4 magnetic fluid accelerates the early hydration of cement and improves its early age compressive strength obviously. Due to the advantages of easy processing, cheap cost, non-toxic and high electromagnetic wave absorption, cement-based composite prepared with nano-Fe 3 O 4 magnetic fluid shows the huge potential application in construction of electromagnetic wave interference shielding buildings. [ABSTRACT FROM AUTHOR]

A series of paramagnetic ionic liquids (PILs) based on N , N ′-bis(alkyl)imidazolium bromotrichloroferrate(III), [(C n ) 2 Im][FeCl 3 Br] (Im = imidazole; C n  = ethyl, butyl, hexyl, octyl, decyl, dodecyl), was prepared and compared against the more traditional [C n C 1 Im][FeCl 3 Br] (C 1  = methyl) analogs. Both series were extensively characterized by physical, chemical, and computational methods including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), spectroscopy (FTIR and UV‐vis-NIR), magnetic susceptibility, surface tensiometry, density, and viscosity. The X-ray crystal structure of [(C 12 ) 2 Im][FeCl 3 Br] was also obtained. Notably, all ionic liquids prepared in this study show short-term thermal stabilities exceeding 300 °C in air and have melting points equal to or lower than 25 °C, which is surprisingly low for ionic liquids containing symmetrical cations. In addition, all presented ionic liquids have relatively low viscosities allowing for easier transitioning into applications. Physical property trends are discussed. [ABSTRACT FROM AUTHOR]

Antiphase boundaries (APBs) are crucial to understand the anomalous temperature dependence of the yield stress of Ni 3 Al. However, the required, accurate prediction of temperature-dependent APB energies has been missing. In particular, the impact of magnetism at elevated temperatures has been mostly neglected, based on the argument that Ni 3 Al is a weak ferromagnet. Here, we show that this is an inappropriate assumption and that – in addition to anharmonic and electronic excitations – thermally-induced magnetic spin fluctuations strongly affect the APB energies, especially for the (100)APB with an increase of nearly up to 40% over the nonmagnetic data. We utilize an ab initio framework that incorporates explicit lattice vibrations, electronic excitations, and the impact of magnetic excitations up to the melting temperature. Our results prompt to take full account of thermally-induced spin fluctuations even for weak itinerant ferromagnetic materials. Consequences for large-scale modeling in Ni-based superalloys, e.g., of dislocations or the elastic–plastic behavior, can be expected. [Display omitted] [ABSTRACT FROM AUTHOR]

Many proteins naturally carry metal centers, with a large share of them being in the active sites of several enzymes. Paramagnetic effects are a powerful source of structural information and, therefore, if the native metal is paramagnetic, or it can be functionally substituted with a paramagnetic one, paramagnetic effects can be used to study the metal sites, as well as the overall structure of the protein. One notable example is cobalt(II) substitution for zinc(II) in carbonic anhydrase. In this manuscript we investigate the effects of sodium thiocyanate on the chemical environment of the metal ion of the human carbonic anhydrase II. The electron paramagnetic resonance (EPR) titration of the cobalt(II) protein with thiocyanate shows that the EPR spectrum changes from A-type to C-type on passing from 1:1 to 1:1000-fold ligand excess. This indicates the occurrence of a change in the electronic structure, which may reflect a sizable change in the metal coordination environment in turn caused by a modification of the frozen solvent glass. However, paramagnetic nuclear magnetic resonance (NMR) data indicate that the metal coordination cage remains unperturbed even in 1:1000-fold ligand excess. This result proves that the C-type EPR spectrum observed at large ligand concentration should be ascribed to the low temperature at which EPR measurements are performed, which impacts on the structure of the protein when it is destabilized by a high concentration of a chaotropic agent. Paramagnetic nuclear magnetic resonance (NMR) is very sensitive to the coordination environment of a paramagnetic metal ion, and it is used here to monitor the effects of sodium thiocyanate at different concentrations on the metal coordination geometry of the cobalt-substituted human carbonic anhydrase II. [Display omitted] • SCN− affects differently NMR and EPR spectra of cobalt(II)‑carbonic anhydrase II. • 1:1 SCN−:protein ratios strongly affect the NMR spectra; excess SCN− has minor effect. • 1:1 SCN−:protein ratios weakly affect the EPR spectra; excess SCN− has major effects. • Circular dichroism and 15N relaxation show weak effect of excess SCN− on protein stability. [ABSTRACT FROM AUTHOR]

