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(In 1-x Er x) 2 O 3 nanoparticles were synthesized by lyophilization of an aqueous solution of indium and erbium acetates and then applying heat treatments. These nanoparticles were characterized regarding their structural, optical, and magnetic properties over a temperature range of 2–300 K. For x ≤ 0.04, all samples were monophasic, crystallized with cubic structure (Ia-3 space group), and characterized by oxygen vacancies. Er doping reduced the crystallite size and increased the lattice strain. However, no change in energy bandgap was observed after erbium dilution in the oxide matrix. The doped samples were paramagnetic over the entire temperature range, but at low temperatures paramagnetism coexisted with a ferromagnetic phase. The ferromagnetism was attributed to the presence of magnetic polarons acting as mediators of the coupling between the Er3+ ions. The low-temperature segments of the magnetization curves, i.e., M(T< 20 K), were successfully fitted based on the Bound Magnetic Polaron model. [Display omitted] • In2-xErxO3 monophasic NPs were successfully synthesized by lyophilization and heat treatments. • The semiconductor In2O3 was for the first doped with a HRE and the solubility limit for Er was 4%at. • Er doping decreased particle size, increased strain, and did not change the semiconductor bandgap. • In2-xErxO3 is PM at and below RT but a FM phase appears at T < 20 K. • The FM phase is due to bound magnetic polarons formed by Er3+ cations. [ABSTRACT FROM AUTHOR]

Iron-gallium borate, Fe x Ga 1− x BO 3 , single crystals have been synthesized by the solution in the melt technique. The exact x -values in the crystals have been determined by X-ray fluorescence analysis and checked by Energy Dispersive X-Ray Spectroscopy. Scanning Electron Microscopy has been used to map distributions of iron and gallium ions in the crystals. The electron magnetic resonance (EMR) spectra as well as field and temperature dependences of the magnetization obtained by SQUID reveal the existence of different magnetic phases in different x ranges, viz. weakly ferromagnetic antiferromagnetic, magnetic cluster and paramagnetic phase. For crystals with 0.32 ≤ x ≤ 0.83, the Néel temperatures, T N , have been determined. The magnetometry of these crystals suggests the existence of another magnetic transition at a temperature well below T N , tentatively ascribed to a Morin type transition. Detailed EMR and SQUID studies of the crystal with x ≈ 0.2 reveal the existence of magnetic nanoclusters showing superparamagnetic behaviour. Using a laboratory developed code based on the Monte-Carlo technique, spatial distributions of dia- and paramagnetic ions in the crystal with x ≈ 0.2 has been visualized and possible cluster sizes have been estimated. • Fe x Ga 1− x BO 3 can be weakly ferro- antiferromagnetic, superpara- or paramagnetic. • Superparamagnetism in magnetically diluted crystals arises from magnetic clusters. • Fe x Ga 1− x BO 3 are promising as fine-tunable materials for advanced applications. [ABSTRACT FROM AUTHOR]

MgNi ferrite nanoparticles were prepared successfully via wet sol-gel route using the nitrates of proposed elements i.e. Mg, Ni and iron were used as precursors with citric acid as fuel. The prepared materials were annealed at a temperature of 900∘C to achieve the best properties. To know structural, morphological, elastic and magnetic properties, the synthesized nanoparticles were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscope (HRTEM), vibrating sample magnetometer (VSM), FTIR spectroscopy and Raman spectroscopy. The results of XRD, FTIR and Raman spectroscopy patterns are indicative of formation of ferrite nanoparticles and the structural studies confirm the inverse-spinel structure with crystallite size 35–61 nm. The formation of spinel ferrite structure is confirmed by absorption bands corresponds to vibration of tetrahedral site-A and by absorption bands corresponds to the octahedral site-B. Crystallite size calculations were carried out using WilliamFson-Hall plot. Rietveld refinement was applied to assure the crystal structure and allied parameters. The magnetic analysis of the prepared samples was carried out by VSM indicates that the nanoparticles exhibited superparamagnetic behavior having high magnetic saturation (M S) and negligible coercivity (H C). The elastic and magnetic properties through absorption bands found degraded at higher magnesium compositions. [Display omitted] • High-Magnesium MgNi ferrite nanoparticles posses elastic stability. • Traces of alpha hematite phase detected in high-magnesium composition. • Magnetic field strength increased. • MgNi ferrites exhibit ferromagnetic characteristics. [ABSTRACT FROM AUTHOR]

In this research, the suitability and potential of two biocompatible mixed valent non-stoichiometric spinel nanoferrites viz., Zn 0.5 Ca 0.5 Fe 2 O 4 (ZCNF) and Mg 0.5 Ca 0.5 Fe 2 O 4 (MCNF) with a minor impurity of CaCO 3 have been explored for magnetic hyperthermia and in-vitro cytotoxicity against normal and lung cancer cell lines. Nanocrystalline samples of ZCNF and MCNF in fcc structure were synthesized using the citrate-based sol-gel method and characterized by a variety of standard techniques. 57Fe Mössbauer spectroscopy, electron spin resonance and dc-magnetometry studies revealed that ZCNF is dominantly superparamagnetic while, MCNF is a soft ferrimagnet at 300 K. The maximum specific absorption rate (SAR) for 1 mg/mL suspension of nanoferrite powder in de-ionized water was found to be 179 W/g and 338 W/g for ZCNF and MCNF, respectively. Further, the highest hyperthermia temperature of 41.5 °C and 52 °C was achieved in 900 s at 15.98 kA/m for ZCNF and MCNF, respectively. Both ZCNF and MCNF showed good cytocompatibility with a tested concentration of 0.5 mg/mL against the human embryonic kidney HEK-293 (>75% cell viability) cell line. Additionally, simulated in-vitro treatment at an optimum magnetic hyperthermia temperature of 45 °C for 30 min in the presence of ZCNF and MCNF powder (up to a concentration of 1 mg/mL) led to suppression of ∼55% lung cancer cell lines (A549) while, in similar simulated condition the cell viability of normal HEK 293 cell lines remain unaffected. In summary, ZCNF and MCNF are appropriate therapeutic nanomaterials for magnetic hyperthermia-related cancer therapies. [Display omitted] • Synthesis of non-stoichiometric Zn 0.5 Ca 0.5 Fe 2 O 4 (ZCNF) and Mg 0.5 Ca 0.5 Fe 2 O 4 (MCNF) nanoferrites by sol-gel route. • SAR = 179 W/g and 338 W/g with decent ILP values of ∼ 2.1 and 3.9nHm2kg−1 for ZCNF and MCNF respectively. • ZCNF and MCNF showed good cytocompatibility with a tested concentration of 0.5 mg/mL on embryonic kidney HEK-293 cells. • Lung cancer A549 cells incubated in the presence of ZCNF and MCNF at 45 °C (simulated hyperthermia conditions) for 30 min led to reduction in cell viability upto 55%. • ZCNF and MCNF are suitable nanomaterials for magnetic hyperthermia based cancer theranostics. [ABSTRACT FROM AUTHOR]

