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Oil-water emulsion causes a wide range of problems, one of which is the emergence of significant decreases in pressure in flow lines resulting in higher pumping and transportation costs. The most widely developed trend among oil/water separation technologies is using demulsifiers based on magnetic nanoparticles (MNPs). MNPs have specific chemical and mechanical properties, providing unique opportunities to solve oil production issues. The key features of such magnetic nanoparticles for their sustainable application are their reusability and stability; the opportunity of remote manipulation using external magnetic fields gives them a singular benefit in transport operations. The main objective of the study is the systematization of MNPs researches for effective oil and water emulsion separation. This review provides MNP demulsifier characteristics, Oil-water emulsions (OWE) separation mechanism, and factors influencing oil-water emulsions efficiency disruption by MNP demulsifier. The relevance of this study is that oil-water emulsions are often encountered in practice during field development. To solve this problem, the use of demulsifiers based on magnetic nanoparticles is proposed. The novelty of the work lies in the fact that the work collects several factors affecting demulsification at once and describes the impact of each factor. Among these factors, the most influential are: emulsion characteristics, water salinity, pH, reservoir temperature, addition of chemical surfactants, time and magnetic field. The mechanism of formation of oil-water emulsions of various types is also described, and negative consequences of emulsion formation are discussed. The results showed that the magnetic nanoparticles need a protective layer and the demulsifier should have good wettability by the continuous phase of the emulsion. [ABSTRACT FROM AUTHOR]

CoCr2O4 is a normal spinel where Co occupies the tetrahedral (A) site and Cr occupies the octahedral (B) site; it is important to examine the cation distribution and magnetic properties by substituting a non-magnetic ion like Zn. In this context, we have synthesized pure phase ZnxCo1-xCr2O4 (x = 0.05, 0.1) of crystallite size 10 nm through conventional co-precipitation technique. Fourier transform of Co, Zn, and Cr K-edge spectra obtained from extended X-ray absorption fine structure demonstrates that while Co and Zn prefer the A site, Cr strongly occupies the B site. The paramagnetic to long range ferrimagnetic transition, TC, decreases from 97 K in CoCr2O4 (bulk) to 87.4 K at x = 0.1 with an intermediate TC of 90 K at x = 0.05. The decrease in TC is ascribed to decrease in A-B exchange interaction confirming the preferential occupation of Zn2+ ions towards the A site. The spin-spiral transition, TS, decreases from 27 K in bulk (CoCr2O4) to 24 K at x = 0.1 followed by a spin lock-in transition, TL, observed at 10 K which remains unchanged with increase in Zn concentration. The diffuse neutron scattering in both compositions shows the evidence of long range spiral ordering in contrast to the simultaneous formation of long and short range order in single crystals of CoCr2O4. The decrease in maximum magnetization from 9 to 8 emu/g and an increase in coercivity from 3.2 to 5.2 kOe at 2 K with an increasing Zn concentration from 0.05 to 0.1 have been explained by considering the Yafet-Kittel model. [ABSTRACT FROM AUTHOR]

Multiferroic samples with composition (1-x)BiFeO3-(x)(Ba0.70Sr0.30)TiO3 (BFO-BST) were synthesized using a sol-gel route to study the effect of BST doping on structural, transport, and magnetic properties in BiFeO3 (BFO). X-ray diffraction studies with Rietveld analysis revealed that a phase transition occurred from rhombohedral (R3c) (0.0 ≤ × ≤ 0.15) to tetragonal (P4 mm) for x = 0.20 and nanocrystalline nature confirmed by transmission electron microscopy measurements. Piezoelectric properties improved as x increased from x = 0.0 (58 pC/N) to x = 0.20 (112 pC/N) increasing distortion in the crystal structure as evinced by Williamson-Hall analysis. Ferromagnetism was observed in doped BFO, different from the antiferromagnetic ordering in bulk BFO, indicating the noteworthy size effects and Fe-O-Fe bond angle variations in the magnetic ordering of BFO. An improvement in ferroelectric properties is observed with doping of BST compared to pristine BFO. Thermally activated conduction behavior occurred at low and high temperature regions as revealed by temperature dependent dc resistivity measurement. Effective improvements in dielectric response, meaning high dielectric constant with a low dielectric loss, were found in the doped samples. [ABSTRACT FROM AUTHOR]

As is known, the multi-sublattice structure of antiferromagnets (AFMs) entails that, under size diminution to the nanoscale, compensation of the sublattice magnetizations becomes incomplete. Due to that, the nanoparticles acquire small, but finite permanent magnetic moments. An AC field applied to such particles induces their magnetic response, the measurement of which is well within the sensitivity range of the experimental technique. Given the small size of the particles, their magnetodynamics is strongly affected by thermal fluctuations, so that their response bears a considerable superparamagnetic contribution. This specific feature is well-known, but usually is accounted for at the estimation accuracy level. Herein, a kinetic model is proposed to account for the magnetic relaxation of AFM nanoparticles, i.e., the processes that take place in the frequency domain well below the magnetic resonance band. Assuming that the particles possess uniaxial magnetic anisotropy, the expressions for the principal components of the both linear static and dynamic susceptibilities are derived, yielding simple analytical expressions, including those for the case of a random distribution of the particle axes. [ABSTRACT FROM AUTHOR]

The CoFe2O4-BaTiO3 core-shell (CFO@BTO) nanocomposites have been synthesized, and a particular volume fraction of 15% CoFe2O4–85% BaTiO3 has been studied for its magnetic, ferroelectric, and magnetoelectric properties. The optimization of synthesis conditions showed that a temperature of at least 800 °C is required to obtain pure phase BaTiO3, whereas for the tetragonality to be visible in the x-ray diffraction (XRD) pattern, BaTiO3 needed to be sintered to at least 1050 °C. Even though the CFO@BTO composite began to react at the interface at 1050 °C and a small amount of the secondary phase was observed in the XRD pattern, the ferroelectric and magnetic properties were found to be not affected. Upon treating the living epithelial cells with either CFO@BTO or BTO nanoparticles, no toxicity was observed for up to 7 days. Together, these results establish the potential for the use of CFO@BTO nanoparticles in biomedical applications. [ABSTRACT FROM AUTHOR]

