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At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Crystal Structure and Phase Relations of the R{sub 2}Fe{sub 14}B–Y{sub 2}Fe{sub 14}B (R = Nd and Pr) Systems

The phase relations in the R{sub 2}Fe{sub 14}B–Y{sub 2}Fe{sub 14}B (R = Nd and Pr) systems have been investigated by means of X-ray powder diffraction (XRD), differential thermal analysis (DTA), and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS). Crystal structure parameters for all studied alloys (R{sub 1−x}Y{sub x}){sub 2}Fe{sub 14}B (R = Nd and Pr) have been determined by Rietveld refinements. Their structures are similar to that of the Nd{sub 2}Fe{sub 14}B phase with tetragonal structure (space group P4{sub 2}/mnm). The continuous solid solutions are formed in these systems. The lattice parameters and unit cell volumes of the (R{sub 1−x}Y{sub x}){sub 2}Fe{sub 14}B (R = Nd and Pr) solid solutions decrease gradually with increasing Y content. The DTA results present that the decomposition temperature of (R{sub 1−x}Y{sub x}){sub 2}Fe{sub 14}B (R = Nd and Pr) rises with x ranging from 0 to 1.0. The vertical sections of the R{sub 2}Fe{sub 14}B–Y{sub 2}Fe{sub 14}B (R = Nd and Pr) systems are presented in this work.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Low-Temperature Short-Time SPS Processes to Produce Fine-Grained High-Coercivity Barium Hexaferrite Ceramics from Polyol Nanoparticles

Barium hexaferrite (BaFe{sub 12}O{sub 19}) ceramics were obtained by combination of polyol-synthesized precursors subsequently consolidated by spark plasma sintering (SPS) at a low temperature (800 {sup ∘}C). X-ray powder diffraction studies showed the influence of the experimental parameters to produce a virtually single- or multiphase material. The room temperature magnetic properties exhibited interesting variety of properties, including exchange coupling (spring magnet) between hexaferrite and other magnetic phases. The saturation magnetization and coercive field, at room temperature, are in the 34–70 emu/g and 4.1–5.0 kOe ranges, respectively. The combination of strong coercive field and magnetization resulted in a maximum energy product [(BH)max] = 10.9 kJ/m{sup 3} for the sample with the highest BaFe{sub 12}O{sub 19} content.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Effect of the Fe/Ba Ratio and Sintering Temperature on Microstructure and Magnetic Properties of Barium Ferrites Prepared by Hydrothermal Method

Magnetoplumbite-type (M-type) hexagonal barium ferrite particles were synthesized by a hydrothermal method. The structure and magnetic properties of barium ferrites were investigated systematically, which indicated that the ratio of Fe/Ba (R{sub F/B}) and sintering temperature have an important effect on structure and performance. Phase composition, micro-morphology, and magnetic properties of the particles were investigated by X-ray powder diffraction (XRD) analysis, scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). When the ratio of Fe/Ba (R{sub F/B}) is even low or high, inferior images of XRD could be attained with certain impurities. When R{sub F/B} = 8, the single phase could be obtained without impurities. Micro-morphology of the particles exhibits the uniform plane hexagonal structures of nano-sized M-type ferrites when sintered at 800 °C. Saturation magnetization (M{sub s}) reaches the maximum value at R{sub F/B} = 7 (M{sub s} = 45.07 emu/g). The value of coercivity (H{sub c}) increases with the growth of R{sub F/B}, and H{sub c} is up to 6207 Oe when R{sub F/B} = 7. The effect of R{sub F/B} and temperature on magnetization (M{sub s}) and coercivity (H{sub c}) was studied in this paper.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