Both theoretical calculations and experiments indicate that a monolayer CoSb/SrTiO 3 film has high-temperature superconductivity resembling the case of FeSe/SrTiO 3. However, no superconductivity was found in the bulk CoSb, even under high pressure. Moreover, the magnetic properties of CoSb have always been controversial. Here, we have studied the electrical property, magnetic property, and X-ray photoelectron spectroscopy (XPS) of CoSb single crystals. Electrical and magnetic transportation measurements reveal that CoSb is a Pauli paramagnetic metal with non-Fermi liquid behavior. The XPS results showed that both Co and Sb in CoSb are in the zero-valence state, and they form an alloy in which the metallic bond is dominant. The Pauli paramagnetism of CoSb originates from its itinerant electrons. Therefore, unveiling the electronic states of CoSb single crystal not only help us understand its magnetic properties, but would also pave the way for searching for the possible high-temperature superconductivity. • CoSb single crystals with large size were synthesized. • CoSb is a Pauli paramagnetic metal with non-Fermi liquid behavior. • XPS analysis indicates that both Co and Sb are in the zero-valence state in CoSb. • The Pauli paramagnetism of CoSb originates from its high-density itinerant electrons. [ABSTRACT FROM AUTHOR]

Superparamagnetic magnetite (Fe 3 O 4) has potential biomedical applications, but its synthesis can be challenging and costly. We present a simple and facile method for synthesizing superparamagnetic magnetite via the co-precipitation method. The pH and stabilizer concentration were optimized to obtain high purity Fe 3 O 4 nanoparticles with superparamagnetic characteristics, despite having an aggregated morphology. The results showed that the synthesized particles were micrometer-sized, and exhibited superparamagnetic behavior with a value of 40 emu/g. The conventional wisdom on superparamagnetic behavior is to attribute the phenomenon to the presence of nanosized crystallites and nanoparticles in the aggregated structure, however, our computational analysis through density functional theory shows that strain-related effects are an underlying cause for the paramagnetism of magnetite as well, which explains our experimental observations. Overall, the co-precipitation method presented in this study offers an easy, non-toxic, and fast method for synthesizing Fe 3 O 4 nanoparticles, which is suitable for industrial-scale production. [Display omitted] • Fe 3 O 4 particles were micron-sized, exhibiting superparamagnetic behavior of 40 emu/g. • Strain-related effects are an underlying cause for the paramagnetism of Fe 3 O 4 powders. • Tetrahedral Fe vacancy formation is favored in nanosize range. • The spin channels are fully symmetric on DOS patterns of strained Fe 3 O 4. [ABSTRACT FROM AUTHOR]

Multiferroic BiFeO 3 -NiO (BFO-NiO) nanocomposites have been synthesized using sol-gel route and investigated via. the first principle DFT calculations, multiferroic-magnetoelectric response, and extremely low-temperature magnetic analysis. Powder X-ray diffraction (XRD) patterns along with Rietveld refinement data confirmed the phase purity viz. rhombohedral distorted perovskite BiFeO 3 - rock salt type NiO crystal structure and composite formation. Temperature dependent magnetic measurements confirmed the enhancement in the magnetism and the exchange bias effect due to the antiferromagnetic (AFM) and ferromagnetic (FM) exchange coupling interactions. Zero field cooled (ZFC) and field cooled (FC) magnetic results demonstrate the observation of typical superparamagnetic (SP) behavior for all the samples at room temperature whereas at low temperature a transition is reported from SP to quantum superparamagnetic (QSP) state through quantum tunneling of magnetic moment for all samples. Maximum polarization of 5.7μC/cm2 is observed for BFO-20% NiO composition. The noticeable change in the ferroelectric P vs E loops in the presence of external magnetic field confirm the evidence of multiferroic and magnetoelectric coupling behavior in the BFO-NiO nanocomposites. The DFT calculations have been done using WIEN2k software and found in well agreement with the reported experimental results. Further, the suitable temperature dependent magnetic squareness, evidence of considerable magnetoelectric coupling, exchange bias effect and SP nature make the BFO-NiO nanocomposites considerable suitable for various device applications such as information storage, magnetic random access memory, targeted drug delivery, magnetic resonance imaging (MRI), bio-sensing and tailoring other photocatalytic applications. [Display omitted] • Experiment and first principal DFT study of multiferroic-NiO nanocomposites. • Rietveld refinement data confirmed the phase purity. • Confirmation of exchange bias effect, super-paramagnetic behavior. • Ferroelectric and magnetic measurements confirm evidence of multiferroic and magnetoelectric coupling. • Magnetic squareness indicates information storage application. [ABSTRACT FROM AUTHOR]

We report a study of structural, magnetic, heat capacity and thermoelectric properties of a Ru-based Heusler alloy, Ru 2 TiGe. The magnetic measurements reveal that at higher temperatures, diamagnetic and Pauli paramagnetic contributions dominate the magnetic behaviour whereas, at lower temperatures (T ≤ 20 K), superparamagnetic interaction among clusters is observed. The development of such magnetism, however, does not exhibit any noticeable influence in thermoelectric properties. Though the temperature dependence of electrical resistivity exhibits a metal-like nature, the large value of Seebeck coefficient leads to an appreciable power factor of the order of 0.54 mW/mK2 at 300 K. Large power factor as well as low thermal conductivity results in a value of zT = 0.025 at 390 K for Ru 2 TiGe that is orders of magnitude higher than that of the other pure Heusler alloys and point towards its high potential for practical thermoelectric applications. [Display omitted] • Ru 2 TiGe exhibits superparamagnetism despite having no magnetic element and VEC 24. • Low thermal conductivity due to heavier element induced enhancement of e-ph and phph scattering. • Highest zT among pristine full-Heusler alloys, despite exhibiting metal-like conductivity. [ABSTRACT FROM AUTHOR]