In this work, we investigated the effects of postdeposition heat treatment on structural and magnetic properties of CoFe2O4 nanoparticles produced by pulsed laser deposition. Structural analysis by X-ray diffraction, transmission electron microscopy (TEM) and Mössbauer spectroscopy indicate the formation of a single phase cobalt ferrite nanoparticles with the size ranging from 4.3 to 33.3 nm depending on the annealing temperature. The magnetic properties of the samples were investigated in a wide temperature range (50–400 K). Noticeable effects of the cubic magnetocrystalline anisotropy on the magnetization process of nanoparticles were observed for samples annealed at 450 °C and 600 °C, while for samples as-deposited and annealed at 300 °C the magnetization properties were dominated by a uniaxial effective anisotropy. ΔM technique was used to investigate the magnetic interaction among the nanoparticles. Only demagnetizing interactions were observed for the sample annealed up to 300 °C, while for the samples treated at 450 °C and 600 °C, both magnetizing and demagnetizing interactions were observed. The results are discussed considering the evolution of the nanoparticles’ nanostructure with anneals and its effects on the magnetic properties. [ABSTRACT FROM AUTHOR]

In our present study, we address in detail magnetic and magneto-transport properties of well known half metallic La0.67Sr0.33MnO3 (LSMO) and charge order suppressed ferromagnetic La0.48Ca0.52MnO3 (LCMO) nanoparticles. The average particle size for LSMO and LCMO is ~20nm and ~25 nm, respectively. With respect to their magnetic properties, both compounds exhibit ferromagnetic behavior, whereas they markedly differ in their magneto-transport characteristics. The magnetoresistive properties of LSMO nanoparticles indicate low field magnetoresistance and tendency for saturation at higher field values. In addition to the sharp low field magnetoresistance, we have achieved significantly large magnetoresistance at higher values of external magnetic field for the ferromagnetic LCMO nanoparticles. To address such anomalous behavior in these two different classes of ferromagnetic materials, we introduce the re-entrant core-shell type structure formation in charge ordered nanoparticles (LCMO) when charge ordering is completely suppressed. [ABSTRACT FROM AUTHOR]

In this study, we report on the optical and magnetic properties of Co-doped ZnO nanoparticles with increasing Co-content (CoxZn1-xO; x=0.000, 0.005, 0.010, 0.030, 0.050, 0.070, and 0.100) synthesized by the combustion reaction method. The X-ray diffraction patterns and the Raman spectra of all samples indicated the formation of the ZnO hexagonal wurtzite phase (space group C4 6V). The Raman data also show the formation of a secondary Co3O4 phase, which is barely seen in the X-ray spectra. Photoacoustic spectroscopy and electron paramagnetic resonance confirm the presence of the two phases (CoxZn1-xO and Co3O4). Vibrating sample magnetometer measurements performed at room temperature exhibited hysteresis loops, indicating the presence of long-range magnetic ordering in the samples. Analysis of the magnetization as a function of magnetic field and temperature shows that the ferromagnetism in the as-synthesized samples comes from small Cometallic inclusions, with an estimated radius of about 4.8 nm and blocking temperature around 595 K. [ABSTRACT FROM AUTHOR]

The chemical synthesis of shape and composition controlled Fe based binary alloys has been challenging due to the highly oxidizing nature of Fe. Here, we report the physical properties of flower-like Fe50Co50 nanoparticles prepared by a unique polyol process based on the addition of precursors at the elevated temperature. The magnetic properties are correlated through synchrotron radiation based X-ray diffraction and 57Fe Mössbauer spectrometry. Transmission electron microscopy analysis exposed the flower-like morphology of the FeCo particles. The FeCo nanoparticles showed a coercivity of 440 Oe, attributed to the shape anisotropy of the flower-like shape. Room temperature Mössbauer investigation revealed hyperfine fields of 34.9 and 36.7 T, suggesting two different Fe environments in the disordered state. Mössbauer analysis also showed the presence of superparamagnetic Fe-oxide with a relative fraction of 17%. [ABSTRACT FROM AUTHOR]

We present a method to evaluate the magnetic moment (m) and the anisotropy energy (E) of magnetic markers, which are the key parameters employed in biosensing applications. The distributions of the m and E values in the marker are evaluated by analyzing the static magnetization (M-H) curve of the suspended markers and the frequency dependence of the AC susceptibility of the immobilized markers, respectively. Then, we obtain the relationship between m and E. In the experiment, four markers made of multicore and single core nanoparticles are examined. We obtain distributions of the m and E values, which show the particular characteristics of each marker. Although the m and E values are widely distributed in the marker, a clear relationship is obtained between the values. Therefore, the obtained m-E curve, as well as the distribution of the m and E values, provides a framework to discuss the dynamic behavior of the immobilized markers. The difference in the estimated m-E curves between the markers is also discussed. [ABSTRACT FROM AUTHOR]

We obtain magnetic properties of magnesioferrite nanoparticles grew in a magnesiowstite crystalline matrix by analyzing the temperature dependence of the coercive field and the magnetization behavior. We introduce a modelling scheme to evaluate those properties in which the input variables are estimated from experimental data. The core of the method relies in sampling for nearby values in order to reach the optimal one that yields the smallest difference between calculated and experimental data. This procedure is efficient and our results match with the ones found in the literature. Thus, our method paves the way for a robust characterization of superparamagnetic nanoparticle materials. [ABSTRACT FROM AUTHOR]

We report a potential way to effectively improve the magnetic properties of BiFeO3 (BFO) nanoparticles through Mg2+ ion substitution at the Fe-sites of BFO lattice. The high purity and structural changes induced by Mg doping are confirmed by X-ray powder diffractometer and Raman spectra. Enhanced magnetic properties are observed in Mg substituted samples, which simultaneously exhibit ferromagnetic and superparamagnetic properties at room temperature. A physical model is proposed to support the observed ferromagnetism of Mg doped samples, and the superparamagnetic properties are revealed by the temperature dependent magnetization measurements. The improved magnetic properties and soft nature obtained by Mg doping in BFO nanoparticles demonstrate the possibility of BFO nanoparticles to practical applications. [ABSTRACT FROM AUTHOR]

