Search

• Nb5+-doped γ - Fe 2 O 3 were synthesized by sol–gel method. • As the Nb doping increases (≥3.8 at.%), the transformation from γ - Fe 2 O 3 to α-Fe 2 O 3 was suppressed up to 600 °C. • At elevated temperature of 700 °C, γ - Fe 2 O 3 went through full transformation to α-Fe 2 O 3 by expelling large amount of Nb to the surface of α-Fe 2 O 3 forming FeNbO 4. Nb5+-doped γ - Fe 2 O 3 was synthesized by sol–gel method followed by calcination at various temperatures from 200 to 700 °C, analyzed using Powder X-ray Diffraction (PXRD), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDS) and Mössbauer Spectroscopy. PXRD results show the formation of γ - Fe 2 O 3 at 300 °C and it begins to transform to α-Fe 2 O 3 at 350 °C for pure and 2 at.% Nb-doped samples. As the Nb doping increases (≥3.8 at.%), the transformation was suppressed up to 600 °C. TEM EDS confirms the incorporation of Nb to γ - Fe 2 O 3 lattice in 9.1 at.% Nb sample calcined at 500 °C. At elevated temperature of 700 °C, γ - Fe 2 O 3 went through full transformation to α-Fe 2 O 3 by expelling large amount of Nb to the surface forming FeNbO 4. TEM EDS confirms the compositional change during this process with reduced Nb content in α-Fe 2 O 3 and Nb-rich nanoparticle on the surface of α-Fe 2 O 3. Superparamagnetic properties were observed for Mössbauer spectra when the Nb doping increased, which is caused by decreased particle size. The slight increase in internal magnetic field also indicated the transformation from γ - Fe 2 O 3 to α-Fe 2 O 3. High Nb doping with 20 and 40 at.% shows the formation of FeNbO 4 at lower temperature where limited or almost no Nb substitution in α-Fe 2 O 3 was detected by EDS. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Fe 3 O 4 nanorods were produced from Fe(II) and Fe(III) ions using Salvia hispanica essential oil. • Advanced statistical methods were applied to find the optimal conditions for size-defined synthesis of Fe 3 O 4 nanorods. • The Fe 3 O 4 nanorods were characterized using TEM, EDX, SAED, XRD, SQUID, and ATR FT-IR. • Fe 3 O 4 nanorods displayed electromagnetic excitation, a feature useful for microwave-imaging of tissues. Abstract Salvia hispanica (chia) essential oil was applied for successful production of magnetic nanorods. The influence of several parameters, i.e. temperature of the reaction mixture, volume of the S. hispanica essential oil solution, stirring speed of the reaction mixture, and flow rate of the N 2 protective gas, on their axial length was studied. A design of experiments (DOE) approach followed by the response surface methodology (RSM) identified the optimal conditions for synthesis of ∼3 nm magnetic nanorods. The granulometric and magnetic properties of these magnetite nanorods were analyzed using transmission electron microscopy (TEM), energy dispersive X-ray scattering (EDX), selected area electron diffraction spectroscopy (SAED), X-ray diffraction (XRD), and superconducting quantum interference device (SQUID) magnetometer. These methods revealed that the produced magnetic nanorods had a crystalline cubic inverse spinel structure with an average axial length of 43.4 ± 20.5 nm, diameter of 3.6 ± 0.9 nm, and aspect ratio of 12.1 ± 5.2 nm, and they suggested the presence of spin glass-like (mictomagnetic) behavior with both ferro- and antiferromagnetic interactions. In addition, attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR) was used to identify functional groups of the organic compounds present in S. hispanica essential oil that were possibly responsible for production and surface functionalization of the magnetite nanorods. The resultant magnetic nanofluid displayed electromagnetic excitation when exposed to microwave radiation, and therefore it could be useful in microwave-imaging of tissues. [ABSTRACT FROM AUTHOR]

Highlights • Cobalt-doped α-Fe 2 O 3 particles exhibits unique hard magnetism. • Without calcination, its coercivity is found to increase as raising temperature. • After calcination, its coercivity falls into decline as temperature rise. • Defects in α-Fe 2 O 3 , Co colonies, FeOOH and CoFe 2 O 4 impurities are responsible. Abstract In this work, hard magnetism was studied on cobalt-doped α-Fe 2 O 3 particles, with special regard to the evolution of coercive fields as well as exchange bias fields. It was found that the coercivity of calcined sample fell into decline as temperature rose. Quite on the contrary, the sample prior to calcination exhibited a monotonical increment as increasing temperature. Further studies showed that lattice defects and voids in α-Fe 2 O 3 host, Co-doped α-Fe 2 O 3 colonies, FeOOH magnetic lattice, and CoFe 2 O 4 impurity phase were responsible for such significantly distinct magnetism evolution. The exhibited large coercivity beyond 10 kOe and pronounced exchange bias field of −660 Oe enabled us to gain deep insight into the transition metal doped magnetic semiconductor and to promote its full exploitation in magnetic-relevant applications. [ABSTRACT FROM AUTHOR]

Highlights • Impact of differently modified dextran coated nanoparticles on HEWL fibrillization. • Nanoparticles inhibit formation of HEWL fibrils in concentration-dependent manner. • Size of nanoparticles influenced the extent of their inhibitory properties. • The highest inhibitory effect was observed for the smallest CMdex NPs. • Dextran coated nanoparticles are not toxic at concentration close to IC 50 values. Abstract More than 50 diseases are associated with a conversion of proteins or peptides from their soluble functional states to highly organized fibrillar aggregates called amyloid fibrils. Due to the specific physico-chemical properties, specifically designed iron oxide nanoparticles may be an effective strategy for inhibiting the amyloid fibrillization of proteins. The inhibitory effect of three types of iron oxide nanoparticles coated with differently modified dextran on lysozyme fibrils formation was studied by Thioflavin T assay and atomic force microscopy. The size and zeta potential of studied nanoparticles were determined by dynamic light scattering. It had been found that nanoparticles are able to inhibit formation of lysozyme amyloid aggregates in concentration-dependent manner. Our results suggest that size of nanoparticles influenced the extent of their inhibitory properties. Moreover, the most effective nanoparticles were not toxic after 48 h incubation with neuroblastoma SH-SY5Y cell line at concentration close to IC 50 values. [ABSTRACT FROM AUTHOR]