The efficient removal of Cr(VI) in water with high solubility and mobility is of great significance because Cr(VI) is one of the most toxic heavy metals, but it also faces some major challenges. The dispersibility and recyclability of nanoadsorbents are closely related to their Cr(VI) removal efficiency. Herein, the self-assembly method was used to synthesize core-shell hybrid nanoparticles, named Fe 3 O 4 @LDH, with a vertically aligned layered double hydroxide (MgAl-LDH) nanosheet shell and a Fe 3 O 4 magnetite core. The obtained Fe 3 O 4 @LDH nanoparticles exhibit a highly porous and well-ordered three-dimensional core-shell structure with a wool-ball-like morphology. The self-assembled morphology of the core-shell structure can be effectively controlled and induced by regulating the Mg2+/Al3+ ratio of the reaction system. The influence mechanism of charge density of LDH brucite-like layers on the self-assembled morphology was proposed. Fe 3 O 4 @LDH nanoparticles exhibit a Cr(VI) adsorption capacity of 108.7 mg/g. The synergetic contribution of the hybrid self-assembly of Fe 3 O 4 and MgAl-LDH leads to more dispersion, better adsorption capability, and faster kinetics. Moreover, because of the super-paramagnetic and highly saturated magnetization (34.53 emu/g) of the Fe 3 O 4 @LDH nanoparticles, they can be used as efficient magnetic adsorbents and easily separated using a magnetic field and reused. The prepared Fe 3 O 4 @LDH nanoparticles are a cost-effective nanoadsorbent for removing Cr(VI) from wastewater and provide a reference for the structural design and construction of nanocomposites. [Display omitted] • Self-assembled 3D hierarchical wool-ball-like Fe 3 O 4 @LDH composite was prepared. • Fe 3 O 4 @LDH exhibits highly porous structure and large specific surface area. • Fe 3 O 4 @LDH has excellent and rapid adsorption capability toward Cr(VI). • Fe 3 O 4 @LDH with superparamagnetism is simple to separate and reuse. [ABSTRACT FROM AUTHOR]

Water-dispersible Mn 2+ -doped Ag 2 Se QDs were synthesized by solvothermal reaction of silver and manganese salts with selenium source and subsequent ligand exchange. The Mn doping level could be tuned by changing the feed amount of the Mn precursor. The Mn 2+ -doped Ag 2 Se QDs had a crystal structure typical of monoclinic α -Ag 2 Se. At the Mn doping level of 0.28%, the photoluminescence quantum yield at 1130 nm remained at 5.7%. Moreover, EPR spectrum and VSM result suggest paramagnetic characteristics of the 0.28% doped QDs. Cytotoxicity test indicates good biocompatibility of the Mn 2+ -doped Ag 2 Se QDs, which have great potential for biomedical imaging. [ABSTRACT FROM AUTHOR]

Cobalt ferrite nanoparticles were synthetized by co-precipitation technique from nitrate precursors. X-ray diffraction confirms the formation of the spinel ferrite. SEM and HRTEM micrographs corroborate the formation of agglomerated nanoparticles of 8–35 nm size range with 21.7 nm average size. The broad size distribution and considerable agglomeration of the particles hamper the superparamagnetic state of the sample, provoking a weak coercivity at room temperature. In contrast to several other magnetic nanostructures, the ZFC-FC curves of cobalt-ferrite nanoparticles revealed an unusually large magnetostriction, evidenced by larger values of magnetization in their ZFC curves than the FC curves in the measured temperature range 20–375 K. The behavior could be reversed on applying high magnetic fields. However, the maximum of ZFC curve reduces on increasing the applied magnetic field. [ABSTRACT FROM AUTHOR]