A series of core/shell Fe-oxide/SiO2 nanoparticles were produced to form Fe-oxide (1:1 Fe3O4 and c-Fe2O3) cores with diameters of approximately 4.6 nm and shell thicknesses ranging from 3.6 to 5.4 nm. Hot press sintering of core/shell nanoparticles created a nanocomposite of Fe-oxide nanoparticles in a SiO2 matrix. The presence of an iron-orthosilicate at the core-shell interface defines the intrinsic magnetic properties of the nanoparticle systems, resulting in an increase in magnetic anisotropy with thicker SiO2 shell. We find that dipole-dipole interactions are mediated by the overall SiO2 shell, and that these interactions are coupling neighbouring particles' magnetization with increasing correlation lengths. When the nanoparticles from a composite material, packing significantly increases the interaction strengths, altering the overall magnetization of the system so that the iron-oxide cores present an approximate 25% increase in (saturation) magnetization to a bulk-like (∼80 emu/g) value. [ABSTRACT FROM AUTHOR]

Symmetries in nanoscale structures can be decisive for their structural, electronic, and magnetic properties, particularly in systems with reduced dimensions. Here we show that the symmetries of a flat metal-organic molecule adsorbed on a transition metal dichalcogenide, a 2-dimensional layered material, have a dramatic effect on the total spin and the intramolecular spin-spin interactions. Using a scanning probe microscope, we find two different molecular spin states by modifying the symmetry of the molecules via the twist angle to the substrate. Additionally, we observe significant non-collinear Dzyaloshinskii–Moriya interaction between two electron spins on the molecule induced by the spin-orbit coupling of the van der Waals coupled layered material with broken inversion symmetry. Our work opens a path for modifying the spin by exploiting symmetries and for studying the nature of surface-induced non-collinear spin-spin interaction within a single molecule which might allow the realization of more complex topological spin structures. Symmetry is key for magnetism of molecules as well as other nanostructures. Here, the authors tune the magnetic moment of a metal-organic molecule deposited on NbSe2 via the adsorption symmetry, and observe a non-collinear intramolecular spin-spin interaction. [ABSTRACT FROM AUTHOR]

Nano-sized magnetic particles show great promise in improving the performance of microwave absorbers with respect to the corresponding bulk materials. In this paper, magnetically hard and soft ferrite nanoparticles (CoFe2O4 and Fe3O4) having an average size of 14 and 11 nm were prepared by co-precipitation method and characterized in terms of morphology, structure, and magnetic properties. Their permeability and permittivity were measured by a waveguide technique, embedding each sample in a host medium. Their parameters at microwave frequencies were retrieved by comparing different effective medium equations. [ABSTRACT FROM AUTHOR]

Second Harmonic Generation (SHG) from BiFeO3 nanocrystals is investigated for the first time to determine their potential as biomarkers for multiphoton imaging. Nanocrystals are produced by an auto-combustion method with 2-amino-2-hydroxymethyl-propane-1,3-diol as a fuel. Stable colloidal suspensions with mean particle diameters in the range 100-120 nm are then obtained after wet-milling and sonication steps. SHG properties are determined using two complementary experimental techniques, Hyper Rayleigh Scattering and nonlinear polarization microscopy. BiFeO3 shows a very high second harmonic efficiency with an averaged hdi coefficient of 79±12 pm/V. From the nonlinear polarization response of individual nanocrystals, relative values of the independent dij coefficients are also determined and compared with recent theoretical and experimental studies. Additionally, the particles show a moderate magnetic response, which is attributed to γ-Fe2O3 impurities. A combination of high nonlinear optical efficiency and magnetic response within the same particle is of great interest for future bio-imaging and diagnostic applications. [ABSTRACT FROM AUTHOR]

A comparative experimental study of the magnetic properties of CoPt3 and CoPt3/Au nanoparticles as well as a detailed study of the structural properties of the samples by X-ray diffraction, Transmission electron microscopy, and vibrating sample magnetometer is presented in this work. In addition, the effect of particle size on the structure and magnetic properties of nanoparticles prepared by microemulsion is studied. The correlation between particle size, crystallinity, and magnetization was studied as well. CoPt nanoparticles have been studied intensively over the last decade because of their increased magnetic anisotropy in the ordered phase that can be interesting for high density magnetic recording. A significant high coercivity for as-prepared CoPt3 and CoPt3-Au nanoparticles was obtained at room temperature and enhanced after annealing. The focused aim of our study is to obtain high coercivity at room temperature that follows the Curie-Weiss law. This indicates an interacting system in which the nanoparticles behave like single domain ferromagnetic materials in the particle size range of 8 to 35 nm. In addition, the interaction increases by cooling the samples to low temperature around 15K. Temperature dependence 1/M graph was obtained to investigate the behavior of nanoparticles at low temperature and shows the best fit with Curie-Weis mode. [ABSTRACT FROM AUTHOR]

We report on a comparative study of the exchange bias effect and magnetic properties of Ni-NiO nanoparticulate systems synthesized by the chemical reduction of NiCl2 solution of two different molar concentrations--1M (high) and 0.05M (low)--followed by annealing of the dried precipitate in the temperature range 400-600 °C in air. Interestingly, the samples derived from the low molarity solution have higher Ni content and larger crystallite size than those prepared from their high molarity counterparts. These molarity dependent features subsequently modulate the magnitude of the exchange bias field in the samples, which is found to be absent or small in the 0.05M series, but of moderate value in the 1M samples. The different physical attributes of the particles derived from different concentrations of Ni-precursor solution are explained by invoking different nucleation kinetics and supersaturation degrees surrounding the viable growing nucleus. Furthermore, an observed increase of exchange bias with increasing annealing temperature, in contrast to the reported agglomeration of particles on annealing and subsequent reduction in bias magnitude, has been explained in correlation to the Ni-NiO interface density. [ABSTRACT FROM AUTHOR]

We reported the effect of boron addition on magnetic properties and structure of CoPt nanoparticles prepared by a polyol method. The magnetic property measurement showed that the CoPt-B sample exhibited a much larger coercivity compared to the sample without B additive at the same annealing temperature. Transmission electron microscopy and energy dispersive X-ray spectroscopy revealed that the average particle size was about 2 nm for the as-synthesized sample with the ratio of Co and Pt close to 1:1. After annealing, the particle sizes increased but the composition was maintained. The phase transformation of the nanoparticles versus temperature was investigated using a combination of X-ray diffraction and in-situ X-ray absorption analysis. It was shown that the phase transition temperature at which the nanoparticles change from the disordered A1 phase to the ordered L10 phase occurs at temperature of 600 °C. We concluded that boron additives could reduce the ordering temperature of CoPt of about 100 °C. [ABSTRACT FROM AUTHOR]

