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1

Conjugation of manganese ferrite nanoparticles to an anti Sticholysin monoclonal antibody and conjugate applications  

Microsoft Academic Search

In this study the potential applications of manganese ferrite (MnFe2O4) nanoparticles for bioanalytical applications are evaluated. These magnetic nanoparticles show peroxidase-like activity similar to that reported for magnetite nanoparticles and peroxidase enzyme. Based on this finding, colloidal suspensions of manganese ferrite were conjugated to an anti-Sticholysin II (StII) monoclonal antibody. The resulting conjugate was then used as a revealing tool

V. Figueroa-Espí; A. Alvarez-Paneque; M. Torrens; A. J. Otero-González; E. Reguera

2011-01-01

2

Relaxivities of hydrogen protons in aqueous solutions of gold-coated manganese ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Manganese ferrite nanoparticles were synthesized using the reverse micelle method and were coated with gold. TEM (transmission electron microscope) pictures showed that the shapes of the synthesized nanoparticles were almost spherical with an average diameter of 12 nm and a standard error of 4 nm. The bonding status of gold on the nanoparticle surfaces was checked using a Fourier transform infrared spectrometer (FTIR). The T1 and the T2 relaxation times of the hydrogen protons in aqueous solutions of the coated manganese-ferrite nanoparticles were determined using magnetic resonance imaging (MRI). The 1/ T 1 and the 1/ T 2 versus concentration curves for the nanoparticles showed a linear dependence. The T1 and the T2 relaxivities were found to be r 1 = 6.01 ± 0.12 and r 2 = 83.3 ± 0.55 mM-1 s -1. The ratio of r 2/ r 1 was 13.9; this is larger than the ratios of r 2/ r 1 for commercial T2 MRI contrast agents, indicating that the nanoparticles studied herein can serve as a T2 contrast agent with high efficacy.

Ahmad, Tanveer; Iqbal, Yousaf; Bae, Hongsub; Rhee, Ilsu; Hong, Sungwook; Chang, Yongmin; Lee, Jaejun

2013-06-01

3

Role of surface charge in cytotoxicity of charged manganese ferrite nanoparticles towards macrophages.  

PubMed

Amphiphilic surfactants have been used to disperse magnetic nanoparticles in biological media, because they exhibit a dual hydrophobic/hydrophilic affinity that facilitates the formation of a nanoemulsion, within which nanoparticle surfaces can be modified to achieve different physicochemical properties. For the investigation of the interactions of cells with charged magnetic nanoparticles in a biological medium, we selected the nanoemulsion method to prepare water-soluble magnetic nanoparticles using amphiphilic surfactant (polysorbate 80). The hydroxyl groups of polysorbate 80 were modified to carboxyl or amine groups. The chemical structures of carboxylated and aminated polysorbate 80 were confirmed, and water-soluble manganese ferrite nanoparticles (MFNPs) were synthesized with three types of polysorbate 80. Colloidal size, morphology, monodispersity, solubility and T2 relaxivity were found to be similar between the three types of MFNP. However, cationic MFNPs exhibited greater cytotoxicity in macrophages (RAW264.7 cells) and lower cellular membrane effective stiffness than anionic and non-ionic MFNPs. Moreover, cationic MFNPs exhibited large uptake efficiency for RAW264.7 cells compared with anionic or non-ionic MFNPs under the same conditions. Therefore, we propose that surface charge should be a key consideration factor in the design of magnetic nanoparticles for theragnostic applications. PMID:23164999

Yang, Seung-Hyun; Heo, Dan; Park, Jinsung; Na, Sungsoo; Suh, Jin-Suck; Haam, Seungjoo; Park, Sahng Wook; Huh, Yong-Min; Yang, Jaemoon

2012-11-19

4

Magnetocaloric effect in ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

A comparative study of the magnetocaloric effect (MCE) is reported in two different types of chemically synthesized magnetic nanoparticle systems—cobalt ferrite and manganese zinc ferrite with mean size around 5 and 15 nm, respectively. While CoFe2O4 nanoparticles were synthesized using co-precipitation, the Mn0.68Zn0.25Fe2.07O4 (MZFO) nanoparticles were prepared by reverse micelle technique using AOT as surfactant. Our results indicate that the change in entropy with the change in applied magnetic field (dS/dH) is reasonably large for this class of nanoparticles and has a wide distribution over a broad temperature range covering the region above and below the blocking temperature. The maximum entropy change is influenced by the particle size, overall distribution in anisotropy and magnetic moments.

Poddar, P.; Gass, J.; Rebar, D. J.; Srinath, S.; Srikanth, H.; Morrison, S. A.; Carpenter, E. E.

2006-12-01

5

Evidence for polaron conduction in nanostructured manganese ferrite  

Microsoft Academic Search

Nanoparticles of manganese ferrite were prepared by the chemical co-precipitation technique. The dielectric parameters, namely, real and imaginary dielectric permittivity (?' and ?''), ac conductivity (sigmaac) and dielectric loss tangent (tandelta), were measured in the frequency range of 100 kHz-8 MHz at different temperatures. The variations of dielectric dispersion (?') and dielectric absorption (?'') with frequency and temperature were also

E. Veena Gopalan; K. A. Malini; S. Saravanan; D. Sakthi Kumar; Yasuhiko Yoshida; M. R. Anantharaman

2008-01-01

6

Evidence for polaron conduction in nanostructured manganese ferrite  

Microsoft Academic Search

Nanoparticles of manganese ferrite were prepared by the chemical co-precipitation technique. The dielectric parameters, namely, real and imaginary dielectric permittivity (?? and ??), ac conductivity (?ac) and dielectric loss tangent (tan?), were measured in the frequency range of 100 kHz–8 MHz at different temperatures. The variations of dielectric dispersion (??) and dielectric absorption (??) with frequency and temperature were also

E Veena Gopalan; K A Malini; S Saravanan; D Sakthi Kumar; Yasuhiko Yoshida; M R Anantharaman

2008-01-01

7

Low-temperature synthesis and thermal study of manganese-zinc ferrite nanoparticles by a ferrioelate precursor method  

NASA Astrophysics Data System (ADS)

The procedure adopted for preparing the ferrite formation was found to be quite sensitive. The chlorine ion concentration and the pH in the solution has played a crucial role in retaining the initial stoichiometry of the solution in the nanoparticles. This work had the objective of studying the nanoparticle Mn-Zn ferrite obtained by the ferrioelate precursor method. In this process, Mn-Zn ferrite, synthesized through solutions of some specific salts led to the formation of crystalline power (10-30nm as evident from X-ray diffraction analysis) at a temperature of 2000C. The synthesis powders were characterized by X-ray diffractometer for identification of the crystalline phases present, by scanning electron microscopy for identification for their morphological structure and properties, thermogarvimetry and differential thermal analysis for identification of the oxidation/ reduction behaviour upon firing. The fourier transformation infrared spectroscopy (FT-IR) shows two main absorption bands v1 and v2 in the range of 4000-500cm-1and Differential Scanning Calorimetry (DSC) of the Mn0.4Zn0.6Fe2O4 powder at 5000C predicts the exothermic and endothermic reaction with the change in temperature with respect to heat flow. The synthesis route is simple, energy saving and cost effective. Details of the synthesis and characterizations of the resultant products were given.

Lal, Madan; Singh, M.

2007-01-01

8

Modification of dielectric and mechanical properties of rubber ferrite composites containing manganese zinc ferrite  

Microsoft Academic Search

Spinel ferrites constitute an important class of magnetic materials. Polycrystalline ferrites are a complex system composed of crystallite grain boundaries and pores. Manganese zinc ferrites have resistivities between 0.01 and 10?m. Making composite materials of ferrites with either natural rubber or plastics will modify the electrical properties of ferrites. Composite materials are ideally suited for many modern applications where ceramic

E. M. Mohammed; K. A. Malini; Philip Kurian; M. R. Anantharaman

2002-01-01

9

40 CFR 721.10223 - Styrenyl surface treated manganese ferrite with acrylic ester polymer (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Styrenyl surface treated manganese ferrite with acrylic ester polymer...721.10223 Styrenyl surface treated manganese ferrite with acrylic ester polymer...generically as styrenyl surface treated manganese ferrite with acrylic ester...

2013-07-01

10

40 CFR 721.10222 - Styrenyl surface treated manganese ferrite (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Styrenyl surface treated manganese ferrite (generic). 721.10222...721.10222 Styrenyl surface treated manganese ferrite (generic). (a) Chemical...generically as styrenyl surface treated manganese ferrite (PMN P-09-581) is...

2013-07-01

11

Manganese Ferrite Grown at Atomic Scale  

SciTech Connect

Manganese spinel ferrite (MnFe{sub 2}O{sub 4}) films were deposited at the atomic scale. In the depositions, laser pulses alternately impinged MnO and Fe{sub 2}O{sub 3} targets and sequentially deposited thin layers ({approx}5 {angstrom}) of MnO and Fe{sub 2}O{sub 3} on MgO substrate, which is referred to as 'artificial' films. The X-ray diffraction measurements showed that the artificial films were of spinel structure. Auger spectroscopy measurements showed that the chemical composition of the artificial ferrites were consistent with that of standard films deposited using a single target of MnFe{sub 2}O{sub 4}. However, extended X-ray absorption fine spectroscopy showed that the artificial growth technique affected the cation distribution to be different from the standard films. As a result, the magnetic properties of the artificial films, including Neel temperature, uniaxial and in-plane anisotropy, were different from the standard films.

Zuo,X.; Yang, F.; Mafhoum, R.; Karim, R.; Tebano, A.; Balestrino, G.; Harris, V.; Vittoria, C.

2004-01-01

12

Investigation of structural and magnetic properties of nanocrystalline manganese substituted lithium ferrites  

SciTech Connect

Nanocrystalline manganese substituted lithium ferrites Li{sub 0.5}Fe{sub 2.5-x}Mn{sub x}O{sub 4} (2.5<=x>=0) were prepared by sol-gel auto-combustion method. X-ray diffraction patterns revealed that as the concentration of manganese increased, the cubic phase changed to tetragonal. Magnetic properties were measured by hysteresis loop tracer technique. All the compositions indicated ferrimagnetic nature. The surface morphology of all the samples was studied by using scanning and transmission electron microscopy. The substitution of manganese ions in the lattice affected the structural as well as magnetic properties of spinels. - Graphical abstract: The synthesized nanoparticles shapes, sizes and size dispersibilities were obtained from the transmission electron microscopy (TEM). The TEM micrographs of synthesized samples revealed that, spherical shape with average particle size 50 nm. Selected area electron diffraction pattern (SAED) suggests the polycrystallinity and also the formation of spinel ferrites.

Hankare, P.P., E-mail: p_hankarep@rediffmail.co [Department of Chemistry, Shivaji University, Kolhapur 416004, Maharashtra (India); Patil, R.P., E-mail: raj_rbm_raj@yahoo.co.i [Department of Chemistry, Shivaji University, Kolhapur 416004, Maharashtra (India); Sankpal, U.B.; Jadhav, S.D. [Department of Chemistry, Shivaji University, Kolhapur 416004, Maharashtra (India); Lokhande, P.D. [Pune University, Pune, Maharashtra, India. (India); Jadhav, K.M. [Dr. B.A.Marathwada University, Aurangabad 431004, Maharashtra (India); Sasikala, R. [Chemistry Division, Bhabha Atomic Research Center, Mumbai 400085, Maharashtra (India)

2009-12-15

13

Influence of manganese doping in multiferroic bismuth ferrite thin films  

Microsoft Academic Search

We have examined the influence of manganese doping to the magnetic properties of manganese-doped bismuth ferrite [BiFe1?xMnxO3 (x=0, 0.05, and 0.2)] thin films grown epitaxially on (LaAlO3)0.3(Sr2AlTaO6)0.7 substrates by pulsed laser deposition technique. Manganese doping gave rise to a gradual increase of spontaneous magnetization along with the clarity of magnetic hysteresis. This enhanced magnetization can be understood by the modification

Kouhei Takahashi; Masayoshi Tonouchi

2007-01-01

14

Ionization Ability of Manganese Nanoparticles  

NASA Astrophysics Data System (ADS)

Manganese oxide nanoparticles (Mn-O NPs) were prepared through our novel method as reagents for laser desorption/ionization mass spectrometry (LDI-MS). Through the control of the reaction time in the chemical preparation method (0.5, 1, and 5 h), we succeeded in preparing three different types of manganese oxide particles. The particles were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and DC magnetization measurements. These characterization results indicated that the manganese ions oxidized in aqueous alkaline solution, and that the spinel structure was retained for the Mn3O4 phase, which then gradually changed into the MnO2 phase. The mass spectra of substance P (MW = 1347.6) were measured by MALDI-TOF mass spectrometry with Mn-O NPs. The Mn-O NPs that reacted with 3-aminopropyltriethoxysilane(?-APTES) for 1 h or 5 h had higher ionization abilities than those reacted for 0.5 h. These different abilities are attributed to the different crystal structures of the prepared manganese oxides.

Hiroki, Tomoyuki; Shigeoka, Daiki; Kimura, Shinji; Mashino, Toshiyuki; Taira, Shu; Ichiyanagi, Yuko

2011-05-01

15

Magnetocaloric effect (MCE) in Nickel Ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

We report on the magneto caloric effect (MCE) in a Nickel ferrite (NiFe2O4) nanoparticle system. The nanoparticles were synthesized using chemical co-precipitation. Extensive characterization of structural and magnetic properties was done using XRD, TEM, DC and AC magnetization, and transverse susceptibility. The change in entropy was calculated using the thermodynamic Maxwell relation from the family of M-H curves taken at different temperatures. Maximum entropy change in nanoparticle systems is influenced by particle size, anisotropy, and collective dipolar behavior. While the MCE is not as large as that reported in bulk systems, there are advantages as ferrite nanoparticles are easily produced and the operational temperature is tuned by the average particle size. In our studies, we observed a sharp peak in M-T curves at around 60K in addition to the blocking transition which occurs at 120 K. This results in a larger entropy change in comparison with the MCE results on other reported ferrite nanoparticles. The origin of this anomalous MCE is analyzed in the context of surface anisotropy and other possible contributions in the NiFe2O4 system. Work supported by NSF through grant CTS-0408933.

Gass, J.; Morales, M. B.; Frey, N. A.; Miner, M. J.; Srinath, S.; Srikanth, H.

2007-03-01

16

Low temperature chemical synthesis of ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Ferrite nanoparticles of Ni0.4Zn0.6-xMnxFe2O4 where x varies from 0 to 0.25 in steps of 0.05 using metal nitrates were prepared by low temperature sol-gel autocombustion method in citric acid matrix. XRD patterns of all the samples exhibit spinel crystal structures and the crystallite sizes estimated using Scherrer equation have been found to be about 30 nm. TEM measurements on these nanoparticles showed the particle sizes to be around 32 nm which are in conformity with the crystallite sizes obtained through XRD. The magnetic measurements carried out using VSM on these NiZn ferrite nanoparticles showed good magnetic performance with Mn substitutions. Deviations, if any, in magnetic properties are attributed to the increased degree of inversion in cationic distributions and also to the spin disorder at the surfaces which contributes to decreased magnetic strength of the cations present in different lattice sites.

Ramesh, S.; Rao, S. N. R.; Rao, B. Parvatheeswara; Subba Rao, P. S. V.

2012-07-01

17

State of adsorption layers of fatty acids on the surfaces of iron, manganese, and copper ferrites  

NASA Astrophysics Data System (ADS)

States of adsorbed substances in surface layers arising during the adsorption of oleic, linoleic, and linolenic acids from carbon tetrachloride, heptane, and cyclohexane solutions on the surfaces of iron, manganese, and copper ferrites, are investigated. Adsorption isotherms and two-dimensional state diagrams of surface layers of iron, manganese, and copper ferrites are obtained experimentally. It is shown that the adsorption of fatty acids from solutions in organic solvents proceeds via filling the volume of the ferrites' porous space with adsorption solutions, while the state of ferrite surface layers changes due to the structural rearrangement of adsorption solutions upon an increase in solute concentration.

Balmasova, O. V.; Ramazanova, A. G.; Korolev, V. V.

2012-07-01

18

Influence of Sn-substitution on temperature dependence and magnetic disaccommodation of manganese-zinc ferrites  

NASA Astrophysics Data System (ADS)

In this paper, the effects of Sn-substitution on temperature dependence and magnetic disaccommodation of manganese-zinc ferrites were investigated. Toroidal cores were prepared by the conventional ceramic process and sintered at 1360 °C for 4 h in atmosphere controlled by using the equation for equilibrium oxygen partial pressure. The experimental results show that the substitution of Sn4+ in manganese-zinc ferrites can influence the thermal stability and disaccommodation remarkably. Secondly, the temperature dependence of the initial permeability ?i and disaccommodation of Sn-substitution manganese-zinc ferrites have an internal relationship. The experimental results are explained and compared with those of Ti-substitution manganese-zinc ferrite.

Ji, Haining; Lan, Zhongwen; Yu, Zhong; Sun, Ke; Li, Lezhong

2009-07-01

19

Magnetic resonance of ferrite nanoparticles  

Microsoft Academic Search

Ferromagnetic resonance (FMR) experiments at 9.26GHz on non-interacting maghemite (?-Fe2O3) nanoparticles of ferrofluids are performed as a function of temperature (3.5–300K) and particle diameter (4.8–10nm). The orientational mobility of the particles inside the fluid is employed to monitor the orientational distribution of the anisotropy axes by solidifying the MF matrix under the external field. On those textured suspensions, angular analysis

F. Gazeau; J. C Bacri; F. Gendron; R. Perzynski; Yu. L Raikher; V. I. Stepanov; E. Dubois

1998-01-01

20

Palladium nanoparticle supported on cobalt ferrite: an efficient magnetically separable catalyst for ligand free Suzuki coupling  

Microsoft Academic Search

Synthesis of Pd nanoparticle supported on cobalt ferrite magnetic nanoparticles has been achieved by direct addition of Pd nanoparticles during synthesis of cobalt ferrite nanoparticles by ultrasound assisted co-precipitation in absence of any surface stabilizers or capping agent. The catalytic performance of the Pd incorporated cobalt ferrite nanoparticles was examined in Suzuki coupling reaction in ethanol under ligand free condition.

Kula Kamal Senapati; Subhasish Roy; Chandan Borgohain; Prodeep Phukan

21

Synthesis and characterization of nickel ferrite magnetic nanoparticles  

Microsoft Academic Search

Nickel ferrite (NiFe2O4) nanoparticles are prepared by a polyvinyl alcohol (PVA) assisted sol–gel auto-combustion method. The structure, composition, morphology and magnetic properties of the gel precursor are characterized by powder XRD, FT-IR, TGA, HR-SEM, TEM, HR-TEM and VSM. XRD confirms the formation of single-phase nickel ferrite with space group of Fd3m and inverse spinel structure. The vibration properties of nanoparticles

P. Sivakumar; R. Ramesh; A. Ramanand; S. Ponnusamy; C. Muthamizhchelvan

2011-01-01

22

Influence of quencher on microstructure and magnetic properties of manganese-zinc ferrites  

NASA Astrophysics Data System (ADS)

The effects of quencher after calcination on the microstructure and magnetic properties of manganese-zinc ferrites were investigated by measuring the magnetic properties, electrical resistivity and density. The powder of Mn0.68Zn0.25Fe2.07O4 composition was prepared by adopting the conventional ceramic technique. Toroidal cores were sintered at 1350 °C for 4 h in atmosphere controlled by using the equation for equilibrium oxygen partial pressure. The fracture surface micrographs of samples were observed by scanning electron microscope. The results show that the inner stress of calcined powder increases, abnormal grains of ferrite grow up, initial permeability goes down and power losses of ferrite rise with the increase in quenching temperature, and the microstructure and magnetic properties of manganese-zinc ferrites can be improved with the gradual cooling of calcined powder to room temperature (25 °C).

Lezhong, Li; Zhongwen, Lan; Zhong, Yu; Ke, Sun; Haining, Ji

2007-11-01

23

Magnetic properties of carbon stabilized multiferroic bismuth ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Carbon-stabilized bismuth ferrite (BiFeO3) nanoparticles have been synthesized by a self-combustion method, under ambient conditions and post annealing at selective temperatures between 400-800°C in air. BiFeO3 nanoparticles in carbon matrix show enhanced magnetic properties compared to its bulk counterpart.

Karan, T.; Ram, S.; Kotnala, R. K.

2012-06-01

24

Tailoring magnetic properties of Co-ferrite soft magnetic nanoparticles  

Microsoft Academic Search

Monodisperse Co-ferrite soft magnetic nanoparticles with particle size from 3 nm to 20 nm and different Co concentration have been synthesized by chemical solution methods. The composition was controlled by varying the mole ratios of the precursors in the solution. It has been found that magnetic properties of the nanoparticles can be tailored by changing the composition, particle size, as

N. Poudyal

2005-01-01

25

Transition metal-substituted cobalt ferrite nanoparticles for biomedical applications.  

PubMed

Transition metals of copper, zinc, chromium and nickel were substituted into cobalt ferrite nanoparticles via a sol-gel route using citric acid as a chelating agent. The microstructure and elemental composition were characterized using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy. Phase analysis of transition metal-substituted cobalt ferrite nanoparticles was performed via X-ray diffraction. Surface wettability was measured using the water contact angle technique. The surface roughness of all nanoparticles was measured using profilometry. Moreover, thermogravimetric analysis and differential scanning calorimetry were performed to determine the temperature at which the decomposition and oxidation of the chelating agents took place. Results indicated that the substitution of transition metals influences strongly the microstructure, crystal structure and antibacterial property of the cobalt ferrite nanoparticles. PMID:23137676

Sanpo, Noppakun; Berndt, Christopher C; Wen, Cuie; Wang, James

2012-11-05

26

The effect of thermal treatment on the magnetic properties of spinel ferrite nanoparticles in magnetic fluids  

Microsoft Academic Search

Magnetic properties of ferrites are dependent on the crystalline structure and location of metal ions in the material. The most commonly used materials of nanoparticles in magnetic fluids are chemical stable spinel (2-3) ferrites. The preparation of ferrite nanoparticles for magnetic fluids synthesis needs a special technology. More commonly used is the wet chemical coprecipitation production technology of magnetic nanoparticles

G. Kronkalns; A. Dreimane; M. M. Maiorov

2008-01-01

27

Transformation Characteristics of Ferrite/Carbide Aggregate in Continuously Cooled, Low Carbon-Manganese Steels  

NASA Astrophysics Data System (ADS)

Transformation characteristics and morphological features of ferrite/carbide aggregate (FCA) in low carbon-manganese steels have been investigated. Work shows that FCA has neither the lamellae structure of pearlite nor the lath structure of bainite and martensite. It consists of a fine dispersion of cementite particles in a smooth ferrite matrix. Carbide morphologies range from arrays of globular particles or short fibers to extended, branched, and densely interconnected fibers. Work demonstrates that FCA forms over similar cooling rate ranges to Widmanstätten ferrite. Rapid transformation of both phases occurs at temperatures between 798 K and 973 K (525 °C and 700 °C). FCA reaction is not simultaneous with Widmanstätten ferrite but occurs at temperatures intermediate between Widmanstätten ferrite and bainite. Austenite carbon content calculations verify that cementite precipitation is thermodynamically possible at FCA reaction temperatures without bainite formation. The pattern of precipitation is confirmed to be discontinuous. CCT diagrams have been constructed that incorporate FCA. At low steel manganese content, Widmanstätten ferrite and bainite bay sizes are significantly reduced so that large amounts of FCA are formed over a wide range of cooling rates.

Di Martino, S. F.; Thewlis, G.

2013-10-01

28

Temperature dependent coercivity and magnetization of nickel ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles of nickel ferrite (size: 24±4 nm) have been synthesized by chemical coprecipitation method using stable ferric and nickel salts. Coercivity of nanoparticles has been found to increase with decrease in temperature of the samples. It has been observed that the coercivity follows a simple model of thermal activation of particle’s moment over the anisotropy barrier in the temperature range (10-300 K), in accordance with Kneller’s law for ferromagnetic materials. Saturation magnetization follows the modified Bloch’s law in the temperature range from 300 to 50 K. However, below 50 K, an abrupt increase in magnetization of nanoparticles was observed. This increase in magnetization at lower temperatures was explained with reference to the presence of freezed surface-spins and some paramagnetic impurities at the shell of nanoparticles that are activated at lower temperatures in core-shell nickel ferrite nanoparticles.

Maaz, K.; Mumtaz, A.; Hasanain, S. K.; Bertino, M. F.

2010-08-01

29

Recycling spent zinc manganese dioxide batteries through synthesizing Zn-Mn ferrite magnetic materials.  

PubMed

A novel process to reclaim spent zinc manganese dioxide batteries (SDBs) through synthesizing Zn-Mn ferrite magnetic materials is present. Firstly, the dismantling, watering, magnetism, baking and griddling steps were consecutively carried out to obtain iron battery shells, zinc grains and manganese compounds using the collected SDBs, and then these separated substances were dissolved with 4 mol L(-1) H(2)SO(4) to prepare FeSO(4), ZnSO(4) and MnSO(4) reactant solutions. Secondly, Zn-Mn ferrites with stoichiometric ratio of Mn(0.26)Zn(0.24)FeO(2) were synthesized using chemical co precipitation process with ammonium oxalate precipitator. The XRD results showed that the obtained Zn-Mn ferrites had spinel structure and high purity at the calcining temperatures of 850-1250 degrees C. With the increase of calcining temperature, the finer crystalline structure could be formed, and their intensity of saturation magnetization reached the highest value at 1150 degrees C. The magnetization performances of Zn-Mn ferrites prepared from the SDBs were similar to that of from analysis reagents, suggesting the feasibility to synthesize Zn-Mn ferrites with high properties from SDBs. PMID:16310946

Nan, Junmin; Han, Dongmei; Cui, Ming; Yang, Minjie; Pan, Linmao

2005-11-28

30

Chitosan Clad Manganese Doped Zinc Suiphide Nanoparticles as Biological Labels  

Microsoft Academic Search

Here the authors report the synthesis in aqueous media of redispersible zinc sulphide quantum dots doped with manganese, capped by biocompatible 'chitosan' molecules. The nanoparticles show highly efficient luminescence with a peak at around 590 nm that has been correlated to the manganese dopants. The synthesis involves very simple precipitation techniques that may lead to the development of a cost

H. C. Warad; C. Thanachayanont; G. Tumcharern; J. Dutta

2007-01-01

31

Susceptibility of cobalt ferrite nanoparticles dispersed in polylactic acid microspheres  

NASA Astrophysics Data System (ADS)

In this study dynamic susceptibility (DS) was used to investigate cobalt ferrite (CoFe2O4) nanoparticles dispersed in polylactic-based microsized spheres. The peak position of the imaginary component of the DS curve was analyzed as a function of the polarizing external field, using a picture of an asymmetric double-well potential for the relaxation of the magnetization associated to the magnetic nanoparticle.

Silveira, L. B.; Santos, J. G.; Oliveira, A. C.; Tedesco, A. C.; Marchetti, J. M.; Lima, E. C. D.; Morais, P. C.

2004-05-01

32

Immobilization of biomolecules on biotinylated magnetic ferrite nanoparticles  

Microsoft Academic Search

We have developed biocompatible ferrite (Fe3O4) nanoparticles whose surfaces are functionalized with biotin molecule. The resulting magnetic nanoparticles with an average diameter of 8nm have a biotin-anchored morphology, which gives an exceptionally high affinity for the Cy3-labeled streptavidin. The spectroscopic and magnetic data results confirmed the presence of the interaction between biotin-anchored Fe3O4 particles and Cy3-labeled streptavidins. These biocompatible magnetic

Jungkweon Choi; Jong In Lee; Yong Bok Lee; Jung Hoon Hong; In Seon Kim; Yong Ki Park; Nam Hwi Hur

2006-01-01

33

Thermal Growth and Performance of Manganese Cobaltite Spinel Protection Layers on Ferritic Stainless Steel SOFC Interconnects  

Microsoft Academic Search

To protect solid oxide fuel cells (SOFCs) from chromium poisoning and improve metallic interconnect stability, manganese cobaltite spinel protection layers with a nominal composition of Mn1.5Co1.5O4 were thermally grown on Crofer22 APU, a ferritic stainless steel. Thermal, electrical and electrochemical investigations indicated that the spinel protection layers not only significantly decreased the contact area specific resistance (ASR) between a LSF

Zhenguo Yang; Guanguang Xia; Steven P. Simner; Jeffry W. Stevenson

2005-01-01

34

An Experimental Study on Electrical Discharge Machining of Manganese–Zinc Ferrite Magnetic Material  

Microsoft Academic Search

The objective of this research is to investigate the machining characteristics of manganese–zinc (Mn–Zn) ferrite magnetic material using electrical-discharge machining (EDM). The material removal rate, the surface topography, the surface roughness, the recast layer, and the chemical composition of the machined surface were studied in terms of EDM processing variables. Experimental results indicate that the morphology of debris revealed the

Y. H. Guu; Kuan-Lin Tsai; Lin-Ke Chen

2007-01-01

35

Cationic behavior and the related magnetic and magnetotransport properties of manganese ferrite thin films  

Microsoft Academic Search

Manganese ferrite (MnxFe3-xO4) thin films have been prepared by a sol-gel method. The samples (x<=1.25) are polycrystalline containing well-defined grains and maintain cubic spinel structure with increasing lattice constant with x. The substituting Mn ions were found to have multi-valence, +2 and +3, by X-ray photoelectron spectroscopy. The saturation magnetization of the Mn-substituted films measured by vibrating sample magnetometry was

Kwang Joo Kim; Hee Jung Lee; Jae Yun Park

2009-01-01

36

Cationic behavior and the related magnetic and magnetotransport properties of manganese ferrite thin films  

Microsoft Academic Search

Manganese ferrite (MnxFe3?xO4) thin films have been prepared by a sol–gel method. The samples (x?1.25) are polycrystalline containing well-defined grains and maintain cubic spinel structure with increasing lattice constant with x. The substituting Mn ions were found to have multi-valence, +2 and +3, by X-ray photoelectron spectroscopy. The saturation magnetization of the Mn-substituted films measured by vibrating sample magnetometry was

Kwang Joo Kim; Hee Jung Lee; Jae Yun Park

2009-01-01

37

Swift heavy ions irradiation studies on some ferrite nanoparticles  

Microsoft Academic Search

Ferrite nanoparticles of two different systems, namely Ni0.65Zn0.375In0.25Ti0.025Fe1.70O4 and Mn0.75Zn0.18Fe2.07O4, have been prepared by two different methods of ball milling (mechano synthesis) and coprecipitation (soft chemistry) respectively to investigate the effect of swift heavy ion irradiations on the structural, magnetic and ferromagnetic resonance parameters on these systems. The powder samples of Ni–Zn and Mn–Zn ferrites were irradiated with 190MeV Ag15+

B. Parvatheeswara Rao; K. H. Rao; P. S. V. Subba Rao; A. Mahesh Kumar; Y. L. N. Murthy; K. Asokan; V. V. Siva Kumar; Ravi Kumar; N. S. Gajbhiye; O. F. Caltun

2006-01-01

38

Structural and magnetic properties of cadmium substituted manganese ferrites prepared by hydrothermal route  

NASA Astrophysics Data System (ADS)

Cd-substituted manganese ferrite Mn1-xCdxFe2O4 powders with x having values 0.0, 0.1, 0.3 and 0.5 have been synthesized by hydrothermal route at 180 °C in presence of NaOH as mineralizer. The obtained ferrite samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM). The XRD analysis showed that pure single phases of cubic ferrites were obtained with x upto 0.3. However, sample with x?0.5 showed hexagonal phase of cadmium hydroxide (Cd(OH)2) besides the ferrite phase. The increase in Cd-substitution upto x=0.3 leads to an increase in the lattice parameter as well as the average crystallite size of the prepared ferrites. The average crystallite size increased by increasing the Cd-content and was in the range of 39-57 nm. According to VSM results, the saturation magnetization increased with Cd ion substitution.

Mostafa, Nasser Y.; Zaki, Z. I.; Heiba, Z. K.

2013-03-01

39

Fluorescent manganese-doped zinc sulphide nanoparticles for spectral shifting  

Microsoft Academic Search

Spectral shifting by luminescent nanoparticles is expected to enhance solar cell performance by avoiding wastage of high energy photons. Manganese-doped zinc sulphide nanoparticles, with a PL emission peak around 600 nm, were selected as a possible candidate for such a luminescent down-shifting material. To investigate their fluorescence properties, ZnS:Mn nanoparticles were synthesized by a chemical route using thiourea to limit

Suranjan Sen; Pratibha Sharma; Chetan Singh Solanki; Rajdip Bandyopadhyaya

2010-01-01

40

Ionic magnetic fluid based on cobalt ferrite nanoparticles: Influence of hydrothermal treatment on the nanoparticle size  

NASA Astrophysics Data System (ADS)

Magnetic fluid based on cobalt ferrite nanoparticles was obtained using a hydrothermal treatment added to the Massart procedure. This treatment increases the average size of the nanoparticles from 11.9 to 18.7 nm and also improves the dispersity and crystallinity of the cobalt ferrite particles. The nanoparticles obtained after the hydrothermal treatment were dispersed in aqueous solvent by the classical procedure for ionic magnetic fluids. The ferrofluid thus obtained is stable at pH 7 and may be useful for hyperthermia applications.

Cabuil, Valérie; Dupuis, Vincent; Talbot, Delphine; Neveu, Sophie

2011-05-01

41

Ultrasonic cavitation induced water in vegetable oil emulsion droplets--a simple and easy technique to synthesize manganese zinc ferrite nanocrystals with improved magnetization.  

PubMed

In the present investigation, synthesis of manganese zinc ferrite (Mn(0.5)Zn(0.5)Fe(2)O(4)) nanoparticles with narrow size distribution have been prepared using ultrasound assisted emulsion (consisting of rapeseed oil as an oil phase and aqueous solution of Mn(2+), Zn(2+) and Fe(2+) acetates) and evaporation processes. The as-prepared ferrite was nanocrystalline. In order to remove the small amount of oil present on the surface of the ferrite, it was subjected to heat treatment at 300 °C for 3h. Both the as-prepared and heat treated ferrites have been characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), TGA/DTA, transmission electron microscopy (TEM) and energy dispersion X-ray spectroscopy (EDS) techniques. As-prepared ferrite is of 20 nm, whereas the heat treated ferrite shows the size of 33 nm. In addition, magnetic properties of the as-prepared as well as the heat treated ferrites have also been carried out and the results of which show that the spontaneous magnetization (?(s)) of the heat treated sample (24.1 emu/g) is significantly higher than that of the as-synthesized sample (1.81 emu/g). The key features of this method are avoiding (a) the cumbersome conditions that exist in the conventional methods; (b) usage of necessary additive components (stabilizers or surfactants, precipitants) and (c) calcination requirements. In addition, rapeseed oil as an oil phase has been used for the first time, replacing the toxic and troublesome organic nonpolar solvents. As a whole, this simple straightforward sonochemical approach results in more phase pure system with improved magnetization. PMID:22113061

Sivakumar, Manickam; Towata, Atsuya; Yasui, Kyuichi; Tuziuti, Toru; Kozuka, Teruyuki; Iida, Yasuo; Maiorov, Michail M; Blums, Elmars; Bhattacharya, Dipten; Sivakumar, Neelagesi; Ashok, M

2011-11-07

42

Dye removal using modified copper ferrite nanoparticle and RSM analysis.  

PubMed

In this paper, copper ferrite nanoparticle (CFN) was synthesized, modified by cetyl trimethylammonium bromide, and characterized. Dye removal ability of the surface modified copper ferrite nanoparticle (SMCFN) from single system was investigated. The physical characteristics of SMCFN were studied using Fourier transform infrared, scanning electron microscopy, and X-ray diffraction. Acid Blue 92, Direct Green 6, Direct Red 23, and Direct Red 80 were used as model compounds. The effect of operational parameters (surfactant concentration, adsorbent dosage, dye concentration, and pH) on dye removal was evaluated. Response surface methodology (RSM) was used for the analysis of the dye removal data. The experimental checking in these optimal conditions confirms good agreements with RSM results. The results showed that the SMCFN being a magnetic adsorbent might be a suitable alternative to remove dyes from colored aqueous solutions. PMID:23852534

Mahmoodi, Niyaz Mohammad; Soltani-Gordefaramarzi, Sajjad; Sadeghi-Kiakhani, Moosa

2013-07-13

43

Chemical synthesis of air-stable manganese nanoparticles.  

PubMed

Elemental manganese has a complex crystal structure and unusual magnetic properties, making it an intriguing target for exploration in nanocrystalline form. However, because of its oxophilicity and the difficulty in reducing soluble metal salts to elemental Mn using the most common solution-phase reducing agents, it has been challenging to synthesize and stabilize elemental Mn nanoparticles using solution chemistry methods. Here we report the chemical synthesis of alpha-Mn nanoparticles using n-butyllithium as a reducing agent. The nanoparticles have been characterized by powder XRD, TEM, electron diffraction, infrared spectroscopy (DRIFT), XPS, and SQUID magnetometry. An amorphous manganese oxide layer bound by oleate ligands helps to render the nanoparticles air-stable. The oxide-coated alpha-Mn nanoparticles are paramagnetic. PMID:19566087

Bondi, James F; Oyler, Karl D; Ke, Xianglin; Schiffer, Peter; Schaak, Raymond E

2009-07-01

44

Size-dependent magnetic properties of calcium ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

The union of nanotechnology with the other fields of science heralds the influx of many newer and better technologies, with the capability to revolutionize the human life. In the present work, calcium ferrite nanoparticles were synthesized by conventional sol-gel method and were characterised by X-ray diffraction, Transmission electron microscope, Vibrating sample magnetometer and Fourier transform infrared spectroscope. The synthesized nanoparticles were calcined at different temperatures and their magnetic behaviour was studied. The synthesized nanoparticles calcined at 900 °C were formed in the shape of capsules and exhibited mixed characteristics of ferrimagnetic and paramagnetic grains with magnetic saturation of 0.85 emu/g whereas nanoparticles calcined at 500 °C were spherical in shape and exhibited superparamagnetic characteristics with saturation magnetization of 37.67 emu/g.

Khanna, Lavanya; Verma, N. K.

2013-06-01

45

Mechanism of ac conduction in nanostructured manganese zinc mixed ferrites  

Microsoft Academic Search

Mn1-xZnxFe2O4 nanoparticles (x = 0 to 1) were synthesized by the wet chemical co-precipitation technique. X-ray diffraction and transmission electron microscopy and high resolution transmission electron microscopy were effectively utilized to investigate the different structural parameters. The ac conductivity of nanosized Mn1-xZnxFe2O4 were investigated as a function of frequency, temperature and composition. The frequency dependence of ac conductivity is analysed

E. Veena Gopalan; K. A. Malini; S. Sagar; D. Sakthi Kumar; Yasuhiko Yoshida; I. A. Al-Omari; M. R. Anantharaman

2009-01-01

46

Mechanism of ac conduction in nanostructured manganese zinc mixed ferrites  

Microsoft Academic Search

Mn1?xZnxFe2O4 nanoparticles (x = 0 to 1) were synthesized by the wet chemical co-precipitation technique. X-ray diffraction and transmission electron microscopy and high resolution transmission electron microscopy were effectively utilized to investigate the different structural parameters. The ac conductivity of nanosized Mn1?xZnxFe2O4 were investigated as a function of frequency, temperature and composition. The frequency dependence of ac conductivity is analysed

E Veena Gopalan; K A Malini; S Sagar; D Sakthi Kumar; Yasuhiko Yoshida; I A Al-Omari; M R Anantharaman

2009-01-01

47

Combined effect of demagnetizing field and induced magnetic anisotropy on the magnetic properties of manganese-zinc ferrite composites  

Microsoft Academic Search

This work is devoted to the analysis of factors responsible for the high-frequency shift of the complex permeability ( mu * ) dispersion region in polymer composites of manganese-zinc (MnZn) ferrite, as well as to the increase in their thermomagnetic stability. The magnetic spectra of the ferrite and its composites with polyurethane (MnZn-PU) and polyaniline (MnZn-PANI) are measured in the

V. Babayan; N. E. Kazantseva; R. Moucka; I. Sapurina; Yu. M. Spivak; V. A. Moshnikov

2012-01-01

48

Asymmetric hydrosilylation of ketones catalyzed by magnetically recoverable and reusable copper ferrite nanoparticles.  

PubMed

Herein we present magnetically recoverable and reusable copper ferrite nanoparticles for asymmetric hydrosilylation of several ketones. Up to 99% enantiometric excess was obtained at room temperature using polymethylhydrosiloxane as the stoichiometric reducing agent. The copper ferrite nanoparticles were magnetically separated, and the efficiency of the catalyst remains almost unaltered up to three cycles. PMID:19518151

Kantam, M Lakshmi; Yadav, Jagjit; Laha, Soumi; Srinivas, Pottabathula; Sreedhar, Bojja; Figueras, F

2009-06-19

49

Structural and some magnetic properties of manganese-substituted lithium ferrites  

NASA Astrophysics Data System (ADS)

The structural and magnetic properties of Mn-substituted lithium ferrites having the general formula Li0.5-0.5xMnxFe2.5-0.5xO4 (where x=0.0-1.0) prepared by the standard ceramic technique have been studied. Single phase cubic structure is confirmed by X-ray diffractometer. This result demonstrates that the samples are homogeneous, and the sharp peaks reveal that the samples are in crystalline form. The lattice parameter 'a' and average grain diameter 'D' increase with increasing Mn2+ ion substitution. The saturation magnetization and the experimental magnetic moment are found to increase with manganese up to x=0.5 and then tends to decrease for x>0.5. The increase in magnetic moment with manganese is attributed to Neel's two sublattice model according to which the magnetic moment is the vector sum of lattice magnetic moment. The decrease in magnetization for x>0.5 obeys the Yafet-Kittel (Y-K) model. The increase in Y-K angles for x?0.5 indicates the increased favor for triangle spin arrangements on B-sites. This suggests the existence of canted spin structure in the ferrite system with higher content of Mn. Hystersis loops were measured. The initial permeability ?i was measured as a function of temperature.

Mazen, S. A.; Abu-Elsaad, N. I.

2012-10-01

50

Chemical and physical characterizations of spinel ferrite nanoparticles containing Nd and B elements.  

PubMed

We first succeeded in synthesizing ferrite nanoparticles containing Nd and B elements by a chemical route using a polyol process. The lattice constants of the ferrite nanoparticles were equivalent to 8.39Å of the lattice constant for Fe(3)O(4) with the spinel structure in a bulk state independently of the size in diameter and composition (Fe:Nd:B). The size in diameter was actually dominated by the amount of ligands (oleic acid and oleylamine) coating the nanoparticles and easily tuned by changing refluxing-time under reaction. The spinel-structured ferrite nanoparticles containing Nd and B elements showed large coercivity as compared to Fe(3)O(4) nanoparticles with the spinel structure, which were prepared by the same chemical method. By doping Nd and B elements into the spinel structure of ferrite, magnetic anisotropy increased in comparison with Fe(3)O(4) nanoparticles. According to the analysis of magnetization curve using the modified Langevin function, the ferrite nanoparticles displayed the coexistence of superparamagnetic and antiferromagnetic phases. The ferrite nanoparticles containing Nd and B elements exhibited magnetic core/shell structure on the basis of various magnetic properties. The interface effect between the superparamagnetic core and antiferromagnetic shell might enhance the effective magnetic anisotropy of the ferrite nanoparticles containing Nd and B elements. PMID:20167330

Iwamoto, Takashi; Komorida, Yuki; Mito, Masaki; Takahara, Atsushi

2010-02-01

51

The Effect of Heat Treatment on the Ferromagnetic Resonance of Lutecium Iron Garnet and Manganese Ferrite Single Crystals.  

National Technical Information Service (NTIS)

In this paper, the Effects of different heat treatments on the ferromagnetic resonance of lutecium iron garnet (Lu3Fe5O12) and manganese ferrite (MnFe2O4) single crystals are investigated. The two heat treatments applied are, respectively, 700C in air for...