Abstract Chromite nanospinels of M Cr 2 O 4 (M = Co, Zn, Mg and Cd) have been synthesized using a microwave combustion method. The spinel phase and average particles size have been investigated by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). Both XRD and TEM reveal an overall average particle size of about 12 nm. UV–Vis optical absorbance measurements at room temperature indicate common wide optical energy gap of about 3.1–3.4 eV. Magnetization processes have been studied via precise field cooled (FC) and zero-field cooled (ZFC) magnetization measurements. The magnetic transition temperatures found in the nanoparticles are slightly below those of corresponding bulk crystals. Survived spiral spin textures below ∼26 K and coexisting spin-glassy state are observed in the Néel-type ferrimagnetic CoCr 2 O 4 nanocrystals with Curie temperature of 92 K. While the antiferromagnetic state of chromites with nonmagnetic divalent cations is observed in ZnCr 2 O 4 nanocrystals below Néel temperature of 11 K, it is significantly suppressed in MgCr 2 O 4 and CdCr 2 O 4 nanocrystals of identical average particle size. Our results indicate increased surface spins contribution with increasing lattice parameter. ESR linewidth and resonance field of M Cr 2 O 4 also show M -cation type dependence. The coexisting spin-glassy-like state in long-range ordered CoCr 2 O 4 and a possible superparamagnetic state in M Cr 2 O 4 (M = Zn, Mg and Cd) nanospinels are discussed as finite-size and Cr-Cr separation effects. Graphical abstract Image 1 Highlights • XRD, FTIR and TEM indicate single nanospinel phase of ∼12 nm in particle size. • Overall wide energy gap of ∼3.2 eV is demonstrated by UV–Vis optical measurements. • FIM CoCr 2 O 4 nanocrystals exhibit coexisting spin glassy and survived spiral spin states. • Varying suppression limit of the AF state in M Cr 2 O 4 (M = Zn, Mg, Cd) nanospinels is observed. • AF suppression is attributed to spin surface contribution depends on lattice parameter. [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]

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 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]

Mechanical (elastic) properties have been derived for polycristalline TiMn 2 from micro-indentation and thermal expansion measurements. With a room temperature (RT) Vicker's hardness of ∼11 GPa, TiMn 2 is a rather hard intermetallic material. The elastic modulus is E = 217 ± 4 GPa at RT. Physical properties (from 1.8 K to 300 K) including specific heat, electrical resistivity and magnetic susceptibility reveal temperature independent paramagnetism and metallic conductivity consistent with a Bloch-Grüneisen behavior. Based on experimental data (X-ray powder diffraction, metallography, SEM and EMPA on 30 alloys prepared by various methods employing arc melting, powder reaction sintering in closed crucibles as well as nitriding binary master alloys in 10 5  Pa nitrogen gas) phase relations in the ternary system Ti-Mn-N have been established and calculated for the isothermal section at 900 °C. The thermodynamic modelling relies on existing thermodynamic assessments of the Mn-N and Ti-N binary systems and on our recent modelling of the Ti-Mn system, which is characterized by a significantly higher thermodynamic stability of the C14-type Laves phase Ti 1-x Mn 2+x than hitherto assumed in the literature. It is this higher stability, which is consistent with the experimental phase triangulation in Ti-Mn-N: as the most important consequence of the higher stability of Ti 1-x Mn 2+x , compatibility exists between the only two congruently melting compounds Ti 1-x Mn 2+x and TiN 1-x . The high melting refractory solution TiN 1-x dominates the liquidus surface pushing all monovariant melting lines close to the Ti-Mn binary. [ABSTRACT FROM AUTHOR]

Ba and Ta co-doped bismuth ferrites with the composition Bi 0.8 Ba 0.2 Fe 1-x Ta x O 3 (where x = 0, 0.05, 0.10 and 0.15) were synthesized employing a solid state reaction method. Rietveld refinement of XRD patterns revealed that Ba doping caused structural transformation in perovskite BFO from rhombohedral ( R 3 c ) to tetragonal ( P 4 mm ) with up to 10% Ta doping. However, with 15% Ta substitution (BBFTO-15) the ceramics exhibited a mixture of tetragonal and rhombohedral structures. Curve fitting of room temperature magnetization vs. magnetic field data showed that the shape of the hysteresis loops for these ceramics were the result of coexistence of single domain and superparamagnetic contributions. For 10% Ta substitution (BBFTO-10), the contribution from superparamagnetic particles was dominant. Polarization with respect to electric field measurements did not yield typical hysteresis loops; instead evidence of high leakage was present in BBFTO-0 and BBFTO-5 while that of BBFTO-10 and BBFTO-15 exhibited a lossy dielectric nature. The I-V characteristics confirmed that Ta doping reduced the leakage current by greater than two orders of magnitude compared to BBFTO-0. It is believed that the reduction in oxygen vacancy in the doped samples was key in reducing the leakage current. As a matter of fact, XPS data revealed a reduction in oxygen vacancy concentration and the percentage of Fe 3+ was also found to increase with increasing Ta doping. Dielectric constant and dielectric loss were also found to decrease with the increase of Ta doping. Impedance spectroscopy confirmed the contribution from multiple impedance components including evidence of a dipolar relaxation that was found in BBFTO-5 and BBFTO-10. Defect associates were proposed to be responsible for such relaxations. [ABSTRACT FROM AUTHOR]

