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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: [•] 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: [•] 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: [•] 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]

Highlights: [•] Co doped ZnAl2O4 nanostructures were synthesized by microwave combustion method. [•] The XRD patterns confirm the formation of single phase ZnAl2O4 without impurities. [•] The direct band gap decreased with increasing Co2+ content from 5.01 to 2.89eV. [•] Magnetic measurements revealed Co doped ZnAl2O4 has superparamagnetic behavior. [ABSTRACT FROM AUTHOR]

Highlights: [•] NixFe1-xFe2O4 samples are synthesized using co-precipitation method. [•] Cation inversion is indicated by XRD and Raman spectroscopy. [•] Due to the cation inversion, the lattice parameter and cell volume is increased. [•] Superparamagnetism and higher saturation is observed for these samples. [•] We explore these samples as a proper choice for magnetic drug delivery. [ABSTRACT FROM AUTHOR]

Abstract: Nanocrystalline Al3+ ions doped Mg0.2Mn0.5Ni0.3Al y Fe2− y O4 compositions, where y =0.0, 0.05 and 0.10 have been synthesized by citrate precursor method. Crystal structure and magnetic properties have been investigated at 300K by means of X-ray diffraction, transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and Mössbauer spectra measurements. XRD study reveals that particle size decreases from 102.25nm to 41.65nm. A decrease in lattice constant and saturation magnetization was attributed to smaller ionic radius of Al3+ ions and weakening of super exchange interaction. Experimental and X-ray density decrease with increasing aluminum concentration. Though Mössbauer spectra of y =0.0 exhibit normal Zeeman split sextets, spectra of samples for y =0.05 and 0.10 are characterized by simultaneous presence of a central paramagnetic doublet. Dependence of Mössbauer parameters such as isomer shift, quadrupole splitting, linewidth and hyperfine magnetic field on Al3+ ions concentration have been discussed. Initial permeability ‘μ i’, saturation magnetization (4πM S), retentivity (M R), Bohr magneton number (), magneto crystalline anisotropy constant (K 1) and magnetic loss decreases while coercivity (H C) increases with increasing substitution of Al3+ ions. Magnetic loss has very low value in the range of 10−3 which is two orders of magnitude less than samples prepared by conventional method. [Copyright &y& Elsevier]

Abstract: The crystal structure of the novel compound Ce3Rh5Si was solved by means of powder diffraction pattern analysis using the charge-flipping method. The refinements yielded the space group Pnma and the orthorhombic unit cell parameters: a =1.52632(2)nm, b =0.55092(1)nm, and c =0.75302(1)nm. A characteristic feature of the crystal structure of Ce3Rh5Si are vertex-sharing [Rh4] and [Rh3Si] tetrahedra, which form a three-dimensional framework with Ce atoms located inside truncated tetrahedral voids. The structure exhibits close relationship with those of CeRh2 (MgCu2-type) and Ce2Rh3Si (Y2Rh3Si-type). Magnetic and electrical resistivity measurements of Ce3Rh5Si were performed down to 2K. The compound was characterized as a Pauli paramagnet with metallic character of the electrical conductivity. [Copyright &y& Elsevier]

Abstract: The crystal structures of several novel quaternary compounds R2PbSi2S8 (R=Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho), R2PbSi2Se8 (R=La, Ce, Pr, Nd, Sm, Gd) and R2PbGe2S8 (R=Ce, Pr) have been determined by means of single-crystal and powder X-ray diffraction. All these phases crystallize with hexagonal unit cells of the La2PbSi2S8 type (space group R-3c, Pearson symbol hR78), in which rare-earth and lead atoms are statistically distributed over centers of bi-capped trigonal prisms made by chalcogen atoms. The magnetic properties of R2PbSi2S8 and R2PbSi2Se8 with R=La, Ce, Pr and Sm have been studied in wide temperature and magnetic field ranges. The La-based materials are weakly diamagnetic, whereas all the other compounds exhibit strongly temperature dependent paramagnetic behaviour due to the presence of well localized magnetic moments of trivalent rare-earth ions. [Copyright &y& Elsevier]