Abstract Magnetic hyperthermia is one of the most effective methods for treatment of cancer. In this work we discuss synthesis of magnetic iron oxide nanorods (IONRds) and their application for enhanced magnetic hyperthermia. By microwave irradiation the monodisperse water-soluble IONRds with clear morphology were obtained. Magnetic measurements showed that such IONRds have high value of coercivity (141 Oe). Moreover, hyperthermia experiments with synthesized samples were carried out. At the frequency and field strength of alternating magnetic field (AMF) f = 261 kHz H = 20 kA m−1 the specific absorption rate (SAR) and intrinsic loss power (ILP) values were equal to 147 W g−1 and 1.4 nHm2 kg−1 respectively, which confirms the efficiency of synthesized nanorods in hyperthermia applications. [ABSTRACT FROM AUTHOR]

Tunable, one-dimensional (1D) nanofiller assembly using oscillating magnetic fields in the low frequency range (<5 Hz) is studied as a scalable and energy-efficient method to structure nanofillers within viscous matrices to deliver anisotropic, multi-functional polymer nanocomposites (PNCs). In this work 1D assembly tailoring was first experimentally studied and demonstrated using the model system of superparamagnetic iron oxide nanoparticles (SPIONs, 15 nm, 0.02–0.08 vol%) in DI water using varying magnetic fields (0–5 Hz frequency, 10–100 G magnetic flux density, and square and sinusoidal waveforms). In addition to lateral assembly of nanofillers, when the field oscillation is turned on, transverse assembly can be introduced as the magnetic moments of the particles respond to the changing fields by Brownian rotation. The degree of transverse assembly, in balance with lateral assembly and the resulting nanofiller patterns, was observed to be determined by the magnetic field parameters, magnetic responsiveness of the nanofillers, and the matrix viscosity. Based on this assembly study, PNCs consisting of ferrimagnetic iron oxide nanofillers in a thermoset polymer, with two different linear nanoparticle patterning, were successfully fabricated using small magnetic fields (<100 G) even in a viscous matrix (70 cP) with a short assembly time of 30 min. This work can contribute to scalable manufacturing and thus bulk application of multi-functional PNCs enabled by more precise nanofiller and interface structuring. [ABSTRACT FROM AUTHOR]

A co-precipitation synthesis method was used to obtain iron oxide nanoparticles coated with Yerba Mate ( Ilex paraguariensis ) extract. These particles have a core–shell structure with the iron oxide phase surrounded by an organic shell provided by an organic component which come from the Yerba Mate extract. Obtained nanoparticles were exhaustively characterized as powders and in aqueous colloidal suspensions using several techniques such as TEM, XRD, SAXS, TGA, ATR-FTIR, Raman and XPS spectroscopy, magnetic moment measurement and specimen ac susceptibility. All results together show that the obtained particles are single-crystal iron oxide particles with magnetite as the most probable phase. Yerba Mate extract shell mass to iron oxide core mass, m S /m c , could be increased up to 6.2 × 10 −2 , depending on the synthesis conditions. As a function of m S /m c the crystallite size of the nanoparticles decreased from about 15 nm to 11 nm, while saturation magnetization Ms and coercive field Hc of powders decreased . Ms. diminution was associated to increasing modification of core surface electronic states due to chemical bond of iron in iron oxide to Yerba Mate extract components; on the other hand, coercivity reduction was modelled on the basis of the increasing interparticle separation and dipolar interaction weakening, which occurs as shell thickness grows. Differences between the particle core mean size obtained with TEM, SAXS, XRD and magnetic measurements are observed. The fact that magnetic size was smaller than particle and crystallite sizes was attributed to the existence of intense dipolar interactions. It was found that low field susceptibility in a colloid sample was about 2.5 times that of the powder specimen, a result that shows that demagnetizing effects prevail in the powder specimen, while they may be absent in the colloid due to the larger interparticle mean separation expected in the latter. Analysis of powder and colloid susceptibility was done based on a recently developed model was in agreement with the one performed for the coercive field behaviour. [ABSTRACT FROM AUTHOR]

In this paper we report single step large scale synthesis of highly crystalline iron oxide nanoparticles viz. magnetite (Fe 3 O 4 ) and maghemite (γ-Fe 2 O 3 ) via gas phase condensation process, where micron sized iron metal powder was used as a precursor. Selective phases of iron oxide were obtained by variation of gas flow rate of oxygen and hence partial pressure of oxygen inside the plasma reactor. Most of the particles were found to possesses average crystallite size of about 20–30 nm. The DC magnetization curves recorded indicate almost super-paramagnetic nature of the iron oxide magnetic nanoparticles. Further, iron oxide nanoparticles were analyzed using Raman spectroscopy, X-ray photoelectron spectroscopy and Mossbauer spectroscopy. In order to explore the feasibility of these nanoparticles for magnetic damper application, rheological studies have been carried out and compared with commercially available Carbonyl Iron (CI) particles. The nanoparticles obtained by thermal plasma route show improved dispersion which is useful for rheological applications. [ABSTRACT FROM AUTHOR]

To realize magnetic hyperthermia as an alternate stand-alone therapeutic procedure for cancer treatment, magnetic nanoparticles with optimal performance, within the biologically safe limits, are to be produced using simple, reproducible and scalable techniques. Herein, we present a simple, one-step approach for synthesis of water-dispersible magnetic nanoclusters (MNCs) of superparamagnetic iron oxide by reducing of Fe 2 (SO 4 ) 3 in sodium acetate (alkali), poly ethylene glycol (capping ligand), and ethylene glycol (solvent and reductant) in a microwave reactor. The average size and saturation magnetization of the MNC’s are tuned from 27 to 52 nm and 32 to 58 emu/g by increasing the reaction time from 10 to 600 s. Transmission electron microscopy images reveal that each MNC composed of large number of primary Fe 3 O 4 nanoparticles. The synthesised MNCs show excellent colloidal stability in aqueous phase due to the adsorbed PEG layer. The highest SAR value of 215 ± 10 W/g Fe observed in 52 nm size MNC at a frequency of 126 kHz and field of 63 kA/m suggest the potential use of these MNC in hyperthermia applications. This study further opens up the possibilities to develop metal ion-doped MNCs with tunable sizes suitable for various biomedical applications using microwave assisted synthesis. [ABSTRACT FROM AUTHOR]

The doping of liquid crystals with magnetic nanoparticles increases the magnetic susceptibility and the sensitivity to small magnetic fields. This offers interesting possibilities for controlling optical properties via external magnetic fields. The stabilization of magnetic nanoparticles in the liquid crystalline host, however, is challenging, since magnetic dipolar interactions and LC-mediated forces may result in their aggregation and even phase separation. So far, only few groups have investigated the long-term stability of these systems. In the present study, a set of magnetic iron oxide nanoparticles with different particle size, shape and surface properties was synthesized by thermal decomposition or co-precipitation. The magnetic nanoparticles were further integrated in a model liquid crystalline host (i.e., the lyotropic system potassium laurate/1-decanol/water) to investigate the effect of the different particle parameters on the stability of the resulting ferrolyotrope. [ABSTRACT FROM AUTHOR]