L. Guo-dong T. Sheng-shu

1966-01-01

52

Influence of austenitizing temperature on fracture toughness of a low manganese austempered ductile iron (ADI) with ferritic as cast structure  

Microsoft Academic Search

An investigation was carried out to examine the influence of austenitizing temperature on the resultant microstructure and mechanical properties of an unalloyed and low manganese ADI and with an as cast (solidified) ferritic structure. The investigation also examined the influence of austenitizing temperature on the fracture toughness of this material. Compact tension and round cylindrical tensile specimens were prepared from

Susil K Putatunda; Pavan K Gadicherla

1999-01-01

53

Low-temperature calorimetric properties of zinc ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Calorimetric measurements between 1 and 40 K by a thermal relaxation technique have been made on zinc ferrite nanoparticles prepared from an aerogel process. The expected ?-type heat-capacity peak near 10 K, which corresponds to a long-range antiferromagnetic transition in the bulk form of this material, is greatly suppressed. Broad peaks begin to prevail after the sample is annealed at 500 or 800 °C, but ball milling of the nanoparticles leads to almost complete disappearance of the low-temperature ordering. In all cases, calorimetrically based magnetic entropy at 40 K accounts for only a fraction of 2R ln(2S+1) with S=5/2 for Fe3+. These results are corroborated by magnetic data, which also indicate magnetic ordering at high temperatures. Such observations can be understood by considering the relative distribution of Fe3+ between two nonequivalent (A and B) sites in the spinel-type lattice. In particular, the as-prepared fine particles show large Fe3+ occupancy of the A sites, whereas these ions prefer the B sites in bulk zinc ferrite. Meanwhile, the lattice heat capacity is enhanced, yielding effective Debye temperatures of 225, 285, 345, and 360 K for the as-prepared, 500 °C-annealed, 800 °C-annealed, and ball milled sample, respectively, in contrast to 425 K for the bulk material.

Ho, J. C.; Hamdeh, H. H.; Chen, Y. Y.; Lin, S. H.; Yao, Y. D.; Willey, R. J.; Oliver, S. A.

1995-10-01

54

Thermal Growth and Performance of Manganese Cobaltite Spinel Protection Layers on Ferritic Stainless Steel SOFC Interconnects  

SciTech Connect

To protect solid oxide fuel cells (SOFCs) from chromium poisoning and improve metallic interconnect stability, manganese cobaltite spinel protection layers with a nominal composition of Mn1.5Co1.5O4 were thermally grown on Crofer22 APU, a ferritic stainless steel. Thermal, electrical and electrochemical investigations indicated that the spinel protection layers not only significantly decreased the contact area specific resistance (ASR) between a LSF cathode and the stainless steel interconnect, but also inhibited the sub-scale growth on the stainless steel by acting as a barrier to the inward diffusion of oxygen. A long-term thermal cycling test demonstrated excellent structural and thermomechanical stability of these spinel protection layers, which also acted as a barrier to outward chromium cation diffusion to the interconnect surface. The reduction in the contact ASR and prevention of Cr migration achieved by application of the spinel protection layers on ferritic stainless steel resulted in improved stability and electrochemical performance of SOFCs.

Yang, Zhenguo; Xia, Guanguang; Simner, Steven P.; Stevenson, Jeffry W.

2005-08-01

55

Comparison of manganese oxide nanoparticles and manganese sulfate with regard to oxidative stress, uptake and apoptosis in alveolar epithelial cells  

Microsoft Academic Search

Due to their physicochemical characteristics, metal oxide nanoparticles (NPs) interact differently with cells compared to larger particles or soluble metals. Oxidative stress and cellular metal uptake were quantified in rat type II alveolar epithelial cells in culture exposed to three different NPs: manganese(II,III) oxide nanoparticles (Mn3O4-NPs), the soluble manganese sulfate (Mn-salt) at corresponding equivalent doses, titanium dioxide (TiO2-NPs) and cerium

Ramon Frick; Björn Müller-Edenborn; Andreas Schlicker; Barbara Rothen-Rutishauser; David O. Raemy; Detlef Günther; Bodo Hattendorf; Wendelin Stark; Beatrice Beck-Schimmer

2011-01-01

56

Dielectric properties of cobalt ferrite nanoparticles in ultrathin nanocomposite films.  

PubMed

Multilayered nanocomposite films (thickness 50-90 nm) of cobalt ferrite nanoparticles (np-CoFe2O4, 18 nm) were deposited on top of interdigitated microelectrodes by the layer-by-layer technique in order to study their dielectric properties. For that purpose, two different types of nanocomposite films were prepared by assembling np-CoFe2O4 either with poly(3,4-ethylenedioxy thiophene):poly(styrene sulfonic acid) or with polyaniline and sulfonated lignin. Despite the different film architectures, the morphology of both was dominated by densely-packed layers of nanoparticles surrounded by polyelectrolytes. The dominant effect of np-CoFe2O4 was also observed after impedance spectroscopy measurements, which revealed that dielectric behavior of the nanocomposites was largely influenced by the charge transport across nanoparticle-polyelectrolyte interfaces. For example, nanocomposites containing np-CoFe2O4 exhibited a single low-frequency relaxation process, with time constants exceeding 15 ms. At 1 kHz, the dielectric constant and the dissipation factor (tan ?) of these nanocomposites were 15 and 0.15, respectively. These values are substantially inferior to those reported for pressed pellets made exclusively of similar nanoparticles. Impedance data were further fitted with equivalent circuit models from which individual contributions of particle's bulk and interfaces to the charge transport within the nanocomposites could be evaluated. The present study evidences that such nanocomposites display a dielectric behavior dissimilar from that exhibited by their individual counterparts much likely due to enlarged nanoparticle-polyelectrolyte interfaces. PMID:24145704

Alcantara, Gustavo B; Paterno, Leonardo G; Fonseca, Fernando J; Pereira-da-Silva, Marcelo A; Morais, Paulo C; Soler, Maria A G

2013-10-22

57

Synthesis and characterization of silica coated potassium ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Silica coated potassium ferrite nanoparticles (KFeO2 NPs) have been synthesized by conventional stöber process. The orthorhombic structure of KFeO2 NPs has been retained even after silica coating, only a slight variation has been observed in the angle range of 20°-25° (occurring due to amorphous silica), as shown by the X-ray diffraction pattern. The crystallite size using Scherrer's formula of bare and silica coated KFeO2 NPs has been calculated to be 21.0 nm and 22.5 nm, respectively. The spherical formation of silica coated KFeO2 NPs has been revealed by transmission electron microscope. Presence of silica on KFeO2 NPs has been confirmed by energy dispersive X-ray spectroscope. A small magnetic saturation value of 3.67emu/g has been observed in the vibrating sample magnetometer analysis.

Khanna, Lavanya; Verma, N. K.

2013-06-01

58

Adsorption isotherms of linoleic and linolenic acids from solutions in carbon tetrachloride on surfaces of highly dispersed manganese and copper ferrites  

NASA Astrophysics Data System (ADS)

A comparative study of adsorption-desorption isotherms of linoleic and linolenic acids from solutions in carbon tetrachloride on surfaces of manganese and copper ferrites is performed by means of equilibrium adsorption. Adsorption isotherms of fatty acids are described in terms of the theory of volume filling of micropores, and the values of the limiting adsorption, the characteristic adsorption energy, and the pore space volume are calculated. It is established that the limiting adsorption values of linoleic and linolenic acids from solutions in carbon tetrachloride on a copper ferrite surface are higher than on a manganese ferrite surface. It is shown that the adsorption-desorption isotherms have a hysteresis loop.

Balmasova, O. V.; Korolev, V. V.; Ramazanova, A. G.

2012-04-01

59

Effect of reaction time on particle size and dielectric properties of manganese substituted CoFe2O4 nanoparticles  

NASA Astrophysics Data System (ADS)

An auto-combustion route was adopted for preparing nanosize manganese substituted cobalt ferrite. The synthesis of the nanoparticles was carried out using different fuel ratio for combustion process. The prepared samples were characterized using XRD and TEM. The impact of fuel ratio on the formation of Co0.6Mn0.4Fe2O4 nanoparticles was analyzed in terms of particle size. The particle is achieved towards smaller range of size as ˜3-51 nm only at the 50% fuel ratio. The 75% and 100% fuel combustion ratio are not supported to attain the particle size on these ranges. The dielectric loss and low value of dielectric constant have been measured in the frequency range of 50 Hz-1 MHz.

Ranjith Kumar, E.; Jayaprakash, R.; ArunKumar, T.; Kumar, Sanjay

2013-01-01

60

Formation and magnetic properties of Mn-Zn ferrites nanoparticles  

Microsoft Academic Search

The magnetic properties of ferrites are dependent on the crystalline structure and the location of metal ions in the material. The correct crystalline structure of a certain ferrite is formed by a special, very complex, technology. Bulk ferrites are synthesized at high temperatures (> 1300 K) under a special, very complex, thermal treatment. On the other hand, the preparation of

G. Kronkalns

2003-01-01

61

Hydrogen peroxide-sensitive amperometric sensor based on manganese dioxide nanoparticles  

Microsoft Academic Search

A method for the synthesis of manganese dioxide nanoparticles in reverse micelles is developed and optimized. Nanoparticles\\u000a are characterized by transmission electron microscopy. An amperometric sensor to detect hydrogen peroxide is developed based\\u000a on thin films of the synthesized manganese dioxide nanoparticles. The possibility of its use for the electrochemical detection\\u000a of hydrogen peroxide and its operational and longterm stability

E. A. Dontsova; I. A. Budashov; A. V. Eremenko; I. N. Kurochkin

2008-01-01

62

Oleate Coated Magnetic Cores Based on Magnetite, Zn Ferrite and Co Ferrite Nanoparticles-Preparation, Physical Characterization and Biological Impact on Helianthus Annuus Photosynthesis  

Microsoft Academic Search

Sodium oleate was used as coating shell for magnetite, Zn ferrite and Co ferrite powders to stabilize them in the form of aqueous magnetic suspensions. The physical characterization was carried out by applying X-ray diffraction and magnetization measurements. Both crystallite size and magnetic core diameter ranged between 7 and 11 nm. The influence of magnetic nanoparticle suspensions (corresponding to magnetic

Manuela Ursache-Oprisan; Ecaterina Foca-Nici; Aurelian Cirlescu; Ovidiu Caltun; Dorina Creanga

2010-01-01

63

Microwave absorbing properties of ferrite-based nanocomposites  

NASA Astrophysics Data System (ADS)

A study of the microwave absorbing properties of polymer (epoxy) based nanocomposites is presented. The ferrite nanoparticles employed as filler materials were produced by a co-precipitation method, which was designed for production of large amounts at low cost. The absorbing properties of different kinds of ferrite nanoparticles, soft (manganese) and hard (cobalt) magnetic nanoparticles, are compared. In addition, the impact of high and low densities of the respective ferrite type has been investigated. Our analysis of the microwave absorbing properties is made over a wide frequency band including both MHz and GHz regions, which is of high interest for a number of different applications both military and civilian.

Jänis, A.; Olsson, R. T.; Savage, S. J.; Gedde, U. W.; Klement, U.

2007-04-01

64

Polyvinyl alcohol functionalized cobalt ferrite nanoparticles for biomedical applications  

NASA Astrophysics Data System (ADS)

In the present work, cobalt ferrite nanoparticles (CoFe2O4 NPs) have been synthesized by combustion method. The surface of the CoFe2O4 NPs was modified with biocompatible polyvinyl alcohol (PVA). To investigate effect and nature of coating on the surface of CoFe2O4 NPs, the NPs were characterized X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The transmission electron microscopy (TEM) and dynamic light scattering (DLS) results demonstrate the monodispersed characteristics of CoFe2O4 NPs after surface modification with PVA. The decrease in contact angle from 162° to 50° with PVA coating on NPs indicates the transition from hydrophobic nature to hydrophilic. The Magnetic properties measurement system (MPMS) results show that the NPs have ferromagnetic behavior with high magnetization of 75.04 and 71.02 emu/g of uncoated and coated CoFe2O4 NPs respectively. These PVA coated NPs exhibit less toxicity over uncoated CoFe2O4 NPs up to 1.8 mg mL-1 when tested with mouse fibroblast L929 cell line.

Salunkhe, A. B.; Khot, V. M.; Thorat, N. D.; Phadatare, M. R.; Sathish, C. I.; Dhawale, D. S.; Pawar, S. H.

2013-01-01

65

Preparation and characterization of cobalt ferrite nanoparticles coated with fucan and oleic acid  

NASA Astrophysics Data System (ADS)

Cobalt ferrite has attracted considerable attention in recent years due to its unique physical properties such as high Curie temperature, large magnetocrystalline anisotropy, moderate saturation magnetization, large magnetostrictive coefficient, excellent chemical stability and mechanical hardness. In this work we present the preparation, of fucan coated cobalt ferrite nanoparticles by a modified co-precipitation method and the study of their structural, microstructural and magnetic characteristics for their application as a solid support for enzymes immobilization and other biotechnology applications. Aqueous suspensions of magnetic particles were prepared by coprecipitation of Fe(III) and Co(II) in the presence of NaOH, acid oleic and fucan polymer. The X-ray diffraction indicates that the funtionalization does not degrade the core cobalt ferrite. The infrared (FTIR) bands, indicate the functional characteristics of the coating on the cobalt ferrite. Mössbauer spectra at room temperature indicate the presence of a broadened sextet plus a doublet which is typical of superparamagnetic relaxation. For the Co-ferrite uncoated and coated with fucan the doublets have areas of 36.1 % and 40.3 % respectively, indicating the presence of non-interacting particles and faster relaxation time. The Co-ferrite coated with oleic acid and oleic acid plus fucan have areas around 17.5 % and 17.1 % respectively which indicate a weak superparamagnetic relaxation due to a slow relaxation time. The magnetization measurements of the cobalt ferrite nanoparticles with and without coating confirm that they are superparamagnetic and this behavior is produced by the core nanoparticles rather than the coatings. The cobalt ferrite nanoparticles coated with oleic acid presented the highest magnetization than when coating with fucan.

Andrade, P. L.; Silva, V. A. J.; Maciel, J. C.; Santillan, M. M.; Moreno, N. O.; De Los Santos Valladares, L.; Bustamante, Angel; Pereira, S. M. B.; Silva, M. P. C.; Albino Aguiar, J.

2013-03-01

66

Substitution of manganese and iron into hydroxyapatite: Core/shell nanoparticles  

SciTech Connect

The bioceramics, hydroxyapatite (HAP), is a material which is biocompatible to the human body and is well suited to be used in hyperthermia applications for the treatment of bone cancer. We investigate the substitution of iron and manganese into the hydroxyapatite to yield ceramics having the empirical formula Ca{sub 9.4}Fe{sub 0.4}Mn{sub 0.2}(PO{sub 4}){sub 6}(OH){sub 2}. The samples were prepared by the co-precipitation method. The formation of the nanocrystallites in the HAP structure as the heating temperatures were raised to obtain a glass-ceramic system are confirmed by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED) and electron spin resonance (ESR). TEM images show the core/shell structure of the nanoparticles, with the core being formed by the ferrites and the shell by the hydroxyapatite. The ED patterns indicate the nanoparticles formed at 500 deg. C have an amorphous structure while the nanoparticles formed at 1000 deg. C are crystalline. ESR spectroscopy indicated that the Fe{sup 3+} ions have a g-factor of 4.23 and the Mn{sup 2+} ions have a g-factor of 2.01. The values of the parameters in the spin Hamiltonian which describes the interaction between the transition metal ions and the Ca{sup 2+} ions, indicate that the Mn{sup 2+} ion substitute into the Ca{sup 2+} sites which are ninefold coordinated, i.e., the Ca(1) sites.

Pon-On, Weeraphat; Meejoo, Siwaporn [Department of Chemistry, Faculty of Science, Mahidol University, Bangkok 10400 (Thailand); Tang, I.-Ming [Department of Physics, Faculty of Science, Mahidol University, Institute of Science and Technology for Research and Development, Salaya Campus, Mahidol University, Nakorn Pathom 71730 (Thailand)], E-mail: scimt@mahidol.ac.th

2008-08-04

67

Manganese oxide nanoparticle-assisted laser desorption\\/ionization mass spectrometry for medical applications  

Microsoft Academic Search

We prepared and characterized manganese oxide magnetic nanoparticles (d =5.6 nm) and developed nanoparticle-assited laser desorption\\/ionization (nano-PALDI) mass spectrometry. The nanoparticles had MnO2 and Mn2O3 cores conjugated with hydroxyl and amino groups, and showed paramagnetism at room temperature. The nanoparticles worked as an ionization assisting reagent in mass spectroscopy. The mass spectra showed no background in the low m\\/z. The

Shu Taira; Kenji Kitajima; Hikaru Katayanagi; Eiichiro Ichiishi; Yuko Ichiyanagi

2009-01-01

68

Study of magnetic and structural properties of ferrofluids based on cobalt-zinc ferrite nanoparticles  

Microsoft Academic Search

Ferrofluids are colloidal systems composed of a single domain of magnetic nanoparticles with a mean diameter around 30 nm, dispersed in a liquid carrier. Magnetic Co(1-x)ZnxFe2O4 (x=0.25, 0.50, 0.75) ferrite nanoparticles were prepared via co-precipitation method from aqueous salt solutions in an alkaline medium. The composition and structure of the samples were characterized through Energy Dispersive X-ray Spectroscopy and X-ray

J. López; L. F. González-Bahamón; J. Prado; J. C. Caicedo; G. Zambrano; M. E. Gómez; J. Esteve; P. Prieto

2012-01-01

69

Synthesis of cobalt ferrite nano-particles and their magnetic characterization  

Microsoft Academic Search

Cobalt ferrite nano-particles (CoFe2O4) were synthesized by the co-precipitation method with ammonium hydroxide as an alkaline solution. The reactions were carried out at different temperatures between 20 and 80°C. The nano-particles have been investigated by magnetic measurements, X-ray powder diffraction and transmission electron microscopy. The average crystallite size of the synthesized samples was between 11 and 45nm, which was found

M. M. El-Okr; M. A. Salem; M. S. Salim; R. M. El-Okr; M. Ashoush; H. M. Talaat

2011-01-01

70

Microwave absorbing properties of structural nanocomposites with surface treated Co ferrite nanoparticles as filler  

NASA Astrophysics Data System (ADS)

An analysis of the microwave absorbing properties of several polymer-(epoxy) based nanocomposites is presented. The nanoparticles of interest for this study were cobalt ferrite nanoparticles. For better dispersion of the nanoparticles in the polymer matrix surface treatment of the nanoparticles with silane compounds was performed. The nanoparticles were surface-treated with 3-glycidoxypropyl- (GPTMS), aminopropyl- (APTMS) or methyl-silsesquioxane (MTMS). The nanoparticles with GPTMS-coating dispersed well in epoxy without sedimentation while the other nanoparticles formed agglomerates in epoxy. The GPTMS-based composites showed higher fracture toughness than the MTMS-based composites. The microwave properties, permittivity and permeability, of GPTMS-based composites were measured in the frequency range between 3.95 GHz and 18 GHz and showed no influence of surface treatment on permeability.

Jänis, A.; Olsson, R. T.; Savage, S. J.; Klement, U.

2010-03-01

71

SAXS study of hexagonal W-type barium ferrite nanoparticles  

Microsoft Academic Search

Hexagonal ferrites are a wide family of ferromagnetic oxides, with peculiar and useful properties. The crystal structure of the different known types of hexagonal ferrites (M, W, X, Y, Z and U) is very complex and can be considered as a superposition of R and S blocks along the hexagonal c axis, RSR*S*for M-typeand RSSR*S*S*forW-type, whereR is a three-oxygen-layerblock with

A. Wacha; L. Trif; Z. Varga; G. Goerigk; A. B ´ ota; U. Vainio

72

Frequency-Dependent Magnetic Susceptibility of Magnetite and Cobalt Ferrite Nanoparticles Embedded in PAA Hydrogel.  

PubMed

Chemically responsive hydrogels with embedded magnetic nanoparticles are of interest for biosensors that magnetically detect chemical changes. A crucial point is the irreversible linkage of nanoparticles to the hydrogel network, preventing loss of nanoparticles upon repeated swelling and shrinking of the gel. Here, acrylic acid monomers are adsorbed onto ferrite nanoparticles, which subsequently participate in polymerization during synthesis of poly(acrylic acid)-based hydrogels (PAA). To demonstrate the fixation of the nanoparticles to the polymer, our original approach is to measure low-field AC magnetic susceptibility spectra in the 0.1 Hz to 1 MHz range. In the hydrogel, the magnetization dynamics of small iron oxide nanoparticles are comparable to those of the particles dispersed in a liquid, due to fast Néel relaxation inside the particles; this renders the ferrogel useful for chemical sensing at frequencies of several kHz. However, ferrogels holding thermally blocked iron oxide or cobalt ferrite nanoparticles show significant decrease of the magnetic susceptibility resulting from a frozen magnetic structure. This confirms that the nanoparticles are unable to rotate thermally inside the hydrogel, in agreement with their irreversible fixation to the polymer network. PMID:23673482

van Berkum, Susanne; Dee, Joris T; Philipse, Albert P; Erné, Ben H

2013-05-14

73

The concentration dependence of relaxation times of hydrogen proton in the aqueous solution of iron ferrite magnetic nanoparticles  

Microsoft Academic Search

By the direct coprecipitation of the aqueous solution of iron salt and tetramethylammonium hydroxide solution the stable iron ferrite nanoparticles were formulated. These nanoparticles were found to have uniform sizes of about 7nm, and also showed no coalescence in the aqueous solution for a few months. The superparamagnetic behavior of these nanoparticles was checked by a vibrating sample magnetometer. Also,

Ilsu Rhee; Chan Kim

2003-01-01

74

Maximizing Hysteretic Losses in Magnetic Ferrite Nanoparticles via Model-Driven Synthesis and Materials Optimization.  

PubMed

This article develops a set of design guidelines for maximizing heat dissipation characteristics of magnetic ferrite MFe2O4 (M = Mn, Fe, Co) nanoparticles in alternating magnetic fields. Using magnetic and structural nanoparticle characterization, we identify key synthetic parameters in the thermal decomposition of organometallic precursors that yield optimized magnetic nanoparticles over a wide range of sizes and compositions. The developed synthetic procedures allow for gram-scale production of magnetic nanoparticles stable in physiological buffer for several months. Our magnetic nanoparticles display some of the highest heat dissipation rates, which are in qualitative agreement with the trends predicted by a dynamic hysteresis model of coherent magnetization reversal in single domain magnetic particles. By combining physical simulations with robust scalable synthesis and materials characterization techniques, this work provides a pathway to a model-driven design of magnetic nanoparticles tailored to a variety of biomedical applications ranging from cancer hyperthermia to remote control of gene expression. PMID:24016039

Chen, Ritchie; Christiansen, Michael G; Anikeeva, Polina

2013-09-12

75

Ni3Zn ferrite octahedral nanoparticles with high microwave permeability and high magnetic loss tangent  

NASA Astrophysics Data System (ADS)

Ni3Zn ferrite octahedral nanoparticles with grain size of about 40 nm were synthesized via a low temperature hydrothermal route. The saturation magnetization (Ms) and coercive force (Hc) of the sample are 57.5 emu/g and 197 Oe, respectively. In 50 MHz-8 GHz frequency range, the complex permeability and complex permittivity for Ni3Zn ferrite/wax composites containing 60 wt% ferrite powders were measured by a vector network analyzer. The real part ?r' of the permeability exhibits high values between 4 and 1.65 in 50 MHz-2 GHz range, and the imaginary part ?r'' of the permeability presents a broad peak with a maximum value of 1.53 at 2.1 GHz, the calculated reflection loss of ferrite/wax coating with the thickness of 8 mm reaches -13 dB at 2.1 GHz. The results indicate the as-prepared Ni3Zn ferrite octahedral nanoparticles can have applications in biomedicine, and microwave absorption and electric devices.

Wang, Zhongzhu; Wu, Mingzai; Jin, Shaowei; Li, Guang; Ma, Yongqing; Wang, Peihong

2013-10-01

76

Ferrites  

Microsoft Academic Search

With d.c. electrical resistivities several orders of magnitude greater than those of the ferromagnetic metals, and magnetic saturation intensities in some cases less than one order of magnitude smaller, the ferrites gave promise of greater `effective permeability' and lower `eddy-current' loss in high-frequency magnetic fields. Attempts to realize these advantages have had limited success, but have led to a deeper

A. Fairweather; F. F. Roberts; A. J. E. Welch

1952-01-01

77

Manganese.  

PubMed

Manganese is a very hard, brittle metal, which is used to increase the strength of steel alloys. Absorption from the gastrointestinal tract occurs in the divalent and tetravalent forms. Permanganates, which are strong oxidizing agents, have a +7 valence. The principal organomanganese compound is the anti-knock additive, methylcyclopentadienyl manganese tricarbonyl. Manganese is a ubiquitous constituent of the environment comprising about 0.1% of the earth's crust. For the general population, food is the most important source of manganese with daily intake ranging from 2-9 mg Mn. Combustion of gasoline containing methylcyclopentadienyl manganese tricarbonyl releases submicron particles of Mn3O4 that are potentially respirable. Biomagnification of manganese in the food chain probably does not occur. The lungs and gastrointestinal tract absorb some manganese, but the relative amounts absorbed from each site are not known. Homeostatic mechanisms limit the absorption of manganese from the gastrointestinal tract. Elimination of manganese occurs primarily by excretion into the bile. Animal studies indicate that manganese is an essential co-factor for enzymes, such as hexokinase, superoxide dismutase, and xanthine oxidase. However, no case of manganese deficiency in humans has been identified. Manganism is a central nervous system disease first described in the 1800s following exposure to high concentrations of manganese oxides. Manganese madness was the term used to describe the initial psychiatric syndrome (compulsive behavior, emotional lability, hallucinations). More commonly, these workers developed a Parkinson's-like syndrome. Currently, the risks of exposure to low concentrations of manganese in the industrial and in the environmental settings (e.g., methylcyclopentadienyl manganese tricarbonyl in gasoline) are being evaluated with regards to the development of subclinical neuropsychological changes. The American Conference of Governmental and Industrial Hygienists recently lowered the TLV-TWA for manganese compounds and inorganic manganese compounds to 0.2 mg Mn/m3. PMID:10382563

Barceloux, D G

1999-01-01

78

Nonlinear spin wave instability processes in manganese substituted zinc Y-type hexagonal ferrites  

Microsoft Academic Search

The large magnetocrystalline anisotropy observed in hexagonal ferrites makes these materials ideally suited for high frequency millimeter-wave applications. However, the large microwave losses observed at low-power levels and the high-power handling capabilities of hexagonal ferrites need to be addressed prior to their wide acceptance in real devices. In order to address the above issues, measurements and analyses of the microwave

Richard G. Cox

2010-01-01

79

Tuning Magnetic Properties of Magnetic Recording Media Cobalt Ferrite NanoParticles by CoPrecipitation Method  

Microsoft Academic Search

Magnetic nano-particles of cobalt ferrite were prepared using co-precipitation method. X-ray diffraction, transmission electron microscope and Raman analysis have confirmed that the formation of cobalt ferrite nano-particles with different particle size depending on the rate of reaction and nucleation. X-ray photoelectron spectrometer analysis indicates that the reaction rate have little influence on the cation distribution in the tetrahedral and octahedral

Shu Chang; Qiao Haoxue

2009-01-01

80

Magnetic properties of bio-synthesized zinc ferrite nanoparticles  

SciTech Connect

The magnetic properties of zinc ferrite (Zn-substituted magnetite, Zn{sub y}Fe{sub 1-y}Fe{sub 2}O{sub 4}) formed by a microbial process compared favorably with chemically synthesized materials. A metal reducing bacterium, Thermoanaerobacter, strain TOR-39 was incubated with Zn{sub x}Fe{sub 1-x}OOH (x=0.01, 0.1, and 0.15) precursors and produced nanoparticulate zinc ferrites. Composition and crystalline structure of the resulting zinc ferrites were verified using X-ray fluorescence, X-ray diffraction, transmission electron microscopy, and neutron diffraction. The average composition from triplicates gave a value for y of 0.02, 0.23, and 0.30 with the greatest standard deviation of 0.02. Average crystallite sizes were determined to be 67, 49, and 25 nm, respectively. While crystallite size decreased with more Zn substitution, the lattice parameter and the unit cell volume showed a gradual increase in agreement with previous literature values. The magnetic properties were characterized using a superconducting quantum interference device magnetometer and were compared with values for the saturation magnetization (M{sub s}) reported in the literature. The averaged M{sub s} values for the triplicates with the largest amount of zinc (y=0.30) gave values of 100.1, 96.5, and 69.7 emu/g at temperatures of 5, 80, and 300 K, respectively indicating increased magnetic properties of the bacterially synthesized zinc ferrites.

Yeary, Lucas W [ORNL; Moon, Ji Won [ORNL; Rawn, Claudia J [ORNL; Love, Lonnie J [ORNL; Rondinone, Adam Justin [ORNL; Thompson, James R [ORNL; Chakoumakos, Bryan C [ORNL; Phelps, Tommy Joe [ORNL

2011-01-01

81

Oleate Coated Magnetic Cores Based on Magnetite, Zn Ferrite and Co Ferrite Nanoparticles-Preparation, Physical Characterization and Biological Impact on Helianthus Annuus Photosynthesis  

NASA Astrophysics Data System (ADS)

Sodium oleate was used as coating shell for magnetite, Zn ferrite and Co ferrite powders to stabilize them in the form of aqueous magnetic suspensions. The physical characterization was carried out by applying X-ray diffraction and magnetization measurements. Both crystallite size and magnetic core diameter ranged between 7 and 11 nm. The influence of magnetic nanoparticle suspensions (corresponding to magnetic nanoparticle levels of 10-14-10-15/cm3) on sunflower seedlings was studied considering the changes in the photosynthesis pigment levels. Similar responses were obtained for magnetite and cobalt ferrite nanoparticle treatment consisting in the apparent inhibition of chlorophyll biosynthesis while for zinc ferrite nanoparticles some concentrations seemed to have stimulatory effects on the chlorophylls as well as on the carotene levels. But the chlorophyll ratio was diminished in the case of all three types of magnetic nanoparticles meaning their slight negative effect on the light harvesting complex II (LHC II) from the chloroplast membranes and consequently on the photosynthesis efficiency.

Ursache-Oprisan, Manuela; Foca-Nici, Ecaterina; Cirlescu, Aurelian; Caltun, Ovidiu; Creanga, Dorina

2010-12-01

82

Effects of SnO2 addition on the magnetic properties of manganese zinc ferrites  

NASA Astrophysics Data System (ADS)

SnO2 was added to high-permeability MnZn ferrites and MnZn ferrites for high-frequency power supplies. The effects of the SnO2 addition were studied. Sn4+ ions can dissolve into the spinel lattice and form stable Fe2+ Sn4+ pairs and hence can compensate the magneto-crystalline anisotropy constant K1 and improve the initial permeability effectively. The initial permeability of ferrites is also improved as abnormal grain growth caused by ion vacancy is controlled with SnO2 doping. In addition, the SnO2 doping also leads to a decrease in the relative loss factor and an increase in density. The power loss and minimum power loss temperature decrease with SnO2 doping.

Aiping, Huang; Huahui, He; Zekun, Feng

2006-06-01

83

Comparative Cytogenetic Study on the Toxicity of Magnetite and Zinc Ferrite Nanoparticles in Sunflower Root Cells  

NASA Astrophysics Data System (ADS)

In this experimental study the authors present their results regarding the cellular division rate and the percentage of chromosomal aberrations in the root meristematic cells of Helianthus annuus cultivated in the presence of different volume fractions of magnetic nanoparticle suspensions, ranging between 20 and 100 microl/l. The aqueous magnetic colloids were prepared from chemically co-precipitated ferrites coated in sodium oleate. Tissue samples from the root meristeme of 2-3 day old germinated seeds were taken to prepare microscope slides following Squash method combined with Fuelgen techniques. Microscope investigation (cytogenetic tests) has resulted in the evaluation of mitotic index and chromosomal aberration index that appeared diminished and respectively increased following the addition of magnetic nanoparticles in the culture medium of the young seedlings. Zinc ferrite toxic influence appeared to be higher than that of magnetite, according to both cytogenetic parameters.

Foca-Nici, Ecaterina; Capraru, Gabriela; Creanga, Dorina

2010-12-01

84

Magnetite-cobalt ferrite nanoparticles for kerosene-based magnetic fluids  

NASA Astrophysics Data System (ADS)

Due to the magnetic anisotropy introduced by the Co2+ ion in octahedral sites of cubic spinel ferrites, it is possible to tailor the magnetic properties by changing the cobalt content. Magnetic fluids with magnetite-cobalt ferrite nanoparticles given by the formula Co(x)Fe(3-x)O4 with x=0, 0.2 and 0.4 were prepared. Kerosene and oleic acid were used as liquid carrier and surfactant, respectively. Spherical magnetic nanoparticles were obtained by coprecipitation from metal salts and ammonium hydroxide; afterwards the magnetic fluids were obtained by a peptization process. Powder properties were characterized by X-ray diffraction (XRD), nitrogen adsorption desorption isotherma (BET), vibrating sample magnetometry (VSM) and fluids by transmission electron microscopy (TEM), thermogravimetric analyzer (TGA), VSM and the short-circuited transmission line technique.

Ayala-Valenzuela, O.; Matutes-Aquino, J.; Betancourt-Galindo, R.; García-Cerda, L. A.; Rodríguez Fernández, O.; Fannin, P. C.; Giannitsis, A. T.

2005-07-01

85

Synthesis of ferrite and nickel ferrite nanoparticles using radio-frequency thermal plasma torch  

Microsoft Academic Search

Nanocrystalline (NC) ferrite powders have been synthesized using a 50 kW-3 MHz rf thermal plasma torch for high-frequency soft magnet applications. A mixed powder of Ni and Fe (Ni:Fe=1:2), a NiFe permalloy powder with additional Fe powder (Ni:Fe=1:2), and a NiFe permalloy powder (Ni:Fe=1:1) were used as precursors for synthesis. Airflow into the reactor chamber was the source of oxygen

S. Son; M. Taheri; E. Carpenter; V. G. Harris; M. E. McHenry

2002-01-01

86

Thermal fluctuation and magnetization of Ni-Zn ferrite nanoparticles by particle size  

Microsoft Academic Search

Summary Ni1-xZnxFe2O4 (0?x?1) mixed ferrite nanoparticles encapsulated with amorphous-SiO2 were prepared by a wet chemical method. Particle sizes were controlled to range from 2.6 to 33.7 nm by heat treatment, and the particle size dependence of saturation magnetization Ms was investigated for the x=0.5 region. The Ms value decreased abruptly for particle sizes below about 6 nm. From the temperature

Y. Ichiyanagi; T. Uehashi; S. Yamada; Y. Kanazawa; T. Yamada

2005-01-01

87

Two-variables scaling of the magnetic viscosity in Ba-ferrite nano-particles  

Microsoft Academic Search

Careful measurements of the magnetic viscosity S = dM\\/ d ln t of non-oriented nano-particles of Ba-ferrite (317 Å as mean diameter) show a remarkable scaling plot vs. two variables: the usual T ln(t\\/tau0 and the applied magnetic field H. This plot takes into account two distributions, the particle size rho(s) and the switching field v(H0) distributions. This last plays

B. Barbara; L. C. Sampaio; A. Marchand; O. Kubo; H. Takeuchi

1994-01-01

88

Fabrication, characterization and magnetic behaviour of alumina-doped zinc ferrite nano-particles  

Microsoft Academic Search

Zinc ferrite nano-powders with a nominal composition of ZnFe2O4 were prepared by combustion synthesis using mixture of urea and ammonium nitrate as fuel. The influence of alumina-doping on the structural, morphological and magnetic properties of ZnFe2O4 nano-particles was investigated by means of X-ray powder diffraction (XRD), infrared (IR) spectroscopy, scanning and transmission electron microscopy (SEM and TEM) and vibrating sample

N. M. Deraz

2011-01-01

89

Highly aluminium doped barium and strontium ferrite nanoparticles prepared by citrate auto-combustion synthesis  

Microsoft Academic Search

Aluminium doped barium and strontium hexaferrite nanoparticles BaAlxFe(12?x)O19 and SrAlxFe(12?x)O19 were synthesised via a sol–gel route using citric acid to complex the ions followed by an auto-combustion reaction. This method shows promise for the synthesis of complex ferrite powders with small particle size. It was found that around half of the iron could be substituted for aluminium in the barium

Neil J.. Shirtcliffe; Simon Thompson; Eoin S. O’Keefe; Steve Appleton; Carole C.. Perry

2007-01-01

90

Mössbauer studies of La Zn substitution effect in strontium ferrite nanoparticles  

Microsoft Academic Search

Many studies on cation substitution have been carried out in sintered magnets application, since intrinsic magnetic properties such as saturation magnetization depend on the cation configuration in the M-type hexagonal structure. La Zn substituted Sr-ferrite nanoparticles were fabricated by a sol gel method. Their magnetic and structural properties were characterized by using the XRD, VSM, TG\\/DTA, and Mössbauer spectroscopy. We

Sang Won Lee; Sung Yong An; In-Bo Shim; Chul Sung Kim

2005-01-01

91

Mössbauer studies of La–Zn substitution effect in strontium ferrite nanoparticles  

Microsoft Academic Search

Many studies on cation substitution have been carried out in sintered magnets application, since intrinsic magnetic properties such as saturation magnetization depend on the cation configuration in the M-type hexagonal structure. La–Zn substituted Sr-ferrite nanoparticles were fabricated by a sol–gel method. Their magnetic and structural properties were characterized by using the XRD, VSM, TG\\/DTA, and Mössbauer spectroscopy. We focused on

Sang Won Lee; Sung Yong An; In-Bo Shim; Chul Sung Kim

2005-01-01

92

Mössbauer studies of superparamagnetic ferrite nanoparticles for functional application  

NASA Astrophysics Data System (ADS)

Nanoparticles of CoFe2O4 and MnFe2O4 prepared for functional applications in nanomedicine were studied using Mössbauer spectrometry. Superparamagnetic properties of nanoparticles of different size and composition were compared applying collective excitations and multilevel models for the description of the Mössbauer spectra.

Mažeika, K.; Jagminas, A.; Kurtinaitien?, M.

2013-04-01

93

Study of magnetic and structural properties of ferrofluids based on cobalt-zinc ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Ferrofluids are colloidal systems composed of a single domain of magnetic nanoparticles with a mean diameter around 30 nm, dispersed in a liquid carrier. Magnetic Co(1-x)ZnxFe2O4 (x=0.25, 0.50, 0.75) ferrite nanoparticles were prepared via co-precipitation method from aqueous salt solutions in an alkaline medium. The composition and structure of the samples were characterized through Energy Dispersive X-ray Spectroscopy and X-ray diffraction, respectively. Transmission Electron Microscopy (TEM) studies permitted determining nanoparticle size; grain size of nanoparticle conglomerates was established via Atomic Force Microscopy. The magnetic behavior of ferrofluids was characterized by Vibrating Sample Magnetometer (VSM); and finally, a magnetic force microscope was used to visualize the magnetic domains of Co(1-x)ZnxFe2O4 nanoparticles. X-ray diffraction patterns of Co(1-x)ZnxFe2O4 show the presence of the most intense peak corresponding to the (311) crystallographic orientation of the spinel phase of CoFe2O4. Fourier Transform Infrared Spectroscopy confirmed the presence of the bonds associated to the spinel structures; particularly for ferrites. The mean size of the crystallite of nanoparticles determined from the full-width at half maximum of the strongest reflection of the (311) peak by using the Scherrer approximation diminished from (9.5±0.3) nm to (5.4±0.2) nm when the Zn concentration increases from 0.21 to 0.75. The size of the Co-Zn ferrite nanoparticles obtained by TEM is in good agreement with the crystallite size calculated from X-ray diffraction patterns, using Scherer's formula. The magnetic properties investigated with the aid of a VSM at room temperature presented super-paramagnetic behavior, determined by the shape of the hysteresis loop. In this study, we established that the coercive field of Co(1-x)ZnxFe2O4 magnetic nanoparticles, the crystal and nanoparticle sizes determined by X-ray Diffraction and TEM, respectively, decrease with the increase of the Zn at%. Finally, our magnetic nanoparticles are not very hard magnetic materials given that the hysteresis loop is small and for this reason Co(1-x)ZnxFe2O4 nanoparticles are considered as soft magnetic material.

López, J.; González-Bahamón, L. F.; Prado, J.; Caicedo, J. C.; Zambrano, G.; Gómez, M. E.; Esteve, J.; Prieto, P.

2012-02-01

94

Morphology of cobalt ferrite nanoparticle-polyelectrolyte multilayered nanocomposites  

NASA Astrophysics Data System (ADS)

Novel magnetic nanocomposite films with controlled morphology were produced via the electrostatic layer-by-layer assembly of cationic CoFe2O4 nanoparticles and anionic poly(3,4-ethylenedioxy thiophene)/poly(styrene sulfonic acid) (PEDOT:PSS) complex. The electrostatic interaction between nanoparticle and the polyelectrolyte complex ensured a stepwise growth of the nanocomposite film with virtually identical amounts of materials being adsorbed at each deposition cycle as observed by UV-vis spectroscopy. AFM images acquired under the tapping mode revealed a globular morphology with dense and continuous layers of nanoparticles with voids being filled with polymeric material.

Alcantara, G. B.; Paterno, L. G.; Fonseca, F. J.; Morais, P. C.; Soler, M. A. G.

2011-05-01

95

Platinum nanoparticles–manganese oxide nanorods as novel binary catalysts for formic acid oxidation  

Microsoft Academic Search

The current study proposes a novel binary catalyst system (composed of metal\\/metal oxide nanoparticles) as a promising electrocatalyst in formic acid oxidation. The electro-catalytic oxidation of formic acid is carried out with binary catalysts of Pt nanoparticles (nano-Pt) and manganese oxide nanorods (nano-MnOx) electrodeposited onto glassy carbon (GC) electrodes. Cyclic voltammetric (CV) measurements showed that unmodified GC and nano-MnOx\\/GC electrodes

Mohamed S. El-Deab

96

On the dielectric dispersion and absorption in nanosized manganese zinc mixed ferrites  

Microsoft Academic Search

The temperature and frequency dependence of dielectric permittivity and dielectric loss of nanosized Mn1-xZnxFe2O4 (for x = 0, 0.2, 0.4, 0.6, 0.8, 1) were investigated. The impact of zinc substitution on the dielectric properties of the mixed ferrite is elucidated. Strong dielectric dispersion and broad relaxation were exhibited by Mn1-xZnxFe2O4. The variation of dielectric relaxation time with temperature suggests the

E. Veena Gopalan; K. A. Malini; D. Sakthi Kumar; Yasuhiko Yoshida; I. A. Al-Omari; S. Saravanan; M. R. Anantharaman

2009-01-01

97

On the dielectric dispersion and absorption in nanosized manganese zinc mixed ferrites  

Microsoft Academic Search

The temperature and frequency dependence of dielectric permittivity and dielectric loss of nanosized Mn1?xZnxFe2O4 (for x = 0, 0.2, 0.4, 0.6, 0.8, 1) were investigated. The impact of zinc substitution on the dielectric properties of the mixed ferrite is elucidated. Strong dielectric dispersion and broad relaxation were exhibited by Mn1?xZnxFe2O4. The variation of dielectric relaxation time with temperature suggests the

E Veena Gopalan; K A Malini; D Sakthi Kumar; Yasuhiko Yoshida; I A Al-Omari; S Saravanan; M R Anantharaman

2009-01-01

98

In vivo bio-distribution of intravenously injected Tc99 m labeled ferrite nanoparticles bounded with biocompatible medicals  

Microsoft Academic Search

In vivo bio-distribution of directly radioisotope (Tc-99 m) labeled with ferrite (Fe3O4) nanoparticles, conjugated with Poly(ethyelene glycol) (PEG), upon intravenous injection into rats was studied. The time evolution of bio-distribution of the radio-beads was investigated by analyzing the scintigrams monitored with a planar gamma camera. From the scintigraphic images, the PEG conjugated ferrite radiobeads have demonstrated a reduction of uptake

Chao-Ming Fu; Yuh-Feng Wang; Yu-Feng Guo; Tang-Yi Lin; Jainn-Shiun Chiu

2005-01-01

99

Development of Manganese-Based Nanoparticles as Contrast Probes for Magnetic Resonance Imaging  

PubMed Central

MRI is one of the most important imaging tools in clinics. It interrogates nuclei of atoms in a living subject, providing detailed delineation with high spatial and temporal resolutions. To compensate the innate low sensitivity, MRI contrast probes were developed and widely used. These are typically paramagnetic or superparamagnetic materials, functioning by reducing relaxation times of nearby protons. Previously, gadolinium(Gd)-based T1 contrast probes were dominantly used. However, it was found recently that their uses are occasionally associated with nephrogenic system fibrosis (NSF), which suggests a need of finding alternatives. Among the efforts, manganese-containing nanoparticles have attracted much attention. By careful engineering, manganese nanoparticles with comparable r1 relaxivities can be yielded. Moreover, other functionalities, be a targeting motif, a therapeutic agent or a second imaging component, can be loaded onto these nanoparticles, resulting in multifunctional nanoplatforms.