Abstract: dl-Thioctic acid (DLTA) coated magnetite (Fe3O4) NP''s have been prepared by the co-precipitation of iron oxide in the presence of DLTA. The product identified as magnetite, which has an average crystallite size of 7±2nm as estimated from X-ray line profile fitting. Particle size was estimated as 11±1nm from TEM micrographs. FT-IR analysis showed that the binding of DLTA on the surface of iron oxide is through carboxyl group is bidentate. VSM analysis explained the super-paramagnetic nature of the nanocomposite. TG analysis showed that the 80% of the nanocomposite was DLTA and 10% was Fe3O4, respectively. The conductivity measurements displayed the magnetic transition at ∼60°C for DLTA–Fe3O4 NPs. Analysis of the conductivities reveals the fact that the a.c. conductivity shows a frequency-dependent behavior while d.c. electrical conductivity is strongly temperature dependent and is classified into two regions over a limited temperature range of up to 120°C. Toxicity was tested measured by LDH assay. [Copyright &y& Elsevier]

Abstract: A facile direct precipitation method has been developed for the synthesis of bifunctional magnetic–luminescent nanocomposites with Fe3O4 nanoparticles as the core and YVO4:Eu3+ as the shell. Transmission electron microscopy (TEM) images revealed that the obtained bifunctional nanocomposites had a core–shell structure and a spherical morphology. The average size was ∼150nm, and the thickness of the shell was ∼15nm. The X-ray diffraction (XRD) patterns showed that a cubic spinel structure of Fe3O4 core and a tetragonal phase of YVO4 shell were obtained. Fourier transform infrared (FT-IR) spectra confirmed that the YVO4:Eu3+ had been successfully deposited on the surface of Fe3O4 nanoparticles. Photoluminescence (PL) spectra indicated that the nanocomposites displayed a strong red characteristic emission of Eu3+. Magnetic measurements showed that the obtained bifunctional nanocomposites exhibited superparamagnetic behavior at room temperature. Therefore, the bifunctional nanocomposites are expected to develop many potential applications in biomedical fields. [Copyright &y& Elsevier]

Abstract: This paper reports the magnetic properties of partially oxidized FeO nanoparticles (NPs) prepared using thermal decomposition of iron acetylacetonate at high temperature. X-ray diffraction (XRD) analysis confirmed that the resulting NPs comprise a mixture of wüstite and magnetite phases, which are subsequently confirmed using high resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED) pattern. Magnetic properties were investigated using vibrating sample magnetometer (VSM), which exhibit superparamagnetic (SPM) behavior at room temperature. Alternatively, below 200K, a large exchange bias field has been observed in field cooled mode whose magnitude increases with the decrease in measuring temperature attaining a maximum value of ∼2.3kOe at 2K accompanied by coercivity enhancement (∼3.4kOe) and high field of irreversibility (>50kOe). The results are discussed taking into account the role of interface exchange coupling on the macroscopic magnetic properties of the nanoparticles. [Copyright &y& Elsevier]

Abstract: Co-substituted ferrite nanoparticles with narrow size distribution have been prepared by coprecipitation method. X-ray diffraction (XRD) showed that the samples have cubic spinel structure of which the lattice constant slightly decreases upon cobalt substitution. The mean crystallite size of the samples was in the range 9.5–11nm as deduced from the XRD line broadening. Energy dispersive X-ray spectroscopy (EDX) verified the presence of cobalt in the substituted samples. The morphology and size distribution of the nanoparticles were studied using transmission electron microscopy (TEM). Magnetic properties were determined using a vibrating sample magnetometer (VSM). The samples are characterized by a superparamagnetic transition at blocking temperatures T B below room temperature. The coercivity H c at low temperatures follows a simple model of thermal activation of particle''s moment over the anisotropy barrier in the temperature range below T B which is in accordance with Kneller''s law for ferromagnetic materials. From the blocking temperature and from the thermal decay of the coercivity, the effective anisotropy constant values were determined to be in order of 106 erg/cm3. The Curie temperature T C and saturation magnetization M s at nanoscale are lower than those of the bulk and decrease with the increase of cobalt content. [Copyright &y& Elsevier]