We present a simple and rapid method for the synthesis of small magnetic nanoparticles (diameters in the order of 5–20 nm) and narrow size distributions (CV's of 20–40%). The magnetite nanoparticles were synthesized in green solvents within minutes and the saturation magnetization of the particles was tunable by changes in the reaction conditions. We show that this particle synthesis method requires minimal processing steps and we present the successful coating of the particles with reactive bisphosphonates after synthesis without washing or centrifugation. We found minimal batch-to-batch variability and show the scalability of the particle synthesis method. We present a full characterization of the particle properties and believe that this synthesis method holds great promise for facile and rapid generation of magnetic nanoparticles with defined surface coatings for magnetic targeting applications. [ABSTRACT FROM AUTHOR]

Ferrogel based on polacryamide network with embedded maghemite nanoparticles with mean number average particle diameter 12 nm was synthesized by radical polymerization in water-based ferrofluid. The network structure of ferrogel was characterized by Flory–Rehner theory and it was shown that the embedded particles were substantially larger than the mesh size. It prevented the translational movement of particles in the ferrogel. The immobilization of particles was confirmed by dynamic light scattering. The adhesion of macromolecular chains to the particles was determined by calorimetry using thermochemical cycle. The enthalpy of interfacial adhesion was found several orders of magnitude higher than the energy of dipoles in typically applied magnetic fields. Despite the differenve in the mobility of particles in ferrofluid and ferrogel the comparative study of their heating in alternating magnetic field, however, revealed their close similarity. In both cases it was goverened by superposing of Neel and Brownian relaxation mechanisms. [ABSTRACT FROM AUTHOR]

• Iron oxide films with variable magnetic anisotropy made by magnetron sputtering. • High resolution X-ray spectroscopy insights chemical phase composition. • Hard X-ray magnetometry extracts substrate-free magnetization profiles. • Coexistence of ferromagnetic and (super)paramagnetic components is proved. • Vertically elongated magnetite intrusions enhance perpendicular magnetic anisotropy. Texture-induced magnetic anisotropy is realized in iron oxide thin films deposited at room temperature onto Si(1 0 0) substrates using reactive magnetron sputtering of a Fe 2 O 3 target. Diversities in morphology and magnetic properties are evidenced by electron microscopy and vibrating sample magnetometry. Additional insight provided by X-ray absorption spectroscopy and X-ray magnetic circular dichroism reveals fundamental differences in chemical composition and element selective magnetic properties between the films deposited in the presence of Ar and N 2 reactive gas. Taking advantage of hard X-ray magnetometry, substrate-free magnetization profiles of the films were derived and deconvoluted into major magnetic components. In addition to ferromagnetic components with anisotropy defined by texture a significant contribution of (super)paramagnetic components due to rich interface structure of these nanocomposite films is observed. [ABSTRACT FROM AUTHOR]

• Size effect of iron oxide NPs (NP10, NP20, NP30, and NP40) was investigated in pumpkin. • TEM and VSM analyses revealed root-to-shoot translocation of all tested NPs. • NP30 exhibits the highest translocation performance, while a negligible amount of NP10 and NP40 reached to the leaves. • The status of nutrient elements significantly altered depend on NP-type. • The findings could be important for selecting the most suitable NP size for agricultural practices. The ability of nanoparticles (NPs) to migrate in the plant body is an important issue to ensure that the NPs reach the desired tissue and to be able to select the most efficient NPs for agricultural applications. In this study, the size impact of four different iron oxide NPs (8–10, 18–20, 20–40, and 30–50 nm referred as NP10, NP20, NP30, and NP40, respectively) on their translocation in pumpkin was elucidated. To assess the root-to-shoot translocation, phloem sap was examined under transmission electron microscope (TEM). In addition, vibrating sample magnetometer (VSM) and inductively coupled plasma optical emission spectrophotometry (ICP-OES) analyses of stem and leaf tissues were performed to confirm size-dependent translocation. TEM and VSM analyses verified root-to-stem translocation of all tested NPs. The NPs treatment significantly altered the abundances of Mn, Cu, K, P, Al, Mg, and Na in tissues. The iron (Fe) content was abundant in plants treated with NP30 and NP20, and the lowest in plants treated with NP10 and NP40. Together with, only NP30 was found to be significantly translocated to the leaves, where it was 393 mg/kg in DW, about 2.3 times that of control. These findings pointed out the size-dependent translocation of NPs. It seems that biological barriers in the vascular bundle appear to restrict the migration, especially for NPs with an average size of 40 nm and above in pumpkins. These findings are important for selecting the most suitable size of iron oxide NPs for use in agricultural practices. [ABSTRACT FROM AUTHOR]

The low cost and high output methods of high-power physical dispersion: the electrical explosion of wire and the laser target evaporation were elaborated for the production of iron oxide magnetic nanoparticles (MNPs) with controlled dispersion parameters and highly reproducible functional properties. The synthesized MNPs were spherical in shape with mean diameter 10 nm and lognormal particle size distribution. The phase composition, shape, particle size and functional properties of MNPs were cross-examined by a variety of contemporary experimental techniques. The phase structure of MNPs corresponds to the inverse spinel of magnetite. Meanwhile, due to the non-equilibrium conditions of the dispersion chemical composition of MNPs is close to maghemite—γ-Fe 2 O 3 . Their magnetic properties are reproducible and very close to the single domain superparamagnetic behavior. The stability of the suspensions of these MNPs and their applicability in the biophysical purposes such as magneto-induced heating have been demonstrated. [ABSTRACT FROM AUTHOR]

Magnetic nanoparticles can be efficient contrast agents for T2 weighted magnetic resonance imaging (MRI) after tuning of some key parameters such as size, surface state, colloidal stability and magnetization, thus motivating the development of new synthetic pathways. In this paper we report the effects of surface coating on the efficiency of two different types of iron based nanoparticles (NPs) as MRI contrast agents. Starting from well-defined hydrophobic iron oxide nanospheres and iron nanocubes of 13 nm size, we have used three methods to increase their hydrophilicity and transfer them into water: surface ligand modification, ligand exchange or encapsulation. The NPs obtained have been characterized by dynamic light scattering and transmission electron microscopy, and the relaxivities of their stable colloidal solutions in water have been determined. Among all samples prepared, iron nanocubes coated by silica display the highest relaxivity ( r 2 ) value: 628 s −1 mM −1 . [ABSTRACT FROM AUTHOR]