Zhen, Zipeng; Xie, Jin

2012-01-01

100

Influence of cobalt on structural and magnetic properties of nickel ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Improving the magnetic response of nanocrystalline nickel ferrites is the key issue in high density recording media. A series of cobalt substituted nickel ferrite nanoparticles with composition Ni(1?x)CoxFe2O4, where 0.0 ? x ? 1.0, are synthesized using co-precipitation method. The XRD spectra revealed the single phase spinel structure and the average sizes of nanoparticles are estimated to be 16–19 nm. These sizes are small enough to achieve the suitable signal to noise ratio in the high density recording media. The lattice parameter and coercivity shows monotonic increment with the increase of Co contents ascribed to the larger ionic radii of the cobalt ion. The specific saturation magnetization (Ms), remanent magnetization (Mr) and the coercivity (Hc) of the spinel ferrites are further improved by the substitutions of Co+2 ions. The values of Ms for NiFe2O4 and CoFe2O4 are found to be 43.92 and 78.59 emu/g, respectively and Hc are in the range of 51–778 Oe. The FTIR spectra of the spinel phase calcinated at 600 °C exhibit two prominent fundamental absorption bands in the range of 350–600 cm?1 assigned to the intrinsic stretching vibrations of the metal at the tetrahedral and octahedral sites. The role played by the Co ions in improving the structural and magnetic properties are analyzed and understood. Our simple, economic and environmental friendly preparation method may contribute towards the controlled growth of high quality ferrite nanopowders, potential candidates for recording.

Ati, Ali A.; Othaman, Zulkafli; Samavati, Alireza

2013-11-01

101

Low temperature polymer assisted hydrothermal synthesis of bismuth ferrite nanoparticles  

Microsoft Academic Search

BFO nanoparticles were successfully synthesized by a polymer assisted hydrothermal method at a temperature as low as 160°C. The as-prepared powders, characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM), exhibited a pure BFO phase about 10nm size and uniform sphere-like shape. It was found that the added polymer played a key role in decreasing the growing speed of

Yonggang Wang; Gang Xu; Zhaohui Ren; Xiao Wei; Wenjian Weng; Piyi Du; Ge Shen; Gaorong Han

2008-01-01

102

Microwave absorption properties of conducting polymer composite with barium ferrite nanoparticles in 12.4-18 GHz  

NASA Astrophysics Data System (ADS)

Conducting polymer nanocomposites of polyphenyl amine with barium ferrite nanoparticles (50-70 nm) have been synthesized via emulsion polymerization. The complex permittivity, permeability, and microwave absorption properties of the composite were studied in the 12.4-18 GHz (Ku band) frequency range. The composite has shown high shielding effectiveness due to absorption (SEA) of 28.9 dB (~99.9%), which strongly depends on dielectric loss, magnetic permeability, and volume fraction of barium ferrite nanoparticles. The high value of SEA suggests that these composites can be used as a promising radar absorbing materials.

Ohlan, Anil; Singh, Kuldeep; Chandra, Amita; Dhawan, S. K.

2008-08-01

103

Manganese oxide nanoparticle-assisted laser desorption/ionization mass spectrometry for medical applications  

NASA Astrophysics Data System (ADS)

We prepared and characterized manganese oxide magnetic nanoparticles (d =5.6 nm) and developed nanoparticle-assited laser desorption/ionization (nano-PALDI) mass spectrometry. The nanoparticles had MnO2 and Mn2O3 cores conjugated with hydroxyl and amino groups, and showed paramagnetism at room temperature. The nanoparticles worked as an ionization assisting reagent in mass spectroscopy. The mass spectra showed no background in the low m/z. The nanoparticles could ionize samples of peptide, drug and proteins (approx. 5000 Da) without using matrix, i.e., 2,5-dihydroxybenzoic acid (DHB), 4-hydroxy-?-cinnamic acid (CHCA) and liquid matrix, as conventional ionization assisting reagents. Post source decay spectra by nano-PALDI mass spectrometry will yield information of the chemical structure of analytes.

Taira, Shu; Kitajima, Kenji; Katayanagi, Hikaru; Ichiishi, Eiichiro; Ichiyanagi, Yuko

2009-06-01

104

Correlation of spin and structure in doped bismuth ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

The mutiferroic Bi1-xEuxFeO3 nanoparticles with x = 0 to 0.4 are studied by x-ray diffraction (XRD), Raman spectra and electron spin resonance (ESR) with X-band (9.53 GHz), in order to investigate the doping effect on crystalline and spin structures. Both XRD and Raman spectrum reveal a structural transformation at x = 0.15, which is associated with the shortening of Bi--O bond length. These structural data are further related to the variation of ESR peak position and peak area, providing evidence for the enhancement of ferromagnetic coupling as x < 0.3.

Lin, J. W.; Tite, Teddy; Tang, Y. H.; Lue, C. S.; Chang, Y. M.; Lin, J. G.

2012-04-01

105

Mesoporous Silica Nanoparticle-Stabilized and Manganese-Modified Rhodium Nanoparticles as Catalysts for Highly Selective Synthesis of Ethanol and Acetaldehyde from Syngas  

SciTech Connect

Well-defined and monodispersed rhodium nanoparticles as small as approximately 2?nm were encapsulated in?situ and stabilized in a mesoporous silica nanoparticle (MSN) framework during the synthesis of the mesoporous material. Although both the activity and selectivity of MSN-encapsulated rhodium nanoparticles in CO hydrogenation could be improved by the addition of manganese oxide as expected, the carbon selectivity for C2 oxygenates (including ethanol and acetaldehyde) was unprecedentedly high at 74.5?% with a very small amount of methanol produced if rhodium nanoparticles were modified by manganese oxide with very close interaction.

Huang, Yulin; Deng, Weihua; Guo, Enruo; Chung, Po-Wen; Chen, Senniang; Trewyn, Brian; Brown, Robert; Lin, Victor

2012-03-30

106

Synthesis of Ni–Zn ferrite nanoparticles in radiofrequency thermal plasma reactor and their use for purification of histidine-tagged proteins  

Microsoft Academic Search

Superparamagnetic Ni–Zn ferrite nanoparticles were synthesized in radiofrequency thermal plasma reactor from aqueous solutions\\u000a of Ni- and Zn-nitrates. The nanoparticles were studied for protein purification performance in both quantitative and qualitative\\u000a terms. For comparison, experiments were also performed by Ni-charged affinity chromatography. It was proved that the Ni–Zn\\u000a ferrite nanoparticles effectively purified histidine-tagged proteins with a maximum protein binding capacity

Tivadar Feczkó; Adél Muskotál; Loránd Gál; János Szépvölgyi; Anett Sebestyén; Ferenc Vonderviszt

2008-01-01

107

Magnetic Properties of Cobalt-Ferrite Nanoparticles Prepared by a Sol-Gel Synthesis Technique  

NASA Astrophysics Data System (ADS)

Cobalt-ferrite nanoparticles have been prepared as highly porous aerogels using a sol-gel technique and characterized by XRD, TEM, and nitrogen-sorption porosimetry measurements. The XRD patterns for calcined Co-ferrite aerogels corresponded to a cubic structure with a lattice parameter near that of bulk Co-ferrite and a particle size of about 6 nm. TEM images indicated a similar particle size and a morphology similar to that of silica aerogels. The magnetic properties of these materials have been studied from 5 K to 340 K. Hysteresis loop measurements indicated that the coercivity and saturation magnetization of these materials evolves from nearly 19 kOe and 56 emu/g at 5 K to less than 10 Oe and 40 emu/g at 340 K. ZFC magnetization curves displayed a broad maximum that smoothly varied between about 300 K in an applied field of 100 Oe to about 180 K in a 10 kOe field. These measurements have been interpreted in terms of a distribution of effective particle sizes arising from a distribution in interparticle interactions.

Ekiert, Thomas; Unruh, Karl; Carpenter, E.; Pettigrew, K.; Long, J.; Rolison, D.

2007-03-01

108

Screen-printing of ferrite magnetic nanoparticles produced by carbon combustion synthesis of oxides  

NASA Astrophysics Data System (ADS)

The feasibility of screen-printing process of hard ferrite magnetic nanoparticles produced by carbon combustion synthesis of oxides (CCSO) is investigated. In CCSO, the exothermic oxidation of carbon generates a smolder thermal reaction wave that propagates through the solid reactant mixture converting it to the desired oxides. The complete conversion of hexaferrites occurs using reactant mixtures containing 11 wt. % of carbon. The BaFe12O19 and SrFe12O19 hexaferrites had hard magnetic properties with coercivity of 3 and 4.5 kOe, respectively. It was shown that the synthesized nanoparticles could be used to fabricate permanent magnet structures by consolidating them using screen-printing techniques.

Martirosyan, Karen S.; Dannangoda, Chamath; Galstyan, Eduard; Litvinov, Dmitri

2012-05-01

109

Synthesis and optical properties of nickel zinc ferrite nanoparticles grown within mesoporous silica template  

NASA Astrophysics Data System (ADS)

Nanocomposite (NC) of nickel zinc ferrite (NZF) in mesoporous silica template (KIT-6) was synthesized and characterized in this work. Impregnation procedure was used to synthesize NZF nanoparticles within the pores of KIT-6. The samples were characterized by transmission electron microscopy (TEM), FTIR and UV-Vis absorption studies and room temperature (RT) photoluminescence (PL) measurement. The morphology from Transmission Electron Microscopy of the NC showed the ordered porous structure of KIT-6 remained undistorted even after the incorporation of NZF nanoparticles within its pores. From UV-Vis spectra of the NC, a blue shift in the absorption band due to quantum confinement effect was found. Due to some defects present a broad PL peak centred at 490 nm after excitation at 428 nm of the NC was observed.

Banerjee, Shilpi; Chakravorty, Dipankar

2012-06-01

110

Ultrafast and continuous synthesis of crystalline ferrite nanoparticles in supercritical ethanol.  

PubMed

Magnetic nanoparticles (NPs) are of increasing interest in various industrially relevant products. For these, the development of greener and faster approaches facilitating scaling-up production is of paramount importance. Here, we report a novel, green and potentially scalable approach for the continuous and ultrafast (90 s) synthesis of superparamagnetic ferrite NPs (MnFe(2)O(4), Fe(3)O(4)) in supercritical ethanol (scEtOH) at a fairly moderate temperature (260 °C). ScEtOH exhibits numerous advantages such as its production from bio-resources, its lack of toxicity and its relatively low supercritical coordinates (p(c) = 6.39 MPa and T(c) = 243 °C), being therefore appropriate for the development of sustainable technologies. The present study is completed by the investigation of both in situ and ex situ NP surface functionalization. The as-obtained nanoparticles present good crystallinity, sizes below 8 nm, superparamagnetic behavior at room temperature and high saturation magnetization. Moreover, depending on the capping strategy, the ferrite NPs present extended (for in situ coated NPs) or short-term (for ex situ coated NPs) colloidal stability. PMID:23386040

Pascu, Oana; Marre, Samuel; Aymonier, Cyril; Roig, Anna

2013-02-05

111

Composition and magnetic properties of cobalt ferrite nano-particles prepared by the co-precipitation method  

Microsoft Academic Search

Cobalt ferrite nano-particles were prepared using the co-precipitation method followed by annealing treatment. The formation of nano-particles with different composition, microstructure and sizes were confirmed by X-ray diffraction, Raman, thermogravimetric-differential thermal analysis and transmission electron microscope. The magnetic hysteresis loops measured at room temperature revealed smaller effective magnetic anisotropy constant, coercivity and remanence ratio for the samples prepared by adding

Yue Zhang; Zhi Yang; Di Yin; Yong Liu; Chunlong Fei; Rui Xiong; Jing Shi; Gaolin Yan

2010-01-01

112

Ceria associated manganese oxide nanoparticles: Synthesis, characterization and arsenic(V) sorption behavior  

Microsoft Academic Search

Four samples of ceria incorporated manganese oxide (NCMO) were prepared by co-precipitation-calcinations and sol–gel methods, and characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, BET surface area etc. The synthetic samples were nanoparticle agglomerates with irregular surface morphology (Ce:Mn=1:1). The NCMO-1b sample, prepared by the calcination of metal hydroxide at 573K for 3.0h, was a

Kaushik Gupta; Sayan Bhattacharya; Dhrubajyoti Chattopadhyay; Aniruddha Mukhopadhyay; Harishankar Biswas; Jagannath Dutta; Nihar Ranjan Ray; Uday Chand Ghosh

2011-01-01

113

Structural and morphological studies of manganese substituted CoFe2O4 and NiFe2O4 nanoparticles  

NASA Astrophysics Data System (ADS)

Nanocrystalline manganese substituted cobalt and nickel ferrites have been synthesized through the evaporation method by using egg white. These powders were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The XRD pattern of manganese substituted spinel ferrites contains some impurity peaks, which are the decomposition of the ferrites to ?-Fe2O3 phase at higher annealing temperature. The microstructure and particle size of the annealed sample analyzed by TEM, which gives the particle size well with XRD. The magnetic properties were measured using Vibrating Sample Magnetometer (VSM). The surface/near-surface chemical states of the nanocrystalline manganese substituted cobalt and nickel ferrites are analyzed by XPS within a range of binding energies of 0-1000 eV.

Ranjith kumar, E.; Jayaprakash, R.; Patel, Rajesh

2013-10-01

114

Valence-driven electrical behavior of manganese-modified bismuth ferrite thin films  

SciTech Connect

BiFe{sub 0.95}R{sub 0.05}O{sub 3} (Mn{sup 2+}, Mn{sup 3+}, and Mn{sup 4+}) thin films with (110) orientation were fabricated on SrRuO{sub 3}/Pt/TiO{sub 2}/SiO{sub 2}/Si(100) substrates via rf sputtering. With the increasing valence of Mn in BiFe{sub 0.95}R{sub 0.05}O{sub 3}, the concentration of Fe{sup 2+} increases, whereas the concentration of oxygen vacancies decreases. The electrical properties of BiFe{sub 0.95}R{sub 0.05}O{sub 3} are correlated with the valence of Mn. Their leakage current density is dependent on the concentration of oxygen vacancies caused by different valences of Mn. Their P-E loops become better with the increasing valence of Mn owing to a lower leakage current density in high electric field regions, and a large remanent polarization of 2P{sub r} {approx} 145.2 {mu}C/cm{sup 2} is obtained for the Mn{sup 4+}-doped film. For the Mn{sup 2+}-doped bismuth ferrite film, the space-charge-limited conduction and Schottky barrier dominate its leakage behavior under a negative electric field, the Ohmic conduction and Schottky barrier are involved in the leakage behavior under a positive electric field, and the interface-limited Fowler-Nordheim tunneling is their dominant mechanism in a high electric field region. In contrast, an Ohmic conduction dominates the leakage behavior of Mn{sup 3+}- and Mn{sup 4+}-doped films regardless of negative and positive directions or measurement temperatures.

Wu Jiagang [Department of Materials Science, Sichuan University, 610064 (China); Department of Materials Science and Engineering, National University of Singapore, 117574 (Singapore); Wang, John [Department of Materials Science and Engineering, National University of Singapore, 117574 (Singapore); Xiao Dingquan; Zhu Jianguo [Department of Materials Science, Sichuan University, 610064 (China)

2011-06-15

115

Magnetic properties of cobalt-ferrite nanoparticles embedded in polystyrene resin  

NASA Astrophysics Data System (ADS)

Samples of maghemite and cobalt-ferrite nanoparticles (sizes, 3-10 nm) were prepared by cross-linking sulfonated polystyrene resin with aqueous solutions of (1) FeCl2, (2) 80%FeCl2+20%CoCl2, (3) FeCl3, and (4) 80%FeCl3+20%CoCl2 by volume. Chemical analysis, x-ray powder-diffraction, and 57Fe Mössbauer spectroscopic measurements show that samples 1 and 3 consist of ?-Fe2O3 nanoparticles (sizes, ~10 and 3 nm) and sample 2 and 4 consist of CoxFe3-xO4 nanoparticles (sizes, ~10 and 4 nm). The temperature dependence of the zero-field-cooled and field-cooled magnetizations at low temperatures, together with a magnetic hysteresis in the M versus H data below blocking temperatures, demonstrate superparamagnetic behavior. The introduction of Co in the iron oxide-resin matrix results in an increase in the blocking temperature of nanoparticles.

Vaishnava, P. P.; Senaratne, U.; Buc, E.; Naik, R.; Naik, V. M.; Tsoi, G.; Wenger, L. E.; Boolchand, P.

2006-04-01

116

Magnetic properties of Co-ferrite-doped hydroxyapatite nanoparticles having a core/shell structure  

NASA Astrophysics Data System (ADS)

The magnetic properties of Co-ferrite-doped hydroxyapatite (HAP) nanoparticles of composition Ca10-3xFe2xCox(PO4)6(OH)2 (where x=0, 0.1, 0.2, 0.3, 0.4 and 0.5% mole) are studied. Transmission electron microscope micrograms show that the 90 nm size nanoparticles annealed at 1250 °C have a core/shell structure. Their electron diffraction patterns show that the shell is composed of the hydroxyapatite and the core is composed of the Co-ferrite, CoFe2O4. Electron spin resonance measurements indicate that the Co2+ ions are being substituted into the Ca(1) sites in HAP lattice. X-ray diffraction studies show the formation of impurity phases as higher amounts of the Fe3+/Co2+ ions which are substituted into the HAP host matrix. The presence of two sextets (one for the A-site Fe3+ and the other for the B-site Fe3+) in the Mössbauer spectrum for all the doped samples clearly indicates that the CoFe2O4.cores are in the ferromagnetic state. Evidence of the impurity phases is seen in the appearance of doublet patterns in the Mössbauer spectrums for the heavier-doped (x=0.4 and 0.5) specimens. The decrease in the saturation magnetizations and other magnetic properties of the nanoparticles at the higher doping levels is consistent with some of the Fe3+ and Co2+ which being used to form the CoO and Fe2O3 impurity phase seen in the XRD patterns.

Petchsang, N.; Pon-On, W.; Hodak, J. H.; Tang, I. M.

2009-07-01

117

Synthesis of manganese spinel nanoparticles at room temperature by coprecipitation  

SciTech Connect

This paper is focused on a new route to synthesize Mn{sub 3}O{sub 4} nanoparticles by alkalisation by sodium hydroxide on a manganeous solution at room temperature. The precipitates obtained at different pH values have been characterized by XRD and TEM. Since the first addition of sodium hydroxide, a white Mn(OH){sub 2} precipitate appears. At pH=7, {gamma}-MnOOH phase is predominant with needle like shaped particles. At pH=10, hausmanite nanoparticles, which exhibits well defined cubic shape in the range 50-120 nm are obtained. This new precipitation route is a fast and easy environmentally friendly process to obtain well crystallized hausmanite nanoparticles. - Graphical abstract: TEM image showing Mn{sub 3}O{sub 4} particles after a precipitation at pH=10. Highlights: Black-Right-Pointing-Pointer A new route to synthesize Mn{sub 3}O{sub 4} nanoparticles has been demonstrated. Black-Right-Pointing-Pointer Synthesis has been performed by precipitation at room temperature. Black-Right-Pointing-Pointer The size of the Mn{sub 3}O{sub 4} nanoparticles is between 50 and 120 nm.

Giovannelli, F., E-mail: fabien.giovannelli@univ-tours.fr [GREMAN, UMR 7347 CNRS-CEA, Universite Francois Rabelais, 15 rue de la chocolaterie, 41000 BLOIS (France); Autret-Lambert, C.; Mathieu, C.; Chartier, T.; Delorme, F. [GREMAN, UMR 7347 CNRS-CEA, Universite Francois Rabelais, 15 rue de la chocolaterie, 41000 BLOIS (France); Seron, A [BRGM, 3 Avenue Claude Guillemin, BP 36009, 45060 ORLEANS Cedex 2 (France)

2012-08-15

118

Synthesis of manganese ferrite/graphene oxide nanocomposites for biomedical applications.  

PubMed

In this study, MnFe(2)O(4) nanoparticle (MFNP)-decorated graphene oxide nanocomposites (MGONCs) are prepared through a simple mini-emulsion and solvent evaporation process. It is demonstrated that the loading of magnetic nanocrystals can be tuned by varying the ratio of graphene oxide/magnetic nanoparticles. On top of that, the hydrodynamic size range of the obtained nanocomposites can be optimized by varying the sonication time during the emulsion process. By fine-tuning the sonication time, MGONCs as small as 56.8 ± 1.1 nm, 55.0 ± 0.6 nm and 56.2 ± 0.4 nm loaded with 6 nm, 11 nm, and 14 nm MFNPs, respectively, are successfully fabricated. In order to improve the colloidal stability of MGONCs in physiological solutions (e.g., phosphate buffered saline or PBS solution), MGONCs are further conjugated with polyethylene glycol (PEG). Heating by exposing MGONCs samples to an alternating magnetic field (AMF) show that the obtained nanocomposites are efficient hyperthermia agents. At concentrations as low as 0.1 mg Fe mL(-1) and under an 59.99 kA m(-1) field, the highest specific absorption rate (SAR) recorded is 1588.83 W g(-1) for MGONCs loaded with 14 nm MFNPs. It is also demonstrated that MGONCs are promising as magnetic resonance imaging (MRI) T(2) contrast agents. A T(2) relaxivity value (r(2) ) as high as 256.2 (mM Fe)(-1) s(-1) could be achieved with MGONCs loaded with 14 nm MFNPs. The cytotoxicity results show that PEGylated MGONCs exhibit an excellent biocompatibility that is suitable for biomedical applications. PMID:22962025

Peng, Erwin; Choo, Eugene Shi Guang; Chandrasekharan, Prashant; Yang, Chang-Tong; Ding, Jun; Chuang, Kai-Hsiang; Xue, Jun Min

2012-09-07

119

Folate conjugated carboxymethyl chitosan–manganese doped zinc sulphide nanoparticles for targeted drug delivery and imaging of cancer cells  

Microsoft Academic Search

We developed a novel folic acid (FA) conjugated carboxymethyl chitosan coordinated to manganese doped zinc sulphide quantum dot (FA–CMC–ZnS:Mn) nanoparticles. The system can be used for targeting, controlled drug delivery and also imaging of cancer cells. The prepared nanoparticles were characterized using SEM, AFM, FT-IR, UV and DLS studies. The size range of 5-FU encapsulated FA–CMC–ZnS:Mn nanoparticles were from 130

Manjusha Elizabeth Mathew; Jithin C. Mohan; K. Manzoor; S. V. Nair; H. Tamura; R. Jayakumar

2010-01-01

120

Iron-based soft magnetic composites with Mn–Zn ferrite nanoparticles coating obtained by sol–gel method  

NASA Astrophysics Data System (ADS)

This paper focuses on iron-based soft magnetic composites which were synthesized by utilizing Mn–Zn ferrite nanoparticles to coat iron powder. The nanocrystalline iron powders, with an average particle diameter of 20 nm, were obtained via the sol–gel method. Scanning electron microscopy, energy dispersive X-ray spectroscopy and distribution maps show that the iron particle surface is covered with a thin layer of Mn–Zn ferrites. Mn–Zn ferrite uniformly coated the surface of the powder particles, resulting in a reduced imaginary permeability, increased electrical resistivity and a higher operating frequency of the synthesized magnets. Mn–Zn ferrite coated samples have higher permeability and lower magnetic loss when compared with the non-magnetic epoxy resin coated compacts. The real part of permeability increases by 33.5% when compared with the epoxy resin coated samples at 10 kHz. The effects of heat treatment temperature on crystalline phase formation and on the magnetic properties of the Mn–Zn ferrite were investigated via X-ray diffraction and a vibrating sample magnetometer. Ferrites decomposed to FeO and MnO after annealing above 400 °C in nitrogen; thus it is the optimum annealing temperature to attain the desired permeability.

Wu, Shen; Sun, Aizhi; Xu, Wenhuan; Zhang, Qian; Zhai, Fuqiang; Logan, Philip; Volinsky, Alex A.

2012-11-01

121

Effect of proton irradiation on the magnetic properties of manganese ferrite.  

PubMed

Cubic-spinel MnFe2O4 magnetic nanoparticles (NPs) were prepared, with an average particle size of about 4 nm determined from a high-resolution transmission electron microscope. When the NPs were proton-irradiated, the lattice constants decreased with increasing proton irradiation. Before the proton irradiation, the NPs exhibited 36.2 +/- 0.1 emu/g magnetization (M(S)) and 11.1 +/- 0.1 Oe coercivity (H(C)). After the irradiation of the samples with 5 and 10 pC/microm2 doses, the M(S) changed to 35.6 and 35.1 +/- 0.1 emu/g, and the H(C) to 11.3 and 12.9 +/- 0.1 Oe, respectively. The room-temperature Mössbauer spectra of the NPs showed superparamagnetic characteristics, with the single-absorption line of two sites and a large relaxation frequency. During the proton irradiation, the relaxation frequency decreased to 156.02 and 134.29 +/- 0.01 Gamma/? from the unirradiated sample's 164.02 +/- 0.01 Gamma/?. It is suggested that the proton irradiation induced the increase in the anisotropy energy of the MnFe2O4 NPs. Moreover, from the external-field-induced Mössbauer spectra at 4.2 K, an increase in the canted angle of the hyperfine field between sites A (tetrahedral) and B (octahedral) was observed with proton irradiation. PMID:22121693

Hyun, Sung Wook; Hong, Sun Chun; Kim, Sam Jin; Kim, Chul Sung

2011-07-01

122

Preparation of spherical and uniform-sized ferrite nanoparticles with diameters between 50 and 150 nm for biomedical applications  

NASA Astrophysics Data System (ADS)

Spherical uniform-sized iron ferrite nanoparticles were synthesized by adding a disaccharide and seed ferrite crystals into an aqueous reaction solution. The average size range 50-150 nm was controlled by choosing one out of five disaccharides and by changing the amount of the seed crystals. The particles had a saturation magnetization and a crystalline structure which are similar to those of intermediate Fe3O4-?-Fe2O3. When coated with citrate, the particles with nearly 100 nm diameter were stably suspended in water for 2 days. These novel particles will be utilized as magnetic carriers in biomedical applications.

Tanaka, Toshiyuki; Shimazu, Ryuichi; Nagai, Hironori; Tada, Masaru; Nakagawa, Takashi; Sandhu, Adarsh; Handa, Hiroshi; Abe, Masanori

2009-05-01

123

Dielectric properties of Mn0.5Zn0.5Fe2O4 ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Mn0.5Zn0.5Fe2O4 ferrite nanoparticles have been prepared by sol-gel auto-combustion method with a view to understand the role of oxidizer to fuel ratio (OFR) on the dielectric properties. XRD study shows the formation of cubic ferrite with spinel structure and particle size increases with the increase in concentration of fuel. Dielectric properties and AC conductivity of the sample measured at room temperature are reported. OFR plays a vital role in determining the dielectric properties and AC conductivity of the prepared samples.

Murugesan, C.; Md Gazzali, P. M.; Sathyamoorthy, B.; Chandrasekaran, G.

2013-02-01

124

Solar photocatalytic degradation of RB5 by ferrite bismuth nanoparticles synthesized via ultrasound.  

PubMed

In this paper, the photocatalytic degradation of Reactive Black 5 (RB5) was investigated with ferrite bismuth synthesized via ultrasound under direct sunlight irradiation. The intensity of absorption peaks of RB5 gradually decreased by increasing the irradiation time and finally vanished in 50 min in acidic medium. The formation of new intermediate was observed in basic medium. The relative concentration of RB5 in solution and on the surface of ferrite bismuth (BiFeO3) nanoparticles was considered during the experiment in acidic and basic media. The effects of various parameters such as amount of catalyst, concentration of dye, and pH of the solution have been studied on the dye degradation. The adsorption isotherm and the kinetic of photocatalytic degradation of RB5 were investigated. The adsorption constants in the dark and in the presence of sunlight irradiation were compared. The photocatalytic degradation mechanism of RB5 has been evaluated through the addition of some scavengers to the solution. In addition, the stability and reusability of the catalyst were examined in this work. PMID:23466007

Soltani, T; Entezari, M H

2013-02-07

125

Giant antiresonance in electromagnetic wave reflection from a 3D structure with ferrite spinel nanoparticles  

NASA Astrophysics Data System (ADS)

We analyze the microwave properties of nanocomposite materials obtained by embedding opal matrices (regular packing of SiO2 spheres about 250 nm in diameter) of ferrite spinel nanoparticles in the interspherical space. It is found that the main reason for microwave changes is the magnetic resonance in a nanocomposite. In addition to the resonance, antiresonance also takes place, which is manifested as a minimum of absorbed power at frequencies higher than a certain frequency characteristic of the given type of ferrite particles. Antiresonance appears in the fields smaller than the resonance field. The amplitude of the reflected signal in antiresonance increases fourfold. The measurements are taken in the frequency range from 26 to 38 GHz. The change in the moduli of transmission and reflection coefficients in the external magnetic field in a rectangular waveguide containing a nanocomposite is analyzed. The modulus of the wave transmittance through a rectangular resonator with a nanocomposite specimen is measured. The structural analysis of nanocomposites is carried out. In addition, the magnetization curves and hysteresis loops are measured.

Ustinov, V. V.; Rinkevich, A. B.; Perov, D. V.; Burkhanov, A. M.; Samoylovich, M. I.; Kleshcheva, S. M.; Kuznetsov, E. A.

2013-04-01

126

Structural characterization of microwave-synthesized zinc-substituted cobalt ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Microwave combustion technique modified by post treatment procedure is used to synthesize single-phase spinel ferrites of cobalt, zinc, and substituted magnetic nanoparticles of typical size 390 Å. The post treatment does not alter the crystal structure but increases the crystallinity. This is confirmed by powder x-ray diffraction and Fourier Transform Infrared (FTIR) studies. Citric acid is used as a fuel. The fresh synthesized sample shows an impurity phase in x-ray and in FTIR. This is due to the unreacted citrate molecule adsorbed on the particle surface. It is shown that by treating the sample with 0.1 M HCl, we can eliminate the impurity phase, and one can obtain a pure single phase. The magnetization at 8 kOe increases by nearly 8% after the removal of impurity. In order to remove surface adsorbed OH- ion, samples are treated with NaCl and heated to 200°C for four hours. The XRD result indicates that after the treatment neither the crystallite size nor the distribution changes, but it removes OH- ion. This is also confirmed by FTIR analysis. Thus, this modified technique can be used to synthesize pure nanocrystalline samples of spinel ferrites.

Parmar, Harshida; Desai, Rucha; Upadhyay, R. V.

2011-07-01

127

Wet chemical synthesis and gas sensing properties of magnesium zinc ferrite nano-particles  

Microsoft Academic Search

In the present work we have synthesized, magnesium ferrite, zinc ferrite, and magnesium zinc ferrite solid solutions using an economic wet chemical synthesis route. To understand the phase formation behavior of the synthesized powders, infra-red spectroscopy in conjunction with X-ray Rietveld refinement analyses has been performed. The structural characteristics of these ferrite powders are correlated with their room temperature magnetic

D. C. Bharti; K. Mukherjee; S. B. Majumder

2010-01-01

128

The alignment of barium ferrite nanoparticles from their suspensions in electric and magnetic fields.  

PubMed

The alignment of plate-like barium ferrite nanoparticles, with diameters of 10-350 nm and thicknesses of 3-10 nm, in electric and/or magnetic fields was studied. Stable suspensions were prepared in 1-butanol with dodecylbenzenesulphonic acid as a surfactant. The deposits were produced from the suspensions with classic electrophoretic deposition, electrophoretic deposition in a magnetic field, and with drying in a magnetic field. The experiments, supported by theoretical calculations, show that the alignment of the nanoplates in the deposits was determined by the interplay between the hydrodynamic, electric, and magnetic forces. The preferential alignment of the nanoplates in plane with the substrate coincided with their magnetic orientation, and it increased with the shape anisotropy of the particles. The deposits were sintered at 1150 °C for 5 h to obtain ceramic films, which showed a magnetic orientation up to 90%. PMID:22834411

Lisjak, Darja; Ovtar, Simona

2012-08-07

129

Aqueous synthesis and transmission electron microscopy observation of seed-grown spherical ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Uniform-sized spherical iron ferrite nanoparticles grew on seed crystals in an aqueous solution containing sucrose. Using the seed crystals which were highly dispersed in acidic or alkaline seed-crystal suspension without relation to pH of the suspension, we widely controlled the particle diameter in the range 20-200 nm by changing the additive amount of the seed crystals. By transmission electron microscopy observation and X-ray diffraction analysis, it indicated that the particles were highly crystalline but not amorphous. Selected area diffraction patterns of the particles by using transmission electron microscope revealed that the particles were composed of one to several crystals. Thus we provided the evidence that the particles grew on clusters composed of one to several seed crystals to which those of several dozen seed crystals were disintegrated.

Tanaka, T.; Tada, M.; Nakagawa, T.; Abe, M.

2012-03-01

130

Controlled synthesis of magnetic spinel-type nickel ferrite nanoparticles by the interface reaction and hydrothermal crystallization  

Microsoft Academic Search

Nearly mono-dispersed nickel ferrite nanoparticles have been synthesized by a solid-liquid interface reaction of Ni2+Fe23+–oleate complex with alkali solution assisted by hydrothermal crystallization. Chemical reactions took place at the interface of the solid and liquid phase and the generated particles were then dispersed into the aqueous solution through Brownian movement. The obtained samples were characterized by X-ray diffraction and transmission

Lei Wang; Jiawen Ren; Yangang Wang; Xiaohui Liu; Yanqin Wang

2010-01-01

131

Synthesis of Fe–Ni nano-particles by low-temperature hydrogen reduction of mechanically alloyed Ni-ferrite  

Microsoft Academic Search

Fe–Ni nano-particles were synthesized by mechanical alloying and subsequent low-temperature hydrogen reduction of oxide mixtures. First, single-phase nickel ferrite was mechanically synthesized for 30h with steel balls to powder weight ratio of 20 while the milling was operated at 300rpm. The as-milled powder was then placed in contact with hydrogen at 600°C for 1h. Reduction reactions resulted in production of

A. Azizi; S. K. Sadrnezhaad

2009-01-01

132

Controlled oxidation of FeCo magnetic nanoparticles to produce faceted FeCo\\/ferrite nanocomposites for rf heating applications  

Microsoft Academic Search

We report the oxidation products and qualitative rates for polydisperse FeCo magnetic nanoparticles (MNPs) synthesized using an induction plasma torch. X-ray diffraction (XRD) and TEM showed MNPs to have a thin ferrite shell. Nanopowders were isochronally annealed to promote oxidation and XRD was used to follow the evolution of the FeCo core and the Fe3O4 and FeO oxide shells. Isothermal

K. N. Collier; N. J. Jones; K. J. Miller; Y. L. Qin; D. E. Laughlin; M. E. McHenry

2009-01-01

133

Method for synthesizing ferrite nanoparticles ~30 nm in diameter on neutral pH condition for biomedical applications  

NASA Astrophysics Data System (ADS)

Nanosized ferrite spherical particles, ~30 nm in diameter as revealed by scanning electron microscopy, were synthesized from an aqueous Fe(OH)2 suspension (pH=7.6-8.0) at 25 °C by oxidizing it with H2O2. The nanoparticles were of a spinel structure of an intermediate between Fe3O4 and ?-Fe2O3, as revealed by x-ray diffraction. Compared to the nanoparticles synthesized by our previous method in which an aqueous solution of Fe2++Fe3+ was oxidized by air (oxygen), the nanoparticles increased in size, from ~10 nm (previous method) to 30 nm. Also saturation magnetization increased, though slightly, from 76 emu/g (previous method) to 80 emu/g (present method). Therefore, the ferrite nanoparticles synthesized by this method will improve the efficiency of magnetic separation. Because synthesis is performed at room temperature and neutral conditions (pH=7.1-7.8), which are compatible with most bioactive molecules (e.g., antibodies and proteins), these molecules will be immobilized onto the surface of the nanoparticles during their syntheses.

Tada, M.; Hatanaka, S.; Sanbonsugi, H.; Matsushita, N.; Abe, M.

2003-05-01

134

Functional Magnetic Nanoparticles  

NASA Astrophysics Data System (ADS)

Nanoparticle system research and characterization is the focal point of this research and dissertation. In the research presented here, magnetite, cobalt, and ferrite nanoparticle systems have been explored in regard to their magnetocaloric effect (MCE) properties, as well as for use in polymer composites. Both areas of study have potential applications across a wide variety of interdisciplinary fields. Magnetite nanoparticles have been successfully dispersed in a polymer. The surface chemistry of the magnetic nanoparticle proves critical to obtaining a homogenous and well separated high density dispersion in PMMA. Theoretical studies found in the literature have indicated that surface interface energy is a critical component in dispersion. Oleic acid is used to alter the surface of magnetite nanoparticles and successfully achieve good dispersion in a PMMA thin film. Polypyrrole is then coated onto the PMMA composite layer. The bilayer is characterized using cross-sectional TEM, cross-sectional SEM, magnetic characterization, and low frequency conductivity. The results show that the superparmagnetic properties of the as synthesized particles are maintained in the composite. With further study of the properties of these nanoparticles for real and functional uses, MCE is studied on a variety of magnetic nanoparticle systems. Magnetite, manganese zinc ferrite, and cobalt ferrite systems show significant broadening of the MCE and the ability to tune the peak temperature of MCE by varying the size of the nanoparticles. Four distinct systems are studied including cobalt, cobalt core silver shell nanoparticles, nickel ferrite, and ball milled zinc ferrite. The results demonstrate the importance of surface characteristics on MCE. Surface spin disorder appears to have a large influence on the low temperature magnetic and magnetocalorie characteristics of these nanoparticle systems.

Gass, James

135

The role of aggregation of ferrite nanoparticles on their magnetic properties.  

PubMed

We have studied the magnetic properties of aggregates of Mn0.5Zn0.5Gd(x)Fe(2-x)O4 ferrite nanoparticles, with x = 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.18, 0.20. The scanning electron microscopy micrographs show significant aggregation of the nanoparticles in all samples. Zero field cooled and field cooled magnetization measurements were conducted on all samples from 400 K down to 5 K. Most zero field cooled curves were found to exhibit the usual behavior but with wide peaked regions. For some x values, the field cooled magnetization was found to increase slowly with decreasing temperature, and becomes nearly constant at low temperatures. The measurements of magnetization versus applied magnetic field were conducted on all samples at 5 K and 305 K in the field range from -15000 to 15000 Oe. At 305 K the magnetization for all samples was observed to saturate, while at 5 K the magnetization did not reach saturation for some values of x. The saturation magnetization values were suggested to be proportional to the size of particles. These results were discussed and suggested to be due to the inter-particle dipolar and exchange interactions between the particles in the aggregates, the large particle size distribution and the surface magnetization effects. PMID:21780381

Obaidat, I M; Issa, B; Haik, Y

2011-05-01

136

Study Of Structural And Dielectric Properties Of Ni-Mg Ferrite Nanoparticles  

SciTech Connect

Ferrite nanoparticles of basic composition Ni{sub 0.7}Mg{sub 0.3}Fe{sub 2-x}Al{sub x}O{sub 4}(0.0{<=}x{<=}0.5) were prepared through citrate gel method and characterized using XRD, TEM and dielectric spectroscopy techniques. The dielectric properties were studied as a function of frequency (42 Hz-5 MHz) at room temperature. The average particle size has been found between 8-17 nm. The dispersion in dielectric properties and ac conductivity ({sigma}{sub ac}), with frequency reveals that the dispersion is due to Maxwell-Wagner type of interfacial polarization in general and the hopping of charge between Fe{sup 2+} and Fe{sup 3+} as well as between Ni{sup 2+} and Ni{sup 3+} ions at B-sites. The dielectric loss tangent (tan {delta}) shows abnormal behavior for the compositions 0.3, 0.4 and 0.5 which has been explained in the light of Rezlescue model.

Nongjai, Razia; Batoo, Khalid Mujasam; Khan, Shakeel [Dept. of Applied Physics, Aligarh Muslim University, Aligarh, 202002 (India) and King Abdullah Institute for Nanotechnology, King Saud University, Riyadh, 11451 (Saudi Arabia)

2010-12-01

137

Manifestation of weak ferromagnetism and photocatalytic activity in bismuth ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Bismuth ferrite (BFO) nanoparticles were synthesized by auto-ignition technique with and without adding ignition fuel such as citric acid. The presence of citric acid in the reaction mixture yielded highly-magnetic BFO/?-Fe2O3 nanocomposite. When this composite was annealed to 650°C, a single phase BFO was formed with average crystallite size of 50 nm and showed weak ferromagnetic behavior. Conversely, the phase pure BFO prepared without adding citric acid exhibited antiferromagnetism because of its larger crystallite size of around 70 nm. The visible-light driven photocatalytic activity of both the pure BFO and BFO/?-Fe2O3 nanocomposite were examined by degrading methyl orange dye. The pure BFO showed a moderate photocatalytic activity; while BFO/?-Fe2O3 nanocomposite showed enhanced activity. This could be probably due to the optimal band gap ratio between BFO and ?-Fe2O3 phases reduced the recombination of electron-hole pairs which aided in the enhancement of photocatalytic activity.

Sakar, M.; Balakumar, S.; Saravanan, P.; Jaisankar, S. N.

2013-02-01

138

Nanoparticle composites having structural intergrowths of hexaferrite and spinel ferrites prepared by gel-to-crystallite conversion and their magnetic properties  

Microsoft Academic Search

Nanoparticle composites of spinel (S) and hexaferrite (W or Y phase) in different ratios were prepared by a wet-chemical process of gel-to-crystallite conversion. The compositions were selected on the line connecting W–S or Y–S in the BaO–NiO–Fe2O3 ternary phase diagram. High-resolution electron micrographs of these crystallites show coherent intergrowth features involving hexaferrite and spinel ferrite structural blocks. Intergrown nickel ferrite

C Sudakar; G. N Subbanna; T. R. N Kutty

2004-01-01

139

Nanoparticle composites having structural intergrowths of hexaferrite and spinel ferrites prepared by gel-to-crystallite conversion and their magnetic properties  

Microsoft Academic Search

Nanoparticle composites of spinel (S) and hexaferrite (W or Y phase) in different ratios were prepared by a wet-chemical process of gel-to-crystallite conversion. The compositions were selected on the line connecting W-S or Y-S in the BaO-NiO-Fe2O3 ternary phase diagram. High-resolution electron micrographs of these crystallites show coherent intergrowth features involving hexaferrite and spinel ferrite structural blocks. Intergrown nickel ferrite

C. Sudakar; G. N. Subbanna; T. R. N. Kutty

2004-01-01

140

Spin-flop transition, magnetic and microwave absorption properties of ?-Fe2O4 spinel type ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

We have prepared NiFe2O4, CoFe2O4, Ni0.6Zn0.4Fe2O4 and ZnFe2O4 spinel type ferrite nanoparticles by surfactant-assisted hydrothermal process using cetyltrimethylammonium bromide (CTAB). The spin-flop transition, magnetic, dielectric and permittivity characterizations have been investigated. The spin-flop transition occurs from antiferromagnetic state to mixed state and then ferromagnetic state for Zn doped samples. The spin-flop transition occurs in the temperature range of 50-250 K. The ionic conduction, dipolar relaxation, atomic polarization and electronic polarization are the main mechanisms that contribute to the permittivity of a dielectric material. The permittivity increases with increasing frequency. This suggests a resonance behavior, which is expected when the ferrite samples are highly conductive and skin effect become significant. These samples will provide great benefits for electromagnetic applications and electromagnetic interference shielding characteristics.