In this paper, the synthesis of rare earth fluoride GdF 3 multiform morphologies via l -arginine hydrothermal method has been fulfilled for the first time. The size and shape of the products could be tuned just by adjusting the pH values of the initial reaction solutions. The morphologies for the products include submicron round disc, submicron flower disc, submicron rods and submicron bulks. Additionally, the possible formation mechanism of multiform morphologies was proposed. Furthermore, we systematically investigate the luminescence properties of different lanthanide ions (Tm 3+ , Dy 3+ , Eu 3+ ) in GdF 3 host. By adjusting their relative doping concentrations in the GdF 3 host, the different color hue of blue and yellow light are obtained by co-doped Tm 3+ ,Dy 3+ and Dy 3+ , Eu 3+ in GdF 3 host, respectively. Besides, there exist two energy transfer pairs in the GdF 3 host: (1) Tm 3+ →Dy 3+ ; (2) Dy 3+ →Eu 3+ . More significantly, in the Tm 3+ , Dy 3+ , Eu 3+ tri-doped GdF 3 phosphors, white light can also be achieved upon excitation of UV light by adjusting the doping concentration of rare earth ion (Tm 3+ , Dy 3+ , Eu 3+ ). Importantly, when the temperature was raised to 225 °C, the emission intensities of Dy 3+ (475 nm) and Eu 3+ (592 nm) was 65% and 71% of the initial value at 25 °C for GdF 3 : Dy 3+ , Eu 3+ , which indicating that the thermal stability of the phosphors of the GdF 3 :2%Dy 3+ , 3%Eu 3+ is excellent. In addition, the obtained samples also exhibit paramagnetic properties at room temperature (300 K). The result shows that the obtained nanophosphors have a promising application in display and lighting fields. [ABSTRACT FROM AUTHOR]

A complete critical behavior study of the paramagnetic to ferromagnetic transition in intermetallics NdScSi and NdScGe has been carried out by means of magnetic as well as calorimetric measurements. The critical exponents α , β , γ and δ have been independently obtained. For NdScSi they are α = −0.015, β = 0.339, γ = 1.297 and δ = 4.94, indicating that it belongs to the 3D-XY universality class, while for NdScGe they are close to the mean field model with α tending to zero, β = 0.446, γ = 1.146 and δ = 3.44. The change from short-range to long-range ordering is discussed in terms of the magnetism mechanisms. [ABSTRACT FROM AUTHOR]

The ternary solid solution system of BiFeO 3 -NdFeO 3 -PbTiO 3 (BF-NF-PT) has been synthesized in the form of ceramics by conventional solid reaction method in order to understand multiferroic properties. The introduction of NdFeO 3 into the BiFeO 3 -PbTiO 3 binary system can effectively increase electrical properties. The ternary system exhibits enhanced piezoelectric properties with optimal piezoelectric constants d 33 = 142 pC/N and 135 pC/N, and reduced coercive fields E C = 32.63 kV/cm and 15.55 kV/cm for 0.52BiFeO 3 -0.08NdFeO 3 -0.40PbTiO 3 and 0.20BiFeO 3 -0.20NdFeO 3 -0.60PbTiO 3 , respectively. The Curie temperature ( T C ) of the BiFeO 3 -NdFeO 3 -PbTiO 3 ceramics varies in the range of 412 °C–260 °C. The magnetic hysteresis loops shows that the ternary system is paramagnetism originated from canting of paramagnetic sublattices in BF-NF-PT, because the exchange interaction between Fe 3+ at the octahedral sites is affected by Nd 3+ ions. [ABSTRACT FROM AUTHOR]

We reported the magnetism, magnetic phase transition behavior and magnetocaloric effect of the ternary Dy 2 CuSi 3 and Ho 2 CuSi 3 compounds. A second order magnetic phase transition from a paramagnetic (PM) to ferromagnetic (FM) state around their respective Curie temperatures were confirmed by using the magnetic measurements and rescaled magnetic entropy change curves in both compounds. A large magnetic entropy change was obtained with the absence of thermal and magnetic hysteresis loss in both compounds. The maximal magnetic entropy change (-Δ S M max ) reach 18.3 and 28.3 J/kg K for a magnetic field change of 0–70 kOe in Dy 2 CuSi 3 and Ho 2 CuSi 3 , respectively. The corresponding values of relative cooling power ( RCP ) are evaluated to be 460 J/kg and 627 J/kg, respectively. [ABSTRACT FROM AUTHOR]

Nanoplates of nickel-substituted manganese ferrite (M 0.8 Ni 0.2 Fe 2 O 4 ) with side-length of 8 ± 2 nm were fabricated by coprecipitation route. The samples were characterized by X-ray powder diffraction, transmission electron microscopy, and Raman spectroscopy, which confirmed the formation of single phase crystalline nanoparticles with plate–like morphologies. Magnetic properties were investigated by vibrating sample magnetometer at room temperature and by zero-field cooled (ZFC) and field cooled (FC) M(T) measurements in the temperature range 20–300 K, which revealed the superparamagnetic nature of the samples with blocking temperature of about 90 K. Benefited from the plate-like morphology of the samples, the electrochemical performance was tested in lithium ion batteries, which shows the initial discharge and charge capacities of ∼1050 mAhg −1 and ∼900 mAhg −1 for the first cycle and excellent coulombic efficiency of higher than 95% after the ten subsequent cycles. This work demonstrates the possibility of using plate–like M 0.8 Ni 0.2 Fe 2 O 4 nanoparticles as the anode materials for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Effect of Mn substitution on the structural, optical, surface and magnetic properties of mixed LaFeO 3 i.e. La Ce nanoferrites (La 0.9 Ce 0.1 Fe 1-x Mn x O 3 ) synthesized by hydrothermal route using ionic liquid surfactant (ILS), 1-hexadecyl-3-methyl imidazolium chloride, [C 16 mim][Cl], have been explored by X-ray diffraction (XRD), IRaman spectroscopy, Brunauer-Emmett-Teller (BET) adsorption isotherm, Vibrating sample magnetometer (VSM) and Mӧssbauer spectroscopy etc. Incorporation of Mn in crystal lattice of La Ce ferrite induced the structural distortion as specified by structural studies. Morphology and the size of the obtained nanoparticles (NPs) get slightly altered by the quantity of dopant as observed from transmission electron microscopy (TEM). The appearance of rod shaped morphology along with spherical NPs indicates the templating effect of ILS. Surface and magnetic properties of Mn doped La Ce NPs have found to be significantly improved than that of undoped La Ce ferrites. Magnetization of the obtained NPs strongly depends on the content of Mn in the lattice. Enhanced magnetization has been observed up to certain extent of Mn doping (x = 0.3). At higher Mn content (x = 0.5), a significant reduction in magnetization has been observed as revealed from Mӧssbauer and magnetic studies. The enhanced surface area (36.18 m 2 /g) of the Mn doped samples over the undoped La Ce ferrite opens the new doors in biological and sensing applications. [ABSTRACT FROM AUTHOR]