SPION@APTES@FA-PEG@Usnic Acid Bionanodrug for Cancer Therapy

In this work, we aimed to develop stable usnic acid (UA)-conjugated superparamagnetic iron oxide nanoparticles (SPIONs) as a potential drug carrier for in vitro analysis of MCF-7 (breast cancer cell line), HeLa (cervix cancer cell line), L929 (mouse fibroblast cell line), U87 (glioblastoma cell line, brain cancer), and A549 (human lung cancer cell line) cell lines. SPIONs were synthesized via the polyol method and functionalized with APTES using the Stöber method. Carboxylated polyethylene glycol (PEG-COOH), folic acid (FA), and carboxylated luteolin (CL) were conjugated on the surface via a carboxylic/amine group using the nanoprecipitation method, respectively. X-ray powder diffraction analysis confirmed the purity of the product with crystallite size of around 11 nm. Fourier-transformed infrared spectrophotometer (FT-IR) analyses explained the conjugation of all functional groups to the surface of SPIONs. The percentages of inorganic and organic content in the products were investigated via thermal gravimetric analyzer (TGA). For morphological analysis, a transmission electron microscope (TEM) was used. The superparamagnetic property of the product was also confirmed by vibrating sample magnetometer (VSM).

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Excess Conductivity Investigation of Y{sub 3}Ba{sub 5}Cu{sub 8}O{sub 18±δ} Superconductors Prepared by Various Parameters of Planetary Ball Milling Technique

Superconducting samples of type Y{sub 3}Ba{sub 5}Cu{sub 8}O{sub 18±δ} were elaborated by using a planetary high-energy ball milling (HEBM) technique with various parameters. Phases, microstructure, and superconductivity have been examined using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and electrical resistivity measurements. SEM investigation shows the occurrence of nanoentities embedded into the superconducting matrix for samples prepared by a ball milling technique. The main objective of this study is to investigate the influence of ball milling parameters on the fluctuation-induced conductivity (FIC). The electrical resistivity versus temperature, ρ(T), above T{sub c} was analyzed using Lawrence–Doniach (LD) and Aslamazov–Larkin (AL) models. Different fluctuation regimes indicated by short-wave fluctuation (SWF) and three-dimensional (3D), two-dimensional (2D), one-dimensional (1D), and critical region (CR) fluctuations were identified. The coherence length at zero temperature, the effective layer thickness, the critical magnetic fields, and the critical current densities are determined. The superconducting parameters strongly depend on the planetary ball milling technique, and the results are explained in relevancy to the microstructure. It was found that the achievement of a microstructure with well-dispersed nanoentities is an effective way for introducing pinning centers for enhancing critical current density and flux pinning capability of bulk Y-358.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Synthesis and Characterization of Er-Doped Nano ZnO Samples

Pure and erbium-doped ZnO nanoparticles (Zn{sub 1−x}Er{sub x}O), (0.00 ≤ x ≤ 0.10), were synthesized by wet chemical co-precipitation method. The structural, optical, and magnetic properties of the prepared samples were investigated using x-ray powder diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV), Fourier transform infrared spectroscopy (FTIR), M-H magnetic hysteresis, and electron paramagnetic resonance (EPR). XRD studies exhibit the presence of a single ZnO wurtzite hexagonal crystal structure for 0.00 ≤ x ≤ 0.06. A secondary phase of Er{sub 2}O{sub 3} appears for x > 0.06. This means that the solubility limit for doping Zn{sup 2+} ions by Er{sup 3+} ions is about x = 0.06 under our preparations condition. The lattice parameter a is not affected by the Erbium doping. On the other hand, the lattice parameter c and the unit cell volume V increase with the increase of x up to x = 0.06. This is attributed to the larger ionic size of Er{sup 3+} ions (0.88 Å) compared to Zn{sup 2+} ions (0.74 Å). Both c and V decrease for x > 0.06. TEM micrographs indicate that the shape and the size of the ZnO nanoparticles are modified by changing the doping level of Er. The UV measurements point out that band gap energy E{sub g} decreases with the increase of x up to x = 0.06. Then, it increases for both x = 0.08 and 0.10. FTIR spectra confirm the presence of O–H and Zn–O stretching modes at 3451.963 and 428.901 cm{sup − 1}, respectively, in pure and doped ZnO samples. The Zn–O stretching mode shifts toward a lower wavenumber for x = 0.06 and toward a higher wavenumber for x = 0.10. M-H hysteresis analysis, at room temperature, reveals that the pure ZnO has a ferromagnetic signal combined with diamagnetic and paramagnetic contributions. This ferromagnetism is reduced for the doped samples up to x = 0.02, and an antiferromagnetic alignment appears for 0.04 ≤ x ≤ 0.10. The saturation magnetization (M{sub s}), the coercivity (H{sub c}), the retentivity (M{sub r}), the anisotropy constant (K{sub a}), and the magnetic moment (μ{sub m}) were estimated and discussed in terms of erbium doping for the different samples. EPR spectra for Zn{sub 1−x}Er{sub x}O were measured at room temperature in order to study the effect of Er substitution on the g value, resonance field (H{sub r}), peak to peak line width (ΔH{sub pp}) and spin–spin relaxation time constant (T{sub 2}).