Yalç?n, Orhan; Bayrakdar, Harun; Özüm, Songül

2013-10-01

141

Size and crystallinity-dependent magnetic properties of copper ferrite nano-particles  

Microsoft Academic Search

Copper ferrite nano-crystals were synthesized by a combustion route depending upon the glycine–nitrate process and also by ceramic method. In order to investigate the effect of degree of crystallinity and crystallite size of copper ferrite system on its magnetic properties, a series of Cu-ferrite samples with different degrees of crystallinity and crystallite size were produced by varying the preparation temperatures

N. M. Deraz

2010-01-01

142

Synthesis of core/shell spinel ferrite/carbon nanoparticles with enhanced cycling stability for lithium ion battery anodes  

NASA Astrophysics Data System (ADS)

Monodispersed core/shell spinel ferrite/carbon nanoparticles are formed by thermolysis of metal (Fe3+, Co2+) oleates followed by carbon coating. The phase and morphology of nanoparticles are characterized by x-ray diffraction and transmission electron microscopy. Pure Fe3O4 and CoFe2O4 nanoparticles are initially prepared through thermal decomposition of metal-oleate precursors at 310?°C and they are found to exhibit poor electrochemical performance because of the easy aggregation of nanoparticles and the resulting increase in the interparticle contact resistance. In contrast, uniform carbon coating of Fe3O4 and CoFe2O4 nanoparticles by low-temperature (180?°C) decomposition of malic acid allowed each nanoparticle to be electrically wired to a current collector through a conducting percolative path. Core/shell Fe3O4/C and CoFe2O4/C nanocomposite electrodes show a high specific capacity that can exceed 700 mAh g-1 after 200 cycles, along with enhanced cycling stability.

Jin, Yun-Ho; Seo, Seung-Deok; Shim, Hyun-Woo; Park, Kyung-Soo; Kim, Dong-Wan

2012-03-01

143

Synthesis of core/shell spinel ferrite/carbon nanoparticles with enhanced cycling stability for lithium ion battery anodes.  

PubMed

Monodispersed core/shell spinel ferrite/carbon nanoparticles are formed by thermolysis of metal (Fe3+, Co2+) oleates followed by carbon coating. The phase and morphology of nanoparticles are characterized by x-ray diffraction and transmission electron microscopy. Pure Fe3O4 and CoFe2O4 nanoparticles are initially prepared through thermal decomposition of metal–oleate precursors at 310 degrees C and they are found to exhibit poor electrochemical performance because of the easy aggregation of nanoparticles and the resulting increase in the interparticle contact resistance. In contrast, uniform carbon coating of Fe3O4 and CoFe2O4 nanoparticles by low-temperature (180 degrees C) decomposition of malic acid allowed each nanoparticle to be electrically wired to a current collector through a conducting percolative path. Core/shell Fe3O4/C and CoFe2O4/C nanocomposite electrodes show a high specific capacity that can exceed 700 mAh g(-1) after 200 cycles, along with enhanced cycling stability. PMID:22414887

Jin, Yun-Ho; Seo, Seung-Deok; Shim, Hyun-Woo; Park, Kyung-Soo; Kim, Dong-Wan

2012-03-30

144

Microwave-absorbing characteristics of epoxy resin composites containing nanoparticles of NiZn- and NiCuZn-ferrites  

Microsoft Academic Search

NiZn- and NiCuZn-ferrite nanoparticles (50-70 nm) with the chemical formula Ni0.5 Zn0.5Fe2O4 (NiZn) and Ni0.35Cu0.15Zn0.5Fe2O4 (NiCuZn) were synthesized by a combustion synthesis method. The nanocrystallite of these materials was characterized by structural and magnetic methods. Saturation magnetization increases from 83 emu\\/g (NiZn) to 91 emu\\/g (NiCuZn). Magnetic permeability and dielectric permittivity were measured on sintered samples (pellets and toroids) in

J. C. Aphesteguy; Abel Damiani; Dalmas Digiovanni; S. E. Jacobo

2009-01-01

145

Microwave-absorbing characteristics of epoxy resin composites containing nanoparticles of NiZn- and NiCuZn-ferrites  

Microsoft Academic Search

NiZn- and NiCuZn-ferrite nanoparticles (50–70nm) with the chemical formula Ni0.5 Zn0.5Fe2O4 (NiZn) and Ni0.35Cu0.15Zn0.5Fe2O4 (NiCuZn) were synthesized by a combustion synthesis method. The nanocrystallite of these materials was characterized by structural and magnetic methods. Saturation magnetization increases from 83emu\\/g (NiZn) to 91emu\\/g (NiCuZn). Magnetic permeability and dielectric permittivity were measured on sintered samples (pellets and toroids) in the frequency range

J. C. Aphesteguy; Abel Damiani; Dalmas DiGiovanni; S. E. Jacobo

2009-01-01

146

A fast route to obtain manganese spinel nanoparticles by reduction of K-birnessite  

SciTech Connect

The K-birnessite (K{sub x}MnO{sub 2}.yH{sub 2}O) reduction reaction has been tested in order to obtain manganese spinel nanoparticles. The addition of 0.25 weight percent of hydrazine hydrate, the reducing agent, during 24 hours is efficient to transform the birnessite powder in a hausmanite Mn{sub 3}O{sub 4} powder. Well crystallised square shape nanoparticles are obtained. Different birnessite precursors have been tested and the reaction kinetics is strongly correlated to the crystallinity and granulometry of the precursor. The effects of aging time and hydrazine hydrate amount have been studied. Well crystallised Mn{sub 3}O{sub 4} is obtained in one hour. The presence of feitknechtite (MnO(OH)) and amorphous nanorods has been detected as an intermediate phase during birnessite conversion into hausmanite. The conversion mechanism is discussed. - Graphical abstract: TEM image showing Mn{sub 3}O{sub 4} particle after treatment of birnessite with an addition of hydrazine during 24 hours.

Giovannelli, F., E-mail: fabien.giovannelli@univ-tours.f [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, 3 place Jean Jaures 41029 BLOIS (France); Chartier, T. [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, 3 place Jean Jaures 41029 BLOIS (France); Autret-Lambert, C. [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, parc de Grandmont 37200 TOURS (France); Delorme, F. [BRGM, 3 Avenue Claude Guillemin, BP 36009, 45060 ORLEANS Cedex 2 (France); CORNING SAS, CETC, 7 bis Avenue Valvins, 77210 AVON (France); Zaghrioui, M. [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, 3 place Jean Jaures 41029 BLOIS (France); Seron, A. [BRGM, 3 Avenue Claude Guillemin, BP 36009, 45060 ORLEANS Cedex 2 (France)

2009-05-15

147

Low temperature-fired Ni-Cu-Zn ferrite nanoparticles through auto-combustion method for multilayer chip inductor applications  

PubMed Central

Ferrite nanoparticles of basic composition Ni0.7-xZnxCu0.3Fe2O4 (0.0 ? x ? 0.2, x = 0.05) were synthesized through auto-combustion method and were characterized for structural properties using X-ray diffraction [XRD], scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy [FT-IR]. XRD analysis of the powder samples sintered at 600°C for 4 h showed the cubic spinel structure for ferrites with a narrow size distribution from 28 to 32 nm. FT-IR showed two absorption bands (v1 and v2) that are attributed to the stretching vibration of tetrahedral and octahedral sites. The effect of Zn doping on the electrical properties was studied using dielectric and impedance spectroscopy at room temperature. The dielectric parameters (?', ??, tan?, and ?ac) show their maximum value for 10% Zn doping. The dielectric constant and loss tangent decrease with increasing frequency of the applied field. The results are explained in the light of dielectric polarization which is similar to the conduction phenomenon. The complex impedance shows that the conduction process in grown nanoparticles takes place predominantly through grain boundary volume. PACS: 75.50.Gg; 78.20; 77.22.Gm.

2012-01-01

148

Microwave-absorbing characteristics of epoxy resin composites containing nanoparticles of NiZn- and NiCuZn-ferrites  

NASA Astrophysics Data System (ADS)

NiZn- and NiCuZn-ferrite nanoparticles (50-70 nm) with the chemical formula Ni0.5 Zn0.5Fe2O4 (NiZn) and Ni0.35Cu0.15Zn0.5Fe2O4 (NiCuZn) were synthesized by a combustion synthesis method. The nanocrystallite of these materials was characterized by structural and magnetic methods. Saturation magnetization increases from 83 emu/g (NiZn) to 91 emu/g (NiCuZn). Magnetic permeability and dielectric permittivity were measured on sintered samples (pellets and toroids) in the frequency range of 1 MHz-1.8 GHz. Reflection losses (RL) for both samples were calculated from complex permeability and permittivity. Cu substitution in NiZn-ferrite enhances permeability and RL. In order to explore microwave-absorbing properties in X-band, magnetic nanoparticles were mixed with an epoxy resin to be converted into a microwave-absorbing composite and microwave behaviors of both materials were studied using a microwave vector network analyzer from 7.5 to 13.5 GHz. Cu substitution diminishes absorption intensity in the range 11.5-12.5 GHz.

Aphesteguy, J. C.; Damiani, Abel; Digiovanni, Dalmas; Jacobo, S. E.

2009-10-01

149

Low temperature synthesis of bismuth ferrite nanoparticles by a ferrioxalate precursor method  

SciTech Connect

The synthesis of bismuth ferrite by solid-state reaction of Bi{sub 2}O{sub 3} and Fe{sub 2}O{sub 3} results in the formation of multiphase products. Even coprecipitation followed by calcination leads to the formation of impurity phases. Here, we report the synthesis of magnetoelectric bismuth ferrite by a ferrioxalate precursor method. In this process, bismuth ferrite, synthesized through solutions of some specific salts led to the formation of phase pure (perovskite) nanocrystalline powder (11-22 nm as evident from X-ray diffraction analysis) at a temperature of 600 deg. C. The synthesized powders were characterized by X-ray diffractometry, thermogravimetry and differential thermal analysis, Fourier transformation infrared spectroscopy and scanning electron microscopy. The synthesis route is simple, energy saving and cost-effective. Such nanosized bismuth ferrite powder may have a potential application in making lead free piezoelectric materials for actuators as well as magnetoelectric sensors.

Ghosh, Sushmita [Central Glass and Ceramic Research Institute, 196 Raja S.C. Mullick Road, Kolkata, West Bengal 700032 (India); Dasgupta, Subrata [Central Glass and Ceramic Research Institute, 196 Raja S.C. Mullick Road, Kolkata, West Bengal 700032 (India)]. E-mail: sdasgupta@cgcri.res.in; Sen, Amarnath [Central Glass and Ceramic Research Institute, 196 Raja S.C. Mullick Road, Kolkata, West Bengal 700032 (India); Maiti, Himadri Sekhar [Central Glass and Ceramic Research Institute, 196 Raja S.C. Mullick Road, Kolkata, West Bengal 700032 (India)

2005-12-08

150

Nanoparticles of Molybdenum Chlorophyllin Photosensitizer and Magnetic Citrate-Coated Cobalt Ferrite Complex Available to Hyperthermia and Photodynamic Therapy Clinical Trials  

Microsoft Academic Search

This study report on the synthesis and characterization of molybdenum chlorophyllin (Mo-Chl) compounds associated in a complex with magnetic nanoparticles (citrate-coated cobalt ferrite), the latter prepared as a biocompatible magnetic fluid (MF). The complex material was developed for application as a synergic drug for cancer treatment using Photodynamic Therapy (PDT) and Hyperthermia (HPT). Chlorophyllin was obtained from alkaline extraction of

Fernando L. Primo; Paloma L. A. G. Cordo; Alberto F. Neto; Paulo C. Morais; Antonio C. Tedesco

2010-01-01

151

Regio- and chemoselective reduction of nitroarenes and carbonyl compounds over recyclable magnetic ferrite-nickel nanoparticles (Fe(3)O(4)-Ni) by using glycerol as a hydrogen source.  

PubMed

Reduction by magnetic nano-Fe(3)O(4)-Ni: a facile, simple and environmentally friendly hydrogen-transfer reaction that takes place over recyclable ferrite-nickel magnetic nanoparticles (Fe(3)O(4)-Ni) by using glycerol as hydrogen source allows aromatic amines and alcohols to be synthesized from the precursor nitroarenes and carbonyl compounds. PMID:22933355

Gawande, Manoj B; Rathi, Anuj K; Branco, Paula S; Nogueira, Isabel D; Velhinho, Alexandre; Shrikhande, Janhavi J; Indulkar, Utkarsha U; Jayaram, Radha V; Ghumman, C Amjad A; Bundaleski, Nenad; Teodoro, Orlando M N D

2012-08-30

152

Microwave Absorption Properties of Mn–Co–Sn Doped Barium Ferrite Nanoparticles  

Microsoft Academic Search

Substituted barium ferrite BaFe9(Mn0.5Co0.5Sn)3\\/2O19 was prepared by sol-gel method. X-ray diffraction (XRD), transmission electron microscope (TEM), AC susceptometer, vibrating sample magnetometer (VSM) and vector network analyzer were used to analyze the structure, static and dynamic magnetic properties of the prepared samples. The prepared ferrite particles possess irregular non spherical shape with a broad size distribution. The substitution was very effective

Ali Ghasemi; Vladimir Sepelak; Xiaoxi Liu; Akimitsu Morisako

2009-01-01

153

Impact of zinc substitution on the structural and magnetic properties of chemically derived nanosized manganese zinc mixed ferrites  

Microsoft Academic Search

Mn1-xZnxFe2O4 nanoparticles (x=0-1) were synthesized by wet chemical co-precipitation techniques. X-ray diffraction, transmission electron microscopy and high-resolution transmission electron microscopy were effectively utilized to investigate the different structural parameters. The elemental analysis was conducted using energy-dispersive spectrum and inductively coupled plasma analysis. The magnetic properties such as magnetization and coercivity were measured using vibrating sample magnetometer. The observed magnetization values

E. Veena Gopalan; I. A. Al-Omari; K. A. Malini; P. A. Joy; D. Sakthi Kumar; Yasuhiko Yoshida; M. R. Anantharaman

2009-01-01

154

Impact of zinc substitution on the structural and magnetic properties of chemically derived nanosized manganese zinc mixed ferrites  

Microsoft Academic Search

Mn(1-x)Zn(x)Fe(2)O(4) nanoparticles (x = 0-1) were synthesized by wet\\u000a chemical co-precipitation techniques. X-ray diffraction, transmission\\u000a electron microscopy and high-resolution transmission electron microscopy\\u000a were effectively utilized to investigate the different structural\\u000a parameters. The elemental analysis was conducted using energy-dispersive\\u000a spectrum and inductively coupled plasma analysis. The magnetic\\u000a properties such as magnetization and coercivity were measured using\\u000a vibrating sample magnetometer. The observed

E. Veena Gopalan; I. A. Al-Omari; K. A. Malini; P. A. Joy; D. Sakthi Kumar; Yasuhiko Yoshida; M. R. Anantharaman

2009-01-01

155

Magnetic properties of nanoparticles of cobalt ferrite at high magnetic field  

Microsoft Academic Search

In this paper we report high magnetic field (? 140 ? H ? 140 kOe) magnetization data for cobalt ferrites (crystallites size ? 42 nm) for temperatures (T) varying from 5 to 340 K. The T-dependence for the cubic magnetocrystalline anisotropy constant K1 was determined by using the “law of approach” (LA) to saturation. The values of K1 were found

A. Franco; F. L. A. Machado; V. S. Zapf

2011-01-01

156

Magnetic properties of nanoparticles of cobalt ferrite at high magnetic field  

Microsoft Academic Search

In this paper we report high magnetic field (- 140 <= H <= 140 kOe) magnetization data for cobalt ferrites (crystallites size ~ 42 nm) for temperatures (T) varying from 5 to 340 K. The T-dependence for the cubic magnetocrystalline anisotropy constant K1 was determined by using the ``law of approach'' (LA) to saturation. The values of K1 were found

A. Franco; F. L. A. Machado; V. S. Zapf

2011-01-01

157

Combustion synthesis of Cobalt ferrite Nanoparticles–Influence of fuel to oxidizer ratio  

Microsoft Academic Search

The effect of fuel characteristics on the processing of nano-sized Cobalt ferrite fine powders by the combustion technique is reported. By using different combinations of glycine fuel and metal nitrates, the adiabatic flame temperature (Tad) of the process as well as product characteristics could be controlled easily. Thermodynamic modelling of the combustion reaction shows that as the fuel-to-oxidant ratio increases,

A. B. Salunkhe; V. M. Khot; M. R. Phadatare; S. H. Pawar

158

Self-assembled organic-inorganic magnetic hybrid adsorbent ferrite based on cyclodextrin nanoparticles.  

PubMed

Organic-inorganic magnetic hybrid materials (MHMs) combine a nonmagnetic and a magnetic component by means of electrostatic interactions or covalent bonds, and notable features can be achieved. Herein, we describe an application of a self-assembled material based on ferrite associated with ?-cyclodextrin (Fe-Ni/Zn/?CD) at the nanoscale level. This MHM and pure ferrite (Fe-Ni/Zn) were used as an adsorbent system for Cr(3+) and Cr(2)O(7) (2-) ions in aqueous solutions. Prior to the adsorption studies, both ferrites were characterized in order to determine the particle size distribution, morphology and available binding sites on the surface of the materials. Microscopy analysis demonstrated that both ferrites present two different size domains, at the micro- and nanoscale level, with the latter being able to self-assemble into larger particles. Fe-Ni/Zn/?CD presented smaller particles and a more homogeneous particle size distribution. Higher porosity for this MHM compared to Fe-Ni/Zn was observed by Brunauer-Emmett-Teller isotherms and positron-annihilation-lifetime spectroscopy. Based on the pKa values, potentiometric titrations demonstrated the presence of ?CD in the inorganic matrix, indicating that the lamellar structures verified by transmission electronic microscopy can be associated with ?CD assembled structures. Colloidal stability was inferred as a function of time at different pH values, indicating the sedimentation rate as a function of pH. Zeta potential measurements identified an amphoteric behavior for the Fe-Ni/Zn/?CD, suggesting its better capability to remove ions (cations and anions) from aqueous solutions compared to that of Fe-Ni/Zn. PMID:23209524

Denadai, Angelo M L; De Sousa, Frederico B; Passos, Joel J; Guatimosim, Fernando C; Barbosa, Kirla D; Burgos, Ana E; de Oliveira, Fernando Castro; da Silva, Jeann C; Neves, Bernardo R A; Mohallem, Nelcy D S; Sinisterra, Rubén D

2012-11-01

159

Using thermal energy produced by irradiation of Mn–Zn ferrite magnetic nanoparticles (MZF-NPs) for heat-inducible gene expression  

Microsoft Academic Search

One of the main advantages of gene therapy over traditional therapy is the potential to target the expression of therapeutic genes in desired cells or tissues. To achieve targeted gene expression, we developed a novel heat-inducible gene expression system in which thermal energy generated by Mn–Zn ferrite magnetic nanoparticles (MZF-NPs) under an alternating magnetic field (AMF) was used to activate

Qiu-sha Tang; Dong-sheng Zhang; Xiao-ming Cong; Mei-ling Wan; Li-qiang Jin

2008-01-01

160

Development of phosphonate modified Fe (1? x) Mn x Fe 2O 4 mixed ferrite nanoparticles: Novel peroxidase mimetics in enzyme linked immunosorbent assay  

Microsoft Academic Search

A highly facile and feasible strategy on the fabrication of advanced intrinsic peroxidase mimetics based on Mn2+ doped mixed ferrite (MnIIxFeII1?xFeIII2O4) nanoparticles was demonstrated for the quantitative and sensitive detection of mouse IgG (as a model analyte). Mn2+ doped Fe1?xMnxFe2O4 nanoparticles were synthesized using varying ratios of Mn2+:Fe2+ ions and characterized by the well known complementary techniques. The increase of

Dipsikha Bhattacharya; Ananya Baksi; Indranil Banerjee; Rajakumar Ananthakrishnan; Tapas K. Maiti; Panchanan Pramanik

2011-01-01

161

4 °C preparation of ferrite nanoparticles having protein molecules immobilized on their surfaces  

NASA Astrophysics Data System (ADS)

Trypsin, a proteolytic enzyme or a protein, was immobilized onto the surfaces of ferrite (a Fe3O4-?Fe2O3 mixed solution) fine particles, ~8 nm in size, during the process in which the particles were synthesized from an aqueous solution. The process was performed in the open air at a temperature as low as 4 °C and on near-neutral condition of pH<=9, which is compatible with most of the bioactive molecules as well as trypsin. Therefore this technique is advantageous for preparing magnetite particles having biomolecules immobilized on their surfaces, which will be used for biomedical applications utilizing magnetic separation technique.

Nishimura, K.; Hasegawa, M.; Ogura, Y.; Nishi, T.; Kataoka, K.; Handa, H.; Abe, M.

2002-05-01

162

Variation of structural and hyperfine parameters in nanoparticles of Cr-substituted Co-Zn ferrites  

NASA Astrophysics Data System (ADS)

The effect of Cr substitution into nanocrystalline Co-Zn ferrite prepared by the chemical coprecipitation method has been studied. Mössbauer studies at a temperature (20K) well below the blocking temperatures of the samples show that Cr goes preferentially into the octahedral B site and that the hyperfine fields at both A and B sites decrease with increase in Cr concentration. Based on the cation distribution obtained from fitting Mössbauer spectra, structural parameters such as lattice parameters, site bond and edge lengths, and the oxygen parameter u have been calculated. The trend of theoretically calculated lattice parameter with Cr content matches well with the experimentally obtained values.

Sharma, Ram Kripal; Sebastian, Varkey; Lakshmi, N.; Venugopalan, K.; Reddy, V. Raghavendra; Gupta, Ajay

2007-04-01

163

Synthesis and Magnetic Properties of New Multi-components Spinel Ferrite Nanoparticles  

Microsoft Academic Search

We synthesized new multi-components spinel ferrite including Ni, Mn, Zn, Co, and Fe in order to improve the magnetic properties in nanosized particles by using a chemical coprecipitation method. The samples were synthesized in the mole ratios of MxMyFe(1_x+y)OldrFe2O3 (Mx My=Ni, Mn, Zn, Co, 0

Seiichi Sugimoto; K. Yagi; Y. Harada; M. Tokuda

2007-01-01

164

High magnetostriction and coupling coefficient for sintered cobalt ferrite derived from superparamagnetic nanoparticles  

NASA Astrophysics Data System (ADS)

High magnetostriction (?) and coupling coefficient (d?/dH) of 315 ppm and 1.97×10-9 A-1m, respectively, are obtained at room temperature for sintered cobalt ferrite derived from nanocrystalline powders. Also, the powder was compacted at a low pressure of 8 MPa and sintered for a short duration of 10 min at 1450 °C. Magnetic annealing at 300 °C in a field of 0.5 T for 30 min further enhanced the magnetostriction coefficient to 345 ppm with a higher coupling coefficient 2.12×10-9 A-1m. The magnetic field above which maximum magnetostriction is observed is reduced by almost half after magnetic annealing.

Khaja Mohaideen, K.; Joy, P. A.

2012-08-01

165

Superparamagnetic Particle Size Limit of Mn-Zn Ferrite Nanoparticles Synthesised Through Aqueous Method  

Microsoft Academic Search

Mn0.67Zn0.33Fe2O4 nanoparticles with size ranging from 20 to 80 nm have been synthesized using the modified oxidation method. The Curie temperatures for all the samples are found to be within 630 +\\/- 5 K suggesting that there is no size-dependent cation distribution. Mössbauer studies on the synthesized nanoparticles suggest that the critical particle size limit for superparamagnetism to be about

R. Justin Joseyphus; A. Narayanasamy; B. Jeyadevan; K. Shinoda; K. Tohji

2006-01-01

166

Preparation of bismuth ferrite nanoparticles and their photocatalytic activity for MO degradation  

Microsoft Academic Search

A modified polyacrylamide gel method was used to fabricate Bi2Fe4O9 nanoparticles. Thermogravimetric (TG) analysis, differential scanning calorimetry (DSC) analysis, fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) were used in combination to investigate the thermal decomposition process of xerogels and the formation of Bi2Fe4O9 phase. It is demonstrated that high-phase-purity Bi2Fe4O9 nanoparticles can be prepared at a calcining temperature

Man Zhang; Hua Yang; Tao Xian; Zhiqiang Wei; Wangjun Feng

2011-01-01

167

Enhanced visible-light-response photocatalytic activity of bismuth ferrite nanoparticles  

Microsoft Academic Search

Multiferroic BiFeO3 nanoparticles were prepared by a sol–gel rapid calcination technique with average diameter of 35nm with narrow size distribution. The band gap was determined to be 2.06eV, indicating their potential application as visible-light-response photocatalyst. The photocatalytic behaviors of BiFeO3 nanoparticles were estimated by the degradation of Rhodamine B (RhB) under visible light irradiation. And the photocatalytic activities under different

Xiong Wang; Ying Lin; Xifeng Ding; Jinguo Jiang

2011-01-01

168

Superparamagnetic Particle Size Limit of Mn-Zn Ferrite Nanoparticles Synthesised Through Aqueous Method  

SciTech Connect

Mn0.67Zn0.33Fe2O4 nanoparticles with size ranging from 20 to 80 nm have been synthesized using the modified oxidation method. The Curie temperatures for all the samples are found to be within 630 {+-} 5 K suggesting that there is no size-dependent cation distribution. Moessbauer studies on the synthesized nanoparticles suggest that the critical particle size limit for superparamagnetism to be about 25 nm at 293 K.

Joseyphus, R. Justin [Graduate School of Environmental Studies, Tohoku University, AramakiAza Aoba-ku, Sendai 980-8579 (Japan); Materials Science Centre, Dept. of Nuclear Physics, University of Madras, Guindy Campus, Chennai-25 (India); Narayanasamy, A. [Materials Science Centre, Dept. of Nuclear Physics, University of Madras, Guindy Campus, Chennai-25 (India); Jeyadevan, B.; Shinoda, K.; Tohji, K. [Graduate School of Environmental Studies, Tohoku University, AramakiAza Aoba-ku, Sendai 980-8579 (Japan)

2006-05-15

169

Influence of aging time of oleate precursor on the magnetic relaxation of cobalt ferrite nanoparticles synthesized by the thermal decomposition method  

NASA Astrophysics Data System (ADS)

Cobalt ferrite nanoparticles are of interest because of their room temperature coercivity and high magnetic anisotropy constant, which make them attractive in applications such as sensors based on the Brownian relaxation mechanism and probes to determine the mechanical properties of complex fluids at the nanoscale. These nanoparticles can be synthesized with a narrow size distribution by the thermal decomposition of an iron-cobalt oleate precursor in a high boiling point solvent. We studied the influence of aging time of the iron-cobalt oleate precursor on the structure, chemical composition, size, and magnetic relaxation of cobalt ferrite nanoparticles synthesized by the thermal decomposition method. The structure and thermal behavior of the iron-cobalt oleate was studied during the aging process. Infrared spectra indicated a shift in the coordination state of the oleate and iron/cobalt ions from bidentate to bridging coordination. Aging seemed to influence the thermal decomposition of the iron-cobalt oleate as determined from thermogravimmetric analysis and differential scanning calorimetry, where shifts in the temperatures corresponding to decomposition events and a narrowing of the endotherms associated with these events were observed. Aging promoted formation of the spinel crystal structure, as determined from X-ray diffraction, and influenced the nanoparticle magnetic properties, resulting in an increase in blocking temperature and magnetocrystalline anisotropy. Mossbauer spectra also indicated changes in the magnetic properties resulting from aging of the precursor oleate. Although all samples exhibited some degree of Brownian relaxation, as determined from complex susceptibility measurements in a liquid medium, aging of the iron-cobalt oleate precursor resulted in crossing of the in-phase ??and out-of-phase ?? components of the complex susceptibility at the frequency of the Brownian magnetic relaxation peak, as expected for nanoparticles that relax through a single relaxation mechanism. The resulting nanoparticles would be suitable for sensors based on the Brownian relaxation mechanism and in determining mechanical properties of complex fluids at the size scale of the nanoparticles.

Herrera, Adriana P.; Polo-Corrales, Liliana; Chavez, Ermides; Cabarcas-Bolivar, Jari; Uwakweh, Oswald N. C.; Rinaldi, Carlos

2013-02-01

170

Magnetic properties of Co1-xNix/2Srx/2Fe2O4 (x = 0-1) ferrite nanoparticles synthesized by self-assembling media of reverse micelles  

NASA Astrophysics Data System (ADS)

Co1-xNix/2Srx/2Fe2O ferrite nanoparticles were prepared using reverse micelle process. Mean particle size of pure ferrite nanoparticles is approximately 9 nm as determined by transmission electron microscopy (TEM). The heating thermograms of samples confirmed that there are no hydroxides in the ferrites fabricated via reverse micelles. Vibrating sample magnetometer (VSM) was employed to probe magnetic properties of nanosized. It was found that with increasing the amount of Ni and Sr in nanosized ferrites, the saturation magnetization decreases. Magnetic dynamics of the samples was studied by the measurement of AC magnetic susceptibility versus temperature at different frequencies. The phenomenological Néel - Brown and Vogel - Fulcher models were employed to distinguish between interacting or non-interacting system. Results show that there is strong interaction between fine particles.

Ghasemi, A.; Kaewrawang, A.; Liu, X.; Morisako, A.

2011-07-01

171

Mössbauer and magnetization studies of nickel ferrite nanoparticles synthesized by the microwave-combustion method  

NASA Astrophysics Data System (ADS)

Nanocrystalline nickel ferrite was synthesized from its stoichiometric metal nitrates and urea mixtures, using a microwave assisted combustion method. The process was a convenient, inexpensive and an efficient method for formation of NiFe2O4 nanomaterials. Effect of urea/metal nitrates ratio on the obtained phases, particle size and magnetic properties has been investigated by various techniques. Saturation magnetization of 50 emu/g was observed at room temperature for larger particles, and it decreases with decreasing particle size. The coercivity attains a maximum value of 170 Oe when the particle size was ~20 nm, and decreases with increasing particle size. Mössbauer spectra measured at RT for some representative samples show a combination of ordered and superparamagnetic behavior, whereas those collected at 20 K elucidate the nature of the obtained phases and cation distribution.

Mahmoud, M. H.; Elshahawy, A. M.; Makhlouf, Salah A.; Hamdeh, H. H.

2013-10-01

172

Magnetic hyperthermia investigation of cobalt ferrite nanoparticles: Comparison between experiment, linear response theory, and dynamic hysteresis simulations  

NASA Astrophysics Data System (ADS)

Considerable effort has been made in recent years to optimize materials properties for magnetic hyperthermia applications. However, due to the complexity of the problem, several aspects pertaining to the combined influence of the different parameters involved still remain unclear. In this paper, we discuss in detail the role of the magnetic anisotropy on the specific absorption rate of cobalt-ferrite nanoparticles with diameters ranging from 3 to 14 nm. The structural characterization was carried out using x-ray diffraction and Rietveld analysis and all relevant magnetic parameters were extracted from vibrating sample magnetometry. Hyperthermia investigations were performed at 500 kHz with a sinusoidal magnetic field amplitude of up to 68 Oe. The specific absorption rate was investigated as a function of the coercive field, saturation magnetization, particle size, and magnetic anisotropy. The experimental results were also compared with theoretical predictions from the linear response theory and dynamic hysteresis simulations, where exceptional agreement was found in both cases. Our results show that the specific absorption rate has a narrow and pronounced maxima for intermediate anisotropy values. This not only highlights the importance of this parameter but also shows that in order to obtain optimum efficiency in hyperthermia applications, it is necessary to carefully tailor the materials properties during the synthesis process.

Verde, E. L.; Landi, G. T.; Gomes, J. A.; Sousa, M. H.; Bakuzis, A. F.

2012-06-01

173

Effect of Dy+3 on the structure and static magnetic properties of spin-glass MnZn ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Structural and static magnetic properties of a series of ferrites nanoparticles (the size ranges from 7.6 to 13.5 nm) having nominal chemical composition DyxMn0.5Zn0.5Fe2-xO4 (x = 0, 0.02, 0.04, 0.06) have been investigated. The x-ray diffraction analysis clarifies that the samples crystallize in typical cubic spinel structure. Incorporation of Dy ions in the Mn0.5Zn0.5Fe2O4 lattice structure has been proved by Raman spectroscopy measurements. Correspondingly, a significant increase in the grain size and a dramatic change in the magnetic properties are observed. The magnetization versus magnetic field M(H) plots are nonhysteretic where the coercivity remains zero and display Langevin-like behavior. The temperature dependence of magnetization M(T) plots in field cooling regime shows spin-glass behavior indicating a strong interaction between the magnetic moments. The blocking temperature determined from M(T) plots in zero field cooling regime increases as the Dy content increases.

Ibrahim, E. M. M.

2013-04-01

174

Structural and magnetic properties of dispersed nickel ferrite nanoparticles synthesized through thermal decomposition route  

NASA Astrophysics Data System (ADS)

Dispersed NiFe2O4 nanoparticles are synthesized through thermal decomposition of mixed-metal (Ni2+Fe3+)-oleate complex in the presence of high boiling point organic solvent 1-octadecene with oleic acid, by tuning the mixed-metal (Ni2+Fe3+)-oleate complex precursor and the temperature. Oleic acid is used as a surfactant, capped on the surface of the particles, which assists the particles to disperse in hexane. The as-synthesized NiFe2O4 nanoparticles have a cubic spinel structure as characterized by x-ray diffraction. The ferrimagnetic nature of these nanoparticles is conformed from the field dependent room temperature magnetization curves measured using vibrating sample magnetometer. The saturation magnetization of these nanoparticles strongly depends on the particle size which can be tuned by the mixed-metal (Ni2+Fe3+)-oleate complex precursor concentration and the synthesis temperature. Transmission electron microscope images show that the particles are nearly monodispersed at high synthesis temperature.

Behera, Bhaskar Chandra; Venkata, Ravindra A.; Srivastava, Chandan; Padhan, Prahallad

2013-02-01

175

Effect of annealing in a reductive environment on the magnetic properties of barium ferrite nanoparticles doped with Ti4+ and Co2+  

NASA Astrophysics Data System (ADS)

It was found experimentally that the annealing of BaFe10.6Co0.7Ti0.7O19 and BaFe10.2Co0.9Ti0.9O19 complex magnetic oxide nanoparticles in paraffin vapor irreversibly increases their coercive force H c and saturation magnetization M s to the H c and M s values for barium ferrite BaFe12O19. The annealing of these nanoparticles, and of particles of magnetic oxides CrO2, ?-Fe2O3, and BaFe12O19 in air and in paraffin vapor, has not been shown to affect their H c and M s values. An explanation in terms of diffusion self-purification of nanoparticles from ion impurities activated by chemical processes on their surface is offered.

Petinov, V. I.

2011-10-01

176

Manganese oxide-based multifunctionalized mesoporous silica nanoparticles for pH-responsive MRI, ultrasonography and circumvention of MDR in cancer cells.  

PubMed

Nano-biotechnology has been introduced into cancer theranostics by engineering a new generation of highly versatile hybrid mesoporous composite nanocapsules (HMCNs) for manganese-based pH-responsive dynamic T(1)-weighted magnetic resonance imaging (MRI) to efficiently respond and detect the tumor acidic microenvironment, which was further integrated with ultrasonographic function based on the intrinsic unique hollow nanostructures of HMCNs for potentially in vitro and in vivo dual-modality cancer imaging. The manganese oxide-based multifunctionalization of hollow mesoporous silica nanoparticles was achieved by an in situ redox reaction using mesopores as the nanoreactors. Due to the dissolution nature of manganese oxide nanoparticles under weak acidic conditions, the relaxation rate r(1) of manganese-based mesoporous MRI-T(1) contrast agents (CAs) could reach 8.81 mM(-1)s(-1), which is a 11-fold magnitude increase compared to the neutral condition, and is almost two times higher than commercial Gd(III)-based complex agents. This is also the highest r(1) value ever reported for manganese oxide nanoparticles-based MRI-T(1) CAs. In addition, the hollow interiors and thin mesoporous silica shells endow HMCNs with the functions of CAs for efficient in vitro and in vivo ultrasonography under both harmonic- and B-modes. Importantly, the well-defined mesopores and large hollow interiors of HMCNs could encapsulate and deliver anticancer agents (doxorubicin) intracellularly to circumvent the multidrug resistance (MDR) of cancer cells and restore the anti-proliferative effect of drugs by nanoparticle-mediated endocytosis process, intracellular drug release and P-gp inhibition/ATP depletion in cancer cells. PMID:22789722

Chen, Yu; Yin, Qi; Ji, Xiufeng; Zhang, Shengjian; Chen, Hangrong; Zheng, Yuanyi; Sun, Yang; Qu, Haiyun; Wang, Zheng; Li, Yaping; Wang, Xia; Zhang, Kun; Zhang, Linlin; Shi, Jianlin

2012-07-11

177

Exchange bias properties and surface spin freezing in magnetic nanoparticles  

Microsoft Academic Search

ZFC and FC magnetization measurements versus field are carried out on manganese ferrite based nanoparticles with a mean diameter of 3.3 nm. The exchange bias field determined from the field shift of hysteresis loops, decreases as the cooling field increases. Magnetization measurements performed at constant applied field H as a function of temperature allows us to separate two H-dependent contributions. One

F. G. Silva; R. Aquino; J. Depeyrot; F. A. Tourinho; V. Dupuis; R. Perzynski

2010-01-01

178

Macroscopic Quantum Tunneling of Magnetization of Single Ferrimagnetic Nanoparticles of Barium Ferrite  

Microsoft Academic Search

Presented are switching field measurements of individual ferrimagnetic and insulating BaFeCoTiO nanoparticles containing about 105muB at very low temperatures (0.1-6 K). For temperatures higher than 0.4 K, the quantitative agreement with the Néel-Brown theory of thermal activated magnetization reversal allowed us to identify unambiguously the magnetization reversal of uniform rotation. Below 0.4 K, strong deviations from this model are evidenced

W. Wernsdorfer; E. Bonet Orozco; K. Hasselbach; A. Benoit; D. Mailly; O. Kubo; H. Nakano; B. Barbara

1997-01-01

179

Chain length dependence of polyol synthesis of zinc ferrite nanoparticles: why is diethylene glycol so different?  

PubMed

Superparamagnetic ZnFe2O4 nanoparticles with size range of 28-38 nm were synthesized by polyol process based on use of varying chain length glycols as solvent. We have offered, for the first time, the plausible mechanism behind in situ formation of zinc ferric oxalate hydroxide hydrate [Fe2Zn(C2O4)2(OH)3](+)·4H2O complex from diethylene and polyethylene glycol. We are also reporting, the magnetic properties of above complexes. We have found a ferromagnetic ordering in precursor complex compounds. The intermediate hydrocarbon chain between the oxalato bridged metal cations plays a crucial role in obtaining anomalous magnetic behavior. ZnFe2O4 nanoparticles obtained after annealing the DEGylated precursor complex (precursor complex formed in diethylene glycol) showed the highest superparamagnetic (SPM) behavior (22.4 emu g(-1)) among others. The reasons for anomalous SPM behavior of ZnFe2O4 nanoparticles are explained on the basis of the degree of inversion of the spinel structure, high surface-to-volume ratio, which causes non-collinear spin arrangement in a surface layer and higher oxygen concentration on the surface of dead organic layer, which increases the unpaired valence electrons leading to uncompensated surface spins. PMID:23423492

Rishikeshi, Supriya N; Joshi, Satyawati S; Temgire, Mayur K; Bellare, Jayesh R

2013-02-19

180

Self-assembly of manganese oxide nanoparticles and hollow spheres. Catalytic activity in carbon monoxide oxidation.  

PubMed

Reactions between MnSO(4) and KMnO(4) in the presence of carboxylic acids provide a facile, one-pot route to nanostructured manganese oxides with high surface areas. Acetic and propionic acid induce formation of hierarchical nanosphere morphologies whereas butyric acid promotes assembly of hollow spheres. The materials are active catalysts for CO oxidation. PMID:21655565

Ching, Stanton; Kriz, David A; Luthy, Kurt M; Njagi, Eric C; Suib, Steven L

2011-06-07

181

Substitutional effect of Cr3+ ions on the properties of Mg-Zn ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

The effect of Cr3+ substitution in Mg-Zn ferrite, with a chemical formula Mg0.5Zn0.5CrxFe2-xO4 (x=0.0-1.0), synthesized by a sol-gel auto-combustion reaction is presented in this paper. The resultant powders were investigated by various techniques, including X-ray diffractometry (XRD), transmission electron microscopy (TEM), infrared spectroscopy (IR), vibrating sample magnetometry (VSM), and DC resistivity. The XRD pattern revealed that the cubic spinel structure is maintained for the all the compositions. The particle sizes measured from XRD and TEM are in good agreement with each other. The cation distribution suggests that Mg2+, Cr3+ and Fe3+ have strong preference towards octahedral B-site. The theoretical lattice constant and experimental lattice constant match each other very well. The IR analysis supports the presently accepted cation distribution. The saturation magnetization decreases linearly with increasing Cr3+ content. Curie temperatures are obtained by the Laoria and AC susceptibility techniques. The dc resistivity has been investigated as a function of temperature and composition.

Haralkar, S. J.; Kadam, R. H.; More, S. S.; Shirsath, Sagar E.; Mane, M. L.; Patil, Swati; Mane, D. R.

2012-11-01

182

Multiple Ferromagnetic Resonance in Ferrite Spheres  

Microsoft Academic Search

Ferromagnetic resonance experiments have been performed on single crystal spheres of manganese and manganese-zinc ferrites placed in field configurations having large gradients in the rf magnetic field at the sample site. Five major and several minor resonant absorptions are observed extending over a region of 700 oersteds at room temperature. The line spacings are essentially independent of sphere size. The

Robert L. White; Irvin H. Solt

1956-01-01

183

Microfluidic system for rapid detection of influenza infection by utilizing magnetic MnFe2O4 nanoparticle-based immunoassay  

Microsoft Academic Search

In this study, new magnetic manganese ferrite (MnFe2O4) nanoparticles with a size around 100 nanometer (nm) in diameter were used to improve the performance of an immunoassay for detection of influenza infection. A new microfluidic system was developed to implement the detection process. In order to apply these new nanoparticles for influenza detection, the design of the micromixer was modified

Lien-Yu Hung; Fong-Yu Cheng; Chih-Chia Huang; Yi-Che Tsai; Chen-Sheng Yeh; Huan-Yao Lei; Gwo-Bin Lee

2012-01-01

184

Magnetocaloric Effect in Nanoparticle Systems and Clathrates  

NASA Astrophysics Data System (ADS)

We report the magnetocaloric effect (MCE) in cobalt ferrite, manganese ferrite, and nickel ferrite nanoparticle systems and also the first observation of a large MCE in Eu8Ga16Ge30 clathrate compounds. The ferrite nanoparticles were synthesized using organometallic precursors in a wet chemical technique and characterized by XPS and XRD. Change in entropy (?S^mag) was calculated using the Maxwell relation from the family of M-H curves at different temperatures. The maximum entropy change in these nanoparticle systems is influenced by the particle size, overall distribution in anisotropy, and moments. Even though the entropy change for these nanoparticles is reasonably large in comparison to previous reports, it is much smaller in comparison to the bulk systems exhibiting giant MCE. We also investigated MCE in a bulk clathrate system and observed large entropy changes of 6 and 9.3 J/kg-K for the Type I and Type VIII clathrate phases, respectively. These results indicate that the clathrates known to possess excellent thermoelectric properties are also promising candidates as magnetic refrigerant materials. HS acknowledges support from NSF grant CTS-0408933

Rebar, D. J.; Gass, J.; Srinath, S.; Srikanth, H.; Nolas, G. S.