Structural and magnetic properties of γ-Fe2O3 nanoparticles of 4 nm diameter, dispersed into silica SiO2 matrix with a wide range value of volume fraction (0.05 to 1), were investigated. Produced γ-Fe2O3@SiO2 nanocomposites consist of an assembly of very small single domain magnetic object (<10 nm) with a random distribution of both inter-particle distance and direction of particle magnetic moment. We focused on the determination of a magnetic percolation threshold, defined as the magnetic particles concentration value above which the magnetic properties of isolated particles vanished in favor of a magnetic collective behavior induced by magnetic interactions. A percolation threshold value of 0.63 was obtained by a local probe technique such as 57Fe Mössbauer spectrometry and confirmed by global magnetic measurements through zero-field cooled, field-cooled, and ac susceptibility data. Below this threshold, dynamic ac magnetization measurements show a thermally activated Arrhenius dependence of the blocking temperature of superparamagnetic nanoparticles and above this critical value, one observes a slowing down of their dynamic properties, which lead toward the establishment of a spin-glass like state. [ABSTRACT FROM AUTHOR]

Magnetic properties of 16nm La0.45Sr0.55MnO3 nanoparticles exhibit superparamagnetic blocking at 160K with a ferromagnetic moment appearing in the antiferromagnetic state. The exchange interaction at the interface between canted ferromagnetic and antiferromagnetic regions within the nanoparticles leads to exchange bias, but the loop shift, coercivity, and remanence asymmetry all decrease strongly with increasing cooling field above 1 T unlike a conventional ferromagnetic/antiferromagnetic exchange bias system. The observations imply a magnetization process involving coalescence of canted ferromagnetic clusters with increasing field, which reduces the interface area with the antiferromagnetic matrix. [ABSTRACT FROM AUTHOR]

Magnetic nanoparticles have attracted increasing attention for biomedical applications in magnetic resonance imaging, high frequency magnetic field hyperthermia therapies, and magnetic-fieldgradient- targeted drug delivery. In this study, three-dimensional (3D) platinum nanostructures with large surface area that features magnetic behavior have been demonstrated. The well-developed 3D nanodendrites consist of plentiful interconnected nano-arms ~4 nm in size. The magnetic behavior of the 3D dendritic Pt nanoparticles is contributed by the localization of surface electrons due to strongly bonded oxygen/Pluronic F127 and the local magnetic moment induced by oxygen vacancies on the neighboring Pt and O atoms. The magnetization of the nanoparticles exhibits a mixed paramagnetic and ferromagnetic state, originating from the core and surface, respectively. The 3D nanodendrite structure is suitable for surface modification and high amounts of drug loading if the transition temperature was enhanced to room temperature properly. [ABSTRACT FROM AUTHOR]

Bismuth ferrite nanoparticles have been extensively investigated over the last few years due to their potential candidacy for application in future memory devices. However, all the work reported so far on bismuth ferrite nanoparticles is on agglomerated nanoparticles. Agglomerated particles can magnetically interact with each other. To utilize them for device application, it is useful to know the properties of the individual particles. Here, de-agglomeration of ~75 nm bismuth ferrite nanoparticles is achieved by polyaniline coating on the surface. The structural and magnetic properties of agglomerated and de-agglomerated nanoparticles are compared. It is observed that there is a change in the lattice parameters and Fe-O-Fe and O-Bi-O bond angles due to polyaniline shell. The coercivity of the bismuth ferrite/polyaniline core shell particles is reduced as compared to pure and agglomerated bismuth ferrite particles. The observed changes in the magnetic properties of coated particles are attributed to the shell induced isolation of individual bismuth ferrite nanoparticles as well as structural changes due to polyaniline coating. [ABSTRACT FROM AUTHOR]

We report magnetic and exchange bias studies on Ni-NiO nanoparticulate systems synthesized by a two-step process, namely, chemical reduction of a Ni salt followed by air annealing of the dried precipitate in the temperature range 400-550 °C. Size of Ni and NiO crystallites as estimated from X-ray diffraction line broadening ranges between 10.5-13.5 nm and 2.3-4 nm, respectively. The magneto-thermal plots (M-T) of these bi-magnetic samples show a well developed peak in the vicinity of 130K. This has been identified as the superparamagnetic blocking temperature "TB" of NiO. Interestingly, all samples exhibit exchange bias even above their respective NiO blocking temperatures, right up to 300K, the maximum temperature of measurement. This is in contrast to previous reports since exchange bias requires the antiferromagnetic NiO to have a stable direction of its moment in order to pin the ferromagnet (Ni) magnetization, whereas such stability is unlikely above TB since the NiO is superparamagnetic, its moment flipping under thermal activation. Our observation is elucidated by taking into account the core-shell morphology of the Ni-NiO nanoparticles whereby clustering of some of these nanoparticles connects their NiO shells to form extended continuous regions of NiO, which because of their large size remain blocked at T > TB, with thermally stable spins capable of pinning the Ni cores and giving rise to exchange bias. The investigated samples may thus be envisaged as being constituted of both isolated core-shell Ni-NiO nanoparticles as well as clustered ones, with TB denoting the blocking temperature of the NiO shell of the isolated particles. [ABSTRACT FROM AUTHOR]

Superparamagnetic nanoparticles are employed in a broad range of applications that demand detailed magnetic characterization for superior performance, e.g., in drug delivery or cancer treatment. Magnetic hysteresis measurements provide information on saturation magnetization and coercive force for bulk material but can be equivocal for particles having a broad size distribution. Here, first-order reversal curves (FORCs) are used to evaluate the effective magnetic particle size and interaction between equally sized magnetic iron oxide (Fe2O3) nanoparticles with three different morphologies: (i) pure Fe2O3, (ii) Janus-like, and (iii) core/shell Fe2O3/SiO2 synthesized using flame technology. By characterizing the distribution in coercive force and interaction field from the FORC diagrams, we find that the presence of SiO2 in the core/shell structures significantly reduces the average coercive force in comparison to the Janus-like Fe2O3/SiO2 and pure Fe2O3 particles. This is attributed to the reduction in the dipolar interaction between particles, which in turn reduces the effective magnetic particle size. Hence, FORC analysis allows for a finer distinction between equally sized Fe2O3 particles with similar magnetic hysteresis curves that can significantly influence the final nanoparticle performance. [ABSTRACT FROM AUTHOR]