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Structural, Magnetic, and XPS Studies of the Double-Perovskite Mn{sub 2}VSbO{sub 6}

The double-perovskite Mn{sub 2}VSbO{sub 6} has been synthesized by solid-state reaction under pressure at 6 GPa and temperature of 1200°C, and its crystal structure has been refined by X-ray powder diffraction date. Mn{sub 2}VSbO{sub 6} crystallizes in monoclinic space group P12{sub 1}/n1 with the following parameters: a = 5.2340 Å (2), b = 5.3932 Å (2), c = 7.6460 Å (3), β = 89.6075° (23), V = 215.826 Å{sup 3} (14), Z = 2. It found that V and Sb atoms are completely ordered in 2d and 2c positions of double-perovskite structure, respectively. According to XPS measurements, manganese in this compound is present as Mn{sup 2+}, while vanadium is V{sup 3+}. The magnetization date suggests that Mn{sub 2}VSbO{sub 6} transforms to an antiferromagnetic state due to simultaneous ordering of V{sup 3+} and Mn{sup 2+} magnetic sublattices at low temperature.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Effect of Annealing Temperature on Magnetic and Mössbauer Properties of ZnFe{sub 2}O{sub 4} Nanoparticles by Sol-gel Approach

In this study, spinel ZnFe{sub 2}O{sub 4} nanoparticles (NPs) were synthesized by citrate sol-gel route using nickel nitrates, ferric nitrates and citric acid by annealing at 900, 1000, and 1100{sup ∘}C. We reported the structural and magnetic properties (including Mössbauer analysis) for anisotropy ZnFe{sub 2}O{sub 4} NPs annealed at different temperatures. Fourier transform infrared (FT-IR) and X-ray powder diffraction (XRD) were utilized to analyze the structural properties of magnetic nanoparticles (MNPs). Morphological features of resultant MNPs were examined by scanning electron microscopy (SEM). The observed XRD results displayed that the crystallite size increased from 38.60 to 49.28 nm with increasing the annealing temperature in a distinct linear trend. The enhancement of saturation magnetization of the uniaxial ZnFe{sub 2}O{sub 4} NPs was studied and varied from 1.28 to 1.66 emu/g as the annealing temperature increases. The Mössbauer spectra results show that ZnFe{sub 2}O{sub 4} ferrites were paramagnetic in nature at room temperature (RT).

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Magnetic Transition and Magnetocaloric Effect of Gd{sub 1−x}Nd{sub x}Mn{sub 2}Ge{sub 2} (x = 0.3 and 0.4) Compounds