Magnetostructural transition and the associated magnetocaloric effect were investigated for Mn 1− x Ni 1− x Co 2 x Si 1− x Ge x system. Co and Ge co-substitution drastically reduces the structural transition temperature from 1200 K to below room temperature. The magnetostructural transition occurring between a ferromagnetic and a paramagnetic state with a sharp jump in magnetization was realized, which is tunable in a broad Curie-temperature window spanning room temperature by altering the composition. Relatively large magnetic entropy changes and broad working temperature ranges were observed. These results suggest that the Mn 1− x Ni 1− x Co 2 x Si 1− x Ge x system can be an attractive platform for the tunable magnetostructural transition and the magnetocaloric effect. [ABSTRACT FROM AUTHOR]

New experimental results on the pressure dependence of magnetic susceptibility χ of SmS in semiconducting phase are obtained with precise measurements of χ as a function of the hydrostatic pressure P up to 2 kbar at liquid nitrogen and room temperatures. A pronounced magnitude of the pressure effect is found to be positive in sign and strongly temperature dependent: the pressure derivatives of χ , d ln χ /d P , are 6.3 ± 0.5 and 14.2 ± 1 Mbar −1 at 300 and 78 K, respectively. The experimental results are supplemented by theoretical calculations of the volume dependent electronic structure of SmS and orbital magnetism of the band electronic states χ VV(band) . It was found that χ VV(band) value appeared to be strongly dependent on pressure, determining the main mechanism of the observed puzzling pressure effects in semiconducting SmS compound. [ABSTRACT FROM AUTHOR]

The co-precipitation method was used to prepare silver ferrite AgFeO 2 . The resulting powders were brick brown flakes. X-ray diffraction and Mössbauer spectroscopy were used as complementary methods to study structure and hyperfine interactions of silver ferrite. It was found that AgFeO 2 has delafossite structure with two polytypes, i.e., rhombohedral 3 R and hexagonal 2 H , wherein the 2 H polytype is dominant. The average crystallite sizes, estimated using Scherrer formula, were in the range of 15–35 nm. The Mössbauer spectrum registered at room temperature is one paramagnetic doublet with isomer shift characteristic for high-spin Fe 3+ ions in an octahedral oxygen environment. In the temperature range of 3.7 K ≤ T ≤ 16 K Mössbauer spectroscopy revealed a distribution of the hyperfine magnetic fields at 57 Fe nuclei connected with complicated collinear and non-collinear magnetic structure of AgFeO 2 . It was found that the value of the average hyperfine magnetic field monotonically decreases with an increase of temperature. [ABSTRACT FROM AUTHOR]

The search of transparent conducting and ferromagnetic properties in Zn 1−x Co x O based diluted magnetic semiconductor is explored either by chemically alloying the different concentration (x) of Co or by n-type co-doping. The present work aims to explore the electrical conduction process at variable temperatures, in order to probe the room and low temperature ferromagnetism triggered in transparent Zn 0.95 Co 0.05 O films using inert xenon ion irradiation. The origin of the paramagnetism and the tunable ferromagnetism in transparent Zn 0.95 Co 0.05 O films is explained from different degree of concentric bound magnetic polarons (BMPs) stabilization inside variable range hopping spheres through implication of strongly and weakly bound carriers to O/Zn related lattice defects and tetrahedrally substituted Co 2+ ions. The paramagnetic behavior in as deposited Zn 0.95 Co 0.05 O film arises from the smallest density of isolated concentric BMPs resulted mainly from marginal concentration of strongly localized carrier due to its highly insulating nature. The progressive enhancement in strongly localized carriers in post irradiated Zn 0.95 Co 0.05 O films as a function of fluence results in overlapping of static concentric BMPs to trigger onset of ferromagnetism. The strength of ferromagnetism is found to be maximal at a particular density of concentric BMPs optimized from the highest concentration of strongly localized carriers in insulating regime and substantial substituted Co 2+ ions. Further enhancement in carrier concentration and reduction in substituted Co 2+ ions is detrimental to ferromagnetism owing to non-static concentric BMPs percolation from the presence of weakly localized nature of carriers in intermediate regime. [ABSTRACT FROM AUTHOR]

Nickel substituted manganese ferrite [Ni x Mn 1−x Fe 2 O 4 (x = 0.2)] nanoplates with cubic shape and controlled sizes were fabricated by chemical coprecipitation technique. Structural analyses confirmed the formation of single phase crystalline nanoplates in the size range 8–24 nm. Magnetic studies showed that coercivity as a function of plate length goes through a maximum, peaking at 162 Oe and then decreases for larger nanoplates, indicating that the single domain limit for Ni x Mn 1−x Fe 2 O 4 (x = 0.2) is ∼21 nm. While negligible coercivity at below 10 nm confirms the superparamagnetic limit in the range 8–10 nm for these nanoplates. Saturation magnetization of the samples was found to increase linearly with plate length in the single domain regime, however this increase was observed slower for the larger nanoplates. Typical blocking effects were studied in the temperature range 20–300 K and it was found the superparamagnetic blocking temperature increases monotonically with increasing size of the nanoplates. The results are discussed in terms of the enhanced surface roles and variation of surface and effective anisotropies with size of the nanoplates that strongly influence their magnetic properties within the domain of Stoner Wohlfarth model for ferromagnetic systems. [ABSTRACT FROM AUTHOR]

The precipitation-hardenable nickel–chromium-based superalloy X-750 exhibits excellent mechanical properties at high-to-cryogenic temperatures. However, little is known about its other properties, even though it is used in a wide range of applications. To elucidate the additional properties of X-750, we studied the effects of its nanostructural evolution on both its mechanical and magnetic properties. We found that precipitation not only mechanically hardens this superalloy, but also induces soft magnetism as well as notable magnetic losses at ultralow temperatures. This information should aid the design of superconducting instruments based on the X-750 superalloy as a structural material. [ABSTRACT FROM AUTHOR]