Abstract: Ag/Co bimetallic nanoparticles in the form of hierarchical spherical structures were prepared by the polyol process using oleic acid and oleylamine as surfactants. The Ag/Co nanoparticles so obtained were characterized by X-ray diffraction (XRD), field-emission scanning electron microscope (FESEM), transmission electron microscope (TEM), UV–vis spectroscopy (UV–Vis), small angle X-ray scattering (SAXS), vibrating sample magnetometer (VSM) and super-conducting quantum interference device (SQUID). The XRD results in complement with the UV–vis studies indicated the absence of Ag–Co alloy formation during the synthesis. The FESEM observations depicted dense and uniform spherical granular structures for the Ag/Co nanoparticles; while the TEM studies apparently revealed a bimodal distribution of nanoparticles exist in the Ag/Co samples. The SAXS analysis on the Ag/Co colloids further validated the TEM results. The VSM studies showed typical ferromagnetic characteristics for the Ag/Co nanoparticles at room temperature; whereas the SQUID measurements demonstrated superparamagnetic nature for these nanoclusters with a blocking temperature close to 250K. The synthetic route presented in this work represents a simple means of producing bimetallic composite superstructures of Ag/Co nanoparticles in the form of spherical granules on a large scale. These spherical aggregates have the potential to be important building blocks for more complex nanostructures and would be interesting for magnetic studies and catalytic applications. [Copyright &y& Elsevier]

Abstract: In an austenitic Fe61.5Mn23Ni7Cr8.5 antiferromagnetic (afm) alloy deformation results in a splitting between magnetisation-vs.-temperature curves measured during field cooling (FC) below the Néel temperature and those measured at the same field after zero-field cooling (ZFC). Furthermore, a thermoremanent magnetisation (TRM) appears that corresponds to the splitting between zero-field and field cooled thermomagnetic measurements for a given cooling field and scales with the degree of deformation. This TRM is attributed to the deformation induced defects which act as a source of uncompensated magnetic moments and interact with the bulk afm moments. This interpretation is also supported by the fact that the net magnetic moments vanish above the Néel temperature. The TRM does not saturate in fields of up to 7T, applied during cooling, and cannot be switched by fields up to 7T. Within the investigated field range of −7T to 7T the magnetisation-vs.-field curves show a stable shift along the magnetisation axis. Thus, the uncompensated moments appear to be strongly exchange coupled to the afm matrix surrounding them. Within the series of experiments the maximum TRM reached after FC in 7T corresponds to about 4×10−4 μ B /atom (Bohr magneton) of the maximum deformed afm sample. The Néel temperature decreases due to deformation. [Copyright &y& Elsevier]

Abstract: Magnetic field dependence of the magnetic entropy change (ΔS M) is the key for magnetic refrigeration. A large magnetic entropy change (ΔS M) associated with the ferromagnetic-paramagnetic transition in Ce-doped La0.7Sr0.3MnO3 material has been observed. It is shown for (La0.56Ce0.14)Sr0.3MnO3 composition at the Curie temperature of 357K, that the maxima of the magnetic entropy changes upon variation of the applied magnetic field at 1 and 5T are about 1.55 and 4.78Jkg−1 K−1, respectively. Due to the large (ΔS M) and high Curie temperature, the (La0.56Ce0.14)Sr0.3MnO3 perovskite is suggested to be used as potential magnetic refrigerants for magnetic refrigeration technology above room temperature. [Copyright &y& Elsevier]

Abstract: The effects of the Mn content on the magnetic properties and microstructure of the Fe–Mn–Mo alloys have been investigated by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction, and Mössbauer spectroscopy. Experiments reveal that two types of thermal-induced martensites, ɛ (h.c.p.) and α′ (b.c.c.) martensites, form in the as-quenched alloys and these transformations have athermal characters. ɛ and α′ martensites coexist in the Fe–Mn–Mo alloys with 13.4–17.2wt%Mn content. However, the Mn content affects considerably the amount of martensites and the amount of α′ martensite decreases drastically while the amount of ɛ martensite increases with an increase in Mn content. Furthermore, only ɛ martensite appears in the case of 20.2wt%Mn. Mössbauer spectra of the alloys reveal a paramagnetic character with a singlet for the γ (f.c.c.) austenite and ɛ martensite phases and a ferromagnetic character with a broad sextet for α′ martensite phase. With an increase in Mn content, the magnetic character of the Fe–Mn–Mo alloys changes and the ferromagnetic character disappears completely in the case of 20.2wt%Mn. [Copyright &y& Elsevier]