Nickel (Ni) based nanoparticles and nanochains were incorporated as fillers in polydimethylsiloxane (PDMS) elastomers and then these mixtures were thermally cured in the presence of a uniform magnetic field. In this way, macroscopically structured-anisotropic PDMS-Ni based magnetorheological composites were obtained with the formation of pseudo-chains-like structures (referred as needles) oriented in the direction of the applied magnetic field when curing. Nanoparticles were synthesized at room temperature, under air ambient atmosphere (open air, atmospheric pressure) and then calcined at 400 °C (in air atmosphere also). The size distribution was obtained by fitting Small Angle X-ray Scattering (SAXS) experiments with a polydisperse hard spheres model and a Schulz-Zimm distribution, obtaining a size distribution centered at (10.0 ± 0.6) nm with polydispersivity given by σ = (8.0 ± 0.2) nm. The SAXS, X-ray powder diffraction, and Transmission Electron Microscope (TEM) experiments are consistent with single crystal nanoparticles of spherical shape (average particle diameter obtained by TEM: (12 ± 1) nm). Nickel-based nanochains (average diameter: 360 nm; average length: 3 μm, obtained by Scanning Electron Microscopy; aspect ratio = length/diameter ∼ 10) were obtained at 85 °C and ambient atmosphere (open air, atmospheric pressure). The magnetic properties of Ni-based nanoparticles and nanochains at room temperature are compared and discussed in terms of surface and size effects. Both Ni-based nanoparticles and nanochains were used as fillers for obtaining the PDMS structured magnetorheological composites, observing the presence of oriented needles. Magnetization curves, ferromagnetic resonance (FMR) spectra, and strain-stress curves of low filler's loading composites (2% w/w of fillers) were determined as functions of the relative orientation with respect to the needles. The results indicate that even at low loadings it is possible to obtain magnetorheological composites with anisotropic properties, with larger anisotropy when using nanochains. For instance, the magnetic remanence, the FMR field, and the elastic response to compression are higher when measured parallel to the needles (about 30% with nanochains as fillers). Analogously, the elastic response is also anisotropic, with larger anisotropy when using nanochains as fillers. Therefore, all experiments performed confirm the high potential of nickel nanochains to induce anisotropic effects in magnetorheological materials. [ABSTRACT FROM AUTHOR]

Bulk NiO is a well-known antiferromagnet with Neel temperature TN(∞) = 524 K and an optical band-gap Eg = 4.3 eV. With decrease in particle size D from 40 nm to 4 nm of NiO, systematic changes of TN and Eg are observed and discussed here. From magnetic measurements, the changes in TN with D are found to fit finite-size scaling equation TN(D) = TN(∞) [1 - (ξo/D)λ] with λ = 3.2 ± 0.5 and ξo = 3.2 ± 0.2 nm, in good agreement with the predictions for a Heisenberg system. The observed blue shifts of Eg with decrease in D reaching Eg = 5.12 eV for D ∼ 4 nm are likely due to quantum confinement and non-stoichiometry. [ABSTRACT FROM AUTHOR]

Unexpected room temperature ferromagnetism (RTFM) in nonmagnetic metal oxide nanoparticles have been reported previously. This unconventional behaviour is primarily attributed to the presence of oxygen vacancies, and in this regard TiO2 is not an exception. This article, therefore, explores the effect of oxygen vacancies on the magnetic properties of TiO2 nanoparticles. TiO2 nanoparticles are prepared by sol-gel method and annealed in vacuum for 3 h and 8 h. These defective TiO2 nanoparticles are found to display RTFM and the highest magnetization is shown by the sample which is exposed for the maximum period of 8 h under vacuum. It is further observed that the RTFM is transformed to paramagnetism on air annealing of the defective TiO2 for 8 h. It is anticipated that oxygen vacancies on the surface and on the grain boundary triggers ferromagnetism in this otherwise nonmagnetic metal oxide system. The localized oxygen vacancies in these regions form oxygen vacancy clusters and undergo strong ferromagnetic exchange interaction. Switching of magnetism from ferro-to para is observed as disappearance of these oxygen vacancies set in. [ABSTRACT FROM AUTHOR]

In this work, the structural and magnetic properties of Er-doped SnO2 (SnO2:Er) nanoparticles are reported. The SnO2:Er nanoparticles have been synthesized by a polymer precursor method with Er content from 1.0% to 10.0%. X-ray diffraction results indicate the formation of only the rutile-type structure in all samples. The estimated mean crystallite size shows a decrease from ∼10 to ∼4 nm when the Er content is increased from 1.0% to 10.0%. The particle size values have been corroborated by transmission electron microscopy technique. The thermal dependence of the magnetization is consistent with the 3+ oxidation state of erbium ions for all samples. A strong paramagnetic-like behavior coexisting with a ferromagnetic phase has been determined for samples with Er content below 5.0%. Above this concentration, only a paramagnetic behavior has been determined. Isothermal magnetization curves are consistent with the occurrence of long-range ferromagnetic order mediated by donor electrons forming bound magnetic polarons which overlap to produce a spin-split impurity band. [ABSTRACT FROM AUTHOR]

Single-phase Bi1-xPrxFeO3 (x = 0.0, 0.05, and 0.10) nanoparticles have been synthesized by propylene glycol-gel route at a temperature of 400 °C. Rietveld refinement of X-ray diffraction data and Raman spectra reflect a structural phase transition from rhombohedral for x = 0 to triclinic for x = 0.10. Magnetic measurements reveal that Pr-doped BiFeO3 nanoparticles for x = 0.10 have enhanced remnant magnetization about 10 times as compared to pure BiFeO3 nanoparticles. It has been shown by 57Fe Mössbauer spectroscopy that the observed enhancement in magnetic properties of BiFeO3 with Pr doping is mainly due to suppression of modulated spiral spin structure near x = 0.10 and not due to Fe multiple valence, i.e., oxygen deficiency. [ABSTRACT FROM AUTHOR]

In this work, the structural and magnetic properties of Al3+ substituted Ni-Zn ferrite powders were investigated. Ni0.7Zn0.3AlxFe2-xO4 (where x = 0.0-0.5) powders were obtained by sol-gel auto combustion method. X-ray diffractometer, vibrating sample magnetometer, scanning electron microscopy, infrared spectroscopy, and permeability were used to study the effects of Al3+ ions on the structural and magnetic properties. X-ray patterns reveal that all the samples have single-phase cubic spinel structure. Infrared spectroscopy was used to locate the absorption bands and to study the influence of Al3+ substitution on the spinel structure of the presently investigated system. The lattice constant and x-ray density were calculated from the XRD data. The density of the samples was measured and consequently the porosity was calculated too. Magnetic properties were carried out by means of magnetization measurement to study the magnetic interaction between the ions. This paper is also focused its discussion on the dependence of the permeability spectra with the frequency variation. The permeability and Curie temperature were determined using the temperature dependent permeability measurements. [ABSTRACT FROM AUTHOR]