Nanoparticles of Mn ferrite (Mn x Fe 3−x O 4 , x = 0.0, 0.2, 0.6, and 0.8) have been successfully prepared by the co-precipitation method using the organic base ethanolamine as the chelating agent. The XRD measurements show well crystalline nano-ferrite particles with a lattice parameter gradually increasing with increasing Mn ions substitution. In contrast, XPS spectra show the existence of Mn3+ and Mn4+ with a crystalline size behavior. Small particle sizes and large specific surface areas in the range of 180–120 m2/g have been detected by HRTEM and BET measurements. The large values of specific surface areas nominate the samples to be good candidates for chemical and biological applications. The FT-IR and Raman spectra have supported the Rietveld refinement of XRD without forming any impurity phases. As Mn doping increases, the FMR and VSM mea-surements have indicated magnetic enhancement in the Mn nanoferrite. • Nanosized Mn x Fe 3−x O 4 were prepared by the co-precipitation method. • Organic base ethanolamine was used as the chelating agent at preparation. • Lattice parameters gradually increased with increasing Mn concentration. • Large specific surface areas in the range of 180–120 m2/g was detected. • Spontaneous magnetization increased with increasing Mn concentration. [ABSTRACT FROM AUTHOR]

High entropy alloy NiFeCrCo was systematically studied in the range of near-equal atomic concentrations, i.e., 10–40 at.%, by first-principles tools and high throughput calculations. Enthalpy of mixing, lattice parameter ( a 0 ), bulk modulus ( B ), and shear modulus ( G ) were calculated by the exact muffin-tin orbital method combined with coherent potential approximation (EMTO-CPA) for over 2700 compositions of the NiFeCrCo alloy as a single-phase solid solution in paramagnetic state. It was found that certain elements have the most significant influence on each property, namely, Cr on enthalpy of mixing, Co on a 0 , Fe on B , Co on G , and Cr on the ratio of B / G . An equation to predict the enthalpy of mixing by use of binary enthalpy data was evaluated and was found to have a good accuracy with a root-mean-square deviation (RMSD) of 42 meV per formula unit in the prediction. A similar equation to predict bulk modulus with weighted contribution from first–shell interaction is proposed and tested on all alloys. This equation was also found to be accurate with a RMSD of 6 GPa. Finally, it was found that shear moduli of all tested alloys are largely dependent on C 44 , while the concentration of Co has a noticeable control on C 44 . Spin polarized calculations were performed for a select group of alloys with both EMTO-CPA and the Vienna ab-initio Simulation Package (VASP) with special quasi-random structure models for comparison. Good agreement was found between these methods. [ABSTRACT FROM AUTHOR]

X-ray analysis revealed that at temperature decreasing from room temperature to T str = 155 K the crystal unit cell GdFe 3 (BO 3 ) 4 is reduced only along the c axis (at 0.01 Å), while the a and b axes are unchanged within the error limits. The volume of the crystal decreases uniformly in the direction of all three axes at 155–80 K. At 80–30 K the crystal volume is decreased only by reduction of the parameters a and b , while the parameter c increases conversely. In the paramagnetic region Mössbauer spectra do not distinguish between the two structural positions of iron ions Fe1 and Fe2, appearing at T < T str . Below the temperature of the magnetic phase transition at T N = 38.0(1) K the Mössbauer data indicate quasi-one-dimensional magnetic ordering of iron moments in the sublattice Fe2 and a two-dimensional one in the iron sublattice Fe1. The dynamics of spin reorientation in sublattices Fe1 and Fe2 is studied in detail. [ABSTRACT FROM AUTHOR]

We reported the continuous preparation and electrochemical behavior toward heavy metal ions of the Fe 3 O 4 nanoparticles (Fe 3 O 4 NPs). This Fe 3 O 4 NPs were fabricated through a novel Impinging Stream-Rotating Packed Bed reactor with a high production rate of 2.23 kg/hour. The as-prepared Fe 3 O 4 NPs were quasi-spherical with a mean diameter of about 10 nm and shown the characteristics of superparamagnetism with the saturated magnetization of 60.5 emu/g. The electrochemical characterization of the as-prepared Fe 3 O 4 NPs toward heavy metal ions were evaluated using square wave anodic stripping voltammetry (SWASV) analysis. The results indicated that the modified electrode could be used to individual detection of Pb(II), Cu(II), Hg(II) and Cd(II). In particular, the modified electrode exhibited the selective detection toward Pb(II) with higher sensitivity of 14.9 μA/μM, while the response to Cu(II), Hg(II) and Cd(II) were negligible. Besides, the modified electrode shown good stability and potential practical applicability in the electrochemical determination of Pb(II). This above results offered a simple method for continuous preparation sensing materials in the application field of electrochemical detection of toxic metal ions through the technology of process intensification. [ABSTRACT FROM AUTHOR]

FePt nanoparticle is under development as ultrahigh density recording material because it retains ferromagnetic properties even if its dimension is reduced below 10 nm. However, the heat treatment, required to transform the superparamagnetism of as-synthesized particle into ferromagnetic phase, brings about undesirable increases in particle size. This work demonstrates that the magnetic phase transition without excessive agglomeration can be obtained by annealing long-range monolayer assembly of FePt based nanoparticles. The magnetic properties are dependent on the type of Fe( β -diketonate) 3 used in the synthesis due to the variations in elemental compositions and mixed phases in annealed nanoparticles. Whereas X-ray characterizations confirm the conversion of FePt 3 /Fe 2 O 3 into FePt by annealing, characteristics of hysteresis also suggest the co-existence of other minor phases. When either Fe(tmhd) 3 or Fe(hfac) 3 is employed as starting materials, the Fe fraction is much less than that of Pt resulting in narrow hysteresis loop with low coercivity. By contrast, the coercivity is enhanced with the Fe:Pt ratio closer to the unity in the case of Fe(acac) 3 and Fe(dbm) 3 . [ABSTRACT FROM AUTHOR]