Abstract: Iron clusters produced in a laser vaporization source were deposited to form cluster-assembled thin films with different thicknesses on highly oriented pyrolytic graphite substrates. The development of oxidation of the clusters with time, up to three years, was investigated by magnetic measurements using an alternating gradient magnetometer. Furthermore, to receive information about the oxidation states, clusters of 57Fe were studied using Mössbauer spectroscopy. The magnetic analysis shows a time evolution of the saturation magnetization, remanence, and coercivity, determined from the hysteresis curves characteristic of a progressing oxidation. The different thicknesses of the iron cluster films as well as a protective layer of vanadium influence the magnetic properties when the samples are subjected to oxidation with time. While the saturation magnetization and remanence decrease and reach half the initial values for almost all the samples after three years, the coercivity increases for all samples and is more substantial for the thickest sample with a vanadium protective layer. This value is three folded after three years. Furthermore, based on a core–shell model and using the saturation magnetization values we have been able to quantitatively calculate the amount of the increase of Fe-oxide as a function of time. The Mössbauer spectroscopy shows peaks corresponding to iron metal and maghemite. [Copyright &y& Elsevier]

• Iron oxide nanoworms could contribute to CAR-T manufacturing and labeling in vitro. • CAR-T cytotoxicity to tumor cells is not affected by iron oxide nanoworms in vitro.. • CAR-T cells labeled with iron oxide nanoworms could be tracked in vivo. Cell based therapies including chimeric antigen receptor (CAR) T cells are promising for treating leukemias and solid cancers. At the same time, there is interest in enhancing the functionality of these cells via surface decoration with nanoparticles (backpacking). Magnetic nanoparticle cell labeling is of particular interest due to opportunities for magnetic separation, in vivo manipulation, drug delivery and magnetic resonance imaging (MRI). While modification of T cells with magnetic nanoparticles (MNPs) was explored before, we questioned whether MNPs are compatible with CAR-T cells when introduced during the manufacturing process. We chose highly aminated 120 nm crosslinked iron oxide nanoworms (CLIO NWs, ~36,000 amines per NW) that could efficiently label different adherent cell lines and we used CD123 CAR-T cells as the labeling model. The CD123 CAR-T cells were produced in the presence of CLIO NWs, CLIO NWs plus protamine sulfate (PS), or PS only. The transduction efficiency of lentiviral CD123 CAR with only NWs was ~ 23% lower than NW + PS and PS groups (~33% and 35%, respectively). The cell viability from these three transduction conditions was not reduced within CAR-T cell groups, though lower compared to non-transduced T cells (mock T). Use of CLIO NWs instead of, or together with cationic protamine sulfate for enhancement of lentiviral transduction resulted in comparable levels of CAR expression and viability but decreased the proportion of CD8 + cells and increased the proportion of CD4 + cells. CD123 CAR-T transduced in the presence of CLIO NWs, CLIO NWs plus PS, or PS only, showed similar level of cytotoxicity against leukemic cell lines. Furthermore, fluorescence microscopy imaging demonstrated that CD123 CAR-T cells labeled with CLIO NW formed rosettes with CD123 + leukemic cells as the non-labeled CAR-T cells, indicating that the CAR-T targeting to tumor cells has maintained after CLIO NW labeling. The in vivo trafficking of the NW labeled CAR-T cells showed the accumulation of CAR-T labeled with NWs primarily in the bone marrow and spleen. CAR-T cells can be magnetically labeled during their production while maintaining functionality using the positively charged iron oxide NWs, which enable the in vivo biodistribution and tracking of CAR-T cells. [ABSTRACT FROM AUTHOR]

Superparamagnetic iron oxide nanoparticles were synthesized by thermal decomposition of iron–oleate complex using triethylene glycol monobutyl ether (TREGBE) as solvent for the first time for more mass of the nanoparticles. The effect of TREGBE on the properties of the nanoparticles was compared with that of 1-hexadecene. The impact of oleic acid concentration on the properties of the nanoparticles was also studied. On the use of TREGBE as compared with 1-hexadecene, the average crystal size reduced from 9.1±2.1 to 8.2±0.7nm whereas the saturation magnetization (M s ) increased from 53.6 to 58.0emu/g. Moreover, more products can be synthesized using TREGBE. Besides, the interactions between particle surfaces and TREGBE are weaker than that of 1-hexadecene according to gravimetric analysis results. X-ray diffraction analysis revealed that crystallinity and particle size scaled up with increasing oleic acid amount in TREGBE. The electron microscopy showed that dot-shaped particles turned into irregular particles with increasing amount of oleic acid molecules using TREGBE. The results disclosed that TREGBE is quite a suitable solvent to synthesize the superparamagnetic iron oxide nanoparticles with the desired size and M s for more mass production at low temperature. [ABSTRACT FROM AUTHOR]

Abstract: Control doping of magnetic nanoparticles and its influence on optical and structural properties of tellurite glass is important from device perspectives. Natural Fe3O4 nanoparticles obtained by extracting and ball milling iron sand, are incorporated in the Er3+ doped tellurite glasses having composition (80−x)TeO2·xFe3O4·18ZnO·1Li2O·1Er2O3 (0≤x≤1.5) in mol% by melt quenching method at 850°C. X-Ray diffraction spectra confirms the presence of iron nanoparticles with estimated sizes 18–70nm and an amorphous structure of the samples. Thermal and optical characterizations are made using diffential thermal analysis, ultraviolet–visible and photoluminescence spectrocopies. It is found that the presence of nanoparticles changes color and thermal stability of the glasses, which is proved by increasing thermal stability factor from 118 to 132°C. Absorption spectra consist of six peaks corresponding to different transition from ground state to the excited states in which the quench of the peak associated with 4F1/2 is attributed to the effect nanoparticles. Moreover, the shift in the absorption edge from ∼400 to ∼500nm indicates a significant decrease of the optical energy band gap for both direct and indirect allowed transitions and a decrease in the Urbach energy as much as 0.116eV is observed. The room temperature down-conversion luminescence spectra obtained under 500nm excitation exhibit two strong peaks related to excited states 4S3/2 and 4F9/2 of Er3+ ions in the absence of nanoparticles. Furthermore, embedding nanoparticles into the glass not only make the peaks weaker but the second peak completely disappears. Interestingly, the emission bands of the Er3+ ion are quenched as concentration of the magnetic nanoparticles is increased. [Copyright &y& Elsevier]