Nanocrystalline GdFeO 3 and Gd 3 Fe 5 O 12 powders were prepared successfully by sol–gel auto-combustion method using a glycine-based gel. The as-prepared GdFeO 3 and Gd 3 Fe 5 O 12 powders presented spherical shape, and composed of continuous porous network structure due to the releasing of a large amount of gases during auto-combustion process. This special microstructure was significant for reducing the magnetic interactions between nanocrystalline powders. The Gd 3 Fe 5 O 12 samples presented ferrimagnetic feature at low temperatures. At 10 K, the saturate magnetization is about 87.9 emu/g. As temperature increased to 300 K, the magnetization decreased rapidly since the thermal fluctuations changed the main magnetic spin ordering. The GdFeO 3 samples presented antiferromagnetic feature at 5 K, and the magnetization reaches 109 emu/g at 50,000 Oe field. As temperature increased to 300 K, the antiferromagnetism decreased rapidly, and the magnetization curve presents linear tendency due to the dominant paramagnetism contribution of Gd 3+ ions. [ABSTRACT FROM AUTHOR]

Cerium dioxide clearly raises the question of whether spontaneous ferromagnetic order is possible at high temperatures without d- electrons. There are many reports in the literature of a ferromagnetic-like response to an applied magnetic field at room temperature for bulk, nanocrystalline or thin film samples, with or without cation doping. Typical values of the saturation magnetization are very small, of order 0.1 kAm −1 , but reports range from zero up to 1000 kAm −1 . The effect is somehow related to lattice defects – Ce 3 + cations or oxygen vacancies – but it is a challenge to understand how electrons associated with these defects could order ferromagnetically at room temperature and above. Straightforward impurity effects are considered, and models based on conventional ferromagnetic superexchange or double exchange are discussed, as is exchange splitting of the 4 f band or a defect-related impurity band. Results are also compared with a new model of athermal giant orbital paramagnetism that involves no spontaneous ferromagnetic order. A key issue is the fraction, if any, of the volume of the CeO 2 samples that is spontaneously ferromagnetic. Detailed analysis of the magnetic properties suggests that the conventional explanations of the magnetism of CeO 2 are untenable, and directions for further research are suggested. [ABSTRACT FROM AUTHOR]

In this paper, by considering a biased random walker hopping on a one-dimensional lattice with a ring geometry, we investigate the fluctuations of the speed of the random walker. We assume that the lattice is heterogeneous i.e. the hopping rate of the random walker between the first and the last lattice sites is different from the hopping rate of the random walker between the other links of the lattice. Assuming that the average speed of the random walker in the steady-state is v ∗ , we have been able to find the unconditional effective dynamics of the random walker where the absolute value of the average speed of the random walker is − v ∗ . Using a perturbative method in the large system-size limit, we have also been able to show that the effective hopping rates of the random walker near the defective link are highly site-dependent. [ABSTRACT FROM AUTHOR]

A new intermetallic compound, ternary antimonide Eu 7 Cu 44 Sb 23-δ [ Fm -3m, a  = 17.4346(1)Å, δ = 0.5(1)] is reported. The compound forms a continuous substitutional solid solution with its Eu 7 Cu 44 As 23 archetype. The gradual substitution of Sb for As evokes partial disorder in the copper–pnictogen framework that becomes more pronounced with an increase of the Sb content and changes magnetic properties. Whereas Eu 7 Cu 44 As 23 is metallic ferromagnet below 17 K, Eu 7 Cu 44 Sb 23-δ shows paramagnetic behavior down to 1.8 K according to the magnetic measurements, while retaining metallic properties according to the DFT calculations. The origin of the disorder, the structure-property relationships, as well as prospects of further substitution in the anionic sublattice are discussed. [ABSTRACT FROM AUTHOR]