Lactoferrin (LF) was used to assist the synthesis of zinc ferrite (ZnFe 2 O 4 , ZFO) semiconductor photocatalysts in this study, and superparamagnetic ZFO nanocrystals with an average crystallite size ranging from 11.3 nm to 20.1 nm were successfully obtained via the hydrothermal method. It was found that LF was conducive to fast formation of ZFO nuclei, which resulted in remarkable crystallinity enhancement of the as-prepared ZFO nanocrystals. The saturation magnetization ( M s ) of the as-prepared ZFO crystals would be greatly improved with increasing the LF content, and the M s of the as-prepared ZFO crystals synthesized with 50 mg of LF (ZFO-50LF) could reach 19.9 emu/g, whereas the M s of the as-prepared ZFO crystals synthesized in the absence of LF (ZFO-0LF) was only 8.8 emu/g. In addition, although the specific surface area of ZFO-0LF nanocrystals (127.2 m 2 /g) was larger than that of ZFO-50LF nanocrystals (101.6 m 2 /g), and ZFO-0LF exhibited a higher absorption of methyl orange (MO) molecules in contrast with ZFO-50LF, but ZFO-50LF possessed a larger optical absorption coefficient, smaller band gap and higher photocatalytic degradation efficiency per unit area. After being irradiated under UV light for 3 h, ZFO-50LF almost could make MO molecules completely degrade. Therefore, the LF-assisted synthesized ZFO nanocrystals have a promising application prospect to be used as a new high-efficiency recyclable photocatalyst. [ABSTRACT FROM AUTHOR]

Co/Au bimetallic fine nanoparticles were prepared employing the method of microemulsion using reverse micelle as nanoreactor, controlling the particles size. Magnetic and structural properties of two different samples Co/Au1 and Co/Au2 with almost comparable size of Co core and different size of Au layer were studied. The investigation of magnetic relaxation processes present in the particles was carried out by means of ac and dc magnetization data obtained at different temperatures and magnitudes of magnetic field. We observed the existence of superspin glass state characterized by the strong inter-particle interactions in the nanoparticle systems. In this paper, we discuss the attributes of novel superspin glass magnetic state reflected on various features (saturated FC magnetization at low temperatures, shift of the Cole–Cole arc downwards) and calculated parameters (relaxation time, critical exponent zv ∼ 10 and frequency dependent criterion p < 0.05). Comparison of the magnetic properties of two studied samples show that the thickness of diamagnetic Au shell significantly influences the magnetic interactions and change the relaxation dynamics. [ABSTRACT FROM AUTHOR]

In the present study, the variation of superparamagnetic (SPM) and ferromagnetic (FM) components and their effect on giant magnetoresistance (GMR) in electrodeposited CoCu/Cu multilayers (ML's) were investigated in the temperature range 30–300 K. For this, two different kinds of ML's, one with discontinuous Co-layer consisting of large superparamagnetic (SPM) ( t Co = 0.2 and 0.3 nm) fractions and the other with continuous Co-layer containing large ferromagnetic (FM) ( t Co = 2 and 3 nm) content were considered. Magnetoresistance measurements showed increase in MR magnitude with decrease in temperature associated with magnetic conversions in the magnetic Co-layers. At 300 K, a substantial difference in magnitude of MR was found for multilayers with t Co = 0.3 (5.07%) and 3 nm (8.82%). However, at 30 K very close values of MR for multilayer pair with t Co = 0.3 (16.48%) and 3 nm (17.72%) ensures a significant transformations of SPM to FM fractions in Co-layer at t Co = 0.3 nm. Similar results were obtained for the other pair of ML's i.e. t Co = 0.2 and 2 nm. This study suggests a suitable minimization of SPM content in the Co-layer could be another effective mechanism in maximizing the MR value. The measured temperature dependence of MR obeyed a simple T 1 law. [ABSTRACT FROM AUTHOR]

The structure, critical exponents and magnetocaloric effect (MCE) of Pr 0.4 Eu 0.2 Sr 0.4 MnO 3 were investigated in detail. A solid state reaction method was used in the preparation phase. Phase purity, structure, size, and crystallinity were investigated using XRD and SEM. The Reitveld refinement of XRD pattern shows that the sample adopts an orthorhombic structure with Pnma space group. Analyzing temperature and field dependences of magnetization around the ferromagnetic–paramagnetic transition reveals the sample undergoing the second-order magnetic phase transition with the critical parameters T C ∼ 238 K, β = 0.310(3), γ = 1.264(1) and δ = 4.761(9).The exponents are close to 3D-Ising values. This reflects an existence of ferromagnetic short-range order in our sample. With these values one can scale the magnetization below and above T C following a single equation of state. However, it is noteworthy that the scaling relations are obeyed indicating renormalization of interactions around the T C . Temperature variation in effective exponents β eff and γ eff resemble with those for disordered ferromagnet. In the vicinity of T C , the magnetic entropy change Δ S reached maximum values of 2.80 and 5.32 J/kg K under magnetic field variations of 2 and 5 T, respectively. The field dependence of the magnetic entropy changes are also analyzed, which show power law dependence Δ S M max ≈ a μ 0 H n at transition temperature. The critical exponent analysis related to magnetocaloric effect is described. Moreover, the temperature dependence of the exponent n for a different magnetic field is also studied. The values of n obey to the Curie Weiss law above the transition temperature. In particularly, n can be related to the critical exponents β, γ and δ at the magnetic transition. We used the scaling hypotheses to scale the magnetic entropy change and heat capacity changes to a single universal curve respectively for Pr 0.4 Eu 0.2 Sr 0.4 MnO 3 sample. [ABSTRACT FROM AUTHOR]

The single crystals of ZnCr 2 Se 4 doped with tin ions having contents of 0.92, 1.01 and 1.26 located in the octahedral sites of the spinel structure were successfully synthesized. The ac and dc magnetic measurements, and as well as the specific heat studies showed the spin-glass-like behaviour for all compositions below the freezing temperatures T f = 13–15 K. Both high positive values of the paramagnetic Curie–Weiss temperature, decreasing from 112 K to 58 K as the Sn-content increases, and the lack of a metamagnetic transition (characteristic for the ZnCr 2 Se 4 matrix) suggest a strong ferromagnetic exchange in the (0 0 1) planes which is randomly frozen below T f between the spins in adjacent (0 0 1) planes. These effects are interpreted in terms of the exchange integral of the spin-glass system including non-stoichiometry, spin and structural defects. [ABSTRACT FROM AUTHOR]