2006-03-01

185

Synthesis of epoxy ferrite nanocomposites in supercritical carbon dioxide  

Microsoft Academic Search

A series of epoxy ferrite nanocomposites (EFNCs) was synthesised through dispersing ferrite nanoparticles (5.0 phr, parts per hundred of resin) into diglycidylether of bisphenol A (0.1 mol) in supercritical carbon dioxide at 85 ± 1°C, 1600 psi over 1 h followed by curing with triethylene tetramine (15 phr) at 40 ± 1°C. For this purpose, ferrite nanoparticles were synthesised through

M. G. H. Zaidi; P. L. Sah; S. Alam; A. K. Rai

2009-01-01

186

Photocatalytic activities of multiferroic bismuth ferrite nanoparticles prepared by glycol-based sol–gel process  

Microsoft Academic Search

The uniform multiferroic BiFeO3 nanoparticles with fairly narrow particle size distribution have been successfully synthesized by a simple glycol-based sol–gel\\u000a route at relatively low temperature. The thus-prepared powders were characterized by X-ray diffractometry (XRD), thermogravimetric\\u000a and differential thermal analysis (DTA\\/TG), and transmission electron microscopy (TEM). Rapid sintering and subsequently quenching\\u000a to room temperature are the two vital important factors for

X. WangY; Y. Lin; Z. C. Zhang; J. Y. Bian

187

Examination of the anisotropy of wear resistance of single crystals of manganese-zinc ferrites in relation to the anisotropy of their brittleness in thin surface films  

Microsoft Academic Search

in the modern high-speed electronic systems for various production applications are made of single crystals of ferrites. In comparison with the metallic materials and also fertile polycrystals, they have higher service characteristics [1]. However, further increases in the severity of the operating conditions, specifically the increase of the speed of magnetic tape to 40 m\\/sec, dictate the need to increase

V. F. Berdikov; O. I. Pushkarev; V. A. Fedorov

1986-01-01

188

Visualization of internalization of functionalized cobalt ferrite nanoparticles and their intracellular fate  

PubMed Central

In recent years, nanoparticles (NPs) and related applications have become an intensive area of research, especially in the biotechnological and biomedical fields, with magnetic NPs being one of the promising tools for tumor treatment and as MRI-contrast enhancers. Several internalization and cytotoxicity studies have been performed, but there are still many unanswered questions concerning NP interactions with cells and NP stability. In this study, we prepared functionalized magnetic NPs coated with polyacrylic acid, which were stable in physiological conditions and which were also nontoxic short-term. Using fluorescence, scanning, and transmission electron microscopy, we were able to observe and determine the internalization pathways of polyacrylic acid–coated NPs in Chinese hamster ovary cells. With scanning electron microscopy we captured what might be the first step of NPs internalization – an endocytic vesicle in the process of formation enclosing NPs bound to the membrane. With fluorescence microscopy we observed that NP aggregates were rapidly internalized, in a time-dependent manner, via macropinocytosis and clathrin-mediated endocytosis. Inside the cytoplasm, aggregated NPs were found enclosed in acidified vesicles accumulated in the perinuclear region 1 hour after exposure, where they stayed for up to 24 hours. High intracellular loading of NPs in the Chinese hamster ovary cells was obtained after 24 hours, with no observable toxic effects. Thus polyacrylic acid–coated NPs have potential for use in biotechnological and biomedical applications.

Bregar, Vladimir B; Lojk, Jasna; Sustar, Vid; Veranic, Peter; Pavlin, Mojca

2013-01-01

189

Photoacoustic Measurement of Thermal Properties of Co-Ni-Li Ferrite Nanoparticles  

NASA Astrophysics Data System (ADS)

A simple home-made open photoacoustic cell is used for measuring some of the thermal properties of nanoparticles of {Co}_{0.5}{Ni}_{0.5{- }2{x}}{Li}_x{ Fe }_{2+{x}}{O}4 (with x ranging from 0.00 to 0.25 in steps of 0.05) prepared by the citrate precursor method. The influence of sintering temperatures on the thermal properties of a selected sample for x=0.25 was also investigated. The thermal-diffusivity and thermal-effusivity measurements of the investigated samples are obtained by measuring the photoacoustic signal as a function of the modulated frequency depending on the existence of a reference sample. The thermal diffusivity of the as-prepared samples decreases as the {Li}^{1+} content increases except for the samples for x=0.15 and x=0.20. These exceptions may be due to a better magnetic ordering in these samples leading to reduced phonon scattering and a higher thermal diffusivity. Finally, the thermal diffusivity of the sintered samples increases as the sintering temperature increases due to the increase in grain size.

Abosheiasha, H. F.; Assar, S. T.; El Nimr, M. K.

2013-06-01

190

Study of structure and magnetic properties of Ni-Zn ferrite nano-particles synthesized via co-precipitation and reverse micro-emulsion technique  

NASA Astrophysics Data System (ADS)

Nano-crystalline Ni-Zn ferrites were synthesized by chemical co-precipitation and reverse micro-emulsion technique with an average crystallite size of 11 and 6 nm, respectively. The reverse micro-emulsion method has been found to be more appropriate for nano-ferrite synthesis as the produced particles are monodisperse and highly crystalline. Zero-field cooled and field cooled magnetization study under different magnetic fields and magnetic hysteresis loops at different temperatures have been performed. The non-saturated M-H loops, absence of hysteresis, and coercivity at room temperature are indicative of the presence of super paramagnetic and single-domain nano-particles for both the materials. In sample `a', the blocking temperature (T B) has been observed to decrease from 255 to 120 K on increasing the magnetic field from 50 to 1,000 Oe, which can be attributed to the reduction of magneto crystalline anisotropy constant. The M S and coercivity were found to be higher for sample `a' as compared with sample `b' since surface effects are neglected on increasing the crystallite size.

Abdullah Dar, M.; Shah, Jyoti; Siddiqui, W. A.; Kotnala, R. K.

2013-06-01

191

Bio-functionalization of Monodisperse Magnetic Nanoparticles and Their Use as Biomolecular Labels in a Magnetic Tunnel Junction Based Sensor  

Microsoft Academic Search

Monodisperse magnetic nanoparticles (NPs) could enable the ultra-sensitive magnetic detection of biological analytes. However, rendering these particles biocompatible has remained a challenge. We report the bio- functionalization and detection of 12-nm manganese ferrite NPs. We have achieved the site-specific binding of biotin-functionalized NPs onto avidin-patterned silicon oxide substrates and DNA-functionalized NPs onto complementary DNA-patterned silicon oxide substrates. Utilizing scanning SQUID

Stephanie G. Grancharov; Hao Zeng; Shouheng Sun; Shan X. Wang; Stephen O'Brien; C. B. Murray; J. R. Kirtley; G. A. Held

2005-01-01

192

Semi-empirical study of ortho-cresol photo degradation in manganese-doped zinc oxide nanoparticles suspensions.  

PubMed

The optimization processes of photo degradation are complicated and expensive when it is performed with traditional methods such as one variable at a time. In this research, the condition of ortho-cresol (o-cresol) photo degradation was optimized by using a semi empirical method. First of all, the experiments were designed with four effective factors including irradiation time, pH, photo catalyst's amount, o-cresol concentration and photo degradation % as response by response surface methodology (RSM). The RSM used central composite design (CCD) method consists of 30 runs to obtain the actual responses. The actual responses were fitted with the second order algebraic polynomial equation to select a model (suggested model). The suggested model was validated by a few numbers of excellent statistical evidences in analysis of variance (ANOVA). The used evidences include high F-value (143.12), very low P-value (<0.0001), non-significant lack of fit, the determination coefficient (R2?=?0.99) and the adequate precision (47.067). To visualize the optimum, the validated model simulated the condition of variables and response (photo degradation %) be using a few number of three dimensional plots (3D). To confirm the model, the optimums were performed in laboratory. The results of performed experiments were quite close to the predicted values. In conclusion, the study indicated that the model is successful to simulate the optimum condition of o-cresol photo degradation under visible-light irradiation by manganese doped ZnO nanoparticles. PMID:22909072

Abdollahi, Yadollah; Zakaria, Azmi; Abdullah, Abdul Halim; Fard Masoumi, Hamid Reza; Jahangirian, Hossein; Shameli, Kamyar; Rezayi, Majid; Banerjee, Santo; Abdollahi, Tahereh

2012-08-21

193

Hot coal gas desulfurization with manganese-based sorbents.  

National Technical Information Service (NTIS)

The focus of work being performed on Hot Coal Gas Desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc ferrite and zinc titanate sorbents; however, prior studies indicated that an alternate sorbent, manganese dioxide-...

M. T. Hepworth R. Ben-Slimane

1994-01-01

194

The effects of La–Zn substitution on the magnetic properties of Sr-magnetoplumbite ferrite nano-particles  

Microsoft Academic Search

The La–Zn substituted Sr-Magnetoplumbite ferrite LaxSr1?xZnxFe12?xO19 (x=0–0.6) fine particles were prepared to investigate the effects of the substitution on the magnetic properties of the samples. It is observed, with increasing substitution rate, that the saturation magnetization Ms as well as the magnetocrystalline anisotropy constant KU1 increased up to a maximum for about x=0.3, then decreased rapidly. The value of dHc\\/dT

Jianmin Bai; Xiaoxi Liu; Tian Xie; Fulin Wei; Zheng Yang

2000-01-01

195

Magnetic and optical properties of multiferroic bismuth ferrite nanoparticles by tartaric acid-assisted sol–gel strategy  

Microsoft Academic Search

Pure BiFeO3 nanoparticles have been successfully synthesized through the tartaric acid-assisted sol–gel method at relatively low temperature. The as-prepared nanoparticles were characterized by a variety of techniques. The success in preparing pure BiFeO3 may be attributed to the formation of heterometallic polynuclear complexes in the tartaric acid system. The ferroelectric phase transition (TC=851°C) was determined, revealing the ferroelectric nature of

Xiong Wang; Yan'ge Zhang; Zhibin Wu

2010-01-01

196

Cation distribution dependence of magnetic properties of sol–gel prepared MnFe 2O 4 spinel ferrite nanoparticles  

Microsoft Academic Search

MnFe2O4 nanoparticles have been synthesized with a sol–gel method. Both differential thermal and thermo-gravimetric analyses indicate that MnFe2O4 nanoparticles form at 400°C. Samples treated at 450 and 500°C exhibit superparamagnetism at room temperature as implied from vibrating sample magnetometry. Mössbauer results indicate that as Mn2+ ions enter into the octahedral sites, Fe3+ ions transfer from octahedral to tetrahedral sites. When

Jianjun Li; Hongming Yuan; Guodong Li; Yanju Liu; Jinsong Leng

2010-01-01

197

Preparation, characterization, in vivo and in vitro studies of arsenic trioxide Mg-Fe ferrite magnetic nanoparticles  

Microsoft Academic Search

Aim:MgFe2O4 magnetic nanoparticle composed of As2O3 (As2O3-MNPs) were prepared and their in vitro and in vivo characteristics were studied.Methods:The solvent-displacement method was applied for preparation of the nanoparticle using Poly-D,L-lactic-co-glycolic acid(PLGA). The characteristics studies of the products included magnetic response, morphology (transmission electron microscopy and scanning electron microscopy), entrapment efficiency, drug loading, particle sizes, zeta potential, in vitro drug release

Guo-fu Yang; Xiang-hui Li; Zhe Zhao; Wen-bo Wang; Wen-bo Wang

2009-01-01

198

NMR-D study of the local spin dynamics and magnetic anisotropy in different nearly monodispersed ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

We present a systematic experimental comparison of the superparamagnetic relaxation time constants obtained by means of dynamic magnetic measurements and 1H-NMR relaxometry, on ferrite-based nanosystems with different composition, various core sizes and dispersed in different solvents. The application of a heuristic model for the relaxivity allowed a comparison between the reversal time of magnetization as seen by NMR and the results from the AC susceptibility experiments, and an estimation of fundamental microscopic properties. A good agreement between the NMR and AC results was found when fitting the AC data to a Vogel-Fulcher law. Key parameters obtained from the model have been exploited to evaluate the impact of the contribution from magnetic anisotropy to the relaxivity curves and estimate the minimum approach distance of the bulk solvent.

Bordonali, L.; Kalaivani, T.; Sabareesh, K. P. V.; Innocenti, C.; Fantechi, E.; Sangregorio, C.; Casula, M. F.; Lartigue, L.; Larionova, J.; Guari, Y.; Corti, M.; Arosio, P.; Lascialfari, A.

2013-02-01

199

NMR-D study of the local spin dynamics and magnetic anisotropy in different nearly monodispersed ferrite nanoparticles.  

PubMed

We present a systematic experimental comparison of the superparamagnetic relaxation time constants obtained by means of dynamic magnetic measurements and (1)H-NMR relaxometry, on ferrite-based nanosystems with different composition, various core sizes and dispersed in different solvents. The application of a heuristic model for the relaxivity allowed a comparison between the reversal time of magnetization as seen by NMR and the results from the AC susceptibility experiments, and an estimation of fundamental microscopic properties. A good agreement between the NMR and AC results was found when fitting the AC data to a Vogel-Fulcher law. Key parameters obtained from the model have been exploited to evaluate the impact of the contribution from magnetic anisotropy to the relaxivity curves and estimate the minimum approach distance of the bulk solvent. PMID:23315450

Bordonali, L; Kalaivani, T; Sabareesh, K P V; Innocenti, C; Fantechi, E; Sangregorio, C; Casula, M F; Lartigue, L; Larionova, J; Guari, Y; Corti, M; Arosio, P; Lascialfari, A

2013-01-11

200

High strength ferritic alloy  

DOEpatents

A high-strength ferritic alloy useful for fast reactor duct and cladding applications where an iron base contains from about 9% to about 13% by weight chromium, from about 4% to about 8% by weight molybdenum, from about 0.2% to about 0.8% by weight niobium, from about 0.1% to about 0.3% by weight vanadium, from about 0.2% to about 0.8% by weight silicon, from about 0.2% to about 0.8% by weight manganese, a maximum of about 0.05% by weight nitrogen, a maximum of about 0.02% by weight sulfur, a maximum of about 0.02% by weight phosphorous, and from about 0.04% to about 0.12% by weight carbon.

Hagel, William C. (Ann Arbor, MI); Smidt, Frederick A. (Springfield, VA); Korenko, Michael K. (Richland, WA)

1977-01-01

201

Cation distribution dependence of magnetic properties of sol-gel prepared MnFe2O4 spinel ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

MnFe2O4 nanoparticles have been synthesized with a sol-gel method. Both differential thermal and thermo-gravimetric analyses indicate that MnFe2O4 nanoparticles form at 400 °C. Samples treated at 450 and 500 °C exhibit superparamagnetism at room temperature as implied from vibrating sample magnetometry. Mössbauer results indicate that as Mn2+ ions enter into the octahedral sites, Fe3+ ions transfer from octahedral to tetrahedral sites. When the calcination temperature increases from 450 to 700 °C, the occupation ratio of Fe3+ ions at the octahedral sites decreases from 43% to 39%. Susceptibility measurements versus magnetic field are reported for various temperatures (from 450 to 700 °C) and interpreted within the Stoner-Wohlfarth model.

Li, Jianjun; Yuan, Hongming; Li, Guodong; Liu, Yanju; Leng, Jinsong

2010-11-01

202

Mössbauer study of nano-particles of spinel ferrites Li xFe 3-xO4  

Microsoft Academic Search

Mössbauer spectra have been recorded on three nano-particle samples in the series Li xFe 3-xO4 (for x = 0.1, 0.2 and 0.3) at 300K and 80K. Spectra could be resolved into two doublets attributed to two crystalline sites, viz., tetrahedral site and octahedral site. Li occupies the octahedral site with a complete preference as in the bulk particle size state.

Subhash Chander; M P Sharma; Anjali Krishnamurthy; Bipin K Srivastava

203

The role of copper ions on the structural and magnetic characteristics of MgZn ferrite nanoparticles and thin films  

NASA Astrophysics Data System (ADS)

In this study CuxMg0.5-xZn0.5Fe2O4 (x=0-0.5) nanoparticles and thin films were prepared by sol-gel processing. The morphologies of nanoparticles were observed by transmission electron microscope (TEM). The Mössbauer spectroscopy (MS) was employed to determine the site preference of the constitutive elements. Magnetic dynamics of the nanoparticles was studied by the measurement of AC magnetic susceptibility versus temperature at different frequencies. The phenomenological Néel-Brown and Vogel-Fulcher models were employed to distinguish between interacting or non-interacting system. Results exhibited that there is strong interaction between fine particles. X-ray diffraction (XRD) patterns of the thin films indicate the formation of single-phase cubic spinel structure. Atomic force microscope (AFM) was employed to evaluate the surface morphologies of the prepared thin films. Vibrating sample magnetometer (VSM) was employed to probe magnetic properties of samples. It was found that with an increase in the amount of copper, the saturation of magnetization and initial permeability increase.

Ghasemi, Ali; Ashrafizadeh, Azadeh; Paesano, Andrea; Cerqueira Machado, Carla Fabiana; Shirsath, Sagar E.; Liu, Xiaoxi; Morisako, Akimitsu

2010-10-01

204

Electrocatalysis by nanoparticles: Oxidation of formic acid at manganese oxide nanorods-modified Pt planar and nanohole-arrays  

Microsoft Academic Search

The electro-oxidation of formic acid (an essential reaction in direct formic acid fuel cells) is a challenging process because of the deactivation of anodes by the adsorption of the poisoning intermediate carbon monoxide (CO). Pt electrodes in two geometries (planar and nanohole-array) were modified by the electrodeposition of manganese oxide nanorods (nano-MnOx). The modified Pt electrodes were then tested for

Mohamed S. El-Deab

2010-01-01

205

Manganese associated nanoparticles agglomerate of iron(III) oxide: Synthesis, characterization and arsenic(III) sorption behavior with mechanism  

Microsoft Academic Search

Three samples of manganese associated hydrous iron(III) oxide (MNHFO), prepared by incinerating metal hydroxide precipitate at T (±5)=90, 300 and 600°C, showed increase of crystalline nature in XRD patterns with decreasing As(III) removal percentages. TEM images showed the increase of crystallinity from sample-1 (MNHFO-1) to sapmple-3 (MNHFO-3). Dimensions (nm) of particles estimated were 5.0, 7.0 and 97.5. Optimization of pH

Kaushik Gupta; Arjun Maity; Uday Chand Ghosh

2010-01-01

206

Synthesis and magnetic properties of the size-controlled Mn–Zn ferrite nanoparticles by oxidation method  

Microsoft Academic Search

Size-controlled Mn0.67Zn0.33Fe2O4 nanoparticles in the wide range from 80 to 20nm have been synthesized, for the first time, using the oxidation method. It has been demonstrated that the particle size can be tailor-made by varying the concentration of the oxidant. The magnetization of the 80nm particles was 49Am2kg?1 compared to 34Am2kg?1 for the 20nm particles. The Curie temperatures for all

R. Justin Joseyphus; A. Narayanasamy; K. Shinoda; B. Jeyadevan; K. Tohji

2006-01-01

207

Hot coal gas desulfurization with manganese-based sorbents  

SciTech Connect

The focus of work being performed on Hot Coal Gas Desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc ferrite and zinc titanate sorbents; however, prior studies indicated that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt % ore + 25 wt % Al{sub 2}O{sub 3}) may be a viable alternative to zinc-based sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc hence it is not as likely to undergo depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron hence the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. In addition, thermodynamic analysis of the manganese-oxygen-sulfur system shows it to be less amenable to sulfation than zinc ferrite. Potential also exists for utilization of manganese at higher temperatures than zinc ferrite or zinc titanate. This annual topical report documents progress in pelletizing and testing via thermo-gravimetric analysis of individual pellet formulations of manganese ore/alumina combinations and also manganese carbonate/alumina with two binders, dextrin and bentonite.

Hepworth, M.T.; Ben-Slimane, R.

1994-12-01

208

Ferrite Catalyst.  

National Technical Information Service (NTIS)

According to this invention, a catalyst consisting of a spinel-type ferrite and having an apparent density of 3.0 g/cm exp 3 can be produced by sintering a mixture of lamellar alpha -Fe sub 2 O sub 3 and other metal oxides. Partly because of the use of a ...

K. Kugimiya Y. Terada

1983-01-01

209

Intragranular ferrite nucleation in medium-carbon vanadium steels  

SciTech Connect

In this study, the mechanism of intragranular ferrite nucleation is investigated. It is found that intragranular ferrite idiomorphs'' nucleate at vanadium nitrides which precipitate at manganese sulfide particles during cooling in the austenite region. It is observed that intragranular ferrite has the Baker-Nutting orientation relationship with vanadium nitride which precipitated at manganese sulfide. According to classical nucleation theory, the proeutectoid ferrite nucleation rate depends on the following factors: (1) the driving free energy for ferrite nucleation, (2) the diffusivity of carbon atoms in austenite, and (3) the increase in the interfacial energy associated with ferrite nucleation. In the Baker-Nutting orientation relationship, the lattice mismatch across the habit planes is likely to be very small. Depleted zones of solute atoms such as vanadium are assumed to be formed in the austenite matrix around precipitates. The effect of the depleted zones on factors (1) and (2) is estimated thermodynamically and it is proved that those effects are negligibly small. Thus, the authors conclude that the most important factor in nucleation kinetics of intragranular ferrite is the formation of precipitates which can develop coherent, low energy interfaces with ferrite.

Ishikawa, Fusao; Takahashi, Toshihiko (Nippon Steel Corp., Chiba (Japan)); Ochi, Tatsurou (Nippon Steel Corp., Hokkaido (Japan). Muroran R D Lab.)

1994-05-01

210

In situ synthesis of cobalt ferrite nanoparticle/polymer hybrid from a mixed Fe-Co methacrylate for magnetic hyperthermia  

NASA Astrophysics Data System (ADS)

Hyperthermic CoFe2O4 nanoparticle (CFO NP)/polymer hybrids were synthesized by hydrolysis-condensation from a complex of Co and Fe possessing methacrylate ligands. Single-crystal analysis revealed that the complex consisted of two Co and four Fe metal atoms coordinated by methacrylate and 2-methoxyethoxy groups. The complex was copolymerized with 2-hydroxyethyl methacrylate (HEMA) and the resulting copolymer was then hydrolyzed to form a CFO NP/copolymer of poly(methacrylate) and poly(2-hydroxyethyl methacrylate) hybrid. Copolymerization with HEMA enhanced the stability of the hybrid in water. The size and magnetic properties of CFO in the hybrid were controlled by adjusting the hydrolysis conditions. Moreover, the hybrid generated heat under an alternating current magnetic field; its exothermal properties depended on the magnetic properties of the hybrid, the strength of the applied field, and the CFO NP content in the agar phantom matrix.

Hayashi, Koichiro; Maeda, Kazuki; Moriya, Makoto; Sakamoto, Wataru; Yogo, Toshinobu

2012-09-01

211

Ferrite synthesis in microstructured media: Template effects and magnetic properties  

Microsoft Academic Search

Inverse micelles and organogels provide novel environments to synthesize ferrite particles. The fluid microstructure provides a template for the synthesis. Our experiments with ferrite synthesis in inverse micelles indicate the formation of superparamagnetic nanoparticles. Of interest is the encapsulation of these particles in polymer microspheres. The encapsulation is done using simple polymer precipitation in the micellar nonsolvent. The process results

C. J. O'Connor; Y. S. L. Buisson; S. Li; S. Banerjee; R. Premchandran; T. Baumgartner; V. T. John; G. L. McPherson; J. A. Akkara; D. L. Kaplan

1997-01-01

212

Influence of initial particle size on the magnetostriction of sintered cobalt ferrite derived from nanocrystalline powders  

NASA Astrophysics Data System (ADS)

The role of initial particle size on the magnetostriction coefficient of sintered cobalt ferrite derived from nanocrystalline powders is studied. Nanoparticles of cobalt ferrite with different sizes in the range 3-80 nm are synthesized by an autocombustion method using metal nitrates and glycine. It has been observed that the initial particle size of the starting powders has a strong influence on the magnetostrictive behavior of sintered cobalt ferrite. Highest magnetostrictive strain and strain derivative are obtained for sintered ferrite derived from nanoparticles of size < 5 nm. The results show that higher magnetostriction coefficient for sintered cobalt ferrite can be achieved by compacting nanocrystalline particles of very small size.

Khaja Mohaideen, K.; Joy, P. A.

2013-11-01

213

Effect of Additional Elements on the Structural Properties, Magnetic Characteristics and Natural Resonance Frequency of Strontium Ferrite Nanoparticles\\/Polymer Composite  

Microsoft Academic Search

Substituted strontium ferrites SrFe12-xMgx\\/2Snx\\/2O19 (x=1 , 2 and 3) were prepared by sol-gel method. X-ray diffraction (XRD), transmission electron microscope (TEM), AC susceptometer, vibrating sample magnetometer (VSM) and vector network analyzer were used to analyze the structure, static and dynamic magnetic properties of the prepared samples. The prepared ferrite particles possess irregular non spherical shape with a broad size distribution.

Ali Ghasemi; Xiaoxi Liu; Akimitsu Morisako

2009-01-01

214

Inverse magnetocaloric effect in sol-gel derived nanosized cobalt ferrite  

Microsoft Academic Search

The magnetocaloric properties of cobalt ferrite nanoparticles were investigated to evaluate the potential of these materials as magnetic refrigerants. Nanosized cobalt ferrites were synthesized by the method of sol-gel combustion. The nanoparticles were found to be spherical with an average crystallite size of 14 nm. The magnetic entropy change (Delta S m) calculated indirectly from magnetization isotherms in the temperature

E. Veena Gopalan; I. A. Al-Omari; D. Sakthi Kumar; Yasuhiko Yoshida; P. A. Joy; M. R. Anantharaman

2010-01-01

215

Preparation of single-crystal copper ferrite nanorods and nanodisks  

SciTech Connect

This article, for the first time, reports the preparation of single-crystal copper ferrite nanorods and nanodisks. Using amorphous copper ferrite nanoparticles synthesized by reverse micelle as reaction precursor, single-crystal copper ferrite nanorods were synthesized via hydrothermal method in the presence of surfactant polyethylene glycol (PEG), however, copper ferrite nanodisks were prepared through the same procedures except the surfactant PEG. The resulting nanomaterials have been characterized by powder X-ray diffraction (XRD), selected electron area diffraction (SEAD), and transmission electron microscopy (TEM). The bulk composition of the samples was determined by means of X-ray photoelectron spectroscopy (XPS)

Du Jimin [Center for Molecular Sciences, CAS Key Laboratory of Colloid, Interfacial and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, No. 2 Beiyijie, Zhongguancun, Beijing 100080 (China); Liu Zhimin [Center for Molecular Sciences, CAS Key Laboratory of Colloid, Interfacial and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, No. 2 Beiyijie, Zhongguancun, Beijing 100080 (China)]. E-mail: liuzm@iccas.ac.cn; Wu Weize [Center for Molecular Sciences, CAS Key Laboratory of Colloid, Interfacial and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, No. 2 Beiyijie, Zhongguancun, Beijing 100080 (China); Li Zhonghao [Center for Molecular Sciences, CAS Key Laboratory of Colloid, Interfacial and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, No. 2 Beiyijie, Zhongguancun, Beijing 100080 (China); Han Buxing [Center for Molecular Sciences, CAS Key Laboratory of Colloid, Interfacial and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, No. 2 Beiyijie, Zhongguancun, Beijing 100080 (China)]. E-mail: hanbx@iccas.ac.cn; Huang Ying [Center for Molecular Sciences, CAS Key Laboratory of Colloid, Interfacial and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, No. 2 Beiyijie, Zhongguancun, Beijing 100080 (China)

2005-06-15

216

Oleic acid adsorption-desorption isotherms on the surface of high-dispersity ferrites from a solution in carbon tetrachloride  

NASA Astrophysics Data System (ADS)

The equilibrium adsorption method was used to comparatively study the adsorption-desorption isotherms of oleic acid on the surfaces of manganese and copper ferrites from a solution in carbon tetrachloride. The adsorption isotherms of the fatty acid were described in terms of the theory of volume filling of micropores. The theory was used to calculate the limiting adsorption values, characteristic energy, and porous space volumes. The isotherm of oleic acid adsorption on the surface of manganese ferrite from a solution in carbon tetrachloride was similar to the isotherms of fatty acid adsorption from solutions in heptane, whereas the isotherm of adsorption on the surface of copper ferrite was similar to the isotherms of fatty acid adsorption from hexane. The limiting adsorption from carbon tetrachloride was higher on the surface of manganese ferrite than on the surface of copper ferrite. The adsorption-desorption isotherms contained hysteresis loops.

Balmasova, O. V.; Korolev, V. V.; Yashkova, V. I.

2010-01-01

217

Ferritic Fe-Mn alloy for cryogenic applications  

DOEpatents

A ferritic, nickel-free alloy steel composition, suitable for cryogenic applications, which consists essentially of about 10-13% manganese, 0.002-0.01% boron, 0.1-0.5% titanium, 0-0.05% aluminum, and the remainder iron and incidental impurities normally associated therewith.

Hwang, Sun-Keun (Rockypoint, NY); Morris, Jr., John W. (Berkeley, CA)

1979-01-01

218

Acid-degradable core-shell nanoparticles for reversed tamoxifen-resistance in breast cancer by silencing manganese superoxide dismutase (MnSOD).  

PubMed

Drug resistance acquired by cancer cells is a significant challenge in the clinic and requires impairing the responsible pathological pathway. Administering chemotherapeutics along with silencing resistance-basis activity using RNA interference (RNAi) is expected to restore the activity of the chemotherapeutic and generate synergistic cancer eradication. This study attempted to reverse tamoxifen (TAM)-resistance in breast cancer by silencing a mitochondrial enzyme, manganese superoxide dismutase (MnSOD), which dismutates TAM-induced reactive oxygen species (ROS) (i.e., superoxide) to less harmful hydrogen peroxide and hampers therapeutic effects. Breast cancer cells were co-treated with TAM and MnSOD siRNA-delivering nanoparticles (NPs) made of a siRNA/poly(amidoamine) (PAMAM) dendriplex core and an acid-degradable polyketal (PK) shell. The (siRNA/PAMAM)-PK NPs were designed for the PK shell to shield siRNA from nucleases, minimize detrimental aggregation in serum, and facilitate cytosolic release of siRNA from endosomal compartments. This method of forming the PK shell around the siRNA/PAMAM core via surface-initiated photo-polymerization enables ease of tuning NPs' size for readily controlled siRNA release kinetics. The resulting NPs were notably homogenous in size, resistant to aggregation in serum, and invulnerable to heparan sulfate-mediated disassembly, compared to siRNA/PAMAM dendriplexes. Gel electrophoresis and confocal microscopy confirmed efficient siRNA release from the (siRNA/PAMAM)-PK NPs upon stimuli-responsive hydrolysis of the PK shell. Sensitization of TAM-resistant MCF7-BK-TR breast cancer cells with (MnSOD siRNA/PAMAM)-PK NPs restored TAM-induced cellular apoptosis in vitro and significantly suppressed tumor growth in vivo, as confirmed by biochemical assays and histological observations. This study implies that combined gene silencing and chemotherapy is a promising strategy to overcoming a significant challenge in cancer therapy. PMID:24055523

Cho, Soo Kyung; Pedram, Ali; Levin, Ellis R; Kwon, Young Jik

2013-09-19

219

Study of the thermodynamics of chromium(III) and chromium(VI) binding to iron(II/III)oxide or magnetite or ferrite and magnanese(II) iron (III) oxide or jacobsite or manganese ferrite nanoparticles.  

PubMed

Removal of chromium(III) or (VI) from aqueous solution was achieved using Fe3O4, and MnFe2O4 nanomaterials. The nanomaterials were synthesized using a precipitation method and characterized using XRD. The size of the nanomaterials was determined to be 22.4±0.9 nm (Fe3O4) and 15.5±0.5 nm (MnFe2O4). The optimal binding pH for chromium(III) and chromium(VI) were pH 6 and pH 3. Isotherm studies were performed, under light and dark conditions, to determine the capacity of the nanomaterials. The capacities for the light studies with MnFe2O4 and Fe3O4 were determined to be 7.189 and 10.63 mg/g, respectively, for chromium(III). The capacities for the light studies with MnFe2O4 and Fe3O4 were 3.21 and 3.46 mg/g, respectively, for chromium(VI). Under dark reaction conditions the binding of chromium(III) to the MnFe2O4 and Fe3O4 nanomaterials were 5.74 and 15.9 mg/g, respectively. The binding capacity for the binding of chromium(VI) to MnFe2O4 and Fe3O4 under dark reaction conditions were 3.87 and 8.54 mg/g, respectively. The thermodynamics for the reactions showed negative ?G values, and positive ?H values. The ?S values were positive for the binding of chromium(III) and for chromium(VI) binding under dark reaction conditions. The ?S values for chromium(VI) binding under the light reaction conditions were determined to be negative. PMID:23558081

Luther, Steven; Brogfeld, Nathan; Kim, Jisoo; Parsons, J G

2013-03-13

220

Electrochemical catalysis of styrene epoxidation with films of manganese dioxide nanoparticles, and, Synthesis of mixed metal oxides using ultrasonic nozzle spray and microwaves  

NASA Astrophysics Data System (ADS)

Films of polyions and octahedral layered manganese oxide (OL-1) nanoparticles on carbon electrodes made by layer-by-layer alternate electrostatic adsorption were active for electrochemical catalysis of styrene epoxidation in solution in the presence of hydrogen peroxide and oxygen. The highest catalytic turnover was obtained by using applied voltage -0.6 V vs. SCE, O2, and 100 mM H2O2. 18O isotope labeling experiments suggested oxygen incorporation from three different sources: molecular oxygen, hydrogen peroxide and/or lattice oxygen from OL-1 depending on the potential applied and the oxygen and hydrogen peroxide concentrations. Oxygen and hydrogen peroxide activate the OL-1 catalyst for the epoxidation. The pathway for styrene epoxidation in the highest yields required oxygen, hydrogen peroxide and a reducing voltage, and may involve an activated oxygen species in the OL-1 matrix. Multicomponent metal oxide (MMO) crystallites were prepared by spraying a reactant solution into a receiving solution or air under microwave radiation at atmospheric pressure. The injection of nitric acid solution through an ultrasonic nozzle into a receiving solution of metal precursor and the use of microwave radiation were combined to form a novel preparation technique called the nozzle-spray/microwave (NMW) method. The inclusion of an additional step, the in situ mixing of precursor solutions prior to their injection through the ultrasonic nozzle spray, led to another procedure called the in situ/nozzle-spray/microwave (INM) method. For comparison, MMO materials with the same metal constituents as those prepared by our novel techniques were prepared by conventional hydrothermal (CH) methods. Fresh materials prepared by NMW, INM and CH methods were heat treated to study the effect of calcination. All materials were characterized before and after calcination using XRD, SEM, Bet, and ICP. The NMW method produces particles with rod-like morphologies different from those obtained using CH methods. The INM method produces an amorphous material that crystallizes after calcination into small (˜200 nm) particles with interesting morphologies. Notably, calcination of materials prepared by both NMW and INM reduces particle size and increases surface area. The present work paves the way to use NMW and INM to prepare MMOs with unique morphologies.

Espinal, Laura

221

A microbial fuel cell using manganese oxide oxygen reduction catalysts  

Microsoft Academic Search

Microbial fuel cells (MFCs) are a potential method for enhanced water and waste treatment, which offer the additional benefit\\u000a of energy generation. Manganese oxide was prepared by a simple chemical oxidation using potassium permanganate. Carbon-supported\\u000a manganese oxide nanoparticles were successfully characterised as cathode materials for MFCs. The manganese oxide particles\\u000a when used in a two-chamber MFC, using inoculum from an

I. Roche; K. Katuri; K. Scott

2010-01-01

222

Nanostructured nickel ferrite: A liquid petroleum gas sensor  

Microsoft Academic Search

The present investigation deals with the synthesis of nanostructured nickel ferrite (NiFe2O4) and their liquid petroleum gas-sensing characteristics. The 15–20nm size nickel ferrite has been synthesized at 700°C by a simple molten-salt route using sodium chloride as grain growth inhibitor. These nanoparticles exhibit significantly high response towards liquid petroleum gas (LPG) in comparison with ethanol vapor, hydrogen sulfide, ammonia and

Sonali L. Darshane; S. S. Suryavanshi; I. S. Mulla

2009-01-01

223

Hot coal gas desulfurization with manganese based sorbents. Quarterly report, June--September 1994  

SciTech Connect

The focus of work being performed on hot coal gas desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc titanate sorbents; however, prior studies indicated that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt% ore + 25 wt% Al{sub 2}O{sub 3}) appears to be a strong contender to zinc-based sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc; hence, it is not as likely to undergo zinc-depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron; hence, the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. In addition, thermodynamic analysis of the manganese-oxygen-sulfur system shows it to be less amenable to sulfation than zinc ferrite. Also manganese chlorides are much less stable and volatile than zinc chlorides. Potential also exists for utilization of manganese at higher temperatures than zinc ferrite or zinc titanate. This Eighth Quarterly Report documents progress in pelletizing and testing via thermo-gravimetric analysis of individual pellet formulations of manganese ore/alumina combinations and also manganese carbonate/alumina with two binders, dextrin and bentonite.

Hepworth, M.T.; Slimane, R.B.

1994-11-01

224

Synthesis, magnetic and optical properties of core/shell Co1-xZnxFe2O4/SiO2 nanoparticles  

PubMed Central

The optical properties of multi-functionalized cobalt ferrite (CoFe2O4), cobalt zinc ferrite (Co0.5Zn0.5Fe2O4), and zinc ferrite (ZnFe2O4) nanoparticles have been enhanced by coating them with silica shell using a modified Stöber method. The ferrites nanoparticles were prepared by a modified citrate gel technique. These core/shell ferrites nanoparticles have been fired at temperatures: 400°C, 600°C and 800°C, respectively, for 2 h. The composition, phase, and morphology of the prepared core/shell ferrites nanoparticles were determined by X-ray diffraction and transmission electron microscopy, respectively. The diffuse reflectance and magnetic properties of the core/shell ferrites nanoparticles at room temperature were investigated using UV/VIS double-beam spectrophotometer and vibrating sample magnetometer, respectively. It was found that, by increasing the firing temperature from 400°C to 800°C, the average crystallite size of the core/shell ferrites nanoparticles increases. The cobalt ferrite nanoparticles fired at temperature 800°C; show the highest saturation magnetization while the zinc ferrite nanoparticles coated with silica shell shows the highest diffuse reflectance. On the other hand, core/shell zinc ferrite/silica nanoparticles fired at 400°C show a ferromagnetic behavior and high diffuse reflectance when compared with all the uncoated or coated ferrites nanoparticles. These characteristics of core/shell zinc ferrite/silica nanostructures make them promising candidates for magneto-optical nanodevice applications.

2011-01-01

225

Liver Manganese in Hemochromatosis.  

National Technical Information Service (NTIS)

A comparative study was performed in which the manganese concentration in liver samples from cases of hemochromatosis was compared with the manganese concentration of normal liver. A higher mean concentration of liver manganese was found in the former gro...

L. B. Altstatt S. Pollack M. H. Feldman R. C. Reba W. H. Crosby

1966-01-01

226

Nanostructured bismuth ferrites synthesized by solvothermal process  

Microsoft Academic Search

Well-crystallized bismuth ferrite nanoparticles were synthesized using the solvothermal method without the help of any mineralizer. The shape of the particles was changed by changing the synthesis temperature during solvothermal process. The as-prepared samples were characterized by an X-ray powder diffractometer (XRD), scanning electron microscope (SEM), thermal analyzer and vibrating sample magnetometer (VSM). It was observed that the change in

A. Chaudhuri; S. Mitra; M. Mandal; K. Mandal

2010-01-01

227

Magnetic properties of barium ferrite nanoparticles: Quantitative test of the Stoner-Wohlfarth theory for uniaxial single-domain magnetic particles  

NASA Astrophysics Data System (ADS)

We have successfully synthesized single-domain barium ferrite particles with uniaxial anisotropy. We have coated them with amorphous silica to reduce interparticle interactions so that the assembly of these particles behaves like a noninteracting randomly oriented uniaxial single-domain particle system, a prototype for the Stoner-Wohlfarth model. From the magnetic hysteresis loops of the particle system in a wide temperature range (10-700 K), we simultaneously determine the magnetic anisotropic field HK, the reduced remanence Mr/Ms, and the coercive field HC in the whole temperature range below the Curie temperature. These complete sets of data allow us to quantitatively test the Stoner-Wohlfarth theory and the agreement between experiment and theory is good.

Duan, Hong-yan; Wang, Jun; Li, Le; Aguilar, Victor; Zhao, Guo-meng

2013-11-01

228

Hot coal gas desulfurization with manganese-based sorbents. Progress report, April 1, 1993--June 30, 1993  

SciTech Connect

Focus of work is primarily in use of zinc ferrite and zinc titanate sorbents; however, an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt % ore + 25 wt % Al{sub 2}O{sub 3}) may be a viable alternative to zinc-based sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc, hence it is not as likely to undergo depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron hence the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. Thermodynamic analysis of the system shows it to be less amenable to sulfation than zinc ferrite. Potential also exists for utilization of manganese higher temperatures than zinc ferrite or titanate. This report gives the thermodynamic background for consideration of manganese-based sorbents as an alternative to zinc ferrite. To date the work is limited to thermogravimetric testing of four formulations of manganese-alumina sorbents to determine the optimum conditions of pelletization and enduration to produce reactive pellets.

Hepworth, M.T.

1993-07-15

229

Bulk Synthesis of Monodisperse Ferrite Nanoparticles at Water-Organic Interfaces under Conventional and Microwave Hydrothermal Treatment and Their Surface Functionalization  

EPA Science Inventory

Synthesis of monodisperse MFe2O4 (M=, Ni, Co, Mn) and ¿-Fe2O3 nanoparticles at a water-toluene interface under conventional as well as microwave hydrothermal conditions using readily available nitrate or chloride salts and oleic acid as the dispersing agent is described. The ens...

230

Hot coal gas desulfurization with manganese-based sorbents. Annual report, September 1992--September 1993  

SciTech Connect

The focus of work being performed on Hot Coal Gas Desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc ferrite and zinc titanate sorbents; however, prior studies at the US Steel Fundamental Research Laboratories in Monroeville, PA, by E. T. Turkdogan indicated that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt % ore + 25 wt % Al{sub 2}O{sub 3}) may be a viable alternative to zinc-based sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc hence it is not as likely to undergo depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron hence the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. In addition, thermodynamic analysis of the manganese-oxygen-sulfur system shows it to be less amenable to sulfation than zinc ferrite. Potential also exists for utilization of manganese at higher temperatures than zinc ferrite or zinc titanate. This Annual Topical Report documents progress in pelletizing and testing via thermo-gravimetric analysis of individual pellet formulations of manganese ore/ alumina combinations and also manganese carbonate/alumina with two binders, dextrin and bentonite. It includes the prior Quarterly Technical Reports which indicate that the manganese carbonate material, being of higher purity than the manganese ore, has a higher degree of sulfur capacity and more rapid absorption kinetics. A 2-inch fixed-bed reactor has been fabricated and is now ready for subjecting pellets to cyclic loading and regeneration.

Hepworth, M.T.

1993-12-01

231

Hot Coal Gas Desulfurization with manganese based sorbents. Quarterly report, August 1, 1993--September 30, 1993  

SciTech Connect

The focus of work being performed on Hot Coal Gas Desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc ferrite and zinc titanate sorbents; however, prior studies at the US Steel Fundamental Research Laboratories in Monroeville, PA, by E. T. Turkdogan indicated that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt % ore + 25 wt % Al{sub 2}O{sub 3}) may be a viable alternative to zinc-based sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc hence it is not as likely to undergo depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron hence the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. In addition, thermodynamic analysis of the manganese-oxygen-sulfur system shows it to be less amenable to sulfation than zinc ferrite. Potential also exists for utilization of manganese at higher temperatures than zinc ferrite or zinc titanate. This report documents progress in pelletizing and testing via thermogravimetric analysis of individual pellet formulations of manganese ore/alumina combinations and also manganese carbonate/alumina with two binders, dextrin and bentonite. Preliminary results indicate that the manganese carbonate material, being of higher purity than the manganese ore, has a higher degree of sulfur capacity and more rapid absorption kinetics. A 2-inch fixed-bed reactor has been fabricated and is now ready for subjecting pellets to cyclic loading and regeneration.

Hepworth, M.T.

1993-10-01

232

Functional Magnetic Nanoparticles  

Microsoft Academic Search

Nanoparticle system research and characterization is the focal point of this research and dissertation. In the research presented here, magnetite, cobalt, and ferrite nanoparticle systems have been explored in regard to their magnetocaloric effect (MCE) properties, as well as for use in polymer composites. Both areas of study have potential applications across a wide variety of interdisciplinary fields.\\u000aMagnetite nanoparticles

James Gass

2012-01-01

233

Comminuting irradiated ferritic steel  

SciTech Connect

Disclosed is a method of comminuting irradiated ferritic steel by placing the steel in a solution of a compound selected from the group consisting of sulfamic acid, bisulfate, and mixtures thereof. The ferritic steel is used as cladding on nuclear fuel rods or other irradiated components.