Abstract: Magnetic particles based on Fe3O4 were prepared by means of the microwave solvothermal method under different reaction conditions with the intention of their utilization as a mediator in magnetic hyperthermia and material for reducing blood flow in the tumor area. The synthesized particles were characterized in terms of their structure, size, shape, and magnetic properties with an emphasis on the correlation between particle morphology and magnetic properties. Most importantly, their heat development when exposed to an alternating magnetic field was determined, as well as the rheological behavior of their suspensions under static magnetic field. Reasonable heat development and substantial flow resistance under the effect of magnetic field indicate their potential for applications such as hyperthermia mediators or substances for temporary embolization. [Copyright &y& Elsevier]

Abstract: Magnetic particles play nowadays an important role in different technological areas with potential applications in fields such as electronics, energy and biomedicine. In this report we will focus on the hyperthermia properties of magnetite nanoparticles and the effect of several chemical/physical parameters on their heating properties. We will discuss about the need of searching new smaller magnetic systems in order to fulfill the required physical properties which allow treating tumoral tissues more efficiently by means of magnetically induced heat. Preliminary results will be shown about the effect of a biocompatible shell of core–shell magnetite NPs on the heating properties by application of a RF magnetic field. [Copyright &y& Elsevier]

Abstract: Samples of ferrofluids containing chemically stabilized nanoparticles of magnetite (Fe3O4) with tetramethylammonium hydroxide (TMAOH) were prepared by a direct reduction–precipitation method. The influences of aging time and temperature on the size and monodispersion characteristics of the produced nanoparticles were investigated. Transmission electron microscopy, powder X-ray diffraction, Fourier-transform infrared, and magnetization measurements with applied magnetic field up to 2T were used to characterize the synthesized iron oxides. Raising the temperature of the synthesized material in autoclave affects positively the monodispersion of the nanoparticles, but it was not found to significantly influence the size itself of individual particles. [Copyright &y& Elsevier]

Abstract: Iron oxide magnetic nano-particles (MNPs) have been prepared in aqueous solution by a modified co-precipitation method. Surface modifications have been carried out using tetraethoxysilane (TEOS), triethoxysilane (TES) and 3-aminopropyltrimethoxysilane (APTMS). The uncoated and coated particle products have been characterized with transmission electron microscope (TEM), energy dispersive X-ray (EDX) spectroscopy, infrared (IR) and Raman spectroscopy, and thermal gravimetric analysis (TGA). The particle sizes were determined from TEM images and found to have mean diameters of 13, 16 and 14nm for Fe3O4, TES/Fe3O4 and APTMS/Fe3O4, respectively. IR and Raman spectroscopy has been applied to study the effect of thermal annealing on the uncoated and coated particles. The results have shown that magnetite nano-particles are converted to maghemite at 109°C and then to hematite by 500°C. In contrast, the study of the effect of thermal annealing of micro-crystalline magnetite by IR spectroscopy revealed that the conversion to hematite began by 300°C and that no maghemite could be identified as an intermediate phase. IR spectra and TGA measurements revealed that the Si–H and 3-aminopropyl functional groups in TES and APTMS coated magnetite nano-particles decomposed below 500°C while the silica layer around the iron oxide core remained unchanged. The molecular ratio of APTMS coating to iron oxide core was determined to be 1:7 from the TGA data. Raman scattering signals have indicated that MNPs could be converted to maghemite and then to hematite using increasing power of laser irradiation in a manner similar to that observed for thermal annealing. [Copyright &y& Elsevier]

Abstract: Magnetic hydrogel composites are promising candidates for a broad field of applications from medicine to mechanical engineering. Here, surface-attached composite films of magnetic nanoparticles (MNP) and a polymeric hydrogel (HG) were prepared from magnetic iron oxide nanoparticles and a carboxymethylated dextran with photoreactive benzophenone substituents. A blend of the MNP and the dextran polymer was prepared by mixing in solution, and after spin-coating and drying the blend film was converted into a stable MNP–HG composite by photocrosslinking through irradiation with UV light. The bulk composite material shows strong mobility in a magnetic field, imparted by the MNPs. By utilizing a surface layer of a photoreactive adhesion promoter on the substrates, the MNP–HG films were covalently immobilized during photocrosslinking. The high stability of the composite was documented by rinsing experiments with UV–Vis spectroscopy, while surface plasmon resonance and optical waveguide mode spectroscopy was employed to investigate the swelling behavior in dependence of the nanoparticle concentration, the particle type, and salt concentration. [Copyright &y& Elsevier]

Abstract: Thermal decomposition of the trinuclear complex [Fe2CrO(CH3COO)6(H2O)3]NO3 at 300, 400 and 500°C gave γ-Fe2O3 nanoparticles along with amorphous chromium oxide, while decomposition of the same starting compound at 600 and 700°C led to the formation of α-(Fe2/3Cr1/3)2O3 nanoparticles. Size of γ-Fe2O3 nanoparticles, determined by X-ray diffraction, was in the range from 9 to 11nm and increased with formation temperature growth. Average size of α-(Fe2/3Cr1/3)2O3 nanoparticles was about 40nm and almost did not depend on the temperature of its formation. γ-Fe2O3 nanoparticles possessed superparamagnetic behavior with blocking temperature 180–250K, saturation magnetization 29–35emu/g at 5K, 44–49emu/g at 300K and coercivity 400–600Oe at 5K. α-(Fe2/3Cr1/3)2O3 nanoparticles were characterized by low magnetization values (2.7emu/g at 70kOe). Such magnetic properties can be caused by non-compensated spins and defects present on the surface of these nanoparticles. The increase of α-(Fe2/3Cr1/3)2O3 formation temperature led to decrease of magnetization (being compared for the same fields), which may be caused by decrease of the quantity of defects or non-compensated spins (due to decrease of particles'' surface). [Copyright &y& Elsevier]