In the present work, we have studied the magnetic properties of magnetic bilayer Kekulene structure with mixed spin-5/2 and spin-2 Ising model using Monte Carlo study. The magnetic phase diagrams of mixed spins Ising model have been given. The thermal total, partial magnetization and magnetic susceptibilities of the mixed spin-5/2 and spin-2 Ising model on a magnetic bilayer Kekulene structure are obtained. The transition temperature has been deduced. The effect of crystal field and exchange interactions on the this bilayers has been studied. The partial and total magnetic hysteresis cycles of the mixed spin-5/2 and spin-2 Ising model on a magnetic bilayer Kekulene structure have been given. The superparamagnetism behavior is observed in magnetic bilayer Kekulene structure. The magnetic coercive field decreases with increasing the exchange interactions between σ-σ and temperatures values and increases with increasing the absolute value of exchange interactions between σ-S. The multiple hysteresis behavior appears. [ABSTRACT FROM AUTHOR]

Ce 1-x In x O 2 (x = 0.0, 0.02, 0.04, 0.06, 0.10 and 0.15) nanoparticles have been successfully synthesized by sol gel method using citric acid as a gelling agent. The gel obtained was characterised using DG-DTA analysis. The XRD confirmed the fluorite phase formation and purity of the compounds. Morphological studies revealed the flaky and porous nature as seen from SEM images. TEM showed that the average particle size obtained is less than 20 nm. The existence of Ce 3+ /Ce +4 oxidation states is confirmed from XPS data which in turn results in the oxygen deficiency in the system. The Electrical studies displayed the typical semiconductor nature of the nano-particles. The dilute magnetic property has been studied using VSM where the existence of very weak room temperature ferromagnetism is seen in pristine sample which is found to be enhanced on indium doping where for Ce 0.85 In 0.15 O 2 composition showed a super-paramagnetic nature with negligible coercivity (H c ) , in magnetisation v/s field studies. The saturation magnetisation ( M s ) and coercivity (H c ) are further found to be enhanced at 50 K. When compared with the bulk sample the magnetism here was found to be lowered or reduced. This suggests that the oxygen vacancies and defects in the nanostructure are responsible for the observed magnetic behaviour in the prepared compounds. [ABSTRACT FROM AUTHOR]

The distribution of lithium ions in heated synthetic montmorillonites was studied by using 19 F, 7 Li MAS and 7 Li{ 19 F} TEDOR nuclear magnetic resonance technics. To get the best of NMR spectroscopy, Na-montmorillonites, free of paramagnetic centres (Fe 2+ , Fe 3+ ), were synthesized in fluoride medium, in order to have substitution of some hydroxyl groups by fluorine in the octahedral layer (Na 0.35 [(Al 1.69 Mg 0.36 ) VI (Si 3.86 Al 0.14 ) IV O 10 (OH 0.95 F 0.05 ) 2 ]). After Li + exchange, mild heat treatments (from 110 to 250 °C during 24 h) were applied to follow the lithium migration. Both 19 F and 7 Li MAS spectra indicate that the lithium migration operates in two steps: at 110 °C, 86% of the lithium ions have moved to the hexagonal site. The remaining interlayer ions move progressively to this site when the heating temperature is in the range [170–250 °C]. For the first time a direct fluorine–lithium distance of 2.23 Å was measured by 7 Li{ 19 F} TEDOR, which uses fluorine as a highly selective and NMR-sensitive witness of atomic-scale motions inside porous media, and which agrees with the preferred hexagonal site for Li + migration. [ABSTRACT FROM AUTHOR]