Bauer, Roger E. (Kennewick, WA); Straalsund, Jerry L. (Kennewick, WA); Chin, Bryan A. (Auburn, AL)

1985-01-01

234

Comminuting irradiated ferritic steel  

SciTech Connect

Disclosed is a method of comminuting irradiated ferritic steel by placing the steel in a solution of a compound selected from the group consisting of sulfamic acid, bisulfate, and mixtures thereof. The ferritic steel is used as cladding on nuclear fuel rods or other irradiated components.

Bauer, R. E.; Chin, B. A.; Straalsund, J. L.

1985-03-26

235

Pharmacokinetics of intravenously injected Tc-99m labeled ferrite nanobeads  

NASA Astrophysics Data System (ADS)

We study the time varying biodistribution of ferrite (Fe3O4) nanoparticles upon in vivo injection. For this purpose, a novel process of directly labeling radioactive Tc-99m with ferrite nanoparticles was developed. The radiobeads serve as a tracer to provide information on the uptake of injected particles by organs. In the course of our study, Tc-99m labeled ferrite beads were intravenously injected into the tail vein of rats. The time course of changes in the radio-intensity of heart, lung, and liver could be achieved by real-time scintigraphic images. It was observed that the particle uptake by organs is very fast and completed within the first few minutes after intravenous injection. The pharmacokinetic behavior of the radiobead uptake was quantitatively described by a two-compartment model.

Fu, Chao-Ming; Wang, Yuh-Feng; Guo, Yu-Feng; Wang, Li-Shin; Chuang, May-Haw; Cham, Thau-Ming

2009-04-01

236

Bismuth ferrite clusters induced hydrogel formation in human serum albumin.  

PubMed

Amyloid-fibril formation in human serum albumin (HSA) led to hydrogel formation in the presence of clusters of bismuth ferrite (BiFeO(3) or BFO) nanoparticles (NPs). Factors responsible for hydrogel formation were size and phase of NPs. PMID:22441202

Thakur, Garima; Kovur, Prashanthi; Leblanc, Roger M; Thundat, Thomas

2012-03-23

237

Effect of alloying on microstructure and precipitate evolution in ferritic weld metal  

Microsoft Academic Search

The effect of alloying on the microstructure of ferritic weld metal produced with an self-shielded flux cored arc welding process (FCAW-S) has been studied. The welding electrode has a flux core that is intentionally alloyed with strong deoxidizers and denitriding elements such as aluminum, titanium and zirconium in addition to austenite formers such as manganese and nickel. This results in

Badri Kannan Narayanan

2009-01-01

238

Synthesis and characterization of magnetic nanoparticles for use as sensors  

Microsoft Academic Search

A comprehensive study of physical and magnetic properties of cobalt substituted ferrite and magnetite nanoparticles synthesized by thermal-decomposition was carried out. Initially, a systematic study of the effect of synthesis conditions on final size, crystalline structure, and composition of cobalt substituted ferrite nanoparticles synthesized by thermal-decomposition was carried out. Using a statistical design of experiments, the impact of the temperature

Victoria L. Calero Diaz Del Castillo

2009-01-01

239

Low temperature synthesis of nanocrystalline lithium ferrite by a modified citrate gel precursor method  

SciTech Connect

Single phase nanocrystalline lithium ferrite is synthesized by a modified citrate gel precursor technique. Ferrite nanoparticles of average size of 8 nm, obtained after calcination of the citrate gel made by the usual method at 450 deg. C, show superparamagnetic behavior. However, small amounts of {alpha}-Fe{sub 2}O{sub 3} is formed as an impurity phase due to the initial formation of some {gamma}-Fe{sub 2}O{sub 3} phase. On the other hand, when the pH of the mixed solution is increased to 7 after the addition of ammonia solution, a lower calcination temperature of 200 deg. C is sufficient for the formation of single phase lithium ferrite nanoparticles of size 30 nm. No impurity phases are detected when the nanocrystalline powders are calcined at higher temperatures. The magnetic properties of the ferrite nanoparticles of different sizes obtained by calcining the powders at different temperatures are studied.

Verma, Seema [Physical and Materials Chemistry Division, National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008 (India); Joy, P.A. [Physical and Materials Chemistry Division, National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008 (India)], E-mail: pa.joy@ncl.res.in

2008-12-01

240

Hot coal gas desulfurization with manganese-based sorbents. Quarterly report, October--December 1993  

Microsoft Academic Search

The focus of work being performed on Hot Coal Gas Desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc ferrite and zinc titanate sorbents; however, prior studies indicated that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt% ore + 25 wt% AlâOâ) may be a viable alternative to zinc-based sorbents. Manganese,

M. T. Hepworth; R. B. Slimane

1994-01-01

241

Magnetic properties and microwave absorption in Ni-Zn and Mn-Zn ferrite nanoparticles synthesized by low-temperature solid-state reaction  

NASA Astrophysics Data System (ADS)

In this work, Mn0.7Zn0.3Fe2O4 and Ni0.7Zn0.3Fe2O4 nanoparticles with super-paramagnetic properties and size distribution from 10 to 52 nm were investigated. These particles were produced by a low-temperature solid-state reaction method without the ball-milling process. The size and morphology of the nanocrystallites were determined by X-ray diffraction, transmission electron microscopy and scanning tunneling microscopy methods. Magnetic measurements such as alternating gradient field magnetometers were used to justify the super-paramagnetic properties of these nanoparticles. Their microwave absorption in the range of 8-18 GHz was studied by a vector network analyzer. Responses of the device under tests were studied. Also, the percentage of the resin, the size and thickness of the mount were determined. The band width of 2.3 GHz was obtained with reflection-loss/written-loss of -16 dB around 10.4 GHz.

Amiri, Gh. R.; Yousefi, M. H.; Abolhassani, M. R.; Manouchehri, S.; Keshavarz, M. H.; Fatahian, S.

2011-03-01

242

Size-Selective Chemical Synthesis of Tartrate Stabilized Cobalt Ferrite Ionic Magnetic Fluid  

Microsoft Academic Search

Ionic magnetic fluid (ferrofluid) is a stable suspension of magnetic nanoparticles in water. Cobalt ferrite nanoparticles are interesting in view of high-density recording storage. The size of the magnetic particles strongly influences the physical properties of the ferrofluids. In this study, we describe the synthesis of ionic magnetic fluid in the presence of tartrate ions. By varying the amount of

S. Neveu; A. Bee; M. Robineau; D. Talbot

2002-01-01

243

Improved Manganese Phosphate Coatings.  

National Technical Information Service (NTIS)

Work was conducted to determine the mechanism by which superior manganese phosphate coatings are produced. The phosphate coatings were applied at temperatures above 212 F and with manganese-organic compounds added to the phosphating solution. Experimental...

H. Crain

1975-01-01

244

Astrocytes and manganese neurotoxicity  

Microsoft Academic Search

Increasing evidence suggests that astrocytes are the site of early dysfunction and damage in manganese neurotoxicity. Astrocytes accumulate manganese by a high affinity, high capacity, specific transport system. Chronic exposure to manganese leads to increased pallidal signal hyperintensities on T1-weighted magnetic resonance images and selective neuronal loss in basal ganglia structures together with characteristic astrocytic changes known as Alzheimer type

Alan S Hazell

2002-01-01

245

High strength ferritic alloy-D53  

DOEpatents

A high strength ferritic alloy is described having from about 0.2% to about 0.8% by weight nickel, from about 2.5% to about 3.6% by weight chromium, from about 2.5% to about 3.5% by weight molybdenum, from about 0.1% to about 0.5% by weight vanadium, from about 0.1% to about 0.5% by weight silicon, from about 0.1% to about 0.6% by weight manganese, from about 0.12% to about 0.20% by weight carbon, from about 0.02% to about 0.1% by weight boron, a maximum of about 0.05% by weight nitrogen, a maximum of about 0.02% by weight phosphorous, a maximum of about 0.02% by weight sulfur, and the balance iron.

Hagel, William C. (Ann Arbor, MI); Smidt, Frederick A. (Springfield, VA); Korenko, Michael K. (Richland, WA)

1977-01-01

246

Impedance calculation for ferrite inserts  

SciTech Connect

Passive ferrite inserts were used to compensate the space charge impedance in high intensity space charge dominated accelerators. They study the narrowband longitudinal impedance of these ferrite inserts. they find that the shunt impedance and the quality factor for ferrite inserts are inversely proportional to the imaginary part of the permeability of ferrite materials. They also provide a recipe for attaining a truly passive space charge impedance compensation and avoiding narrowband microwave instabilities.

Breitzmann, S.C.; Lee, S.Y.; /Indiana U.; Ng, K.Y.; /Fermilab

2005-01-01

247

Effect of austempering time on mechanical properties of a low manganese austempered ductile iron  

Microsoft Academic Search

An investigation was carried out to examine the influence of austempering time on the resultant microstructure and the room-temperature mechanical properties of an unalloyed and low manganese ductile cast iron with initially ferritic as-cast structure. The effect of austempering time on the plane strain fracture toughness of this material was also studied. Compact tension and round cylindrical tensile specimens were

Susil K. Putatunda; Pavan K. Gadicherla

2000-01-01

248

Broadband Reciprocal Ferrite Phase Shifters  

Microsoft Academic Search

Broadband ferrite phase shifters were constructed in X band waveguide by locating wide ferrite slabs along the center line of the broad waveguide wall and applying a longitudinal magnetic field. The bandwidth of these phase shifters was optimized through proper selection of ferrite dimensions and the amount of dielectric loading or by an appropriate choice of guiding structure. The relative

T. D. Geiszler; R. A. Henschke

1960-01-01

249

Nanowires of NiCo\\/barium ferrite magnetic composite by electrodeposition  

Microsoft Academic Search

Electrodeposition has been demonstrated to be useful in preparing well defined composite nanowires and as a way to modify their magnetic properties. A sulphamate bath containing barium ferrite nanoparticles has been used to test nanoparticle incorporation during an alloy (NiCo) electrodeposition process. The nanoparticles enter the membrane pores during the electrodeposition, being uniformly distributed into them.Home-made alumina membranes prepared in

P. Cojocaru; L. Magagnin; E. Gomez; E. Vallés

2011-01-01

250

EPR Study of Manganese-Doped TiO2 Nanorods  

Microsoft Academic Search

Titanium dioxide nanoparticles and nanorods were prepared by a hydrothermal method using scrolled anatase nanotubes as the starting material. The addition of manganese ions to scrolled nanotube precursors was found to unroll the nanotubes into sheet-like structures indicating a strong adsorption of manganese ions at undercoordinated sites that terminate layers of scrolled titanium dioxide nanotubes. Hydrothermal treatment of Mn^2+ unscrolled

Tijana Rajh

2005-01-01

251

Hot Coal Gas Desulfurization with manganese-based sorbents. Quarterly report, April--June 1994  

SciTech Connect

The focus of work being performed on Hot Coal Gas Desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc titanate sorbents; however, prior studies indicated that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt% ore + 25 wt% Al{sub 2}O{sub 3}) appears to be a strong contender to zincbased sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc; hence, it is not as likely to undergo zinc-depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron; hence, the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. In addition, thermodynamic analysis of the manganese-oxygen-sulfur system shows it to be less amenable to sulfation than zinc ferrite. Also manganese chlorides are much less stable and volatile than zinc chlorides. Potential also exists for utilization of manganese at higher temperatures than zinc ferrite or zinc titanate. This Seventh Quarterly Report documents progress in bench-scale testing of a leading manganese-based sorbent pellets (FORM4-A). This formulation is a high-purity manganese carbonate-based material. This formulation was subjected to 20 consecutive cycles of sulfidation and regeneration at 900{degrees}C in a 2-inch fixed bed reactor. The sulfidation gas was a simulated Tampella U-gas with an increased hydrogen sulfide content of 3% by volume to accelerate the rate of breakthrough, arbitrarily taken as 500 ppmv. Consistent with thermo-gravimetric analysis (TGA) on individual pellets, the fixed bed tests show small improvement in capacity and kinetics with the sulfur-loading capacity being about 22% by weight of the original pellet, which corresponds to approximately 90% bed utilization!

Hepworth, M.T.; Slimane, R.B.

1994-06-01

252

Effect of Cadmium Substitution on Structural and Magnetic Properties of Nano Sized Nickel Ferrite  

NASA Astrophysics Data System (ADS)

The structure and crystal phase of the nanocrystalline powders of Ni1-xCdxFe2O4 (0<=x<=0.5) mixed ferrite, synthesized by wet chemical co-precipitation method, were characterized by X-ray diffraction. Results showed that the lattice parameter increased with increasing Cd concentration. Microstructure was studied by scanning electron microscopy. TG/DTA studies were carried out on co-precipitated sulphate complexes. These studies revealed the low ferritization temperature (650 °C) of the ferrite system synthesized by presently adopted route of synthesis and occurrence of simultaneous decomposition and ferritization processes. Further studies by infrared spectroscopy were also conducted. Moreover, magnetic properties of the prepared nanoparticles were studied by magnetization and a.c. susceptibility measurements. The response of prepared Ni1-xCdxFe2O4 mixed ferrites to magnetic field was investigated. Results show that, magnetic susceptibility, Curie temperature, and effective magnetic moment decreased as the Cd content increases.

Pralhadrao Jadhav, Sanjay; Ghanshamji Toksha, Bhagwan; Marutirao Jadhav, Kamalakar; Dadarao Shinde, Narayan

2010-08-01

253

Manganese action in brain function  

Microsoft Academic Search

Manganese, an essential trace metal, is supplied to the brain via both the blood–brain and the blood–cerebrospinal fluid barriers. There are some mechanisms in this process and transferrin may be involved in manganese transport into the brain. A large portion of manganese is bound to manganese metalloproteins, especially glutamine synthetase in astrocytes. A portion of manganese probably exists in the

Atsushi Takeda

2003-01-01

254

Friction and Wear of Single-Crystal and Polycrystalline Managanese-Zinc Ferrite in Contact with Various Metals.  

National Technical Information Service (NTIS)

Sliding friction experiments were conducted with single-crystal (SCF) and hot-pressed polycrystalline (HPF) manganese-zinc ferrite in contact with various metals. Results indicate that the coefficients of friction for SCF and HPF are related to the relati...

K. Miyoshi D. H. Buckley

1977-01-01

255

Mechanosynthesis and process characterization of nanostructured manganese ferrite  

Microsoft Academic Search

Nanocrystalline MnFe2O4 particles were synthesized by a high-energy ball milling technique, starting from a manganosite (MnO) and hematite (?-Fe2O3) stoichiometric powder mixture. The mechanosynthesis process was performed at room temperature both in hardened steel and in tungsten carbide vials. X-ray powder diffraction quantitative phase analysis by the Rietveld method was used to study the chemical transformations promoted by the milling

F. Padella; C. Alvani; A. La Barbera; G. Ennas; R. Liberatore; F. Varsano

2005-01-01

256

Effect of the ferrite tiles gap on ferrite electromagnetic wave absorber  

Microsoft Academic Search

The gap between ferrite tiles degrades the characteristics of ferrite electromagnetic wave absorbers at low frequency. In order to circumvent this, the authors investigated the effect of inserting ferrite powder or rubber ferrite into the gap. Both numerical calculations and experimental studies show that, when the gap is filled with the ferrite powder or the rubber ferrite, the degradation of

H. Anzai; Y. Naito; T. Mizumoto; M. Takahashi

1995-01-01

257

Process for producing manganese dioxide  

SciTech Connect

The invention relates to the manufacture of manganese dioxide by a chemical process. The resulting manganese dioxide product takes the form of particles characterized by filament-like protrusions jutting out from its surface. The manganese dioxide particles having such surface features can be manufactured by reacting manganese sulfate with sodium peroxodisulfate in an aqueous solution. The process can be controlled to yield high density manganese dioxide. The manganese dioxide formed in the process can be deposited directly onto the surface of electrolytic manganese dioxide (EMD). The manganese dioxide product the is particularly suitable for use as a cathode active material in electrochemical cells. 16 figs.

Wang, E.I.; Lin, L.; Bowden, W.L.

1994-01-11

258

Inverse magnetocaloric effect in sol-gel derived nanosized cobalt ferrite  

Microsoft Academic Search

The magnetocaloric properties of cobalt ferrite nanoparticles were\\u000a investigated to evaluate the potential of these materials as magnetic\\u000a refrigerants. Nanosized cobalt ferrites were synthesized by the method\\u000a of sol-gel combustion. The nanoparticles were found to be spherical with\\u000a an average crystallite size of 14 nm. The magnetic entropy change (Delta\\u000a S (m)) calculated indirectly from magnetization isotherms in the\\u000a temperature

E. Veena Gopalan; I. A. Al-Omari; D. Sakthi Kumar; Yasuhiko Yoshida; P. A. Joy; M. R. Anantharaman

2010-01-01

259

On the structural, magnetic and electrical properties of sol-gel derived nanosized cobalt ferrite  

Microsoft Academic Search

Nanoparticles of cobalt ferrite were synthesized by sol gel method.\\u000a These particles were structurally characterized by using X-Ray\\u000a Diffraction and Transmission Electron Microscopy, High Resolution\\u000a Transmission Electron Microscopy, Energy Dispersive Spectrum and\\u000a Inductively Coupled Plasma Analysis and the results confirmed the\\u000a formation of spherically shaped nanoparticles of cobalt ferrite having a\\u000a size lying in the range of 13-14 nm. The

E. Veena Gopalan; P. A. Joy; I. A. Al-Omari; D. Sakthi Kumar; Yasuhiko Yoshida; M. R. Anantharaman

2009-01-01

260

Low activation ferritic alloys  

DOEpatents

Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

Gelles, D.S.; Ghoniem, N.M.; Powell, R.W.

1985-02-07

261

Evolution of Microstructures During Austempering of Ductile Irons Alloyed with Manganese and Copper  

NASA Astrophysics Data System (ADS)

The influences of relatively high manganese (0.45 through 1.0 wt pct) and copper (0.56 through 1.13 wt pct) contents on microstructure development and phase transformation in three austempered ductile irons have been studied. The experimental ductile irons alloyed with copper and manganese are found to be practically free from intercellular manganese segregation. This suggests that the positive segregation of manganese is largely neutralized by the negative segregation of copper when these alloying elements are added in appropriate proportions. The drop in unreacted austenite volume (UAV) with increasing austempering temperature and time is quite significant in irons alloyed with copper and manganese. The ausferrite morphology also undergoes a transition from lenticular to feathery appearance of increasing coarseness with the increasing austempering temperature and time. SEM micrographs of the austempered samples from the base alloy containing manganese only, as well as copper plus manganese-alloyed irons, clearly reveal the presence of some martensite along with retained austenite and ferrite. X-ray diffraction analysis also confirms the presence of these phases. SEM examination further reveals the presence of twinned martensite in the copper plus manganese-alloyed samples. The possibility of strain-induced transformation of austenite to martensite during austempering heat treatment is suggested.

Dasgupta, Ranjan Kumar; Mondal, Dipak Kumar; Chakrabarti, Ajit Kumar

2013-03-01

262

Process for producing manganese dioxide  

Microsoft Academic Search

The invention relates to the manufacture of manganese dioxide by a chemical process. The resulting manganese dioxide product takes the form of particles characterized by filament-like protrusions jutting out from its surface. The manganese dioxide particles having such surface features can be manufactured by reacting manganese sulfate with sodium peroxodisulfate in an aqueous solution. The process can be controlled to

E. I. Wang; L. Lin; W. L. Bowden

1994-01-01

263

Manganese-Cobalt Mixed Spinel Oxides as Surface Modifiers for Stainless Steel Interconnects of Solid Oxide Fuel Cells  

Microsoft Academic Search

Ferritic stainless steels are promising candidates for interconnect applications in low- and mid-temperature solid oxide fuel cells (SOFCs). A couple of issues however remain for the particular application, including the chromium poisoning due to chromia evaporation, and long-term surface and electrical stability of the scale grown on these steels. Application of a manganese colbaltite spinel protection layer on the steels

Gordon Xia; Z Gary Yang; Jeffry W. Stevenson

2006-01-01

264

Synthesis and characterization of polymer nanocomposites containing magnetic nanoparticles  

Microsoft Academic Search

Magnetic poly(methyl methacrylate) nanocomposites were prepared using oleic acid coated cobalt ferrite and magnetite nanoparticles. Both nanofillers had a similar effect in shifting the glass transition temperature from that of the neat polymer. The cobalt ferrite nanocomposite had magnetic hysteresis at 2 and 300 K and the magnetite nanocomposite had magnetic hysteresis at 2 K and superparamagnetic behavior at 300

Edwin de La Cruz-Montoya; Carlos Rinaldi

2010-01-01

265

Manganese-modified natural sand in the remediation of aquatic environment contaminated with heavy metal toxic ions  

Microsoft Academic Search

The present communication aims towards the possible exploitation of modified natural sand materials in the remediation of the heavy metal toxic ions contaminated aquatic environment. The surface of the sand was modified as depositing the nano-particles of manganese (i.e., manganese-modified natural sand: MMNS) and the mineral phase of manganese was perhaps depicted to be pyrolusite as indicated by the XRD

Diwakar Tiwari; C. Laldanwngliana; Chul-Ho Choi; Seung Mok Lee

2011-01-01

266

Ferrite phase shifters using stress insensitive materials. Final report, July 1991-July 1993  

SciTech Connect

This RD program sponsored by the Naval Research Laboratory and being conducted by EMS Technologies, Inc., Norcross, Georgia, is focused toward achieving improved performance in microwave switching components via use of stress insensitive' microwave ferrite materials for applications where stable hysteresis characteristics of the materials are critical to the RF performance. The program, therefore, primarily addresses how to relieve or improve the magnetostrictive characteristics of the materials with emphasis on the specific application and demonstration of these materials in microwave switching components, particularly ferrite toroidal phase shifters. Material investigations were focused on Mn+3 substitutions in Yttrium-gadolinium iron garnet. These compounds were evaluated in dual toroid waveguide phase shifter structures with temperature, pressure Rf power as variables Manganese substitution per formula unit for Fe+3 of 0.11 to 0.13 (2.2 to 2.6%) produced compounds which exhibited stable performance from magnetostrictive stresses in phaser structures. Ferrite phase shifters, Stress insensitive materials Manganese substitution in garnets, Magnetostrictive, Stresses in ferrite phasers.

Vaughn, T.; Cox, P.; Harrison, G.; Rodrigue, P.

1993-10-01

267

Magnetic and catalytic properties of copper ferrite nanopowders prepared by combustion process.  

PubMed

Copper ferrite nano-particles with Fe/Cu ratios varying from 2 to 12 were successfully synthesized by combustion process using copper nitrate, iron nitrate and urea. The resultant powders were investigated by scanning electron microscopy (SEM), vibrating sample magnetometer (VSM). The results revealed that the copper ferrite powders are uniform in the range of 250-300 nm. The copper ferrite with Fe/Cu ratio of 2 possessed a saturation magnetization of 5.47 emu/g, and an intrinsic coercive force of 241.98 Oe, with Fe/Cu ratio of 12 possessed a saturation magnetization of 22.06 emu/g and an intrinsic coercive force of 247.94 Oe. Moreover, these copper ferrite magnetic nano-particles also acted as catalyst for the oxidation of 2,3,6-trimethylphenol to synthesize 2,3,5-trimethylhydrogenquinone and 2,3,5-trimethyl-1,4-benzoquinone for the first time. The conversion of 2,3,6-trimethylphenol in the kinetic behavior of oxidation was investigated in detail. The reaction shows dramatically enhanced by the addition of copper-ferrite nano-particles to the solution. PMID:19441554

Liu, B L; Fu, Y P; Wang, M L

2009-02-01

268

Longitudinal MRI contrast enhanced monitoring of early tumour development with manganese chloride (MnCl2) and superparamagnetic iron oxide nanoparticles (SPIOs) in a CT1258 based in vivo model of prostate cancer  

PubMed Central

Background Cell lines represent a key tool in cancer research allowing the generation of neoplasias which resemble initial tumours in in-vivo animal models. The characterisation of early tumour development is of major interest in order to evaluate the efficacy of therapeutic agents. Magnetic resonance imaging (MRI) based in-vivo characterisation allows visualisation and characterisation of tumour development in early stages prior to manual palpation. Contrast agents for MRI such as superparamagnetic iron oxide nanoparticles (SPIOs) and manganese chloride (MnCl2) represent powerful tools for the in-vivo characterisation of early stage tumours. In this experimental study, we labelled prostate cancer cells with MnCl2 or SPIOs in vitro and used 1?T MRI for tracing labelled cells in-vitro and 7?T MRI for tracking in an in-vivo animal model. Methods Labelling of prostate cancer cells CT1258 was established in-vitro with MnCl2 and SPIOs. In-vitro detection of labelled cells in an agar phantom was carried out through 1?T MRI while in-vivo detection was performed using 7?T MRI after subcutaneous (s.c.) injection of labelled cells into NOD-Scid mice (n?=?20). The animals were scanned in regular intervals until euthanization. The respective tumour volumes were analysed and corresponding tumour masses were subjected to histologic examination. Results MnCl2in-vitro labelling resulted in no significant metabolic effects on proliferation and cell vitality. In-vitro detection-limit accounted 105 cells for MnCl2 as well as for SPIOs labelling. In-vivo 7?T MRI scans allowed detection of 103 and 104 cells. In-vivo MnCl2 labelled cells were detectable from days 4–16 while SPIO labelling allowed detection until 4?days after s.c. injection. MnCl2 labelled cells were highly tumourigenic in NOD-Scid mice and the tumour volume development was characterised in a time dependent manner. The amount of injected cells correlated with tumour size development and disease progression. Histological analysis of the induced tumour masses demonstrated characteristic morphologies of prostate adenocarcinoma. Conclusions To the best of our knowledge, this is the first study reporting direct in-vitro MnCl2 labelling and 7?T based in-vivo MRI tracing of cancer cells in a model of prostate cancer. MnCl2 labelling was found to be suitable for in-vivo tracing allowing long detection periods. The labelled cells kept their highly tumourigenic potential in-vivo. Tumour volume development was visualised prior to manual palpation allowing tumour characterisation in early stages of the disease.

2012-01-01

269

Structure and morphology of spinel MFe 2O 4 (M = Fe, Co, Ni) nanoparticles chemically synthesized from heterometallic complexes  

Microsoft Academic Search

We synthesized magnetic spinel ferrites from trimetallic single-source precursors. Fe(II), Co(II), and Ni(II) ferrite nanoparticles in the range of 9–25nm were synthesized by solvothermal decomposition of trimetallic acetate complex precursors in benzyl ether in the presence of oleic acid and oleylamine, using 1,2-dodecanediol as the reducing agent. For comparison, spinel ferrite nanoparticles were synthesized by stoichiometric mixtures of metal acetate

Karine Priscila Naidek; Flavia Bianconi; Tulio Costa Rizuti da Rocha; Daniela Zanchet; Juliano Alves Bonacin; Miguel Alexandre Novak; Maria das Graças Fialho Vaz; Herbert Winnischofer

2011-01-01

270

Magnetic hard/soft nanocomposite ferrite aligned hollow microfibers and remanence enhancement.  

PubMed

The nanocomposite SrFe(12)O(19)/Ni(0.5)Zn(0.5)Fe(2)O(4) ferrite aligned hollow microfibers with the hollow diameter to the fiber diameter estimated about 3/5 have been prepared by the gel precursor transformation process. The nanocomposite binary ferrites with different mass ratios are formed after the precursor calcined at 900°C for 2h, fabricating from SrFe(12)O(19) nanoparticles and Ni(0.5)Zn(0.5)Fe(2)O(4) nanoparticles with a uniform phase distribution. These nanocomposite ferrite microfibers show a combination of magnetic characteristics for the hard (SrFe(12)O(19)) and soft (Ni(0.5)Zn(0.5)Fe(2)O(4)) phase with an enhanced remanence owing to the exchange-coupling interactions. The aligned microfibers exhibit a shape anisotropy. PMID:21144534

Song, Fuzhan; Shen, Xiangqian; Liu, Mingquan; Xiang, Jun

2010-12-08

271

21 CFR 184.1449 - Manganese citrate.  

Code of Federal Regulations, 2010 CFR

... § 184.1449 Manganese citrate. (a) Manganese citrate (Mn3 (C6 H5 O7 )2 ...white powder. It is obtained by precipitating manganese carbonate from manganese sulfate and sodium carbonate solutions. The...

2009-04-01

272

21 CFR 184.1449 - Manganese citrate.  

Code of Federal Regulations, 2013 CFR

... § 184.1449 Manganese citrate. (a) Manganese citrate (Mn3 (C6 H5 O7 )2, ...white powder. It is obtained by precipitating manganese carbonate from manganese sulfate and sodium carbonate solutions. The...

2013-04-01

273

21 CFR 184.1449 - Manganese citrate.  

Code of Federal Regulations, 2010 CFR

... § 184.1449 Manganese citrate. (a) Manganese citrate (Mn3 (C6 H5 O7 )2 ...white powder. It is obtained by precipitating manganese carbonate from manganese sulfate and sodium carbonate solutions. The...

2010-01-01

274

Astrocytes and manganese neurotoxicity.  

PubMed

Increasing evidence suggests that astrocytes are the site of early dysfunction and damage in manganese neurotoxicity. Astrocytes accumulate manganese by a high affinity, high capacity, specific transport system. Chronic exposure to manganese leads to increased pallidal signal hyperintensities on T1-weighted magnetic resonance images and selective neuronal loss in basal ganglia structures together with characteristic astrocytic changes known as Alzheimer type II astrocytosis. Manganese is sequestered in mitochondria where it inhibits oxidative phosphorylation. Exposure of astrocytes to manganese results in important changes including (i) decreased uptake of glutamate; (ii) increased densities of binding sites for the "peripheral-type" benzodiazepine receptor (PTBR), a class of receptor localized to mitochondria of astrocytes and involved in oxidative metabolism, mitochondrial proliferation, and neurosteroid synthesis; (iii) increased gene expression and activity of the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH), known to be associated with apoptosis; (iv) increased uptake of L-arginine, a precursor of nitric oxide, together with increased expression of the inducible form of nitric oxide synthase (iNOS). Potential consequences of these alterations in astrocytic gene expression include failure of energy metabolism, production of reactive oxygen species (ROS), increased extracellular glutamate concentration and excitotoxicity which could play a key role in manganese-induced neuronal cell death as a direct result of impaired astrocytic-neuronal interactions. PMID:12106778

Hazell, Alan S

2002-10-01

275

In vivo investigation of cobalt ferrite-based magnetic fluid and magnetoliposomes using morphological tests  

Microsoft Academic Search

Morphological studies were carried out after endovenous injection of a magnetic fluid and magnetoliposome samples, all containing cobalt ferrite magnetic nanoparticles (MNPs). Twenty four hours after injection, the three investigated samples presented differences concerning blood clearance, phagocytosis susceptibility, and MNP cluster size and amount. Our data suggest that the samples investigated are biocompatible and could be used as material basis

S. Kückelhaus; S. C. Reis; M. F. Carneiro; A. C. Tedesco; D. M. Oliveira; E. C. D. Lima; P. C. Morais; R. B. Azevedo; Z. G. M. Lacava

2004-01-01

276

Chapter 11 magnetic nanoparticles in oxide glasses  

Microsoft Academic Search

Unique properties of the potassium-aluminum-boron glasses doped with low concentrations of MnO and Fe2O3 to make them magnetically ordered and optically transparent in the IR and visible ranges are due to the formation of nanoparticles\\u000a of a cubic ferrite. Assembling and properties of nanosized ferrite particles in the glasses have been investigated by X-ray\\u000a diffraction, differential dissolution analysis, high-resolution transmission

I. S. Edelman; R. D. Ivantsov; I. G. Vasil’eva; A. D. Vasil’ev; O. A. Bayukov; O. S. Ivanova; D. E. Prokof’ev; S. A. Stepanov; E. E. Kornilova; T. V. Zarubina; V. V. Malakhov; V. A. Zaikovskii

2006-01-01

277

Dielectric properties of rubber ferrite composites containing mixed ferrites  

Microsoft Academic Search

Rubber ferrite composites (RFC) are important since they have useful applications as microwave absorbers and flexible magnets. The mouldability of these composites into complex shapes is another advantage. The evaluation of their dielectric and magnetic properties is important in understanding the physical properties of these composites. Pre-characterized nickel zinc ferrites (Ni1-xZnxFe2O4 where 0icons\\/Journals\\/Common\\/leq\\

M. R. Anantharaman; S. Sindhu; S. Jagatheesan; K. A. Malini; P. Kurian

1999-01-01

278

Structural, morphological, dielectrical and magnetic properties of Mn substituted cobalt ferrite  

NASA Astrophysics Data System (ADS)

The Co1-xMnxFe2O4 (0 <= x <= 0.5) ferrite system is synthesized by using an auto combustion technique using metal nitrates. The influence of Mn substitution on the structural, electrical, impedance and magnetic properties of cobalt ferrite is reported. X-ray diffraction patterns of the prepared samples confirm that the Bragg's peak belongs to a spinel cubic crystal structure. The lattice constant of cobalt ferrite increases with the increase in Mn content. The microstructural study is carried out by using the SEM technique and the average grain size continues to increase with increasing manganese content. AC conductivity analysis suggests that the conduction is due to small polaron hopping. DC electrical resistivity decreases with increasing temperature for a Co1-xMnxFe2O4 system showing semiconducting behavior. The activation energy is found to be higher in the paramagnetic region than the ferromagnetic region. Curie temperature decreases with Mn substitution in the host ferrite system. Dielectric dispersion having Maxwell—Wagner-type interfacial polarization has been observed for cobalt ferrite samples. Magnetic properties have been studied by measuring M—H plots. The saturation and remanent magnetization increases with Mn substitution.

Yadav, S. P.; Shinde, S. S.; Kadam, A. A.; Rajpure, K. Y.

2013-09-01

279

Effect of austempering time on mechanical properties of a low manganese austempered ductile iron  

Microsoft Academic Search

An investigation was carried out to examine the influence of austempering time on the resultant microstructure and the room-temperature\\u000a mechanical properties of an unalloyed and low manganese ductile cast iron with initially ferritic as-cast structure. The effect\\u000a of austempering time on the plane strain fracture toughness of this material was also studied. Compact tension and round cylindrical\\u000a tensile specimens were

Susil K. Putatunda; Pavan K. Gadicherla

2000-01-01

280

INFLUENCE OF AUSTEMPERING TEMPERATURE ON FRACTURE TOUGHNESS OF A LOW MANGANESE AUSTEMPERED DUCTILE IRON (ADI)  

Microsoft Academic Search

The influence of microstructure on the plane strain fracture toughness of an unalloyed, austempered ductile cast iron (ADI) with low manganese content (<0.15 wt %) and with predominantly as-cast (solidified) ferritic structure was studied. Test specimens were austenitized at 927°C (1700°F) for 2 hr and then austempered over a range of temperatures to produce different microstructures. The microstructures were characterized

Susil K. Putatunda

2001-01-01

281

Study of Manganese Phosphating Reactions.  

National Technical Information Service (NTIS)

Work was conducted to determine the composition of and the reactions associated with the formation of manganese-phosphate coatings. An improved phosphate coating was studied as produced from a stock manganese phosphating bath to which an addition of manga...

J. Menke

1971-01-01

282

High Power Ferrite Phase Shifter.  

National Technical Information Service (NTIS)

Theoretical and experimental investigations of the microwave properties of ferrites at magnetic fields above ferromagnetic resonance are described. The program goal is the development of high power reciprocal phase shifters for X-band and C-band operation...

1965-01-01

283

Epitaxial Garnets and Hexagonal Ferrites.  

National Technical Information Service (NTIS)

The objective of this research is to develop new and improved epitaxial ferrite materials for use in microwave and millimeter-wave signal processing devices. The major emphasis has been on multiple layer magnetic garnet structures for magnetostatic wave (...

H. L. Glass L. R. Adkins

1982-01-01

284

Carbon-supported manganese oxide nanocatalysts for rechargeable lithium–air batteries  

Microsoft Academic Search

Manganese oxide based catalysts were synthesised in the form of nano-particles using a redox reaction of MnSO4 and KMnO4, housed into the pores of a carbon matrix and followed by a thermal treatment. Particle sizes of the manganese oxide nanocatalysts were around 50nm, based on the tunnelling electron microscope measurement. They were uniformly distributed in the carbon matrix, which contributed

H. Cheng; K. Scott

2010-01-01

285

Energetic basis of catalytic activity of layered nanophase calcium manganese oxides for water oxidation.  

PubMed

Previous measurements show that calcium manganese oxide nanoparticles are better water oxidation catalysts than binary manganese oxides (Mn3O4, Mn2O3, and MnO2). The probable reasons for such enhancement involve a combination of factors: The calcium manganese oxide materials have a layered structure with considerable thermodynamic stability and a high surface area, their low surface energy suggests relatively loose binding of H2O on the internal and external surfaces, and they possess mixed-valent manganese with internal oxidation enthalpy independent of the Mn(3+)/Mn(4+) ratio and much smaller in magnitude than the Mn2O3-MnO2 couple. These factors enhance catalytic ability by providing easy access for solutes and water to active sites and facile electron transfer between manganese in different oxidation states. PMID:23667149

Birkner, Nancy; Nayeri, Sara; Pashaei, Babak; Najafpour, Mohammad Mahdi; Casey, William H; Navrotsky, Alexandra

2013-05-10

286

Manganese biomining: A review.  

PubMed

Biomining comprises of processing and extraction of metal from their ores and concentrates using microbial techniques. Currently this is used by the mining industry to extract copper, uranium and gold from low grade ores but not for low grade manganese ore in industrial scale. The study of microbial genomes, metabolites and regulatory pathways provide novel insights to the metabolism of bioleaching microorganisms and their synergistic action during bioleaching operations. This will promote understanding of the universal regulatory responses that the biomining microbial community uses to adapt to their changing environment leading to high metal recovery. Possibility exists of findings ways to imitate the entire process during industrial manganese biomining endeavor. This paper reviews the current status of manganese biomining research operations around the world, identifies factors that drive the selection of biomining as a processing technology, describes challenges in exploiting these innovations, and concludes with a discussion of Mn biomining's future. PMID:21632238

Das, A P; Sukla, L B; Pradhan, N; Nayak, S

2011-05-14

287

HRTEM and FTIR investigation of nanosized zinc ferrite irradiated with 100 MeV oxygen ions.  

PubMed

Present work aims to investigate effect of 100 MeV oxygen ion irradiation on the vibrational modes of zinc ferrite nanoparticles. Nanosize zinc ferrite systems of different crystallite size ranging from 12-62 nm were irradiated at the fluence of 1×10(13) and 5×10(13) ions/cm(2). High resolution transmission electron micrograph study indicates the structural disorder induced by ion irradiation. Bands corresponding to various vibrational modes in Fourier transform infrared spectra exhibit changes and are affected by the crystallite size/microstructure of pristine samples. The irradiation induced changes are dominated for sample ZF1000. PMID:23434561

Singh, Jitendra Pal; Dixit, Gagan; Srivastava, R C; Negi, Puneet; Agrawal, H M; Kumar, Ravi

2013-01-10

288

Hot coal gas desulfurization with manganese-based sorbents  

SciTech Connect

The primary major deposit of manganese in the US which can be readily mined by an in situ process is located in the Emily district of Minnesota. The US Bureau of Mines Research Centers at both the Twin Cities and Salt Lake City have developed a process for extracting and refining manganese in the form of a high-purity carbonate product. This product has been formulated into pellets by a multi-step process of drying, calcination, and induration to produce relatively high-strength formulations which are capable of being used for hot fuel gas desulfurization. These pellets, which have been developed at the University of Minnesota under joint sponsorship of the US Department of Energy and the US Bureau of Mines, appear superior to other, more expensive, formulations of zinc titanate and zinc ferrite which have previously been studied for multi-cycle loading (desulfurization) and regeneration (evolution of high-strength SO{sub 2} and restoration of pellet reactivity). Although these other formulations have been under development for the past twelve years, their prices still exceed $7 per pound. If manganese pellets perform as predicted in fixed bed testing, and if a significant number of utilities which burn high-sulfur coals incorporate combined-cycle gasification with hot coal gas desulfurization as a viable means of increasing conversion efficiencies, then the potential market for manganese pellets may be as high as 200,000 tons per year at a price not less than $3 per pound. This paper discusses the role of manganese pellets in the desulfurization process with respect to the integrated gasification combined-cycle (IGCC) for power generation.

Hepworth, M.T.; Ben-Slimane, R.

1995-11-01

289

An X-Band Ferrite Phase Shifter.  

National Technical Information Service (NTIS)

Research with ferrites has shown that these materials possess a number of nonreciprocal properties when used in the microwave frequency range. This unusual behavior has led to an increased usage of ferrites in microwave devices. Extensive experiments cond...

F. L. Roach

1964-01-01

290

Hydrothermal synthesis of nanostructured spinel lithium manganese oxide  

Microsoft Academic Search

Nanostructured spherical spinel lithium manganese oxide (LiMnO) with about 200nm in diameter was synthesized for the first time by mild hydrothermal method. The formation of the nanostructured spheres was through self-assembly of the nanoparticles and nanobelts. The influence of the reaction temperature and the time of formation of the nanostructures have been systematically studied. The thermal stability of the nanostructures

Zhanqiang Liu; Wen-Lou Wang; Xianming Liu; Minchang Wu; Dan Li; Zhen Zeng

2004-01-01

291

Monitoring colloidal stability of polymer-coated magnetic nanoparticles using AC susceptibility measurements  

Microsoft Academic Search

The application of the response of magnetic nanoparticles to oscillating magnetic fields to probe transitions in colloidal state and structure of polymer-coated nanoparticles is demonstrated. Cobalt ferrite nanoparticles with narrow size distribution were prepared and shown to respond to oscillating magnetic fields through a Brownian relaxation mechanism, which is dependent on the mechanical coupling between the particle dipoles and the

Adriana P. Herrera; Carola Barrera; Yashira Zayas; Carlos Rinaldi

2010-01-01

292

Effect of ferrite on cast stainless steels  

SciTech Connect

Premature failure of stainless steel castings in bleach washing service is attributed to poor casting quality high porosity and to a high ferrite content, which makes the castings susceptible to corrosion by hot acid chloride solutions. A survey of the chemical compositions and ferrite contents of corrosion-resistant castings in bleach plants at three pulp mills found high [delta]-ferrite levels in the austenitic matrix due to the improper balance between austenite and ferrite stabilizers.

Nadezhdin, A.; Cooper, K. (Noranda Technology Centre, Pointe Claire, Quebec (Canada)); Timbers, G. (James Maclaren Inc., Quebec (Canada). Kraft Pulp Division)

1994-09-01

293

A Low Cost Lithium Ferrite Phase Shifter  

Microsoft Academic Search

Low cost construction techniques for twin slab ferrite phase shifters are presented along with an experimental comparison of garnet and lithium ferrite materials. A 3-bit phase shifter with lithium ferrite material which is approximately half the price of garnet material had a measured loss of 0.4 dB and a peak power handling of 4.5 kW.

D. A. Charlton

1973-01-01

294

Tissue Manganese Concentrations in Young Male Rhesus Monkeys following Subchronic Manganese Sulfate Inhalation  

Microsoft Academic Search

High-dose human exposure to manganese results in manganese accumulation in the basal ganglia and dopaminergic neuropa- thology. Occupational manganese neurotoxicity is most frequently linked with manganese oxide inhalation; however, exposure to other forms of manganese may lead to higher body burdens. The objective of this study was to determine tissue manganese con- centrations in rhesus monkeys following subchronic (6 h\\/day,

David C. Dorman; Melanie F. Struve; Marianne W. Marshall; Carl U. Parkinson; R. Arden James; Brian A. Wong

2006-01-01

295

CONVERSATION OF DISSOLVED MANGANESE TO PARTICULATE MANGANESE DURING DIATOM BLOOM: EFFECTS ON THE MANGANESE CYCLE IN THE MERL MICROCOSMS  

EPA Science Inventory

Conversion of dissolved manganese to particulate manganese occurred during a minor diatom bloom during August and September 1978 in the MERL microcosms. Correlations between chlorophyll a and particulate manganese suggest that 29 moles Mn were transferred to the particulate phase...