Abstract: Radio-frequency heated magnetic nanoaparticle suspensions have potential applications in cancer hyperthermia. To optimize these systems for hyperthermia applications it is important to be able to predict how their heat generation or specific absorption rate (SAR) is influenced by various factors, including nanoparticle coating or functionalization and aggregation. However, at present it is unclear how well-existing models predict experimental SAR results. Direct comparisons between predicted and measured SAR are scarce, despite an abundance of works reporting on heat generation rate of various magnetic nanoparticles suspensions. The main objective of this paper is to experimentally assess the validity of current models for SAR and extract information on the effects of coating and aggregation on heat generation rate. In this context, AC susceptibility and magnetization of suspensions of uncoated particles, as well as particles with aminosilane and carboxymethyl-dextran functionalizations, were measured. These properties were then used to predict the heat generation rate in alternating magnetic field starting from first principles, which was then compared to measured SAR. It was found that experimental SAR agrees relatively well with predictions (by a factor of two) when using experimental susceptibility values for the SAR calculation. However, for uncoated and amine-functionalized particles poor agreement (more than an order of magnitude difference) was found when the experimental susceptibility was substituted with predictions based on the Debye model. This apparent discrepancy is attributed to dipolar interactions between nanoparticles within aggregates in these samples, which enhances the imaginary part of the susceptibility and, consequently, the SAR values. The results also suggest that the thermal resistance effect of the coating has little influence on the SAR. [Copyright &y& Elsevier]

Abstract: Magnetic iron oxide nanoparticles are promising tools for medical applications like hyperthermia or magnetic drug targeting. The relevant properties in these applications strongly depend on particle size and size distribution. In order to investigate the influence of mean size as well as size distribution, iron oxide powders from particles by a cyclic method based on “conventional” precipitation from Fe-salt solution were prepared. Increasing mean particle size with increasing number of cycles is confirmed by XRD. Magnetic parameters of the saturation hysteresis loop, hysteresis losses calculated from minor loops and switching field distributions are shown. A fractionation experiment on a fluid sample of particles prepared by 3 cycles was carried out in order to improve the hysteresis losses. [Copyright &y& Elsevier]

Abstract: We demonstrate a single-step facile approach for the fabrication of citric acid functionalized (citrate-stabilized) Fe3O4 aqueous colloidal magnetic nanoparticles (CA-MNP) of size 8–10nm using soft chemical route. The surface functionalization of Fe3O4 nanoparticles with citric acid was evident from infrared spectroscopy, thermal and elemental analyses, and zeta-potential measurements. The drug-loading efficiency of CA-MNP was investigated using doxorubicin hydrochloride (DOX) as a model drug to evaluate their potential as a carrier system. The quenching of fluorescence intensity and decrease in surface charge of drug loaded CA-MNP strongly suggest the interaction/attachment of drug molecules with CA-MNP. More specifically, the present investigation discusses a method for entrapping positively charged drugs onto the surface of negatively charged CA-MNP through electrostatic interactions and suggests that bound drug molecules will be released in appreciable amounts in the mild acidic environments of the tumors. Furthermore, the aqueous colloidal stability, optimal magnetization, good specific absorption rate (under external AC magnetic field) and cytocompatibility with cells suggested that CA-MNP is appropriate candidate for biomedical applications. [ABSTRACT FROM AUTHOR]

Abstract: Mesoporous molecular sieves of MCM-48 type were loaded with iron by the wet impregnation method, using Fe(III) nitrate or Fe(II) sulfate aqueous solutions as Fe sources, to obtain a magnetic porous composite. The iron loaded materials were characterized by XRD, N2 adsorption and DRUV-vis and compared with the Si-MCM-48 host. Their magnetic properties were studied by measuring the hysteresis loops up to 1.5T at different temperatures (5–300K) and by magnetization vs. temperature curves following the conventional zero field cooling (ZFC) and field cooling (FC) protocols. Materials with high structure regularity and surface area are obtained, which exhibit a mixed paramagnetic and superparamagnetic behavior, arising in isolated iron ions inserted in the host framework, and in small iron oxide clusters or nanoparticles forming inside the pores, respectively. Larger hematite particles (8–13nm) grown on the external surface provide a quite small ferromagnetic contribution to the hysteresis loop. [ABSTRACT FROM AUTHOR]

Abstract: Materials containing hybrid spheres of aluminum oxide and superparamagnetic nanoparticles of iron oxides were obtained from a chemical precursor prepared by admixing chitosan and iron and aluminum hydroxides. The oxides were first characterized with scanning electron microscopy, X-ray diffraction, and Mössbauer spectroscopy. Scanning electron microscopy micrographs showed the size distribution of the resulting spheres to be highly homogeneous. The occurrence of nano-composites containing aluminum oxides and iron oxides was confirmed from powder X-ray diffraction patterns; except for the sample with no aluminum, the superparamagnetic relaxation due to iron oxide particles were observed from Mössbauer spectra obtained at 298 and 110K; the onset six line-spectrum collected at 20K indicates a magnetic ordering related to the blocking relaxation effect for significant portion of small spheres in the sample with a molar ratio Al:Fe of 2:1. [Copyright &y& Elsevier]

Abstract: Citric acid coated magnetite nanoparticles were synthesized using a one-step and two-step co-precipitation method at different temperatures. The stability of the nanoparticles in aqueous media was compared. The magnetic heating characteristics in an alternating magnetic field were examined and specific absorption rates were determined. The nanoparticles were characterized by various techniques (Fourier transform infrared, UV spectrophotometry, thermogravimetric analysis, dynamic light scattering, transmission electron microscopy, X-ray diffraction and vibrating sample magnetometry). The temperature of synthesis and mode of functionalizing the particles affected their physical and magnetic properties. Higher temperatures led to increased specific absorption rates for both methods but more stable hydrophilic superparamagnetic nanoparticles were obtained in the one-step method. [Copyright &y& Elsevier]

Abstract: A magnetic field of 12T was applied during the annealing of amorphous α-Fe2O3 microspheres. The authors demonstrate that magnetic field processing leads to the formation of γ-Fe2O3 phases in the microspheres, and the field-treated microspheres exhibit typical room-temperature ferromagnetic behavior, whereas non-field-heated sample presents paramagnetism. The improvement in magnetic properties is considered to be a result of magnetic field-induced transformation from α-Fe2O3 to γ-Fe2O3. [Copyright &y& Elsevier]

Abstract: Rhenium sulfide nanoparticles are associated with magnetic iron oxide through coprecipitation of iron salts with tetramethylammonium hydroxide. Sizes of the formed magnetic rhenium sulfide composite particles are in the range 5.5–12.5nm. X-ray diffraction and energy-dispersive analysis of X-rays spectra demonstrate the coexistence of Fe3O4 and ReS2 in the composite particle, which confirm the formation of the magnetic rhenium sulfide composite nanoparticles. The association of rhenium sulfide with iron oxide not only keeps electronic state and composition of the rhenium sulfide nanoparticles, but also introduces magnetism with the level of 24.1emug–1 at 14kOe. Surface modification with monocarboxyl-terminated poly(ethylene glycol) (MPEG-COOH) has the role of deaggregating the composite nanoparticles to be with average hydrodynamic size of 27.3nm and improving the dispersion and the stability of the composite nanoparticles in water. [Copyright &y& Elsevier]