Dimeric cytochromes bc are central components of photosynthetic and respiratory electron transport chains. In their catalytic core, four hemes b connect four quinone (Q) binding sites. Two of these sites, Q i sites, reduce quinone to quinol (QH 2 ) in a step-wise reaction, involving a stable semiquinone intermediate (SQ i ). However, the interaction of the SQ i with the adjacent hemes remains largely unexplored. Here, by revealing the existence of two populations of SQ i differing in paramagnetic relaxation, we present a new mechanistic insight into this interaction. Benefiting from a clear separation of these SQ i species in mutants with a changed redox midpoint potential of hemes b , we identified that the fast-relaxing SQ i (SQ iF ) corresponds to the form magnetically coupled with the oxidized heme b H (the heme b adjacent to the Q i site), while the slow-relaxing SQ i (SQ iS ) reflects the form present alongside the reduced (and diamagnetic) heme b H . This so far unreported SQ iF calls for a reinvestigation of the thermodynamic properties of SQ i and the Q i site. The existence of SQ iF in the native enzyme reveals a possibility of an extended electron equilibration within the dimer, involving all four hemes b and both Q i sites. This substantiates the predicted earlier electron transfer acting to sweep the b-chain of reduced hemes b to diminish generation of reactive oxygen species by cytochrome bc 1 . In analogy to the Q i site, we anticipate that the quinone binding sites in other enzymes may contain yet undetected semiquinones which interact magnetically with oxidized hemes upon progress of catalytic reactions. [ABSTRACT FROM AUTHOR]

In this study, nondegradable poly (carbonate urethane) (PCU) and poly (carbonate urethane) incorporated variable Fe 3 O 4 content microspheres (PCU/Fe 3 O 4 ) were synthesized using pre-polymerization and suspension polymerization. Synthesis was confirmed through Fourier transform infrared spectroscopy (FTIR). The effect of Fe 3 O 4 incorporation was investigated on crystalline, thermal, shape memory and degradation properties by X-Ray diffraction (XRD), Differential scanning calorimetery (DSC), compression test and degradation in vitro, respectively. Otherwise, the assessment of magnetic characteristics by vibrational sample magnetometry (VSM) disclosed superparamagnetic behavior. The tunable superparamagnetic behavior depends on the amount of magnetic particles incorporated within the networks. The biological study results of as-synthesized polymers from the platelet adhesion test and the cell proliferation inhibition test indicated they were biocompatible in vitro. Fe 3 O 4 incorporation was conductive to reducing platelet adhesion in blood contacting test and promotion of rat vascular smooth muscle cell proliferation and growth. These nondegradable, superparamagnetic, biocompatible polymers, combined with their good shape memory properties may allow for their future exploitation in the biomedical field, such as, in cardiovascular implants, targeted tumor treatment, tissue engineering and artificial organ's engineering. [ABSTRACT FROM AUTHOR]

One-pot reactions of pre-assigned molar ratios of appropriate metal (II) salts and HL 1 (2-acetylpyridine nicotinoylhydrazone) or HL 2 (2-acetylpyridine isonicotinoylhydrazone) in MeOH solutions at room temperature afford 1D coordination polymeric chain [Cu(μ-L 1 ) (Cl)] n ( 1 ) and a mononuclear complex [Ni(L 2 ) 2 ] ( 2 ). The compounds ( 1) and ( 2 ) were characterized using elemental analyses, spectral and other physicochemical methods. Single crystal X-ray diffraction measurements for ( 1 ) and ( 2 ) have been made to define the molecular aggregates and crystalline architectures. In ( 1 ), each copper (II) center adopts a distorted square pyramidal geometry with a CuN 3 OCl chromophore linked through μ-L 1 to form the 1D polymeric chain. While in ( 2 ) each Ni(II) cation is six-coordinate with octahedral structure having NiN 4 O 2 chromophore containing two L 2 units each functioning as a classical tridentate (N,N,O) chelator. Different weak non-covalent interactions promote dimensionalities in the compounds. A Hirshfeld surface analysis was employed to gain additional insight into interactions responsible for packing of ( 1 ) and ( 2 ). Magnetic susceptibility measurement of (1 ) in the 4–300 K range reveals simple paramagnetism. [ABSTRACT FROM AUTHOR]