Abstract: The magnetic behaviors of the paramagnetic dysprosium gallium garnet (DyGaG) are theoretically investigated in terms of an extensional molecular-field theory. The contribution of the exchange interaction between the dysprosium ions to the magnetic properties of DyGaG is further explored. Here, as to DyGaG, in our model, two magnetic sublattices A and B are suggested. The corresponding magnetic properties of the two magnetic sublattices are discussed, and it is found that χ A > χ B in DyGaG. Meanwhile, the exchange field coefficients λ 1 and λ 2 are qualitatively analyzed. The optimum fitting parameters α A and α B associated with the exchange interaction are provided, and some interesting conclusions about these parameters are drawn. Then, the available experiments are successfully fitted by our theoretical model. Additionally, an analysis of the high-field magnetic properties in DyGaG is presented. [Copyright &y& Elsevier]

Abstract: A low temperature chemical approach which beats the miscibility barrier of Fe and Mg has been designed to synthesize Fe–Mg2 nanoalloy and tested to result nanoparticles of average 30nm size. The nanoalloy is amorphous in nature and characterized by XPRD, AFM, magnetometery, Mössbauer and impedance spectroscopies. The result of magnetic measurement suggests the sample to be superparamagnetic as evidenced by the 57Fe Mössbauer spectroscopy. The two Mg atoms occupy different positions around iron resulting in two phase system as shown by Mössbauer and impedance spectroscopies. [Copyright &y& Elsevier]

Abstract: The magnetic behavior of Fe-doped TiO2 anatase nanoparticles (2.8 and 5.4at.%) was investigated throughout magnetizations versus applied field measurements between 2 and 300K temperatures. The experimental results were well-fitted by using the Brillouin function, giving rise to a moment per isolated Fe atom of about 5 μ B. The thermal evolution of the number of magnetic ions shows that a decrease of ions in paramagnetic state occurs below 50K for the most diluted sample. However for the 5.4at.% sample the fall even at room temperature is evident. These moments probably order antiferromagnetically via superexchange interactions. Taking into account the low concentration of dopant and the high fraction of interacting ions, a correlated substitution of Fe in cation sites of TiO2 structure needs to be considered. [Copyright &y& Elsevier]

Abstract: We report the magnetic characterization of ZnO nanopowders with an average grain size of about 50nm prepared by sol–gel method. At room temperature, ZnO nanopowders exhibit diamagnetism like bulk ZnO. However, strong paramagnetism was observed at 4K. With increasing temperature, ferromagnetic to paramagnetic transition happens at around 90K. Paramagnetism changes to diamagnetism at around 100K, which is due to the competition between the paramagnetism from defects and diamagnetism from the bulk ZnO. Our work clearly demonstrates that the interaction between the defects is short-range. Thus the interaction between the defects is weak due to low defect concentration. It is suggested that a high defect concentration is needed for room temperature ferromagnetism. [Copyright &y& Elsevier]

Abstract: The present study was focused to investigate the effect of Co concentration on structural and, magnetic properties of Co–SiO2 nanocomposite thin films. Co–SiO2 nanocomposite films with different cobalt atomic concentration up to 49at% were synthesized using direct current (DC) and radiofrequency (RF) magnetron co-sputtering. TEM and XRD analyses reveal the formation of both FCC (111) and HCP (101) phases in all the samples. The particle size and surface roughness of these films is found to increase with increase in cobalt concentration. Magnetic measurements reveal that the embedded cobalt nanoparticles behave as superparamagnets when their size is ≤16nm. The coercivity at 3K decreases while value of blocking temperature increases with increase in the size of embedded Co nanoparticles. [ABSTRACT FROM AUTHOR]