Abstract: The identification by 57Fe internal field nuclear magnetic resonance (NMR) of hyperfine fields at four Fe sites in the (average) tetragonal unit cell of vacancy-ordered γ-Fe2O3 (maghemite) is reported. The effects of vacancy redistribution due to annealing the partially vacancy-ordered form has been observed in the 57Fe lineshape. In addition, the reduction of the particle size of the vacancy-ordered form has been observed to gradually eliminate the vacancy ordering and then to cause a transition from ferrimagnetism to superparamagnetism. [Copyright &y& Elsevier]

Abstract: We report a novel flocculation–redispersion method to synthesize and purify the biocompatible superparamagnetic ultrasmall iron oxide (USPIO) nanoparticles coated with carboxyl dextran derivative. First, USPIO nanoparticles were synthesized and flocculated to form the large clusters through bridging effect of polyvinyl alcohol (PVA) during coprecipitation process. Then the flocculated USPIO was separated and purified from the solution conveniently through magnetic sedimentation. Finally, USPIO in the clusters were released again and well dispersed through electrostatic repelling effect of citric acid with the aid of ultrasonic. The dispersed carboxyl-functionalized USPIO was conjugated with the monoclonal antibodies. And it has been proved that the antibodies anchored on USPIO still retained their bioactivity after the conjugation. These results implied that the USPIO synthesized have good potential as active targeting molecular probe in biomedical application. [Copyright &y& Elsevier]

Abstract: In this study, a new method is proposed for the preparation of Fe3O4 from iron oxyhydroxides (goethite, akaganeite, lepidocrocite, feroxyhyte and ferrihydrite) or iron oxide (hematite) and ferrous salt in aqueous solution. The product is magnetite with various particle sizes. Products are characterized by X-ray powder diffraction, IR spectra and vibrating sample magnetometery. [Copyright &y& Elsevier]

Abstract: We demonstrate a single-step facile approach for highly water-stable assembly of amine-functionalized Fe3O4 nanoparticles using thermal decomposition of Fe-chloride precursors in ethylene glycol medium in the presence of ethylenediamine. The average size of nanoassemblies is 40±1nm, wherein the individual nanoparticles are about 6nm. Amine-functionalized properties are evident from Fourier transform infrared spectrometer (FTIR), thermal and elemental analyses. The saturation magnetization and spin-echo r 2 of the nanoassemblies were measured to be 64.3emu/g and 314.6mM−1 s−1, respectively. The higher value of relaxivity ratio (r 2/r 1=143) indicates that nanoassemblies are a promising high-efficiency T2 contrast agent platform. [Copyright &y& Elsevier]

Abstract: Commercial nanoparticles supplied by Chemicell, Micromod and Bayer-Schering were characterised with regard to their nanocrystalline diameter, hydrodynamic diameter, total iron content and relative ferrous iron content. Additionally, calorimetric measurements were taken using a 900kHz AC magnetic field of amplitude 5.66kA/m. It was found that those samples containing relatively high (>18%) ferrous content generated a substantially smaller (12% on average) intrinsic loss power (ILP) than those samples with a lower ferrous content. Two nominally identical Chemicell samples that differed only in their production date showed significantly different ILPs, attributed to a variation in batch-to-batch crystallite sizes. The highest ILP values in the cohort, ca. 3.1nHm2/kg, were achieved for particles with hydrodynamic diameters of ca. 70nm and nanocrystalline diameters of ca. 12nm. These compare favourably with most samples prepared in academic laboratories, although they are not as high as the ca. 23.4nHm2/kg reported for naturally occurring bacterial magnetosomes. [Copyright &y& Elsevier]

Abstract: We present the results of the interaction of iron oxide nanoparticles with some biologically active surfactants, namely, oleic acid and cytotoxic alkanolamine derivatives. Physico-chemical properties, as magnetization, magnetite concentration and particle diameter, of the prepared magnetic samples were studied. The nanoparticle size of 11nm for toluene magnetic fluid determined by TEM is in good agreement with the data obtained by the method of magnetogranulometry. In vitro cytotoxic effect of water-soluble nanoparticles with different iron oxide:oleic acid molar ratio were revealed against human fibrosarcoma and mouse hepatoma cells. In vivo results using a sarcoma mouse model showed observable antitumor action. [Copyright &y& Elsevier]

Abstract: Magnetic glyconanoparticles were synthesized via the co-precipitation method. Iron (II) and iron (III) chloride were co-precipitated out of solution by the addition of ammonium hydroxide in an aqueous solution containing carbohydrate stabilizers such as d-gluconic acid, lactobionic acid and Ficoll® at 75–80°C. Stable magnetic glyconanoparticles were formed in a simple and direct process. Dynamic light scattering and transmission electron microscopy were used to characterize the surface-coated magnetic nanoparticles. In vitro cell viability studies of the glyconanoparticles were conducted with the mouse fibroblast cell lines. The magnetic glyconanoparticles revealed to be non-toxic at a concentration as high as 0.1mg/mL. [Copyright &y& Elsevier]

Abstract: The CO2 laser evaporation technique is not only well suited for the production of magnetic iron oxide nanopowders, but also allows for their conditioning. Two optional methods, the ‘in situ’ coating and the co-laser evaporation, are introduced. Laser-generated magnetic Fe x O y nanoparticles very frequently form chain-like structures, which were stabilized by ‘in situ’ coating with stearic acid. A first attempt was made to align these chains in a magnet field before the coating process. Homogeneous hematite/silica mixtures were co-laser evaporated in order to embed Fe x O y nanoparticles in a silica matrix. The produced nanopowders were analyzed with TEM, X-ray diffraction (XRD), and magnetic measurements. [Copyright &y& Elsevier]

Abstract: Ferromagnetic iron oxide nanoparticles of about 33nm in diameter were synthesized by high-temperature decomposition of an iron–oleate complex, using octadecene as the solvent. These particles were subsequently coated with polyN-isopropylacrylamide (pNIPAAm) by a surfactant exchange method. Temperature-sensitive behavior of these particles was studied using ac susceptibility and dynamic light scattering (DLS) measurements. Shifts in the imaginary part of the ac susceptibility are correlated with swelling and collapse of pNIPAAm as a function of temperature. [Copyright &y& Elsevier]