296

Effect of austempering time on mechanical properties of a low manganese austempered ductile iron  

NASA Astrophysics Data System (ADS)

An investigation was carried out to examine the influence of austempering time on the resultant microstructure and the room-temperature mechanical properties of an unalloyed and low manganese ductile cast iron with initially ferritic as-cast structure. The effect of austempering time on the plane strain fracture toughness of this material was also studied. Compact tension and round cylindrical tensile specimens were prepared from unalloyed ductile cast iron with low manganese content and with a ferritic as-cast (solidified) structure. These specimens were then austempered in the upper (371 °C) and lower (260 °C) bainitic temperature ranges for different time periods, ranging from 30 min. to 4 h. Microstructural features such as type of bainite and the volume fraction of ferrite and austenite and its carbon content were evaluated by X-ray diffraction to examine the influence of microstructure on the mechanical properties and fracture toughness of this material. The results of the present investigation indicate that for this low manganese austempered ductile iron (ADI), upper ausferritic microstructures exhibit higher fracture toughness than lower ausferritic microstructures. Yield and tensile strength of the material was found to increase with an increase in austempering time in a lower bainitic temperature range, whereas in the upper bainitic temperature range, time has no significant effect on the mechanical properties. A retained austenite content between 30 to 35% was found to provide optimum fracture toughness. Fracture toughness was found to increase with the parameter ( X?C?/d)1/2, where X? is the volume fraction of austenite, C? is the carbon content of the austenite, and d is the mean free path of dislocation motion in ferrite.

Putatunda, Susil K.; Gadicherla, Pavan K.

2000-04-01

297

Effect of austempering time on mechanical properties of a low manganese austempered ductile iron  

SciTech Connect

An investigation was carried out to examine the influence of austempering time on the resultant microstructure and the room-temperature mechanical properties of an unalloyed and low manganese ductile cast iron with initially ferritic as-cast structure. The effect of austempering time on the plane strain fracture toughness of this material was also studied. Compact tension and round cylindrical tensile specimens were prepared from unalloyed ductile cast iron with low manganese content and with a ferritic as-cast (solidified) structure. These specimens were then austempered in the upper (371 C) and lower (260 C) bainitic temperature ranges for different time periods, ranging from 30 min. to 3 h. Microstructural features such as type of bainite and the volume fraction of ferrite and austenite and its carbon content were evaluated by X-ray diffraction to examine the influence of microstructure on the mechanical properties and fracture toughness of this material. The results of the present investigation indicate that for this low manganese austempered ductile iron (ADI), upper ausferritic microstructures exhibit higher fracture toughness than lower ausferritic microstructures. Yield and tensile strength of the material was found to increase with an increase in austempering time in a lower bainitic temperature range, whereas in the upper bainitic temperature range, time has no significant effect on the mechanical properties. A retained austenite content between 30 to 35% was found to provide optimum fracture toughness. Fracture toughness was found to increase with the parameter (X{gamma}C{gamma}/d){sup 1/2}, where X{gamma} is the volume fraction of austenite, C{gamma} is the carbon content of the austenite, and d is the mean free path of dislocation motion in ferrite.

Putatunda, S.K.; Gadicherla, P.K.

2000-04-01

298

Tuning of magnetic properties in cobalt ferrite by varying Fe+2 and Co+2 molar ratios  

NASA Astrophysics Data System (ADS)

Different grades of magnetic cobalt ferrite (CoFe2O4) nanoparticles were synthesized with various molar ratios of Fe+2 to Co+2 ions in the initial salt solutions by the co-precipitation method. The crystal structure and morphology of the nanoparticles are obtained from X-ray diffraction and transmission electron microscopy studies. Fourier transform infrared spectroscopy analysis exhibited the Fe-O stretching vibration ~540 cm-1, confirming the formation of metal oxide. The magnetic studies demonstrate that all of the nanoparticles are superparamagnetic at 300 K. The saturation magnetization and coercivity of the CoFe2O4 nanoparticles are affected by the molar ratios of Fe+2 to Co+2 ions. Among all the synthesized nanoparticles, the system with 75:25 molar ratio of Fe+2 to Co+2 ions with a particle size of 13 nm showed a high magnetization of 90 emu/g.

Biswal, Dipti; Peeples, Brianna N.; Peeples, Caryn; Pradhan, Aswini K.

2013-11-01

299

The Effect of Heat-Treatment Modes on Microstructure of Reduced-Activation Ferritic-Martensitic Steel EK-181  

NASA Astrophysics Data System (ADS)

The effect of heat-treatment (HT) modes on the structural-phase state of heat-resistant ferritic-martensitic steel EK-191 is investigated. The use of intermediate (between quenching and tempering) annealing at reduced temperatures is shown to result in a higher dispersion of nanoparticles of vanadium carbonitride than that achieved by traditional heat treatment. The HT modes ensuring high density of nanoparticles and a simultaneous reduction of the martensite tempering intensity are found out.

Shevyako, N. A.; Litovchenko, I. Yu.; Tyumentsev, A. N.; Astafurova, E. G.; Leontieva-Smirnova, M. V.; Chernov, V. M.; Andreev, A. V.

2013-10-01

300

21 CFR 582.5455 - Manganese glycerophosphate.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Manganese glycerophosphate. 582.5455 Section...or Dietary Supplements 1 § 582.5455 Manganese glycerophosphate. (a) Product. Manganese glycerophosphate. (b) Conditions...

2013-04-01

301

Controllable hydrogen generation by use smart hydrogel reactor containing Ru nano catalyst and magnetic iron nanoparticles  

Microsoft Academic Search

In this study, p(AMPS) hydrogels are synthesized from 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS) via a photo polymerization technique. The hydrogels are used as template for metal nanoparticles and magnetic ferrite nanoparticles, and also as a catalysis vessel in the generation of hydrogen from the hydrolysis of NaBH4. Approximately 5nm Ru (0) and 20–30nm magnetic ferrite particles are generated in situ inside this

Nurettin Sahiner; Ozgur Ozay; Erk Inger; Nahit Aktas

2011-01-01

302

Magneto-optics of ferrites  

Microsoft Academic Search

The optical and magneto-optical properties of ferrites are reviewed with the main emphasis on yttrium iron garnet and iron borate. The various effects are summarized and described in terms of a macroscopic dielectric tensor. Next, the microscopic origins are explained by exchange and spin-orbit coupling of excited electronic states of the magnetic ions. Two types of transitions are dominant: charge

W. Wettling

1976-01-01

303

Widmanstatten ferrite in lunar iron  

Microsoft Academic Search

Fragments of lunar matter recovered by Luna 16 are subjected to metallographic analyses. Based on thermodynamic analyses, the specific nature of the Widmanstatten ferrite found in the high-iron lunar metal is discussed. The Widmanstatten microstructure of the iron-nickel lunar metal differs morphologically from the Widmanstatten structure found in meteorities. Chemical data indicate similar processes are responsible for the development of

R. I. Mints; T. M. Petukhova; V. M. Segal; L. S. Tarasov

1975-01-01

304

Widmanstatten ferrite in lunar iron  

Microsoft Academic Search

Fragments of lunar matter recovered by Luna 16 are subjected to metallographic analyses. Based on thermodynamic analyses, the specific nature of the Widmanstatten ferrite found in the high-iron lunar metal is discussed. The Widmanstatten microstructure of the iron-nickel lunar metal differs morphologically from the Widmanstatten structure found in meteorities. Chemical data indicate similar processes are responsible for the development of

R. I. Mints; T. M. Petukhova; V. M. Segal; L. S. Tarasov

1974-01-01

305

Epitaxial garnets and hexagonal ferrites  

Microsoft Academic Search

Epitaxial ferrite materials were developed for use in microwave and millimeter wave signal processing devices. Multiple layer magnetic garnet structures for magnetostatic wave (MSW) delay lines were emphasized. Theoretical analysis and experiments were performed on propagation of magnetostatic surface waves (MSSW), magnetostatic forward volume waves (MSFVW) and magnetostatic backward volume waves in structures containing up to four layers. In the

H. L. Glass; L. R. Adkins

1982-01-01

306

Periodically Loaded Ferrite Phase Shifters  

Microsoft Academic Search

This paper describes a general treatment of periodically-loaded ferrite phase-shifters by considering the loading essentially continuous if there are many obstacles per wavelength. Its advantage over an attempt made to treat the structure as a cascade of transmission line sections loaded by shunt susceptances is pointed out. In its generality the method can be used to analyse both cases of

A. J. F. Orlando; B. Chambers

1975-01-01

307

Reciprocal Latching Ferrite Phase Shifter  

Microsoft Academic Search

In a latching ferrite phase shifter the magnetic material is used in sample shapes such as toroids in which the magnetic flux can be closed onto itself. This has the advantage that in the operation of the device no holding current is required. The switching is performed by means of current pulses. According to their direction, these current pulses either

E. Schlomann; M. Harris; J. J. Green

1966-01-01

308

Three New Ferrite Phase Shifters  

Microsoft Academic Search

Three new devices for the electrical control of microwave phase shift are discussed. The first of these, the bucking rotator phase shifter, is a reciprocal unit. It employs two series ferrite rotators, the field coils of which are connected so as to produce opposing longitudinal magnetic fields. It is shown that the total rotation is zero independent of coil current,

Howard Scharfman

1956-01-01

309

Multiferroic bismuth ferrite material core based inductive displacement sensor  

NASA Astrophysics Data System (ADS)

In this research, an inductive displacement sensor with multiferroic bismuth ferrite core has been realized. The bismuth ferrite sample is synthesized and its structural and dielectric properties are studied. A rod-shaped bismuth ferrite core is prepared and displaced through the inductor of a RLC circuit. The performance of the prepared bismuth ferrite core has been compared with a commercially available ferrite core.

Rajeswari, R.; Biswal, M. R.; Nanda, J.; Mishra, N. C.

2012-07-01

310

The Structure and Properties of Plasma Sprayed Iron Oxide Doped Manganese Cobalt Oxide Spinel Coatings for SOFC Metallic Interconnectors  

Microsoft Academic Search

Manganese cobalt oxide spinel doped with Fe2O3 was studied as a protective coating on ferritic stainless steel interconnects. Chromium alloying causes problems at high\\u000a operation temperatures in such oxidizing conditions where chromium compounds evaporate and poison the cathode active area,\\u000a causing the degradation of the solid oxide fuel cell. In order to prevent chromium evaporation, these interconnectors need\\u000a a protective

Jouni Puranen; Juha Lagerbom; Leo Hyvärinen; Mikko Kylmälahti; Olli Himanen; Mikko Pihlatie; Jari Kiviaho; Petri Vuoristo

2011-01-01

311

Magnetic and relaxometric properties of Mn ferrites  

NASA Astrophysics Data System (ADS)

We present the magnetic properties and the 1H nuclear magnetic resonance dispersion profiles of Mn-ferrites-based compounds, as possible novel contrast agents (CAs) for magnetic resonance imaging (MRI). The samples consist of nanoparticles (NPs) with the magnetic core made of Mn1+xFe2-xO4, obtained by the rapid decomposition of metalcarbonyl into a hot solvent containing an oxidizer and a coordinating surfactant; by this procedure, monodisperse capped NPs with different sizes have been obtained. We have performed structural and morphological investigation by x-ray powder diffraction and transmission electron microscopy techniques and SQUID magnetometry experiments to investigate the magnetic behaviour of the samples. As required for MRI applications using negative CAs, the samples are superparamagnetic at room temperature, having blocking temperatures in the range 14-80 K. The longitudinal r1 and transverse r2 nuclear relaxivities appear to vary strongly with the magnetic core size, their values being comparable to commercial compounds in the high-frequency range ? > 100 MHz. The experimental results suggest that our samples are suitable for high-frequency MRI imagers in general and in particular for the 3 T clinical imager, as indeed suggested by a recent report (Tromsdorf et al 2007 Nanoletters 7 2422).

Boni, A.; Marinone, M.; Innocenti, C.; Sangregorio, C.; Corti, M.; Lascialfari, A.; Mariani, M.; Orsini, F.; Poletti, G.; Casula, M. F.

2008-07-01

312

Oxidative basis of manganese neurotoxicity.  

PubMed

Exposure to excessive levels of manganese, an essential trace element, can evoke severe psychiatric and extrapyramidal motor dysfunction closely resembling Parkinson's disease. The clinical manifestations of manganese toxicity arise from focal injury to the basal ganglia. This region, characterized by intense consumption of oxygen and significant dopamine content, can incur mitochondrial dysfunction, depletion of levels of peroxidase and catalase, and catecholamine biochemical imbalances following manganese exposure. The site specificity of the pathology and the nature of the cellular damage caused by manganese have been attributed to its capacity to produce cytotoxic levels of free radicals. However, support for such a pro-oxidant role for manganese has been largely limited to inferences drawn from histopathological observations. More recently, research efforts into the molecular details of manganese toxicity have provided evidence of an etiological relationship between oxidative stress and manganese-related neurodegeneration. This review focuses on studies that evaluate the redox chemistry of manganese during the neurodegenerative process and its molecular consequences. PMID:15105260

HaMai, Diem; Bondy, Stephen C

2004-03-01

313

Preparation and Characteristics of Liquid Silicone Rubber Nanocomposite Containing Ultrafine Magnesium Ferrite Powder  

Microsoft Academic Search

Liquid silicone rubber with high thermal conductivity and effective electromagnetic interference (EMI) shielding properties was prepared. Silicone-based polymers were prepared by the equilibrium polymerization of cyclic siloxane and end-blockers. Magnesium ferrite nanoparticles having spinel magnetic properties were synthesized by the sol-gel method. A liquid silicone rubber (LSR) nanocomposite was prepared by compounding a,?-vinyl poly(dimethyl\\/methylpenylsiloxane) prepolymer (VPMPS), a, ?-hydrogen poly(dimethyl\\/hydrogenmethylsiloxane) prepolymer

Doo Whan Kang; Hak Gue Yeo; Kweon Soo Lee

2004-01-01

314

Ferrite Morphology and Variations in Ferrite Content in Austenitic Stainless Steel Welds.  

National Technical Information Service (NTIS)

Four distinct ferrite morphologies have been identified in type 308 stainless steel multipass welds: vermicular, lacy, acicular, and globular. The first three ferrite types are related to transformations following solidification and the fourth is related ...

S. A. David S. E. Hanzelka C. P. Haltom

1981-01-01

315

Method for dehydrating manganese dioxide  

SciTech Connect

A method is described for preparing a water-free lithium-manganese dioxide battery comprising: assembling the battery comprising lithium anode, a cathode comprising carbon and manganese dioxide, and a cell container; adding to the cell container a fluid containing a dehydrating agent which reacts with water bound to the manganese dioxide to form a reaction product that is extractable from the manganese dioxide; removing the fluid from the cell container; hermetically sealing and connecting the container to a vacuum source; establishing a vacuum within the compartment to pull off any remaining amount of the fluid and any volatile reaction product from the manganese dioxide; releasing the vacuum; and adding anhydrous electrolyte and hermetically sealing the cell.

Marincic, N.; Fuksa, R.

1987-05-05

316

Diode fabricated by layer by layer deposition of semiconductor nanoparticles  

Microsoft Academic Search

We report the development of a modified polyelectrolyte deposition technique for building multilayer thin films. The quantum dots of zinc sulphide nanoparticles doped with manganese were synthesized by co-precipitation techniques and the nanoparticles were found to consist of crystallites that were estimated to be around 2.2 nm. The modified polyelectrolyte deposition technique has been used for the growth of multifunctional

B. Hemtanon; C. Thanachayanont; D. Das; J. Dutta

2005-01-01

317

Ferrite Treatment of Actinide Waste Solutions: Alternative Methods of Ferrite Production for Use in Waste Treatment.  

National Technical Information Service (NTIS)

Two alternative sources of ferrite for use in actinide removal from process waste solutions at Rocky Flats were investigated to simplify the ferrite process for plant use. These included the formation of iron ferrite (FeO Fe sub 2 O sub 3 ) by the partial...

T. E. Boyd R. L. Kochen M. Y. Price

1985-01-01

318

Review of Ferrite Phase Shifter Technology  

Microsoft Academic Search

Ferrite phase shifter technology is reviewed. Particular emphasis is placed on discussion of nonreciprocal, toroidal waveguide phasers and dual mode reciprocal phasers for use in phased array antennas.

L. R. Whicker

1973-01-01

319

Progress in ferrite phase shifters  

NASA Astrophysics Data System (ADS)

Advances in the technology of reciprocal ferrite phase shifters are outlined. Nonlatching rotary-field phase shifters have been produced with enhanced phase accuracy and modest control power. A significant quantity of dual-mode latching units has been built at 35 GHz, with good results. Both types of phase shifter can be adapted to perform other functions in addition to phase shifting. Examples of phase shifters that perform duplexing and polarization switching functions are given.

Boyd, C. R., Jr.

1983-10-01

320

Ferrite-filled cavity resonators  

Microsoft Academic Search

An approximation technique is developed for the electromagnetic resonances and electric fields inside a cavity of arbitrary\\u000a shape whose walls are perfectly conducting and which is filled with a lossless ferrite. Operator notation is introduced and\\u000a it is proved that the operator for this problem is self-adjoint. A variational expression is introduced and this functional\\u000a is minimized by employing the

D. A. Taggart; F. W. Schott

1972-01-01

321

Strength correlation with residual ferrite fraction in 9CrODS ferritic steel  

NASA Astrophysics Data System (ADS)

The microstructure and tensile properties at 973 K in 9CrODS steels were investigated with respect to various fractions of the residual ferrite from zero to 47 vol.%. The formation of the residual ferrite was discussed from a balance between a chemical driving force for ? to ? reverse transformation and the oxide particle pinning force, while 0.04 mass% carbon sample could contain an equilibrium ?-ferrite. With increasing volume fraction of the residual ferrite, strength at 973 K increases but ductility decreases, which is attributed to the fact that the residual ferrite is harder than the tempered martensite.

Miyata, R.; Ukai, S.; Wu, X.; Oono, N.; Hayashi, S.; Ohtsuka, S.; Kaito, T.

2013-11-01

322

Preparation of chemical manganese dioxide from manganese sulfate  

Microsoft Academic Search

Chemical Manganese Dioxide (CMD) was prepared by an alkali-oxidation method. There are several virtues to this environmental friendly and clean process, including the nontoxic and harmless reagents and products, easy operations, no pollutants, easily obtained raw materials and moderate reaction conditions. The synthesized manganese dioxide was characterized by XRD and SEM. The particles were small, consisting primarily of ?-MnO2 and

Jiangang FU; Zhangxing HE; Hui WANG; Wei LIANG; Chao GUO

2010-01-01

323

NIOBIUM IN FERRITIC AND MARTENSITIC STAINLESS STEELS  

Microsoft Academic Search

A review has been presented of the effects of niobium in ferritic and martensitic stainless steels, introducing some new stainless steels containing niobium. An addition of niobium to the steel has a beneficial effect on improving the corrosion resistance of ferritic stainless steel, since niobium reacts with carbon to form stable carbides, consequently, resulting in keeping effective content of chromium

Naoto Hiramatsu

324

Dielectric Waveguide Reciprocal Ferrite Phase Shifter.  

National Technical Information Service (NTIS)

A dielectric waveguide reciprocal ferrite phase shifter is provided for use in a dielectric waveguide transmission line. The phase shifter is comprised of a length of ferrite of the same cross-sectional dimension as that of the dielectric waveguide and in...

R. W. Babbitt R. A. Stern

1982-01-01

325

A Twin Toroid Ferrite Phase Shifter  

Microsoft Academic Search

Ferrite phase shift and control components designed with low reluctance magnetic bias circuits help to reduce space, weight and energy consumption in microwave systems. Avoiding air-gaps is essential and one suitable geometrical arrangement is the toroidal shaped ferrite positioned inside a rectangular waveguide. A finite element method is presented to model the nonuniform magnetization and partially magnetized state of this

A. Abuelma'atti; I. Khairuddin; A. Gibson; I. Morgan; A. Haigh

2007-01-01

326

Ferrite Phase Shifters in Rectangular Wave Guide  

Microsoft Academic Search

The problem of the propagation of electromagnetic energy down an infinitely long rectangular wave guide partially filled by a ferrite slab is solved. The solution is expressed in the form of a transcendental equation involving the propagation constant. Calculations are carried out for a lossless ferrite, and the phase constant is evaluated as a function of the appropriate parameters, namely,

Benjamin Lax; Kenneth J. Button; LAURA M. ROTHt

1954-01-01

327

Precise Control of Ferrite Phase Shifters  

Microsoft Academic Search

Hysteresis and thermal drifts can prevent accurate calibration of ferrite phase shifters. To provide a precise setting of phase in response to a control signal a servo system has been developed. This system utilizes a control frequency to determine uniquely the phase shift in a ferrite element. The desired phase shift is then a function only of control frequency and

D. D. King; C. M. Johnson; C. M. Barrack

1959-01-01

328

Magnetic properties of hexagonal ferrite dot arrays  

Microsoft Academic Search

Patterned magnetic media have been considered as one of the promising candidates for future ultra-high-density magnetic recording. In this paper, a new kind of patterned medium based on hexagonal ferrite have been studied. We have successfully fabricated strontium ferrite dot arrays by electron beam lithography. Their magnetic properties are evaluated by magnetic force microscopy (MFM) and superconducting quantum interference device

Xiaoxi Liu; Akimitsu Morisako

2006-01-01

329

Synthesis Of Different Phases Of Nano Manganese Oxides And Their Dielectric Behaviour In Chitosan Composites  

NASA Astrophysics Data System (ADS)

Nanoscale oxides of transition metals, particularly manganese, are desirable for many applications in designing electric, magnetic and heterogeneous catalytic materials. Manganese oxides exist in different phases, viz. MnO, MnO2, Mn2O3, Mn2O7 and Mn3O4. Using different synthetic routes it is possible to synthesize different phases of manganese oxides. Moreover, composites of these oxides with polymer have the potential to address the needs of emerging dielectric technologies. In the present work, using manganese chloride and hydrazine hydrate, Mn3O4 and Mn2O3 nanoparticles were successfully synthesized by conventional and hydrothermal method respectively. The variation in the formation of the different phases has been discussed. The nanoparticles were well characterized by X-ray Diffraction and using the Debye Scherrer formula, the average size of Mn3O4 and Mn2O3 nanoparticles were calculated to be 35 nm and 25 nm respectively. Using solution casting method, nanocomposites of chitosan/Mn3O4 were prepared and their electrochemical properties were studied using electrochemical impedance spectroscopy. It was observed that with increase in the content of nano oxides, the conductivity of the films increased. Also, the variation in the permittivity of these samples with respect to frequency was studied. The results suggest that the composites have a fair chance to be used in energy storage devices.

Harshita, B. A.; Bhat, D. Krishna; Bhatt, Aarti S.

2011-10-01

330

Hybrid ternary rice paper-manganese oxide-carbon nanotube nanocomposites for flexible supercapacitors.  

PubMed

Modern portable electronic devices create a strong demand for flexible energy storage devices. Paper based nanocomposites are attractive as sustainable materials for such applications. Here, we directly explored the hydroxyl chemistry of cellulose fibers to synthesize hybrid ternary nanocomposites, comprised of rice paper, single-walled carbon nanotubes (SWCNTs) and manganese oxide nanoparticles. The functional groups on cellulose fibers can react with adsorbed permanganate ions, resulting in uniform deposition of manganese oxide nanoparticles. SWCNTs coated on top of manganese oxide nanoparticles form a highly conductive network connecting individual manganese oxide particles. By using the hybrid ternary composites as electrodes, the assembled two-electrode supercapacitors demonstrated high capacitance (260.2 F g(-1)), energy (9.0 W h kg(-1)), power (59.7 kW kg(-1)), and cycle stability (12% drop after 3000 cycles). In addition, the nanocomposites show good strength and excellent mechanical flexibility, and their capacitance shows negligible changes after bending more than 100 times. These findings suggest that opportunities exist to further explore the rich chemistry of cellulose fibers for innovative energy applications. PMID:24077360

Jiang, Wenchao; Zhang, Kaixi; Wei, Li; Yu, Dingshan; Wei, Jun; Chen, Yuan

2013-09-27

331

The effect of reaction temperature on the particle size, structure and magnetic properties of coprecipitated CoFe 2O 4 nanoparticles  

Microsoft Academic Search

Magnetic nanoparticles of cobalt ferrite have been synthesized at different temperatures without any subsequent heat treatment. The particle size, crystal structure and magnetic properties of as-synthesized particles were investigated by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy and vibrating sample magnetometer. The nanoparticles are of cubic spinel structure and equiaxial shape. The average size of nanoparticles increases

Yuqiu Qu; Haibin Yang; Nan Yang; Yuzun Fan; Hongyang Zhu; Guangtian Zou

2006-01-01

332

Nanocrystalline transition metal ferrites: Synthesis, characterization and surface functionalization  

NASA Astrophysics Data System (ADS)

In this thesis, a new synthetic methodology for the high yield synthesis of spinel-type transition metal ferrite nanoparticles has been developed. This approach is based on the complexation of the first-row transition metal cations with diethylene glycol (DEG) followed by the hydrolysis of the resulting chelate iron alkoxide complexes in the presence of an alkaline hydroxide. Due to the passivation of their surfaces with DEG molecules, the as-prepared nanoparticles are stable against agglomeration and can be easily dispersed in polar protic solvents (water, alcohols, etc.). Alternatively, a postsynthesis passivation with carboxylate ions can render the iron oxide nanocrystals highly dispersible in non-polar solvents. Optimization of the reaction conditions suggested that the size of the nanocrystals could be controlled by changing the complexing strength of the reaction medium. This hypothesis was verified in the case of the Fe3O4 nanoparticles: their sizes vary from 5.7 nm when the reaction is performed in neat diethylene glycol to 16.8 nm in N-methyl diethanolamine (NMDEA), whereas a 1:1 (%wt) mixture of these solvents yields nanocrystals with an average size of and 12.7 nm. A detailed characterization by using a wide variety of techniques, including powder X-Ray diffraction, IR spectroscopy, thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and 1H-NMR spectrometry was performed in order to elucidate the composition and the morphology of the variable-sized iron oxide nanoparticles. Both finite size and interparticle interaction effects were identified to influence the magnetic behavior of the oleate-capped nanosized particles. At low temperatures the Fe3O 4 nanocrystals exhibit a ferromagnetic behavior with blocking temperatures which increase with the average particle size, whereas at room temperature, except for the largest nanoparticles, they undergo a superparamagnetic relaxation. We exploited the high surface reactivity of the 10 nm Fe3O 4 nanoparticles to attach 2-3 nm gold grains to their surfaces through a simple, two-step chemically controlled procedure. By chemically bonding bioactive molecules to the attached Au nanoparticles these novel nanoarchitectures open up new opportunities for the implementation of the magnetic nanoparticles as a platform for various applications in the biomedical field.

Caruntu, Daniela

333

Manganese sulfide formation via concomitant microbial manganese oxide and thiosulfate reduction.  

PubMed

The dissimilatory metal-reducing bacterium, Shewanella oneidensis MR-1 produced ?-MnS (rambergite) nanoparticles during the concurrent reduction of MnO? and thiosulfate coupled to H? oxidation. To investigate effect of direct microbial reduction of MnO? on MnS formation, two MR-1 mutants defective in outer membrane c-type cytochromes (?mtrC/?omcA and ?mtrC/?omcA/?mtrF) were also used and it was determined that direct reduction of MnO? was dominant relative to chemical reduction by biogenic sulfide generated from thiosulfate reduction. Although bicarbonate was excluded from the medium, incubations of strain MR-1 with lactate as the electron donor produced MnCO? (rhodochrosite) as well as MnS in nearly equivalent amounts as estimated by micro X-ray diffraction (micro-XRD) analysis. It was concluded that carbonate released from lactate metabolism promoted MnCO? formation and that Mn(II) mineralogy was strongly affected by carbonate ions even in the presence of abundant sulfide and weakly alkaline conditions expected to favour the precipitation of MnS. Formation of MnS, as determined by a combination of micro-XRD, transmission electron microscopy, energy dispersive X-ray spectroscopy, and selected area electron diffraction analyses was consistent with equilibrium speciation modelling predictions. Biogenic manganese sulfide may be a manganese sink in the Mn biogeochemical cycle in select environments such as deep anoxic marine basins within the Baltic Sea. PMID:21951417

Lee, Ji-Hoon; Kennedy, David W; Dohnalkova, Alice; Moore, Dean A; Nachimuthu, Ponnusamy; Reed, Samantha B; Fredrickson, James K

2011-09-27

334

Application of Ferrite to Electromagnetic Wave Absorber and its Characteristics  

Microsoft Academic Search

An electromagnetic wave absorber utilizing ferrite or rubber ferrite composed of ferrite powder and rubber is described. In our investigation, the existence of a matching frequency fm and a matching thickness tm has been found. The terms fm and tm mean that the ferrite which is backed with a conducting plate can be a perfect absorber only under the conditions

YOSHIYUKI NAITO; KUNIHIRO SUETAKE

1971-01-01

335

Surface Induced Suppression of Magnetization and Surface magnetization Reversal in Magnetic Nanoparticles  

Microsoft Academic Search

Ferrite nanoparticles show strong size and surface dependent magnetic properties. These manifest themselves as a reduced magnetization with decreasing size and an unconventional temperature dependence of magnetization. These effects can be attributed to competing exchange interactions that contribute differently at the nanoparticle surface and interior, leading to reduced ferromagnetic order at the surface. A simple model is constructed that are

Chaehyun Kim; Wei Lai; Renat Sabirianov; Yuhang Ren; Hao Zeng

2010-01-01

336

Gas sensing properties of ZnFe2O4 nanoparticles  

NASA Astrophysics Data System (ADS)

Gas sensing performance of ZnFe2O4 ferrite nanoparticles towards various organic volatile compounds is investigated. A self-combustion of a citrate-gel precursor at ~90 °C in ambient air followed by annealing at 400 °C for 2 h has been explored to prepare a single phase spinel ferrite powder containing granular nanoparticles of average 23 nm diameters. A powder compact measures chemiresistive sensitivity of 59, 51, and 67% for organic vapor-analytes methanol, ethanol, and acetone respectively of 200 ppm at 250 °C. Excellent sensitivity of the granular nanoparticles results due to a large surface area to volume ratio effect.

Misra, Susmita; Ram, S.

2013-06-01

337

HRTEM Study of Irradiation-Induced Cavities in Oxide-Dispersed Ferritic Steel  

NASA Astrophysics Data System (ADS)

Structures of oxide nanoparticles and the effects of matrix/nanoparticle interfaces on irradiation-induced cavity nucleation and distribution in Fe-16Cr-4.5Al-0.3Ti-2W-0.37Y2O3 oxide-dispersed ferritic steel have been studied using high-resolution transmission electron microscopy techniques. The frequent observations of partially crystallized complex-oxide nanoparticles in as-fabricated steel provide an implication into the formation mechanism of nanoparticles. The mechanism involves the solid-state mixing of pre-alloyed metallic powder and Y2O3 powder to form an amorphous solid solution and from which the nucleation of high density complex-oxide nanoparticles (on the order of ~1 × 1022 m-3). Simultaneous dual ion beams consisting of iron and helium were employed to irradiate the oxide-dispersed steel at 698 K (425 °C). The result shows that the defective oxide nanoparticles have a positive effect on the mitigation of dimensional swelling as a result of the preferred nucleation of helium-filled cavities at the matrix/nanoparticle interfaces.

Hsiung, Luke L.

2013-10-01

338

Synthesis of copper ferrite from thermolysis of copper ferrimalonate precursor (invited)  

NASA Astrophysics Data System (ADS)

The thermolysis of copper ferrimalonate Cu3[Fe(CH2C2O4)3]2.9H2O has been investigated up to 1073 K in flowing air atmosphere employing various physico-chemical techniques, i.e., simultaneous TG-DTG-DSC, XRD, Mössbauer, IR, and TEM. The precursor undergoes dehydration and decomposition simultaneously to yield copper malonate and iron(II) malonate intermediates at 433 K. At higher temperature (548 K) these intermediate species decompose to CuO and ?-Fe2O3, respectively. Finally, copper ferrite, CuFe2O4, has been obtained as a result of solid state reaction between ?-Fe2O3 and CuO at a temperature (623 K) much lower than that for conventional ceramic method. The TEM analysis of the final thermolysis product reveals the formation of monodisperse copper ferrite nanoparticles with an average particle size of 33 nm. Magnetic studies show that these nanoparticles exhibit saturation magnetization of 2783 G and Curie temperature of 709 K. Lower magnitude of these parameters as compared with the bulk values may be attributed to the ultrafine grain size of the ferrite particles.

Singh, Jashanpreet; Kaur, Harpreet; Kaur, Manpreet; Randhawa, B. S.

2010-05-01

339

Extraction of manganese from electrolytic manganese residue by bioleaching.  

PubMed

Extraction of manganese from electrolytic manganese residues using bioleaching was investigated in this paper. The maximum extraction efficiency of Mn was 93% by sulfur-oxidizing bacteria at 4.0 g/l sulfur after bioleaching of 9days, while the maximum extraction efficiency of Mn was 81% by pyrite-leaching bacteria at 4.0 g/l pyrite. The series bioleaching first by sulfur-oxidizing bacteria and followed by pyrite-leaching bacteria evidently promoted the extraction of manganese, witnessing the maximum extraction efficiency of 98.1%. In the case of sulfur-oxidizing bacteria, the strong dissolution of bio-generated sulfuric acid resulted in extraction of soluble Mn2+, while both the Fe2+ catalyzed reduction of Mn4+ and weak acidic dissolution of Mn2+ accounted for the extraction of manganese with pyrite-leaching bacteria. The chemical simulation of bioleaching process further confirmed that the acid dissolution of Mn2+ and Fe2+ catalyzed reduction of Mn4+ were the bioleaching mechanisms involved for Mn extraction from electrolytic manganese residues. PMID:21050747

Xin, Baoping; Chen, Bing; Duan, Ning; Zhou, Changbo

2010-11-02

340

Structure of complex oxide nanoparticles in a Fe-14Cr-2W-0.3Ti-0.3Y2O3 ODS RAF steel  

NASA Astrophysics Data System (ADS)

One of the most crucial steps in the development of oxide dispersion strengthened (ODS) reduced activation ferritic (RAF) steels is the engineering of their microstructure, which includes control of the type and size of oxide nanoparticles.

Unifantowicz, P.; P?oci?ski, T.; Williams, C. A.; Schäublin, R.; Baluc, N.

2013-11-01

341

Maternal–fetal Distribution of Manganese in the Rat Following Inhalation Exposure to Manganese Sulfate  

Microsoft Academic Search

Studies examining the pharmacokinetics of manganese during pregnancy have largely focused on the oral route of exposure and have shown that the amount of manganese that crosses the rodent placenta is low. However, limited information exists regarding the distribution of manganese in fetal tissues following inhalation. The objective of this study was to determine manganese body burden in CD rats

David C. Dorman; Anna M. McElveen; Marianne W. Marshall; Carl U. Parkinson; R. Arden James; Melanie F. Struve; Brian A. Wong

2005-01-01

342

21 CFR 73.2775 - Manganese violet.  

Code of Federal Regulations, 2013 CFR

...OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2775 Manganese violet. (a) Identity...Manganese violet is safe for use in coloring cosmetics generally, including cosmetics applied to the area of the eye, in...

2013-04-01

343

21 CFR 582.5452 - Manganese gluconate.  

Code of Federal Regulations, 2013 CFR

...AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5452 Manganese gluconate. (a) Product. Manganese gluconate. (b)...

2013-04-01

344

21 CFR 582.5449 - Manganese citrate.  

Code of Federal Regulations, 2013 CFR

...AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5449 Manganese citrate. (a) Product. Manganese citrate. (b)...

2013-04-01

345

21 CFR 582.5458 - Manganese hypophosphite.  

Code of Federal Regulations, 2013 CFR

...AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5458 Manganese hypophosphite. (a) Product. Manganese hypophosphite....

2013-04-01

346

Toxicological Profile for Manganese and Compounds.  

National Technical Information Service (NTIS)

The ATSDR Toxicological Profile is intended to characterize succinctly the toxicological and health effects information for manganese compounds. It identifies and reviews the key literature that describes manganese compounds' toxicological properties. Oth...

1992-01-01

347

Ferritic steel melt and FLiBe\\/steel experiment : melting ferritic steel  

Microsoft Academic Search

In preparation for developing a Z-pinch IFE power plant, the interaction of ferritic steel with the coolant, FLiBe, must be explored. Sandia National Laboratories Fusion Technology Department was asked to drop molten ferritic steel and FLiBe in a vacuum system and determine the gas byproducts and ability to recycle the steel. We tried various methods of resistive heating of ferritic

Kenneth P. Troncosa; Brandon M. Smith; Tina Joan Tanaka

2004-01-01

348

New barium ferrite particles: Spherical shape  

NASA Astrophysics Data System (ADS)

Pure and ZnTi-doped spherical barium ferrite particles were prepared using two different methods: semicoprecipitation and ultrasonic spray pyrolysis. The ultrasonic spray pyrolysis method was more effective in controlling particle shape. Particle size was in between 0.27 and 0.3 ?m. Coercivity and saturation magnetization were in the range of 1000 to 5000 Oe and 49 to 53 emu/g, respectively. Crystallization of amorphous Ba-Fe-O spherical precursors occurs at a lower temperature than Ba-Fe-Zn-Ti-O precursors. ?M measurement shows that magnetic interaction in spherical barium ferrite tape is weaker than hexagonal platelet barium ferrite.

Hong, Y. K.; Jung, H. S.

1999-04-01

349

Über den Einfluß von Wirbelströmen auf die Frequenzabhängigkeit der komplexen Permeabilität hochpermeabler Mangan-Zink-Ferrite  

NASA Astrophysics Data System (ADS)

Nach der Einleitung, in der die Bedeutung der Wirbelströme für den Anstieg der Verluste mit der Frequenz in hochpermeablen Mn-Zn-Ferriten dargelegt wird, werden in Abschn. 2 gemessene Ortskurven der komplexen Permeabilität von Mn-Zn-Ferriten mit Werten der Anfangspermeabilität von 4000 bis 8000 und des spezifischen Widerstandes von 7 bis 138 cm (bei R. T.) vorgestellt. In Abschn. 3 wird der Versuch erläutert, einen gewissen Anfangsteil dieser Ortskurve durch theoretische Wirbelstromortskurven der komplexen Permeabilität, bei denen die Relaxation der komplexen Leitfähigkeit in Form eines von GRANT angegebenen Ausdruckes berücksichtigt ist, wiederzugeben. Die Ergebnisse, die in Abschn. 4 diskutiert werden, erlauben den Schluß, daß die mit der Relaxation der Leitfähigkeit verknüpften kapazitiven Wirbelströme für den Charakter des Anfangsverlaufes der an Ringkernen gemessenen Ortskurven der komplexen Permeabilität von hochpermeablen Mn-Zn-Ferriten bestimmend sein können.Translated AbstractOn the Effect of Eddy Currents on the Magnetic Spectra of High-permeability Manganese-zinc FerritesAfter stressing the importance of eddy currents on the increase of magnetic losses with frequency on high-permeability Mn-Zn-ferrites (in the introduction), experimental curves in the complex plane of the variation of the complex permeability with frequency of Mn-Zn-Ferrites with an initial permeability of 4000 up to 8000 and resistivity of 7 up to 130 ohm . cm are presented in section 2. In section 3 the attempt is stated of reproducing a certain initial part of the curve of complex permeability by theoretical eddy current curves, taking into account the relaxation of complex conductivity in form of an expression given by GRANT. The results discussed in section 4 permit the conclusion, that the capacitive eddy currents due to the relaxation of conductivity may be the essential factor determining the character of the initial turn of the complex magnetic dispersion curve of high-permeability Mn-Zn-ferrites measured on toroidal samples.

Dietzmann, G.; Schaefer, M.

350

MANGANESE OXIDE REDUCTION IN LABORATORY MICROCOSMS  

Microsoft Academic Search

Manganese biogeochemistry holds special interest for the characterization of passive treatment systems designed to treat acidic mine waters while meeting enforceable effluent discharge limits set for manganese. In the present study, an initial anoxic enrichment culture was developed for use as an inoculum in experimental systems. Standard anoxic microcosms capable of reducing manganese from ~n~' to ~n'' were established from

Richard A. Royer; Richard F. Unz

2006-01-01

351

Manganese oxide cathodes for rechargeable batteries  

Microsoft Academic Search

Manganese oxides are considered as promising cathodes for rechargeable batteries due to their low cost and low toxicity as well as the abundant natural resources. In this dissertation, manganese oxides have been investigated as cathodes for both rechargeable lithium and alkaline batteries. Nanostructured lithium manganese oxides designed for rechargeable lithium cells have been synthesized by reducing lithium permanganate with methanol

Dongmin Im

2002-01-01

352

Autonomic Function in Manganese Alloy Workers  

Microsoft Academic Search

The observation of orthostatic hypotension in an index case of manganese toxicity lead to this prospective attempt to evaluate cardiovascular autonomic function and cognitive and emotional neurotoxicity in eight manganese alloy welders and machinists. The subjects consisted of a convenience sample consisting of an index case of manganese dementia, his four co-workers in a “frog shop” for gouging, welding, and

William W. Barrington; Carol R. Angle; Nancy K. Willcockson; Marjorie A. Padula; Thomas Korn

1998-01-01

353

21 CFR 184.1461 - Manganese sulfate.  

Code of Federal Regulations, 2010 CFR

...sulfate. (a) Manganese sulfate (MnSO4 ·H2...obtained by reacting manganese compounds with...byproduct in the manufacture of hydroquinone...on a slurry of manganese dioxide in sulfuric...with solid ferrous sulfate and coal,...

2010-01-01

354

21 CFR 184.1461 - Manganese sulfate.  

Code of Federal Regulations, 2010 CFR

...sulfate. (a) Manganese sulfate (MnSO4 ·H2...obtained by reacting manganese compounds with...byproduct in the manufacture of hydroquinone...on a slurry of manganese dioxide in sulfuric...with solid ferrous sulfate and coal,...

2009-04-01

355

Magnetic nanoparticles produced by surfactant-assisted ball milling  

Microsoft Academic Search

However, the size distribution of the particles obtained by ball milling can be quite wide compared with the chemical methods. The chemical methods, nevertheless, have had lim- ited success in the synthesis of hard magnetic nanoparticles of rare-earth compounds.7,8 Traditionally, surfactant-assisted ball milling technique has been used mainly for preparing ferrite nanoparticles, and not many studies have been con- ducted

V. M. Chakka; B. Altuncevahir; Z. Q. Jin; Y. Li; J. P. Liua

356

Magnetic micromachines prepared by ferrite plating technique  

NASA Astrophysics Data System (ADS)

By the sterolithography technique and the ferrite plating, we fabricated three types of magnetic micromachines which coated Fe3O4, Co0.39Fe2.61O4, and Co0.45Fe2.55O4, respectively. The stereolithography technique enables one to form the spiral-shape resinous templates and the ferrite plating enables one to coat the ferrites uniformly onto these templates from an aqueous solution. The total machine weight is light because a resin of the template body is almost the same density as water. We verified that the machines swim freely and wirelessly in water by applying a rotational magnetic field. As these machines coated with ferrites have the biocompatibility, there is the possibility of medical microrobots which swim in the human body for medical operations.

Nishimura, K.; Uchida, H.; Inoue, M.; Sendoh, M.; Ishiyama, K.; Arai, K. I.

2003-05-01

357

ALL-FERRITE RHIC INJECTION KICKER  

SciTech Connect

Ion beams are transferred from the AGS into RHIC in boxcar fashion as single bunches. The nominal design assumes 60 bunches per ring but increasing the number of bunches to gain luminosity is possible, thereby requiring injection kickers with a shorter rise time. The original injection system consists of traveling-wave dielectric loaded kicker magnets and a Blumlein pulser with a rise time adequate for the present operation. Voltage breakdown in the dielectric kickers suggested the use of all-ferrite magnets. In order to minimize the conversion cost, the design of the all-ferrite kicker uses the same components as the dielectric loaded units. The all-ferrite kickers showed in bench measured good breakdown properties and a current rise time of < 50 ns. A prototype kicker has been installed in the blue ring and was tested with beam. Beam measurements indicate suitability of all-ferrite kicker magnets for upgraded operation.

HAHN,H.; FISCHER,W.; PTITSYN,V.I.; TUOZZOLO,J.E.

2001-06-18

358

Microwave Reciprocal Latching Ferrite Phase Shifters.  