The formation of agglomerates by salt-induced double layer compression of magnetic nanoparticles in the absence and presence of an external magnetic field was investigated experimentally as well as computationally in this study. The structures of the agglomerates were analyzed through scanning electron microscopy and proved to be highly porous and composed of large spaces among the branches of a convoluted network. In the absence of an external magnetic field, the branches of such a network were observed to be oriented in no particular direction. In contrast, when the agglomeration process was allowed to occur in the presence of an external magnetic field, these branches appeared to be oriented predominantly in one direction. A modified Discrete Element Method was applied to simulate the agglomeration process of magnetic nanoparticles both in the absence and presence of an external magnetic field. The simulations show that agglomeration occurred by the formation of random clusters of nanoparticles which then joined to form a network. In the presence of anisotropic magnetic forces, these clusters were rotated to align along the direction of the magnetic field and the final network formed consisted largely of elongated branches of magnetic nanoparticles. [ABSTRACT FROM AUTHOR]

We report a theoretical discussion of the impact the composition on the maximum energy product ((BH)max) of core@shell FePt@CoFe2 and FePt@Fe nanocylinders. We have found that the best composition is determined by the competing trends imposed by a strong ferromagnetic core@shell interface exchange energy, and the core@shell dipolar interaction energy. The dipolar interaction has a negative impact on the nanocylinder (BH)max value, for shell thickness above a shell material dependent threshold value. We have also found that Fe is the best shell material owing to its much larger exchange stiffness. [ABSTRACT FROM AUTHOR]

New lead tellurite glass ceramics doped with terbium (III) oxide and co-doped with AgNPs and CuNPs were obtained by melt quenching technique. The samples were analyzed by XRD, photoluminescence, UV–Vis spectroscopy and magnetic measurements. XRD data were used to estimate the nature of the obtained samples and also to determine the crystallites size. UV–Vis spectra reveal the presence of terbium ions in the batch and, for the samples co-doped with CuNPs, the presence of Cu2+ ions octahedrally surrounded by six oxygen atoms. Optical band gap energy values were calculated based on the UV–Vis data. The photoluminescence spectra exhibit the emission from terbium ions and also reveal the influence of the co-dopant nature on this emission. Magnetic measurements data show a complex behavior due the presence of Tb3+ ions, metal nanoparticles and to the microstructure of samples. • TeO 2 -PbO-Tb 2 O 3 glass ceramics co-doped with AgNPs, CuNPs or without NPs were prepared. • The differences on optical properties of TeO 2 -PbO-Tb 2 O 3 systems were described. • The most intense emission peak was the green one, the samples being promising materials for solid state lasers. • The emissions from rare-earth ions were enhanced by AgNPs until 3 mol% Tb 2 O 3. • The magnetic behavior of the samples is due to the Tb3+, but the presence of NPs must be considered too. [ABSTRACT FROM AUTHOR]

In this study, we present the synthesis of Tb 3 Ga 5 O 12 nanoparticles doped with Er3+, Yb3+, and Sc3+ ions, prepared using a co-precipitation method. These materials have well-defined magnetic-fluorescence properties. The effects of Yb3+ ion concentration on the structural characteristics, morphology, luminescence, and magnetic properties of the nanoparticles were investigated in detail using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, photoluminescence spectroscopy, and vibrating sample magnetometer measurements. Under 980-nm laser diode excitation, the nanoparticles displayed bright up-conversion luminescence, showing evidence of resonant energy transfer from the Yb3+ to Er3+ ions. Intense green and red emissions located at approximately 526, 548, and 656 nm were attributed to the radiant transitions of 2H 11/2 → 4I 15/2 , 4S 3/2 → 4I 15/2 , and 4F 9/2 → 4I 15/2 of Er3+, respectively. These observations indicate that Tb 3 Ga 5 O 12 :Er3+, Yb3+, Sc3+ magnetic–fluorescent bifunctional nanoparticles are promising materials for use in bioimaging and magnetic bio-separation applications. Image 1 • Novel synthesis of Tb 3 Ga 5 O 12 nanoparticles doped with Er3+, Yb3+, Sc3+ ions. • The nanoparticles exhibit bifunctional magnetic-fluorescent properties. • Yb3+ concentrations critical for controlling morphology, luminance, and magnetism. [ABSTRACT FROM AUTHOR]

In the present study, spinel structure CoFe2O4 nanoparticles were successfully synthesized by the sol‐gel auto‐combustion technique. The effect of apple cider vinegar (ACV) addition as an organic biocompatible agent on the size, morphology, and magnetic properties of CoFe2O4 nanoparticles was investigated in detail. The phase evolution, particle size, and lattice parameter changes of the synthesized phase have been estimated by using Rietveld structure refinement analysis of X‐ray powder diffraction data. Also, Fourier transform infrared spectra (FT‐IR) of the samples verified the presence of two expected bands correspond to tetrahedral and octahedral metal‐oxygen complexes within the spinel structure. Furthermore, microstructural observations revealed that ultrafine particles have a semi‐spherical morphology. It was shown that the particles size decreased from ~45 to ~17 nm with an increase in the amount of ACV. Magnetic properties were carried out by vibrating sample magnetometer (VSM) at room temperature. Both the saturation magnetization (Ms) and coercivity (Hc) were found to be significantly dependent on the crystallite size and the amount of ACV. [ABSTRACT FROM AUTHOR]