Magnetic Fe 3 O 4 /ZnO-CdO/reduced graphene oxide (MFZC/RGO) has been synthesized by simple hydrothermal method. The structure and morphology were investigated by X-ray diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), Diffuse reflectance spectroscopy (DRS), Vibrating sample magnetometer (VSM), Raman and Fourier-transform infrared spectroscopy (FTIR). MFZC/RGO was applied as catalyst in degradation of methylene blue (MB), rhodamin B (RhB) and methylorange (MO) under ultrasonic irradiation. Based on the results, excellent degradation efficiencies of MB, RhB and MO (>99%) were achieved within 10, 20 and 20 min, respectively under oxygen flow. Moreover the catalytic property of MFZC/RGO was investigated in oxidation of styrene, α-methyl styrene, cyclohexene and cyclooctene under oxygen flow. In addition, MFZC/RGO can be easily collected and separated by an external magnet. The catalyst displayed negligible loss in activity and selectivity within several successive runs due to super paramagnetism. [ABSTRACT FROM AUTHOR]

In this work, a new intercalated FeS compound: (C 2 H 8 N 2 ) 0.4 Fe 2 S 2 was synthesized via the solvothermal route. The product is stable in air and shows the micron-sized plate shape. Structure refinement indicates that (C 2 H 8 N 2 ) 0.4 Fe 2 S 2 adopts the I 4/ m space group with the lattice constants a = 3.6906(6) and c = 20.4215(11) Å. The [FeS] layer crystallizes into the anti-fluorite structure with edge-sharing tetrahedrons and the C 2 H 8 N 2 molecules are inserted in between the layers. (C 2 H 8 N 2 ) 0.4 Fe 2 S 2 is the first intercalated FeS compound reported up to now that contains the electroneutral guest layers. This specific feature leads to the paramagnetic behavior without any magnetic transition in the measured temperature range. Furthermore, we find that the ferromagnetic interaction can also be easily induced in this compound by inserting the extra Fe in between the layers, indicating the controllable magnetism of the title compound. The absence of superconductivity in (C 2 H 8 N 2 ) 0.4 Fe 2 S 2 is mainly due to the external pressure on FeS layers induced by En intercalation. [ABSTRACT FROM AUTHOR]

The use of rare earths (RE) as dopant of materials has led the development of advanced materials for many applications such as optical tracers, special alloys, semiconductors, as well as radiation dosimeters. The development of new dosimetric materials based on REs is a great challenge in innovation of materials. Yttria (Y 2 O 3 ) presents luminescent proprieties and is a promising material for radiation dosimetry. The present paper aims to evaluate paramagnetic defects of Y 2 O 3 rods obtained via bio-prototyping by using Electron Paramagnetic Resonance (EPR) technique at room temperature. Ceramic rods were irradiated with gamma doses from 0.001 to 150 kGy and evaluated by EPR at room temperature with X-band EPR. According to EPR results, as sintered samples exhibited an EPR signal with principal g tensor of 2.020 and maximum line width around 2.3 mT, which is ascribed to interstitial oxygen ion. Dose response behaviour exhibited two distinct dose ranges, one is from 1 to 100Gy and the second is from 0.1 to 70 kGy. Thermal annealing approaches reveal that defect centres of yttria decay significantly at high temperature. These innovative results make Y 2 O 3 a promising material for radiation dosimetry. [ABSTRACT FROM AUTHOR]

A series of (Sr 0.6 Ca 0.4 ) (Co y Mn 1-y ) O 3 (0.2 ≤ y ≤ 1.0) ceramic were synthesized by the simple cost effective chemical co-precipitation method. X-ray diffraction analysis show that all samples having orthorhombic crystal structure. Replacement of Mn by Co plays an important role in changing the magnetic properties. The (Sr 0.6 Ca 0.4 ) (Co y Mn 1-y ) O 3 (0.2 ≤ y ≤ 1.0) ceramic shows Paramagnetic to Antiferromagnetic (PM-AFM) transition, at temperature T = 175 K. Negative magnetization is observed for all samples except Co = 1.0. [ABSTRACT FROM AUTHOR]