The as-prepared Cu 1 − x Mg x Fe 2 O 4 nanoferrites, 0 ⩽ x ⩽ 1, were synthesized using the co-precipitation method. The samples were characterized using the X-ray diffraction, transmission electron microscopy, infrared (IR) and Mössbauer spectroscopy and vibrating sample magnetometer. This study proved that the samples have single-phase cubic spinel structure, nanometric size and superparamagnetic behavior. The nanoparticle and crystallite size ( R ) showed a dependence on the Mg ion content x . The Mössbauer spectra were analyzed and assigned to two magnetic subpatterns and/or two quadrupole doublets due to Fe ions among the tetrahedral A-sites and octahedral B-sites. Six IR absorption bands were observed and assigned to the corresponding vibration modes. The saturation magnetization showed decrease against x and proved dependence on R . The lattice constant, hopping lengths, strain, site characteristic bands and B-site force constant showed x dependence, whereas oxygen parameter and A-site force constant did not. The site ionic radii and edges, density, porosity, Debye temperature, stiffness constant, hyperfine interaction and magnetic parameters were deduced and discussed as functions of x and the cation distributions were estimated. [ABSTRACT FROM AUTHOR]

A systematic study focusing on the magnetic and transport properties of Mn 0.48 Si 0.52 semiconductor films is performed. The Mn 0.48 Si 0.52 films show superparamagnetism above 17 K. The temperature dependence of the electrical transport reveals that electron–electron and electron–phonon interactions dominate the conductivity of weakly localized carriers. Very small negative magnetoresistance suggests that spin-dependent scattering between conductive carriers and local magnetic moments of Mn atoms is rather weak. On the contrary, the anomalous Hall effect due to the skew scattering is observed in the whole temperature range, indicating the spin–orbit coupling of the conducting carriers is significantly strong. [ABSTRACT FROM AUTHOR]

• Nanocrystal GdVO 4 presents enhanced paramagnetic-like behavior with the reduction of grain size. • The enhanced paramagnetic-like behavior leads to a giant entropy change of -Δ S M = 45 J/kg K at 3 K for Δ = H = 7 T. • The decrease of the saturated magnetization and -Δ S M with the grain size reduce to 30 nm is due to the aggregation effec. • Introducing paramagnetism in AFM materials provides a promising way to adjust the magnetic entropy of these materials. We investigated the magnetization and electron spin resonance (ESR) in nanocrystals of antiferromagnet GdVO 4 with the grain size ranging from 30 nm to 5 µm. Our nanoparticles with an average size reduction from 5 µm to 300 nm exhibited enhanced paramagnetic-like behavior, in which the weakly coupled spins can be well aligned along the direction of an external magnetic field, resulting in a giant entropy change of -Δ S M = 45 J/kg K at 3 K for Δ H = 7 T. Moreover, with a further reduction of grain size to ~ 30 nm, the saturation magnetization together with the negative entropy change -Δ S M , max decreased dramatically. The aggregation effect is believed to be responsible for the decline in -Δ S M , max , in which small nanoparticles agglomerating to 'large' grains made them behave like bulk material. Finding the critical point of positive size effect on magnetocaloric effect offered a new way to achieve large magnetic entropy change. [ABSTRACT FROM AUTHOR]

Highlights: [•] Gd doping has modest influence on the internal structure of TiO2. [•] The doped samples exhibit paramagnetism at room temperature. [•] Isolated magnetic spin of Gd3+ ions contribute towards paramagnetism. [•] Superexchange interaction of Gd3+ ions via O2 − ions induces antiferromagnetism. [Copyright &y& Elsevier]

Highlights: [•] Single phase ferrites synthesized by chemical co-precipitation. [•] With the increase of Mg concentration the lattice constant was decreased. [•] The grain size of particles was below 100nm. [•] Hc for all the samples revealed that the samples are super paramagnetic. [•] The samples x =0.2, 0.3, 0.5 may be recommended for the hyperthermia applications. [Copyright &y& Elsevier]

Highlights: [•] Ultrafine Ni3Fe nanoalloy nanoparticles were synthesized via a modified novel sol–gel process. [•] The prepared Ni3Fe nanoalloy nanoparticles have a narrow size distribution. [•] The Ni3Fe nanoparticles exhibit superparamagnetic behaviors at room temperature. [ABSTRACT FROM AUTHOR]

Highlights: [•] Nano zinc ferrite compound has been prepared by eco-friendly hydrothermal method. [•] Compound is well characterized by PXRD, SEM, FTIR, UV–Vis, DLS and Zeta profiler. [•] Material shows superparamagnetic behavior at room temperature. [•] Material is good for spintronics due to low coercivity and moderate conductivity. [ABSTRACT FROM AUTHOR]

Highlights: [•] Hexagonal phase prism-like NaYbF4 microtubes were synthesized by a hydrothermal method. [•] Tunable multicolor can be obtained by simply tuning Tm3+ and Ho3+ concentration in NaYbF4 system. [•] Tunable multicolor emissions can be achieved via increasing excitation pumping power. [•] Excellent paramagnetic property of NaYbF4 has been studied for the first time. [Copyright &y& Elsevier]

Highlights: [•] The magnetic behavior of Tl9CeTe6, Tl9PrTe6, Tl9TbTe6, Tl9SmTe6, is presented. [•] All samples are paramagnetic at low magnetic fields. [•] The Ce representative stands out with different thermoelectric properties and lower unit cell volume. [•] Fitting the magnetic susceptibility data reveals the existence of mixed valent cerium. [Copyright &y& Elsevier]

Highlights: [•] The critical behavior is sensitive to the disorder. [•] The critical exponents not fit with any model for J4 and J5 samples. [•] The scaling plots show that the critical exponents are reliable. [•] The Griffiths phase and metamagnetic behavior lead to novel critical exponents. [ABSTRACT FROM AUTHOR]

Highlights: [•] Hematite particles inside porous silica with 2D hexagonal and 3D cubic symmetry. [•] Magnetic properties are strongly affected by the dimensionality of porous matrix. [•] Weak dipolar interactions observed in superparamagnetic hexagonal α-Fe2O3@SBA-15. [•] Strong interactions leading to superspin-glass observed in cubic α-Fe2O3@SBA-16. [ABSTRACT FROM AUTHOR]

Highlights: [•] Magnetic properties of Neodymium nanorods depend on calcination temperature. [•] The as-synthesized Nd ferrite nanorods are superparamagnetic at room temperature. [•] The blocking temperature is higher than room temperature. [ABSTRACT FROM AUTHOR]