Highlights • Zn-Mn magnetite NPs prepared by a facile one-step hydrothermal method. • Effect of reducing agent and pH of the solution on NP formation is studied. • NPs show potential for cancer diagnostic and therapeutic applications. Abstract Super-paramagnetic, mono-dispersed and single-phased Mn-substituted Zn-ferrite nanoparticles (NPs) with a narrow size distribution were synthesized by a one-step citric acid-assisted hydrothermal method. X-ray diffraction (XRD), Scanning electron microscopy (SEM), vibrating sample magnetometry (VSM) and Fourier-transform infrared spectroscopy (FTIR) techniques were utilized to determine characteristics of the NPs. The as-prepared Zn 0.3 Fe 2.7 O 4 NPs were highly crystalline with uniform size (14.5 ± 2.65) and good stability in an aqueous medium. The effects of Mn concentration (x = 0.25, 0.5, 0.75 and 1) and pH on the formation of Zn 0.3 Mn x Fe 2.7−x O 4 NPs were thoroughly studied. The maximum saturation magnetization of 55 emu/g was obtained for the Zn-ferrite sample substituted with x = 0.5 of Mn. Increasing x firstly resulted in an increased saturation magnetization from 47.1 emu/g (x = 0.25) to 55 emu/g (x = 0.5), followed by a decrease to 37 emu/g (x = 1). The variation of saturation magnetization was correlated with the distribution of Mn2+ ions in tetrahedral and octahedral sites. [ABSTRACT FROM AUTHOR]

Tuning the enhanced optical and magnetic properties of rare earth doped glasses by embedding nanoparticles is a never-ending quest. Influences of heat treatment (annealing) in modifying the spectral features of melt-quench synthesized manganese oxide nanoparticles (Mn 3 O 4 NPs) embedded Eu3+-doped borotellurite glasses are reported. The growth of NPs is tuned by varying the annealing time. TEM micrograph reveals the nucleation of heat treated Mn 3 O 4 NPs and SAED manifest their growth along the (1 1 2) crystallographic planes having average size in the range of 5.2 to 21.4 nm. The SPR bands are evidenced in the range 350 to 700 nm that validates the growth of Mn 3 O 4 NPs in the glass matrix. The luminescence spectra reveal four major emission peaks at 591, 614, 651 and 700 nm originating from 7F 1 , 7F 2 7F 3 , and 7F 4 transitions levels, respectively. Intensity enhancement displayed by heat treated glass samples is attributed to the local field effect of Mn 3 O 4 NPs while a quenching is due to the energy transfer from Eu3+ to Mn 3 O 4 NPs. The intensity parameters related to the radiative transitions within 4f configuration of Eu3+ ions are determined and analyzed using Judd-Ofelt theory. The magnetization versus field (M-H) at 12 h of Mn 3 O 4 NPs shows the highest saturation magnetization. The ESR spectrum exhibits resonance signals with effective isotropic g values at 1.9, 3.0 and 4.3 where g at 1.9 are attributed to Mn2+ centers in an octahedral asymmetry and g at 3.0 and 4.3 are attributed to the rhombic symmetry of the Mn2+ ions. Present glass compositions are established to be promising for the development of photonic devices. • Annealing time dependent optical and magnetic properties of melt quenching synthesized Eu3+ doped BT glasses containing Mn 3 O 4 NPs are reported. • The TEM result without and with annealed reveals the size of NPs while its planar spacing are determined by HRTEM. • The spectroscopic properties of the proposed glasses are determined. • J-O intensity parameters and radiative lifetimes, stimulated emission cross-section and quantum efficiencies are evaluated. • The magnetization measurement of glass sample is carried out using VSM and ESR. [ABSTRACT FROM AUTHOR]

Surface functionalized tri-metallic strontium magnesium ferrite (Sr 0.3 Mg 0.7 Fe 2 O 4 , SMF) nanoparticles were synthesized by using facile solvent less green oleo polyol method. Various analytical techniques (XRD, XPS, FT-IR, TEM, SEM, BET, and VSM) were used for the investigation of the crystal lattice, surface functionalization, morphology, surface area, and magnetic properties of these nanoparticles. SEM and TEM analysis revealed that the nanoparticles exhibit mesoporous morphology with cubic structure. These mesoporous nanoparticles have been exploited for the removal of toxic organic pollutant (Congo red, CR) from the aqueous solution. Detailed investigations on the adsorption of CR dye by these nanoparticles have been conducted via the rate kinetics study using various adsorption isotherms (Freundlich, Langmuir, Temkin, etc.). These studies revealed that the mesoporous SMF nanoparticles with the high surface area (21.85 m2g−1), have exhibited superior adsorption capacity (>90% within 30 min) and fast separation ability under the influence of external magnetic field along with good recyclability (∼93%). The adsorption analysis of magnetic SMF revealed pseudo-second order dye removal kinetics and follow Freundlich isotherms. These properties of magnetic SMF nanocubes provide an extra edge over other such reported systems and may find its potential as a cost-effective magnetic adsorbent for water treatment application. Image 1 • Cost-effective oleo polyol method have been used to synthesize Sr 0.3 Mg 0.7 Fe 2 O 4 nanoparticles. • SEM and TEM confirms the formation of mesoporous morphology with cubic structure. • These nanoparticles exhibited excellent magnetic properties with a high surface area. • They displayed excellent dye absorption capacity (∼ 90% within 30 min). • Fast removal of toxic dye (Congo red) make their potential in water treatment. [ABSTRACT FROM AUTHOR]

In this investigation we analyze an unprecedented difference in the behavior of nanoparticles when compared to the corresponding bulk. We have found that a chemical substitution can have the opposite effect on the magnetic properties of nanoparticles compared to the bulk, as revealed for the first time in the case of Sc-substituted barium-hexaferrite nanoplatelets. Even though the Sc substitution is known to greatly decrease the saturation magnetization, M S , of the bulk barium hexaferrite, it showed the opposite effect for nanoplatelets. The M S values of the nanoplatelets (in average 50 nm wide and approximately 3 nm thick) increased to over 38 Am2/kg, compared to ∼16 Am2/kg for unsubstituted nanoplatelets of comparable average size. The Sc incorporation was investigated with a combination of atomic-resolution imaging and elemental mappings in a scanning-transmission electron microscope. As in the bulk, the Sc3+ ions showed a clear preference for incorporation into an R block of the hexaferrite SRS∗R∗ structure for the nanoplatelets (R and S represent a hexagonal (BaFe 6 O 11)2- and a cubic (Fe 6 O 8)2+ structural block, respectively). A clear difference between the nano and the bulk observed for the first time was in the partial substitution of the Sc3+ for the Ba2+ in the nanoplatelets; however, this cannot explain the large increase in M S. Ab-initio calculations suggest that the opposite effect of the Sc substitution in the nanoplatelets to that in the bulk can be ascribed to specific, two-dimensional magnetic ordering in the platelets. Image 1 [ABSTRACT FROM AUTHOR]