Gd{sub 1−x}Nd{sub x}Mn{sub 2}Ge{sub 2} compounds with x = 0.3 and 0.4 were prepared by arc melting and crystallized in the ThCr{sub 2}Si{sub 2}-type structure with the space group I4/mmm based on X-ray powder diffraction (XRD) results. Magnetic transition and magnetocaloric effect (MCE) of the Gd{sub 1−x}Nd{sub x}Mn{sub 2}Ge{sub 2} compounds were investigated by magnetic measurements on a physical property measurement system (PPMS). Gd{sub 0.7}Nd{sub 0.3}Mn{sub 2}Ge{sub 2} compound exhibits complicated magnetic transitions at around 63 K (T{sub comp}), 86 K (T{sub 1}), 136 K (T{sub C}), 260 K (T{sub N}{sup inter}), and 347 K (T{sub C}{sup inter}), respectively, while Gd{sub 0.6}Nd{sub 0.4}Mn{sub 2}Ge{sub 2} compound shows a spin re-orientation transition at about 52 K. Combined with isothermal magnetization curves and the Maxwell relation, the maximum magnetic entropy changes of Gd{sub 0.7}Nd{sub 0.3}Mn{sub 2}Ge{sub 2} and Gd{sub 0.6}Nd{sub 0.4}Mn{sub 2}Ge{sub 2} were calculated to be 4.31 and 5.15 J kg{sup − 1} K{sup − 1} under the applied magnetic field changing from 0 to 5 T, respectively.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Structural and Magnetic Properties of La-Substituted M-Type Hexagonal Sr–Ni Ferrites Synthesized by Ball-Milling-Assisted Ceramic Process

Sr{sub 0.5}Ni{sub 0.5}La{sub x}Fe{sub 12 − x}O{sub 19} (x = 0, 0.08, 0.16, and 0.24) hexaferrites have been synthesized by ball-milling-assisted ceramic process. The calcined samples are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), and vibrating sample magnetometry (VSM). XRD reveals that all samples consist of the main M-type hexagonal Sr ferrite phase and a low amount of rhombohedral Fe{sub 2}O{sub 3} as secondary phase, and a continuous increase of the hexagonal lattice parameters with substitution content (x). Magnetic characterization indicates that all Sr{sub 0.5}Ni{sub 0.5}La{sub x}Fe{sub 12 − x}O{sub 19} samples have a hard magnetic property. Substitution of Fe{sup 3+} ions by La{sup 3+} ions can obviously improve the specific saturation magnetization, remanence, magnetic moment, and effective anisotropy constant. Specific saturation magnetization, remanence, and the magnetic moment reach a maximum at x= 0.24 and calcination temperature of 1050 {sup ∘}C.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Comparative Study of the Effect of Magnetic Nanoparticle CoFe{sub 2}O{sub 4} on Fluctuation-Induced Conductivity of Y-123 and Y-358 Superconductors

In this study, a comparative investigation of the electrical conductivity fluctuations in nano-CoFe{sub 2}O{sub 4} added to Y{sub 3}Ba{sub 5}Cu{sub 8}O{sub 18±x} (Y-358) and YBa{sub 2}Cu{sub 3}O{sub 7−d} (Y-123) products is performed. All products were made using the solid-state reaction process. X-ray powder diffraction (XRD) analyses confirmed the formation of different phases. Scanning electron microscope (SEM) analysis shows the reduction of grain size with increasing the quantity of nano-CoFe{sub 2}O{sub 4} particles for both the Y-123 and Y-358 samples. The decrease of grain size is more accentuated in the case of the Y-358 samples compared with the Y-123 ones. The data of conductivity fluctuations are examined in terms of the derivative of the electrical resistivity with respect to temperature and the logarithmic derivative of the conductivity with regard to temperature. The results illustrate the existence of a transition with two stages; intragrain and intergrain. It is demonstrated that the addition of CoFe{sub 2}O{sub 4} nanoparticles affects the electrical conductivity fluctuations, the values of the critical exponents, and the fluctuation dimensionality in YBCO systems.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

The Structural, Electronic, and Magnetic Features of Co{sub 2}Mn{sub 1−x}Al{sub x}Ti (0 ≤ x ≤ 0.6) Heusler Alloys