Abstract: Superparamagnetic nanoparticles have been widely applied in various bio-medical applications. To date, it is still a challenge to synthesize nanosized Fe3O4 particles with controlled size and distribution. In this paper, a novel solvent-free thermal decomposition method is reported for synthesizing Fe3O4 nanoparticles. Size and morphology of the nanoparticles are determined by TEM while the structure of the nanoparticles is identified by FTIR, XPS and TGA measurements. Magnetic properties of the obtained particles are determined using VSM and SQUID measurement. The particle size of the Fe3O4 can be tailored by adjusting either reaction temperature or time. When the reaction temperature is increased to 330°C and the reaction time is extended to 4h, the average particle size of the obtained nanoparticles is ∼9nm, while Ms value reaches ∼76emu/g. The as synthesized Fe3O4 nanoparticles show well-established superparamagnetic properties with the blocking temperature at around 100K. [Copyright &y& Elsevier]

Abstract: Angle-dependent electron magnetic resonance was performed on 4.9, 8.0, and 19nm iron oxide nanoparticles encapsulated within protein capsids and suspended in water. Measurements were taken at liquid nitrogen temperature after cooling in a 1T field to partially align the particles. The angle dependence of the shifts in the resonance field for the iron oxide nanoparticles (synthesized within Listeria-Dps, horse spleen ferritin, and cowpea chlorotic mottle virus) all show evidence of a uniaxial anisotropy. Using a Boltzmann distribution for the particles’ easy-axis direction, we are able to use the resonance field shifts to extract a value for the anisotropy energy, showing that the anisotropy energy density increases with decreasing particle size. This suggests that surface anisotropy plays a significant role in magnetic nanoparticles of this size. [Copyright &y& Elsevier]

Abstract: The aim of this research is to elucidate the size effect of magnetic nanoparticles on the resultant magneto-dielectric properties of polymer nanocomposites at radio frequencies. The block copolymer of [styrene-b-ethylene/butylene-b-styrene] (SEBS) was utilized as a matrix for the templating of magnetic nanoparticles. Surfactant-modified iron oxide () nanoparticles of various sizes were successfully synthesized by a seed-mediated growth method. The surfactant prevented aggregation and provided compatibility with the polymer matrix. The nucleation and growth of nanoparticles was controlled by changing the concentration ratio of surfactant to iron-precursor. The free iron ions present during synthesis are the major factor contributing to the growth of larger particles. The nanoparticle critical size for superparamagnetic to ferrimagnetic transition was determined to be near 30nm at room temperature. The dielectric permittivity of the polymer composite increased with increasing amount of doping, and was not influenced by nanoparticle size. However, the magnetic permeability () of the composites was significantly influenced by the size of nanoparticles templated within the block copolymer matrix due to thermal energy fluctuations from the nanoparticle surroundings. [Copyright &y& Elsevier]

Abstract: A ferrofluid (FF) was synthesized in air using a co-precipitation method. Some rheological properties and magnetoviscous effects of this sample were studied. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used for characterization of the solid particles, and the rheological properties were investigated with a special rheometer with variable magnetic field. Magnetic particles with mean particle size of 10.6nm were obtained. Rheological results show that the shear thinning behavior in the absence and presence of magnetic field is different from that based fluid behavior. Moreover, contrary to expectation, the magnetoviscous effect showed an initial increase at low shear rates (near 15s−1) and decrease at higher shear rates. The rheological properties of FF depend on the rearrangement of nanoparticles. In addition, time is an effective factor in the formation and destruction of magnetically induced structures. [Copyright &y& Elsevier]

Abstract: The preparation of superparamagnetic magnetite (Fe3O4) nanoparticles by electro-precipitation in ethanol is proposed. Particle average size can be set from 4.4 to 9nm with a standard deviation around 20%. Combination of wide-angle X-ray scattering (WAXS), Electron energy loss spectroscopy (EELS) and Mössbauer spectroscopy characterizations clearly identifies the particles as magnetite single-crystals (Fe3O4). [Copyright &y& Elsevier]

In this work, we have reported a novel observation of diffraction patterns when a laser is passed through dilute ferrofluids. An experimental set up has been built to study the static magneto-optical properties of ferrofluids. The effect of size distribution and dilution of ferrofluids on the diffraction pattern has been investigated. [Display omitted] • Diffraction patterns observation in FFs with varying size and dilutions. • Novel method for the investigation of chain formation in FFs. • Use of high-power laser to investigate the static MO properties of FFs. This article proposes a novel approach to investigate the field-induced structuration in ferrofluids (FFs) at room temperature. The in-house experimental setup has been fabricated to perceive the influence of dipolar interaction and particle size of dispersed magnetic nanoparticles (MNPs) in FFs on the static magneto-optical (MO) properties under the influence of an external magnetic field. The diffraction fringes are observed in FF when a high-power laser passing from the diluted fluid system which appearing at a specific dilution and varies with the different sizes and volume fraction of MNPs. The change in shape and size of the diffraction fringes is observed with the variation of both, size of dispersed MNPs and the Dilution of the FFs which is used to calculate the refractive index coefficient. The number of diffraction rings increases with an increase in the size of dispersed MNPs and its diameter decrease with an increase in particle volume fraction. The effect of thermal lens and nonlinear optical (NLO) behavior gives the validation of field-induced refractive index coefficient appearing in FFs commutated by the fringe diffraction method. Further, the variation of intensity of transmitted light has been corroborated with the forward scattering resulting from the Brownian motion of the nanoparticle. The experiment validates the chain formation in FFs, as MNPs are working as mesoscopic cylinders resulting in specified scattering patterns. This experimental approach can lead to a new pathway for the development of potential applications such as tunable optical filters, optical limiters, and various photonics fields based on the tunable MO properties of FFs. [ABSTRACT FROM AUTHOR]

Abstract: Iron oxide nanoparticles of diameter 14nm were synthesized by applying Pt seed-assisted heterogeneous thermal decomposition of Fe(CO)5 in a two-stage procedure. The intense heating treatment resulted in a remarkable mean volume increment compared to previous studies. This method is able to control the nanoparticle mean diameter, keeping the demand for thermal energy at low levels. High-resolution electron microscopy images and the corresponding electron diffraction patterns revealed the appearance of a FePt3 core in each nanoparticle, surrounded by highly crystallized inverse spinel Fe3O4 formed after atmospheric oxidation, as shown by a combination of X-ray diffraction and chemical analysis. Magnetic measurements indicated that the presence of Pt-rich core does not cause any visible modification to the values of saturation magnetization and anisotropy constant of nanoparticles, compared to homogeneously nucleated iron oxide particles of the same size. [Copyright &y& Elsevier]