Pure and Co-doped CeO 2 nanoparticles were synthesized successfully by the solvothermal method. The effect of Co substitution and external magnetic field on the morphologies and magnetic properties of nanoparticles was investigated. Results showed that synthesized Co-doped CeO 2 had the face-centered cubic structure and no other impurities existed in the samples with the increase of Co concentration from 5 to 75 wt%. The increasing Co concentration made the morphologies of Co-doped CeO 2 nanoparticles vary from the hollow sphere, solid sphere to rod-like shape. The applied external magnetic field of 5T decreased the nanoparticle size effectively including the diameter of hollow sphere with low Co concentration and rod-like particles with high Co concentration. Moreover, the wall thickness of hollow sphere particles was also decreased from 35 nm to 18 nm for pure CeO 2. The Co-doped CeO 2 nanoparticles showed the weak ferromagnetic behavior. With the increase of Co concentration, the saturation magnetization (M s) value increased first and then decreased. The Co-doped CeO 2 with 30 wt% showed the highest value of 3.65 × 10−2 emu/g (M s). The M s value of Co-doped CeO 2 prepared in 5T showed an increasing trend with the Co concentration. The highest value (M s) reached 4.21 × 10−2 emu/g for doped CeO 2 with 75 wt% Co. [ABSTRACT FROM AUTHOR]

We investigate magnetic properties of nickel nanoparticles electrodeposited on TiO 2 nanotubes by different techniques including direct current (DC) and cyclic voltammetry (CV) deposition. TiO 2 nanotubes were fabricated by anodic oxidation from an organic electrolyte under constant voltage on Ti substrates. Using scanning and transmission electron microscopies, we observe that each technique provides different morphologies: DC electrodeposition makes large coalesced Ni nanoparticles mostly accumulated on top surface and mouths of the nanotubes, whereas CV deposition produces a homogenous dispersion of Ni nanoparticles across the nanotubes. The variation of coercivity and saturation magnetization values recorded is consistent with our scenario, though owing to large number of nanoparticles with size and shape varieties. The first order reversal curve (FORC) diagrams help to reveal the magnetic behavior of nanoparticle ensembles in relation to their morphology and crystal structure. Image 1 [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Superparamagnetic nanoparticles of Mn 0.5 Zn 0.5 Nd x Fe 2−x O 4 ferrites are synthesized. • Formation of cubical spinel structure is confirmed with XRD and FTIR studies. • Phase change from paramagnetic to superparamagnetic behavior is found for x > 0.025. • An anti-Stokes shift is observed with Nd doping in Mn-Zn nanoferrites. Abstract Superparamagnetic nanoparticles have astounding applications in the field of biomedical. Co-precipitated Nd3+ doped Mn 0.5 Zn 0.5 Nd x Fe 2−x O 4 , where x = 0, 0.025, 0.050, 0.075, 0.1 ferrite nanoparticles are examined utilizing various characterization methods at room temperature. XRD, FE-SEM and FTIR analysis reveal the origination of cubical spinel ferrite structure. A transition from paramagnetic to superparamagnetic nature has been observed with Nd3+ addition (x > 0.025). To comprehend the relationship of structural and magnetic properties a cation distribution has been proposed and found to be in agreement with experimental observations. Absorption spectra show a red shift with Nd3+ doping. PL spectra show a blue shift in band edge emission upto x = 0.050. The results obtained from UV–visible spectroscopy and PL spectroscopy show an anti-Stokes shift with Nd3+ doping owing to the photon upconversion process. The obtained magnetic results in fusion with optical results for ferrite nanoparticles are prospective in imaging and biomedical applications. [ABSTRACT FROM AUTHOR]

Highlights • A new drug-release technology using liposomal nanoparticles with magnetic controls. • Evaluating the drug-release potentials with spin-correlated radical pair mechanisms. • Influence of radical pair-unrelated photoreaction products. • Liposomal membrane packing to generate the pair-unrelated product. Abstract In this paper, we used anti-cancer flutamide (FM) as a radical pair-forming drug to investigate whether magnetic fields can control a liposomal drug release through differences in the physical properties of biomembranes. Irradiations of FM-incorporated liposomal nanoparticles (FM-LNs) were performed using an original air-cooled UV-LED irradiation system. Exposure to a static magnetic field of 0.2 T was performed using a pair of commercially available permanent magnets. For evaluating the drug-release potentials with spin-correlated radical pair mechanisms on the photochemical reactions developing in biomembranes, we prepared various types of FM-LNs equipped with possible magnetic controls. According to the overall result of the prepared FM-LNs, the drug release is deemed not to be caused by only the pair mechanisms. But the tests observing the magnetic field effects on the mechanisms must provide useful information on drug targeting. We strongly propose a new drug-release technology using these liposomal nanoparticles equipped with magnetic controls. [ABSTRACT FROM AUTHOR]

Abstract With the objective of finding an avenue for development of magnetic nanomaterials which were incorporated into cells for induction of cell death in human cancerous cell lines, an environmental friendly synthesis method was investigated. The present work aimed to synthesis magnetic NiCo 2 O 4 /NiO nanoparticles by a novel, simple, environmental friendly and cost effective method in the presence of Dactylopius Coccus. The ultra-fine NiCo 2 O 4 /NiO ceramic nanocomposites (NNC) were characterized by X-ray diffraction pattern (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), energy dispersive spectrometry (EDS) as well as vibrating sample magnetometer (VSM) used to study the magnetic properties of NNC nanoparticles. MTT cytotoxicity assay performed to determine the anti-proliferative effect of NNC nanoparticles against 4T1 breast cancer cell lines. The results demonstrated that the NNC nanoparticles meaningfully reduced the survival percentage of the 4T1 cells of the murine invasive breast cancer with an IC 50 was of 4 mg/ml. The dominant mechanism of cell death was apoptosis, along with an increase in cellular oxidative stress. Consequently, based on the obtained results, it can be concluded that NiCo 2 O 4 /NiO nanoparticles can potentially be used as a chemotherapeutic agent against invasive breast cancer cells. Graphical abstract Image 1 Highlights • NiCo 2 O 4 /NiO porous nanocomposites has been synthesized by assistance green cochineal dye for the first time. • These uniform nanoparticles has been prepared using ultrasonic assisted thermal treatment method. • The role of ultrasonic waves and mechanism was investigated. • For the first time the anticancer of NiCo 2 O 4 /NiO nanoparticles against 4T1 cells lines. • MTT cytotoxicity assay was performed to determine the anti-proliferative effect of nanoparticles against 4T1. [ABSTRACT FROM AUTHOR]