The structural, electronic, and magnetic features of Co{sub 2}Mn{sub 1−x}Al{sub x}Ti (0 ≤ x ≤ 0.6) Heusler alloys (HAs) have been systematically investigated by experimental techniques (X-ray powder diffraction, scanning electron microscopy, and magnetization measurements) and ab initio theoretical calculations. Whole alloys have cubic structures at room temperature and exhibit ferromagnetic properties. The Curie temperature of Co{sub 2}Mn{sub 1−x}Al{sub x}Ti (x = 0) is approximately 790 K, which is compatible with other studies. By increasing Al content, the temperature dependence of magnetization trials has proved a linear diminishment on Curie temperature and saturation magnetization.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Influence of Non-magnetic Ti{sup 4+} Ion Doping at Mn Site on Structural, Magnetic, and Magnetocaloric Properties of La{sub 0.5}Pr{sub 0.2}Sr{sub 0.3}Mn{sub 1−x}Ti{sub x}O{sub 3} Manganites (x = 0.0 and 0.1)

Polycrystalline perovskite AMn{sub 1−x}TiO{sub 3} with A = La{sub 0.5}Pr{sub 0.2}Sr{sub 0.3} (x = 0.0 and 0.1) have been prepared using solid-state reaction method. X-ray powder diffraction and Rietveld refinement revealed that all samples crystallize in a rhombohedral structure with space group R 3-bar c From M–T curve, we determined the Curie temperature, where the magnetization value decreases abruptly. The Curie temperature (T{sub C}) decreases from 280 to 123 K when the percentage of Ti increases to 10%. The values of the magnetization M(H) decrease when increasing the Ti content. Moreover, the magnetocaloric effect (MCE) was estimated in terms of isothermal entropy change (−ΔS{sub M}) using the M(T, μ{sub 0}H) data and employing the thermodynamic Maxwell equation. In addition, using a phenomenological model, we determine magnetocaloric effect from the calculation of magnetization as a function of temperature under different external magnetic fields. Also, we can determine the relative cooling power (RCP) and the specific heat which varies from 2.803 to 7.354 J/(kg/K) for the undoped sample from M(T, μ{sub 0}H) data at different magnetic fields theoretically.

36 MATERIALS SCIENCE↗
DOE OSTI2019

The Effects of La Doping on the Crystal Structure, Magnetic, and Microwave Absorption Properties of Nd{sub 2}Fe{sub 14}B Compound

The crystal structure, magnetic, and microwave absorption properties of the (Nd{sub 1−x}La{sub x}){sub 2}Fe{sub 14}B system have been investigated. The La{sub 2}Fe{sub 14}B compound was successfully synthesized and refined, giving a tetragonal structure, space group P4{sub 2}/mnm with the Nd{sub 2}Fe{sub 14}B-type structure. The crystal structure parameters of the (Nd{sub 1−x}La{sub x}){sub 2}Fe{sub 14}B compounds were determined by full-profile Rietveld refinements. The results revealed that all intermediate alloys form a continuous solid solution. The normalized lattice parameters of the (Nd{sub 1−x}La{sub x}){sub 2}Fe{sub 14}B compounds increase linearly with an increase of La concentration. Based on the results of DSC measurements and X-ray powder diffraction examinations, the phase diagram of the Nd{sub 2}Fe{sub 14}B-La{sub 2}Fe{sub 14}B system has been constructed. The remanence (M{sub r}) and coercivity (H{sub c}) of (Nd{sub 1−x}La{sub x}){sub 2}Fe{sub 14}B (x = 0.00, 0.10, 0.20, 0.30, and 0.40) gradually decrease. The highest reflection loss is − 29.8, − 27.4, − 24.1, − 18.6, and − 14.2 dB at 9.8, 8.9, 7.5, 6.9, and 6.5 GHz, respectively. The absorption peak shifts toward from higher frequency region to lower frequency region and the absorption bandwidth widens with the increase of the La substitution.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Effect of Ca Doping on the Structure and Magnetic and Electronic Properties of La{sub 1 − x}Ca{sub x}Cr{sub 0.8}Cu{sub 0.2}O{sub 3} (x = 0~0.3)

A series of La{sub 1 − x}Ca{sub x}Cr{sub 0.8}Cu{sub 0.2}O{sub 3} samples were successfully prepared by sol-gel method, and their crystal structures were refined by using X-ray powder diffraction data. All samples had orthorhombic structure with a space group Pbnm. Two magnetic transitions were observed for all of samples, and the paramagnetism-antiferromagnetism transition temperature decreased, and the antiferromagnetism-ferromagnetism transition temperature increased with increasing Ca content. Moreover, Cu and Ca co-doping improved conductivity and active energy.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Vickers Microhardness Studies for SmBa{sub 2}Cu{sub 3}O{sub 7-δ} Added with NiO Nanosized Particles

The effect of nanosized particles NiO addition on the Vickers microhardness of polycrystalline SmBa{sub 2}Cu{sub 3}O{sub 7-δ} was investigated. Various amounts of nanosized particles NiO (x = 0.00, 0.02, 0.04, 0.08, and 0.12 wt%) were added to SmBa{sub 2}Cu{sub 3}O{sub 7-δ} prepared by the solid-state reaction method. Sample characterizations were carried out using X-ray powder diffraction (XRD), particle induced X-ray emission (PIXE), Rutherford backscattering (RBS), and scanning electron microscopy (SEM). The nanosized particle addition does not influence the orthorhombic structure of SmBa{sub 2}Cu{sub 3}O{sub 7-δ}, whereas it affects the oxygen content δ. The electrical and mechanical properties of (NiO){sub x}SmBa{sub 2}Cu{sub 3}O{sub 7-δ} samples were measured using four-standard probe technique and Vickers microhardness in order to investigate the effect of NiO nanosized particles on superconducting transition temperature and Vickers microhardness number H{sub v}. The Vickers microhardness data were analyzed using Hays and Kendall (HK), elastic plastic deformation (EPD), and modified proportional specimen resistance (MPSR) models. The analysis showed that the MPSR model was found to be the best to describe the behavior of H{sub v}.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Mössbauer, Magnetization and Structure Characterizations of the Annealed Sr{sub 1/3}Mn{sub 1/3}Co{sub 1/3}Fe{sub 2}O{sub 4} Ferrite Nanoparticles

Sr{sub 1/3}Mn{sub 1/3}Co{sub 1/3}Fe{sub 2}O{sub 4} ferrite nanoparticles were synthesized by glycol thermal technique. The structure and morphology of the Nano ferrites were studied by X-ray powder diffraction, Fourier transform infrared FTIR, high-resolution scanning electron microscopy, and high-resolution transmission electron microscopy. The induced internal strains were investigated by Williamson plots. The results show mono-dispersive property of the sample and particle sizes that increase with increasing annealing temperature, T{sub A}. The magnetic hyperfine fields were found to be sensitive to T{sub A} as seen from room temperature {sup 57}Fe Mössbauer measurements. The magnetic hysteresis loops were performed in external magnetic field of up to 50 kOe. Room temperature M − H loops showed that the coercive fields increased to a maximum at T{sub A} of 500 °C and then decreased thereafter. Significant increases in coercive fields were observed at a measuring temperature of 4 K. Distortions in the hysteresis loops at 4 K were observed where thermal annealing effect appears to induce strong linear correlation between coercive fields and saturation magnetizations.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Synthesis and Characterization of Hydrophobic Fe{sub 3}O{sub 4} Magnetic Nanoparticles with High Saturation Magnetization

A simple one-step solvothermal method is proposed to prepare hydrophobic Fe{sub 3}O{sub 4} nanoparticles (MNPs) using iron acetylacetonate (Fe(acac){sub 3}), oleylamine (OAm), and ethylene glycol (EG). X-ray powder diffraction, scanning electron microscope, infrared spectroscopy, transmission electron microscopy, X-ray photoelectron spectrometry, and vibrating sample magnetometer are used to characterize the structure, morphology, and properties of products. The testing results indicate that the as-synthesized products are spherical-like hydrophobic MNPs, superparamagnetic at room temperature, with a saturation magnetization up to 76.8 emu/g. The good hydrophobic property of MNPs is attributed to the coverage of oleylamine, without causing a remarkable loss of magnetic property. In addition, the influences of material ratio, aging time, oleic acid, and stearic acid used as additives are studied in our research.

77 NANOSCIENCE AND NANOTECHNOLOGY↗