National Technical Information Service (NTIS)

The report describes analytical and experimental investigations carried out on dual-mode, reciprocal, latching ferrite phase shifters, with special emphasis placed on low insertion loss and low potential cost for production quantities. Analytical work has...

C. R. Boyd

1975-01-01

359

Temperature Compensated Latching Ferrite Phase Shifter.  

National Technical Information Service (NTIS)

The patent application describes a nonreciprocal latching phase shifter that is compensated for changes in temperature. A pair of ferrite rectangular toroids in series connection are inserted into a rectangular waveguide and a dielectric material is inser...

I. Bardash

1973-01-01

360

A Reciprocal TEM Latching Ferrite Phase Shifter  

Microsoft Academic Search

Considerable work has been done previously on latching ferrite phase shifters of the nonreciprocal variety. However, the requirement herein for reciprocity imposes new design problems and demands new thinking about switching techniques

J. W. Simon; W. K. Alverson; J. E. Pippin

1966-01-01

361

Ferrite HOM Absorber for the RHIC ERL  

SciTech Connect

A superconducting Energy Recovery Linac is under construction at Brookhaven National Laboratory to serve as test bed for RHIC upgrades. The damping of higher-order modes in the superconducting five-cell cavity for the Energy-Recovery linac at RHIC is performed exclusively by two ferrite absorbers. The ferrite properties have been measured in ferrite-loaded pill box cavities resulting in the permeability values given by a first-order Debye model for the tiled absorber structure and an equivalent permeability value for computer simulations with solid ring dampers. Measured and simulated results for the higher-order modes in the prototype copper cavity are discussed. First room-temperature measurements of the finished niobium cavity are presented which confirm the effective damping of higher-order modes in the ERL. by the ferrite absorbers.

Hahn,H.; Choi, E.M.; Hammons, L.

2008-10-01

362

Electrocatalytic oxidation of hydrazine at a glassy carbon electrode modified with nickel ferrite and multi-walled carbon nanotubes  

Microsoft Academic Search

A hydrothermal technique was used to synthesize nickel ferrite nanoparticles (NF-NPs) deposited on multi-walled carbon nanotubes\\u000a (MWCNTs). The material was characterized by scanning electron microscopy, energy dispersive spectrometry, and X-ray powder\\u000a diffraction which showed that the NF-NPs are located on the surface of the carboxylated MWCNTs. The material was used to modify\\u000a a glassy carbon electrode which then was characterized

Bin Fang; Yuehua Feng; Min Liu; Guangfeng Wang; Xiaojun Zhang; Meifang Wang

363

Carcinogenicity, mutagenicity and teratogenicity of manganese compounds.  

PubMed

Manganese, an essential trace element, is one of the most used metals in the industry. Recently, several new manganese compounds have been introduced as fungicide, as antiknock agent in petrol and as contrasting agent in nuclear magnetic resonance tomography. Manganese displays a somewhat unique behaviour with regard to its toxicity. It is relatively non-toxic to the adult organism except to the brain where it causes Parkinson-like symptoms when inhaled even at moderate amounts over longer periods of time. Relatively high doses of manganese affect DNA replication and repair in bacteria and causes mutations in microorganism and mammalian cells although the Ames test does not appear to be particularly responsive to manganese. In mammalian cells, manganese causes DNA damage and chromosome aberrations. Information on organic manganese derivatives is still insufficient. Large amounts of manganese affect fertility in mammals and are toxic to the embryo and foetus. The fungicide MANEB and the contrasting agent MnDPDP also can be embryotoxic, but the latter only at doses much higher than those clinically employed. Information on the anti-knock agent MMT is inadequate. On the other hand, manganese deficiency can also affect fertility and be teratogenic. Information on cancer due to manganese is scanty but the results available do not indicate that inorganic manganese is carcinogenic. More information is desirable with regard to the organic manganese derivatives. It may surprise that an agent that causes mutations is not also carcinogenic. The experience with manganese shows that conclusions with regard to carcinogenicity of an agent based on the observation of mutations are subject to uncertainties. Altogether, it appears that, because of the very high doses at which positive effects have been found, manganese would not represent a significant carcinogenic risk to the population and workers. Care must, however, be exercised with respect to central-nervous symptoms after chronic exposure and with respect to effects on the embryo. Pregnant women should not be exposed to manganese at the work place. PMID:11923066

Gerber, G B; Léonard, A; Hantson, Ph

2002-04-01

364

Nanostructured ferrites: Structural analysis and catalytic activity  

Microsoft Academic Search

In this work, we have investigated the structural and catalytic properties of Co, Cu and Ni spinel ferrites. Nanostructured ferrites with particle diameters varying from 3 to 10nm were obtained by the co-precipitation process. X-ray diffraction, X-ray fluorescence, X-ray photoelectron spectroscopy and Mössbauer spectroscopy were used for chemical and structural characterization. The catalytic efficiency of the samples was evaluated by

Adriana S. de Albuquerque; Marcus V. C. Tolentino; José D. Ardisson; Flávia C. C. Moura; Renato de Mendonça; Waldemar A. A. Macedo

365

New technologies for production of Ferrite cores  

Microsoft Academic Search

New technologies for producing ferrite memory cores include the incorporation of ferrite powder into sheets with a high binder content; fast multiple tooling presses stamping memory cores out of sheets; cheap high-capacity automated and highly controllable furnaces; and time-saving powder-processing equipment. The combination of processes and equipment meets the needs for increasingly larger numbers of cores, cheaper costs, smaller cores,

W. Wiechec

1968-01-01

366

A 30GHz Hexagonal Ferrite Phase Shifter  

Microsoft Academic Search

Highly-anisotropic hexaferrites, such as barium ferrite BaFe12O19 (BFO), are ideal for millimeter wave phase shifters due to a large ferromagnetic resonance frequency at low magnetic bias field H. It enables one to make millimeter-wave devices with compact magnetic systems. Here we discuss the design, fabrication and characterization of a BFO phase shifter. A microstrip line deposited on a ferrite substrate

A. S. Semenov; A. N. Slavin; J. V. Mantese

2005-01-01

367

A Waveguide Reciprocal Latching Ferrite Phase Shifter  

Microsoft Academic Search

The development of the non-reciprocal latching ferrite phase shifter may be considered to be one of the major factors in the realization of phased array RADAR systems. Its non-reciprocal characteristics however make it impractical for use with certain systems such as high p.r. f. and short range RADARS. A waveguide reciprocal Iatching ferrite phase shifter has been developed for use

I. Bardash; J. J. Maune

1968-01-01

368

Ferrite insertion at Recycler Flying Wire System  

SciTech Connect

Ferrite rods are installed inside the flying-wire cavity of the Recycler Ring and at entrance and exit beam pipes in order to absorb high-frequency electromagnetic waves excited by the beam. However, these rods may also deteriorate the vacuum pressure of the ring. An investigation is made to analyze the necessity of the ferrite rods at the entrance and exit beam pipes.

K.Y. Ng

2004-02-27

369

Magnetic nanoparticle properties and microstructure formation in liquid dispersions  

Microsoft Academic Search

The physical properties and microstructures of magnetite and cobalt ferrite nanoparticles, dispersed in liquid matrices, are studied. Qualitative and quantitative analyses of static magnetization curves were performed. Magneto-granulometric results were obtained and interactions and agglomerations were evidenced, as a function of the preparation techniques as well as carrier liquids and surfactants used

L. V. M. Rasa; D. Bica

2000-01-01

370

MO.Fe2O3 nanoparticles for self-controlled magnetic hyperthermia  

Microsoft Academic Search

Using a model Hamiltonian and the Green’s function technique for the Zn doped Mn-ferrite, Mn1-xZnxO.Fe2O3, and the Gd doped Zn-ferrite, ZnGdxFe(2-x)O4, nanoparticles of different compositions x were studied. The phase transition temperature, TC, and the coercive field, Hc, for different samples dependent upon composition, particle size, and shape were investigated. An attempt was made to enhance or to lower the

A. T. Apostolov; I. N. Apostolova; J. M. Wesselinowa

2011-01-01

371

MO.Fe2O3 nanoparticles for self-controlled magnetic hyperthermia  

Microsoft Academic Search

Using a model Hamiltonian and the Green's function technique for the Zn doped Mn-ferrite, Mn1-xZnxO.Fe2O3, and the Gd doped Zn-ferrite, ZnGdxFe(2-x)O4, nanoparticles of different compositions x were studied. The phase transition temperature, TC, and the coercive field, Hc, for different samples dependent upon composition, particle size, and shape were investigated. An attempt was made to enhance or to lower the

A. T. Apostolov; I. N. Apostolova; J. M. Wesselinowa

2011-01-01

372

Manganese and nitrogen in stainless steel SMA welds for cryogenic service  

SciTech Connect

Evaluation of a shielded metal arc (SMA) weld test matrix in which manganese (1.5 to 10 wt-%) and nitrogen (0.04 to 0.26wt-%) were varied independently has clarified the effect of these elements on cryogenic mechanical properties and predicted ferrite number (FN). Several molybdenum and boron additions were also made, but they had no observable effect on strength or Charpy V-notch (CVN) absorbed energy. The matrix was based on a type 308L stainless steel weld metal composition. Desired compositions and constant FN were attained through alloy additions to the electrode coating. For each weld, one all-weld metal 4-K tensile specimen and five 76-K CVN impact specimens were tested. Increasing the nitrogen content from 0.05 to 0.25 wt-% linearly increased the 4-K yield strength from 600 to 1300 MPa (87 to 188.5 ksi) and decreased the 76-K lateral expansion from 0.6 to 0.1 mm (0.24 to 0.04 in.). Nitrogen reduced the 76-K CVN absorbed energy but not linearly. The addition of manganese slightly increased the yield strength and slightly decreased the lateral expansion. The 4-K tensile strength was relatively unaffected by alloy additions; values varied between 1300 and 1500 MPa (188.5 and 217.5 ksi). The DeLong FN predictive equation was improved by substituting the Szumachowski-Kotecki constant manganese term of 0.35 into the DeLong nickel equivalent. Analysis of the remaining FN deviation revealed an interaction between nitrogen and manganese. Addition of manganese-nitrogen interactive terms to the nickel equivalent increased the accuracy of the FN prediction.

Mc Cowan, C.N.; Siewart, T.A.; Reed, R.P.; Lake, F.B.

1987-03-01

373

Dielectric properties of rubber ferrite composites containing mixed ferrites  

NASA Astrophysics Data System (ADS)

Rubber ferrite composites (RFC) are important since they have useful applications as microwave absorbers and flexible magnets. The mouldability of these composites into complex shapes is another advantage. The evaluation of their dielectric and magnetic properties is important in understanding the physical properties of these composites. Pre-characterized nickel zinc ferrites (Ni1-xZnxFe2O4 where 0icons/Journals/Common/leq" ALT="leq" ALIGN="TOP"/> xicons/Journals/Common/leq" ALT="leq" ALIGN="TOP"/>1 in steps of 0.2) prepared by ceramic techniques were incorporated in to a butyl rubber matrix according to a specific recipe to yield RFCs. The dielectric constant of ceramic Ni1-xZnxFe2O4 and the butyl rubber composites incorporated with Ni1-xZnxFe2O4 are studied as a function of frequency, composition, loading and temperature. The observed data indicates that the dependence of the dielectric constant on frequency follows Maxwell-Wagner interfacial polarization. The compositional (zinc content, i.e. x value) dependence shows that the dielectric constant increases initially and reaches a maximum value for the composition corresponding to x = 0.6 and thereafter it decreases. This can be explained on the basis of porosity and alternating current (AC) conductivity. It was also observed that the dielectric constant of the composite material increases with an increase of the volume fraction of the magnetic filler. These observations satisfy some mixture equations, which correlate the dielectric constant of the matrix, filler and the composites. The temperature dependence of the dielectric constant of the ceramic samples as well as the RFCs shows an increase with an increase of temperature at low frequencies. The dielectric constant of the blank butyl rubber was also determined. It was observed that for a blank sample (without filler) the dielectric constant decreases with an increase of temperature. This is due to the decrease in polymer density with increase in temperature. These results suggest that the magnetic and dielectric properties of RFCs can be manipulated by appropriate loading and a judicious choice of the magnetic filler. The modification of these properties will aid in the design of composite materials for microwave absorbers.

Anantharaman, M. R.; Sindhu, S.; Jagatheesan, S.; Malini, K. A.; Kurian, P.

1999-08-01

374

Origin of Oceanic Manganese Minerals  

Microsoft Academic Search

A criterion is suggested for discrimination between ferromanganese oxide minerals, deposited after the introduction of manganese and associated elements in sea water solution at submarine vulcanism, and minerals which are slowly formed from dilute solution, largely of continental origin. The simultaneous injection of thorium into the ocean by submarine vulcanism is indicated, and its differentiation from continental thorium introduced into

G. Arrhenius; J. Mero; J. Korkisch

1964-01-01

375

Manganese Star Iota Coronae Borealis.  

National Technical Information Service (NTIS)

An abundance analysis of the manganese star Iota Coronae Borealis is carried out in detail by making use of a model atmosphere with theta sub e = 0.458, log g = 3.7, N(He)/N(H) = 0.12. The energy distribution and H gamma profile are reproduced by this mod...

J. E. Ross L. H. Aller

1969-01-01

376

An X-ray absorption spectroscopy study of the inversion degree in zinc ferrite nanocrystals dispersed on a highly porous silica aerogel matrix.  

PubMed

The structural properties of zinc ferrite nanoparticles with spinel structure dispersed in a highly porous SiO(2) aerogel matrix were compared with a bulk zinc ferrite sample. In particular, the details of the cation distribution between the octahedral (B) and tetrahedral (A) sites of the spinel structure were determined using X-ray absorption spectroscopy. The analysis of both the X-ray absorption near edge structure and the extended X-ray absorption fine structure indicates that the degree of inversion of the zinc ferrite spinel structures varies with particle size. In particular, in the bulk microcrystalline sample, Zn(2+) ions are at the tetrahedral sites and trivalent Fe(3+) ions occupy octahedral sites (normal spinel). When particle size decreases, Zn(2+) ions are transferred to octahedral sites and the degree of inversion is found to increase as the nanoparticle size decreases. This is the first time that a variation of the degree of inversion with particle size is observed in ferrite nanoparticles grown within an aerogel matrix. PMID:23406136

Carta, D; Marras, C; Loche, D; Mountjoy, G; Ahmed, S I; Corrias, A

2013-02-01

377

An X-ray absorption spectroscopy study of the inversion degree in zinc ferrite nanocrystals dispersed on a highly porous silica aerogel matrix  

NASA Astrophysics Data System (ADS)

The structural properties of zinc ferrite nanoparticles with spinel structure dispersed in a highly porous SiO2 aerogel matrix were compared with a bulk zinc ferrite sample. In particular, the details of the cation distribution between the octahedral (B) and tetrahedral (A) sites of the spinel structure were determined using X-ray absorption spectroscopy. The analysis of both the X-ray absorption near edge structure and the extended X-ray absorption fine structure indicates that the degree of inversion of the zinc ferrite spinel structures varies with particle size. In particular, in the bulk microcrystalline sample, Zn2+ ions are at the tetrahedral sites and trivalent Fe3+ ions occupy octahedral sites (normal spinel). When particle size decreases, Zn2+ ions are transferred to octahedral sites and the degree of inversion is found to increase as the nanoparticle size decreases. This is the first time that a variation of the degree of inversion with particle size is observed in ferrite nanoparticles grown within an aerogel matrix.

Carta, D.; Marras, C.; Loche, D.; Mountjoy, G.; Ahmed, S. I.; Corrias, A.

2013-02-01

378

Novel magnetic SPE method based on carbon nanotubes filled with cobalt ferrite for the analysis of organochlorine pesticides in honey and tea.  

PubMed

A novel magnetic SPE method based on magnetic cobalt ferrite filled carbon nanotubes (MFCNTs) coupled with GC with electron capture detection was developed to determine organochlorine pesticides (OCPs) in tea and honey samples. The MFCNTs were prepared through the capillarity of carbon nanotubes for drawing mixed cobalt and iron nitrates solution into their inner cavity followed by heating to 550°C under Ar to form the cobalt ferrite nanoparticles. SEM images provided visible evidence of the filled cobalt ferrite nanoparticles in the multiwalled nanotubes. X-ray photoelectron spectroscopy indicated no adhesion of cobalt ferrite nanoparticles and metal salts on the outer surface of the MFCNTs. Eight OCPs were extracted with the MFCNTs. The enrichment factors were in the range of 52-68 for eight OCPs. The LODs for the eight OCPs were in the range of 1.3-3.6 ng/L. The recoveries of the OCPs for honey and tea samples were 83.2-128.7 and 72.6-111.0%, respectively. The RSDs for these samples were below 6.8%. The new method is particularly suited to extract nonpolar and weakly polar analytes from a complex matrix and could potentially be extended to other target analytes. PMID:23926126

Du, Zhuo; Liu, Miao; Li, Gongke

2013-09-01

379

Biological investigation of a citrate-coated cobalt-ferrite-based magnetic fluid  

NASA Astrophysics Data System (ADS)

The present study reports on several in vivo biological tests carried out with a cobalt-ferrite, citrate-coated, magnetic fluid sample developed for biomedical purposes. Systematic biological investigation was performed after endovenous injection in mice. Morphological analysis showed magnetic nanoparticle (MNP) infiltration in the parenchyma or vessels of all investigated organs. Nevertheless, at the investigated dose and period of treatment, no cell damage or inflammatory processes were observed. Cytometry alterations and genotoxic effects were not observed. Although precipitation of MNPs in tissues may be taken as undesirable, the absence of morphological alterations is very promising. The data show that the investigated sample is biocompatible and useful for biomedical applications.

Kückelhaus, S.; Garcia, V. A. P.; Lacava, L. M.; Azevedo, R. B.; Lacava, Z. G. M.; Lima, E. C. D.; Figueiredo, F.; Tedesco, A. C.; Morais, P. C.

2003-05-01

380

Stability tests of permanent magnets built with strontium ferrite.  

National Technical Information Service (NTIS)

Permanent magnets built using strontium ferrite bricks have been tested for stability against demagnetization. Ten test dipoles were built to monitor ferrite behavior under a variety of stressing conditions, including irradiation, mechanical shock, extrem...

H. D. Glass B. C. Brown G. W. Foster W. B. Fowler R. Gustafson

1997-01-01

381

Flash microwave synthesis of trevorite nanoparticles  

SciTech Connect

Nickel ferrite nanoparticles have several possible applications as cathode materials for rechargeable batteries, named 'lithium-ion' batteries. In this study, NiFe{sub 2}O{sub 4} was prepared by microwave induced thermohydrolysis. The obtained nanoparticles were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), BET method, transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). All the results show that the microwave one-step flash synthesis leads in a very short time to NiFe{sub 2}O{sub 4} nanoparticles with elementary particles size close to 4-5 nm, and high specific surfaces (close to 240 m{sup 2}/g). Thus, microwave heating appears as an efficient source of energy to produce quickly nanoparticles with complex composition as ferrite. - Graphical abstract: At the end of the 20th century, a new concept of battery was introduced, named 'Li ion', where electrodes are both lithium-storage materials. Compounds with a spinel structure are so investigated and microwave heating appears as an efficient source of energy to produce nanoparticles in a very short time and at low temperature, with controlled size (4-5 nm) and high specific area (240 m{sup 2}/g). Legend: Pictogram represents our original microwave reactor, the RAMO (French acronym of Reacteur Autoclave Micro-Onde), containing the reactants and submitted to the microwave irradiation. Multicolor candy represents obtained material.

Bousquet-Berthelin, C. [NANOSCIENCES-GERM - Groupe d'Etudes et de Recherches en Microondes, I.C.B. (Institut Carnot de Bourgogne), UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, B.P. 47870, 21078 Dijon Cedex (France)], E-mail: christelle.bousquet@u-bourgogne.fr; Chaumont, D.; Stuerga, D. [NANOSCIENCES-GERM - Groupe d'Etudes et de Recherches en Microondes, I.C.B. (Institut Carnot de Bourgogne), UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, B.P. 47870, 21078 Dijon Cedex (France)

2008-03-15

382

Soluble manganese removal by porous media filtration.  

PubMed

Filtration experiments were conducted to investigate soluble manganese removal in granular media filtration; sand, manganese oxide coated sand (MOCS), sand + MOCS (1:1) and granular activated carbon (GAC) were used as filter media. Manganese removal, manganese oxide accumulation, turbidity removal, and regeneration of MOCS under various conditions were examined. Soluble manganese removal by the MOCS column was rapid and efficient; most of the removal happened at the top (e.g. 5 cm) of the filter. When filter influent with an average manganese concentration of 0.204 mg l(-1) was fed through the filter columns, the sand + MOCS and MOCS columns removed 98.9% and 99.2% of manganese, respectively. However, manganese removal in sand and the GAC columns was not significant during the initial stage of filtration, but after eight months of filter run they could remove 99% and 35% of manganese, respectively. It was revealed that partial replacement of sand with MOCS showed comparable manganese removal to that of the MOCS filter media. PMID:19149348

Kim, J; Jung, S

2008-12-01

383

Effects of annealing conditions on microstructure and mechanical properties of low carbon, manganese transformation-induced plasticity steel  

Microsoft Academic Search

The effects of annealing conditions on microstructural evolution and mechanical properties have been investigated in low carbon,\\u000a manganese TRIP (Mn TRIP) steel based on a 0.12C-6Mn-0.5Si-3Al alloy system. The microstructure of cold-rolled sheet subjected\\u000a to annealing at 760 °C to 800 °C for 30 s to 1800 s consists of a recrystallized ferrite matrix and fine-grained austenite\\u000a with a phase

Jae-Myeong Jang; Sung-Joon Kim; Nam Hyun Kang; Kyung-Mox Cho; Dong-Woo Suh

2009-01-01

384

The microwave absorbing phenomena of ferrite microwave absorbers  

Microsoft Academic Search

The complex permeability dispersions and the microwave absorbing phenomena are investigated in ferrite microwave absorbers. The complex permeability of hexagonal (Y- and Z-type) and spinel (NiZn ferrite and NiZnCo ferrite) ferrite microwave absorbers were measured in 200 MHz-16 GHz range. The theoretical matching frequencies are determined by plotting the measured complex permeability loci on the impedance matching solution map. One

J. Y. Shin; J. H. Oh

1993-01-01

385

High-Quality Factor Ni-Zn Ferrite Planar Inductor  

Microsoft Academic Search

Ferrite and air-core planar inductor arrays were fabricated on 4 inch Si wafer to characterize inductor performance. Three micron thick Ni0.5Zn0.5Fe2O4 film was deposited by a low temperature electrophoresis ferrite deposition process. All ferrite inductors in the array showed 35% higher inductance (L) and 130% higher quality factor (Q) than air-core inductor. The maximum Q of ferrite inductor was found

Jae-Jin Lee; Yang-Ki Hong; Seok Bae; Ji-Hoon Park; Jeevan Jalli; Gavin S. Abo; Ryan Syslo; Byoung-Chul Choi; Gregory W. Donohoe

2010-01-01

386

Microstructure and Mechanical Properties of As-Cast Ductile Irons Alloyed with Manganese and Copper  

NASA Astrophysics Data System (ADS)

The present investigation was carried out to study the effect of manganese and copper addition, singly as well as in combination, on the microstructure, micro-segregation, and mechanical properties of ductile irons. Alloy A (3.18C, 2.64Si, 0.45Mn), alloy B (3.35C, 2.51Si, 0.82Mn), alloy C (3.16C, 2.80Si, 1.08Mn, 0.56Cu), and alloy D (3.18C, 3.00Si, 1.04Mn, 1.13Cu) were melted and cast in the form of Y-block test pieces. The cast microstructures varied from ferrito-pearlitic in alloys A, B, and C to pearlitic in alloy D. However, on XRD analysis and SEM examination, the presence of martensite patches was also detected. There was a marginal decrease in nodule count in alloy B. In alloys C and D, nodule counts were higher, but the proportion of ferrite decreased drastically. Alloy D was found to be the strongest (UTS ? 800 MPa, El = 5%) with alloys A and C coming next in strength; while alloy B was weakest of the four. The presence of martensite patches in association with pearlite appears to be responsible for low toughness of these alloys. Microprobe analysis shows some silicon segregation near the graphite nodules and practically little segregation of manganese. Elemental mapping by FE-SEM does not indicate any manganese segregation.

Dasgupta, Ranjan Kumar; Mondal, Dipak Kumar; Chakrabarti, Ajit Kumar; Ganguli, Ashis Chandra

2012-08-01

387

IMPROVEMENT OF SCREENING FOR MANGANESE EFFICIENCY BY PRODUCING SEED WITH SIMILAR MANGANESE CONTENT IN DIFFERENT GENOTYPES AND GENETIC STOCKS  

Microsoft Academic Search

Genetic improvement of manganese efficiency of crops demands a precise bioassay that avoids the confounding effect of seed manganese on the bioassay for the trait, for a proper comparison of the genotypes the seed manganese content must be similar. Variation in seed manganese can be minimized by the addition of manganese to individual seeds to be planted providing the effect

H. Khabaz-Saberi; R. D. Graham

2002-01-01

388

Imaging nanoparticle flow using magneto-motive optical Doppler tomography.  

PubMed

We introduce a novel approach for imaging solutions of superparamagnetic iron oxide (SPIO) nanoparticles using magneto-motive optical Doppler tomography (MM-ODT). MM-ODT combines an externally applied temporally oscillating high-strength magnetic field with ODT to detect nanoparticles flowing through a microfluidic channel. A solenoid with a cone-shaped ferrite core extensively increased the magnetic field strength (B(max) = 1 T, [Formula: see text]) at the tip of the core and also focused the magnetic field in microfluidic channels containing nanoparticle solutions. Nanoparticle contrast was demonstrated in a microfluidic channel filled with an SPIO solution by imaging the Doppler frequency shift which was observed independently of the nanoparticle flow rate and direction. Results suggest that MM-ODT may be applied to image Doppler shift of SPIO nanoparticles in microfluidic flows with high contrast. PMID:19636123

Kim, Jeehyun; Oh, Junghwan; Milner, Thomas E; Nelson, J Stuart

2007-01-03

389

Effect of alloying on microstructure and precipitate evolution in ferritic weld metal  

NASA Astrophysics Data System (ADS)

The effect of alloying on the microstructure of ferritic weld metal produced with an self-shielded flux cored arc welding process (FCAW-S) has been studied. The welding electrode has a flux core that is intentionally alloyed with strong deoxidizers and denitriding elements such as aluminum, titanium and zirconium in addition to austenite formers such as manganese and nickel. This results in formation of microstructure consisting of carbide free bainite, retained austenite and twinned martensite. The work focuses on characterization of the microstructures and the precipitates formed during solidification and the allotropic phase transformation of the weld metal. Aluminum, manganese and nickel have significant solubility in iron while aluminum, titanium and zirconium have very strong affinity for nitrogen and oxygen. The effect of these alloying elements on the phase transformation and precipitation of oxides and nitrides have been studied with various characterization techniques. In-situ X-ray synchrotron diffraction has been used to characterize the solidification path and the effect of heating and cooling rates on microstructure evolution. Scanning Transmission Electron Microscopy (STEM) in conjunction with Energy Dispersive Spectroscopy (EDS) and Electron energy loss spectroscopy (EELS) was used to study the effect of micro-alloying additions on inclusion evolution. The formation of core-shell structure of oxide/nitride is identified as being key to improvement in toughness of the weld metal. Electron Back Scattered Diffraction (EBSD) in combination with Orientation Imaging Microscopy (OIM) and Transmission electron microscopy (TEM) has been employed to study the effect of alloying on austenite to ferrite transformation modes. The prevention of twinned martensite has been identified to be key to improving ductility for achieving high strength weld metal.

Narayanan, Badri Kannan

390

Variations in Weld Ferrite Content Due to P and S.  

National Technical Information Service (NTIS)

It was found that additions of P and S can have a considerable effect on the amount of weld ferrite in Fe-Ni-Cr austenitic alloys. These impurities significantly increased the ferrite content of welds containing primarily the lathy ferrite morphology, but...

J. A. Brooks A. W. Thompson J. C. Williams

1982-01-01

391

The waveguide ferrite phase shifter for a millimeter wave region  

Microsoft Academic Search

The results of the design and experimental investigation of a waveguide ferrite phase shifter with magnetic memory for 3 mm-wave phased antenna arrays are discussed. The phase shifter is based on a longitudinally magnetized ferrite rod and operates with circularly polarized waves. The system of magnetization includes a coil and a system of ferrite conductors. This construction of the phase

V. M. Krekhtunov; N. A. Bogatyrev; M. E. Golubtsov; E. V. Komissarova

2001-01-01

392

Simulations of ferrite-dielectric-wire composite negative index materials  

Microsoft Academic Search

We have performed extensive finite difference time domain (FDTD) simulations to design ferrite based negative index of refraction (NIM) composites. Our simulations center on the use of Barium M type ferrite with in-plane anisotropy. A wire grid is employed to provide negative permittivity. The ferrite and wire grid interact to provide both negative and positive index of refraction transmission peaks

Frederic Rachford; Douglas Armstead; Vincent Harris; Carmine Vittoria

2007-01-01

393

Miniature, tunable, and power efficient ferrite phase shifter devices  

Microsoft Academic Search

Ferrite phase shifter devices having drastically reduced bias field requirements are demonstrated at C and Ku band utilizing polycrystalline YIG and single crystal hexagonal Y-type ferrite materials. Phase shifts on the order of 100 degrees with bias fields below 100 Oe are achieved. A novel numerical analysis method for modeling anisotropic ferrites is presented and a good agreement between calculation

A. L. Geiler; J. Wang; I. Viswanathan; S. D. Yoon; J. S. Gao; Y. Chen; C. Vittoria; V. G. Harris

2009-01-01

394

Fabrication and performance of ferrite phase shifters for millimeter frequencies  

Microsoft Academic Search

Ferrite devices for millimeter frequencies, 35 GHz to 94 GHz, are difficult to fabricate and have marginal performance. This paper discusses the design and arc plasma fabrication process for non-reciprocal ferrite phase shifters for millimeter frequencies. Design and fabrication techniques were developed for 35 GHz, prior to the initial fabrication of 94 GHz phase shifters. A lithium ferrite powder with

R. Babbitt; R. Stern

1979-01-01

395

Latching Ferrite Phase Shifter for Scanning Dielectric Lens  

Microsoft Academic Search

In recent years, numerous latching ferrite phase shifters have been designed in rectangular and circular waveguide, stripline, and slow-wave structures. In all these devices, metal walls have surrounded the ferrite and played a major role in guiding the wave. A new device is now described in which no metal walls surround the phase shifter and the ferrite itself guides the

P. J. Meier; B. J. Musso

1967-01-01

396

Optimum Filling of Ferrite Phase Shifters of Uniform Dielectric Constant  

Microsoft Academic Search

Approximation methods are used to calculate the phase shift and loss for phase shifters containing ferrite and dielectric, with a uniform dielectric constant throughout the waveguide. If the RF magnetic loss in the ferrite is a significant fraction of the total loss, the overall performance of a phase shifter that is partially filled with ferrite may be superior to the

C. R. Boyd

1974-01-01

397

Preparation of ferrite single crystals by new floating zone technique  

Microsoft Academic Search

Single crystals of Ni ferrites and Ni-Zn ferrites having good uniformity were prepared by a new floating zone technique. In the preparation of the Ni-ferrite single crystal the initial molten zone was made from the material having a composition different from that of seed crystal. This made the composition of precipitate from molten zone the same as that of the

T. Akashi; K. Matumi; T. Okada; T. Mizutani

1969-01-01

398

40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Cobalt lithium manganese nickel oxide. 721...Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. ...The chemical substance identified as cobalt lithium manganese nickel...

2013-07-01

399

40 CFR 721.10011 - Barium calcium manganese strontium oxide.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Barium calcium manganese strontium oxide. ...Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. ...The chemical substance identified as barium calcium manganese strontium...

2010-07-01

400

40 CFR 721.10011 - Barium calcium manganese strontium oxide.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Barium calcium manganese strontium oxide. ...Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. ...The chemical substance identified as barium calcium manganese strontium...

2009-07-01

401

40 CFR 721.10011 - Barium calcium manganese strontium oxide.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Barium calcium manganese strontium oxide. 721.10011...Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a...chemical substance identified as barium calcium manganese strontium oxide (PMN...

2013-07-01

402

40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Manganese heterocyclic tetraamine complex (generic...Chemical Substances § 721.10003 Manganese heterocyclic tetraamine complex (generic...chemical substances identified generically as manganese heterocyclic tetraamine...

2010-07-01

403

40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Manganese heterocyclic tetraamine complex (generic...Chemical Substances § 721.10003 Manganese heterocyclic tetraamine complex (generic...chemical substances identified generically as manganese heterocyclic tetraamine...

2013-07-01

404

Manganese oxide reduction in laboratory microcosms  

Microsoft Academic Search

Manganese biogeochemistry holds special interest for the characterization of passive treatment systems designed to treat acidic\\u000a mine waters while meeting enforceable effluent discharge limits set for manganese. In the present study, an initial anoxic\\u000a enrichment culture was developed for use as an inoculum in experimental systems. Standard anoxic microcosms capable of reducing\\u000a manganese from Mn4+ to Mn2+ were established from

Richard A. Royer; Richard F. Unz

1999-01-01

405

Microalgal-facilitated bacterial oxidation of manganese  

Microsoft Academic Search

In the presence of unicellular microalgae, bacterial manganese oxidation was increased by up to ten times the rate produced by bacterial oxidation alone. Azide-poisoned controls demonstrated that the manganese-oxidizing bacteria were active in the algal-bacterial oxidation of manganese. Scanning electron microscopy showed that oxide formation occurred in a number of structurally different deposits on the surface of the alga. Studies

R M Stuetz; A C Greene; J C Madgwick

1996-01-01

406

Methylcyclopentadienyl Manganese Tricarbonyl: Effect on Manganese Emissions from Vehicles on the Road  

Microsoft Academic Search

This note describes some measurements of manganese concentrations and manganese emission rates, categorized as to vehicle type, from cars and trucks at two tunnels on the Pennsylvania Turnpike. These measurements were made during the period that methylcyclopentadienyl manganese tricarbonyl (MMT) came into use as an alternative to organo-lead compounds for improving combustion in gasoline engines.

William R. Pierson; Douglas E. McKee; Wanda W. Brachaczek; James W. Butler

1978-01-01

407

Influence of Dietary Manganese on the Pharmacokinetics of Inhaled Manganese Sulfate in Male CD Rats  

Microsoft Academic Search

Concerns exist as to whether individuals with relative manga- nese deficiency or excess may be at increased risk for manganese toxicity following inhalation exposure. The objective of this study was to determine whether manganese body burden influences the pharmacokinetics of inhaled manganese sulfate (MnSO4). Postna- tal day (PND) 10 rats were placed on either a low (2 ppm), sufficient (10

David C. Dorman; Melanie F. Struve; R. Arden James; Brian E. McManus; Marianne W. Marshall; Brian A. Wong

2001-01-01

408

Study of Structural and Magnetic Properties of In3+ Substituted Mg-Mn-Ni Spinel Ferrites  

NASA Astrophysics Data System (ADS)

Effect of substitution of trivalent indium ions in stoichiometric magnesium-manganese-nickel ferrites has been studied with composition Mg0.2Mn0.5Ni0.3InxFe2-xO4 with x varying from 0.1 to 0.3 in steps of 0.1 using citrate precursor technique Single-phase cubic spinel structure of these samples has been confirmed from X-ray analyses. Ferrites have been investigated for their electric and magnetic properties such as dc resistivity, saturation magnetization, initial permeability and relative loss factor (RLF). DC electrical resistivity (?) decreases with increase in temperature exhibiting semiconductor like behavior Bulk density increases and initial permeability (?i) decrease with increasing In3+ substitution. But ?i increase with increasing sintering temperature for all composition. Fairly constant value of initial permeability over a wide frequency range (0.1-15 MHz) and low values of relative loss factor of order of 10-6-10-5 are main achievements of present investigation. Saturation magnetization (Ms) and retentivity decreases while coercivity (Hc) increases with increasing substitution of indium ion.

Verma, Satish; Singh, M.

2011-07-01

409

Thermal expansion of manganese carbonate  

Microsoft Academic Search

Precision lattice parameters of manganese carbonate have been determined at different temperatures by the X-ray powder method in the temperature range 28 to 265° C. The data has been used to evaluate, by a graphical method, the two coefficients of thermal expansion,$$\\\\begin{gathered} \\\\alpha _\\\\parallel = 22.942 \\\\times 10^{ - 6} - 5.555 \\\\times 10^{ - 8} T + 3.361 \\\\times

K. V. Krishna Rao; K. Satyanaryana Murthy

1970-01-01

410

Manganese Nodule Exploration System Manganknollen - Explorationssystem.  

National Technical Information Service (NTIS)

Different tools for manganese nodule exploration are thoroughly investigated. Certain tools are selected applying technical and economical criteria. Three optimized exploration systems are designed as examples. (Author)

G. Braun H. Ristow H. Weichart

1973-01-01

411

Lithium ferrite for gas sensing applications  

Microsoft Academic Search

Microstructure and gas sensing properties of pure and samarium-substituted lithium ferrites, Li0.5SmxFe2.5?xO4 (x=0, 0.05, 0.1 and 0.2), prepared by sol–gel self-combustion were studied. Ethanol, methanol, LPG and ammonia were used as test gases. SEM investigation evidenced that Sm ions induced microstructural changes of the Li ferrite. The finest granulation (about 100nm) and highest porosity (44%) were observed in Li0.5Sm0.2Fe2.3O4. The

N. Rezlescu; C. Doroftei; E. Rezlescu; P. D. Popa

2008-01-01

412

Development of Lanthanum Ferrite SOFC Cathodes  

SciTech Connect

A number of studies have been conducted concerning compositional/microstructural modifications of a Sr-doped lanthanum ferrite (LSF) cathode and protective Sm-doped ceria (SDC) layer in an anode supported solid oxide fuel cell (SOFC). Emphasis was placed on achieving enhanced low temperature (700-800 degrees C) performance, and long-term cell stability. Investigations involved manipulation of the lanthanum ferrite chemistry, addition of noble metal oxygen reduction catalysts, incorporation of active cathode layer compositions containing Co, Fe and higher Sr contents, and attempts to optimize the ceria barrier layer between the LSF cathode and YSZ electrolyte.

Simner, Steve P.; Bonnett, Jeff F.; Canfield, Nathan L.; Meinhardt, Kerry D.; Shelton, Jayne P.; Sprenkle, Vince L.; Stevenson, Jeffry W.

2003-01-01

413

Battles with Iron: Manganese in Oxidative Stress Protection*  

PubMed Central

The redox-active metal manganese plays a key role in cellular adaptation to oxidative stress. As a cofactor for manganese superoxide dismutase or through formation of non-proteinaceous manganese antioxidants, this metal can combat oxidative damage without deleterious side effects of Fenton chemistry. In either case, the antioxidant properties of manganese are vulnerable to iron. Cellular pools of iron can outcompete manganese for binding to manganese superoxide dismutase, and through Fenton chemistry, iron may counteract the benefits of non-proteinaceous manganese antioxidants. In this minireview, we highlight ways in which cells maximize the efficacy of manganese as an antioxidant in the midst of pro-oxidant iron.

Aguirre, J. Dafhne; Culotta, Valeria C.

2012-01-01

414

Valence-driven electrical behavior of manganese-modified bismuth ferrite thin films  

Microsoft Academic Search

BiFe0.95R0.05O3 (Mn2+, Mn3+, and Mn4+) thin films with (110) orientation were fabricated on SrRuO3\\/Pt\\/TiO2\\/SiO2\\/Si(100) substrates via rf sputtering. With the increasing valence of Mn in BiFe0.95R0.05O3, the concentration of Fe2+ increases, whereas the concentration of oxygen vacancies decreases. The electrical properties of BiFe0.95R0.05O3 are correlated with the valence of Mn. Their leakage current density is dependent on the concentration of

Jiagang Wu; John Wang; Dingquan Xiao; Jianguo Zhu

2011-01-01

415

Surfactant-controlled morphology and magnetic property of manganese ferrite nanocrystal contrast agent  

Microsoft Academic Search

MnFe2O4 nanocrystals (NCs) coated with three different surfactants (oleic acid, oleylamine or 1,2-hexadecanediol) and their mixtures, with sizes in range 6-12 nm, were synthesized by high-temperature decomposition of organometallic precursors. The effects of morphology and surface chemistry of MnFe2O4 NCs on the magnetic properties were systematically investigated by comparing their saturation magnetization values and their capability to improve the negative

He Hu; Zhi-qing Tian; Jie Liang; Hong Yang; An-tao Dai; Lu An; Hui-xia Wu; Shi-ping Yang

2011-01-01

416

Surfactant-controlled morphology and magnetic property of manganese ferrite nanocrystal contrast agent  

NASA Astrophysics Data System (ADS)

MnFe2O4 nanocrystals (NCs) coated with three different surfactants (oleic acid, oleylamine or 1,2-hexadecanediol) and their mixtures, with sizes in range 6-12 nm, were synthesized by high-temperature decomposition of organometallic precursors. The effects of morphology and surface chemistry of MnFe2O4 NCs on the magnetic properties were systematically investigated by comparing their saturation magnetization values and their capability to improve the negative contrast for magnetic resonance imaging (MRI) after converting the hydrophobic NCs to hydrophilic ones by a ligand exchange protocol. An important finding is that the magnetization values and proton relaxivity rates of MnFe2O4 NCs are strongly dependent on the size and surface state of the particles that covalently bonded with different hydrophobic ligands before ligand exchange. In particular, monodisperse cubic MnFe2O4 NCs could be obtained when oleylamine and 1,2-hexadecanediol were used as mixed stabilizers, and showed excellent morphology and magnetic properties. Furthermore, the low cytotoxicity and good cell uptake MR imaging of the dopamine capped MnFe2O4 NCs make them promising candidates for use as bio-imaging probes.

Hu, He; Tian, Zhi-qing; Liang, Jie; Yang, Hong; Dai, An-tao; An, Lu; Wu, Hui-xia; Yang, Shi-ping

2011-02-01

417

Surfactant-controlled morphology and magnetic property of manganese ferrite nanocrystal contrast agent.  

PubMed

MnFe(2)O(4) nanocrystals (NCs) coated with three different surfactants (oleic acid, oleylamine or 1,2-hexadecanediol) and their mixtures, with sizes in range 6-12 nm, were synthesized by high-temperature decomposition of organometallic precursors. The effects of morphology and surface chemistry of MnFe(2)O(4) NCs on the magnetic properties were systematically investigated by comparing their saturation magnetization values and their capability to improve the negative contrast for magnetic resonance imaging (MRI) after converting the hydrophobic NCs to hydrophilic ones by a ligand exchange protocol. An important finding is that the magnetization values and proton relaxivity rates of MnFe(2)O(4) NCs are strongly dependent on the size and surface state of the particles that covalently bonded with different hydrophobic ligands before ligand exchange. In particular, monodisperse cubic MnFe(2)O(4) NCs could be obtained when oleylamine and 1,2-hexadecanediol were used as mixed stabilizers, and showed excellent morphology and magnetic properties. Furthermore, the low cytotoxicity and good cell uptake MR imaging of the dopamine capped MnFe(2)O(4) NCs make them promising candidates for use as bio-imaging probes. PMID:21242632

Hu, He; Tian, Zhi-qing; Liang, Jie; Yang, Hong; Dai, An-tao; An, Lu; Wu, Hui-xia; Yang, Shi-ping

2011-01-18

418

Structural characterization and magnetic properties of smart CuCd ferrite/LaSrCo manganite nanocomposites  

NASA Astrophysics Data System (ADS)

Smart nanocomposites Cu0.7Cd0.3Fe2O4/La0.67Sr0.33Mn0.98Co0.02O3 in different weight ratios were prepared and characterized by different techniques. The parent compounds were prepared by the citrate-nitrate autocombustion method. Phase formation and crystal structure were investigated by X-ray diffraction. Morphological properties of the nanoparticles were studied using high resolution transmission electron microscopy. Thermal dc magnetization curves were measured from 200 to800 K for the nanocomposites and showed a characteristic peak near the blocking temperature of LaSrCo manganite shifted toward higher temperature with increasing CuCd ferrite percentage. Such behavior was explained in light of granular model of exchange bias. Vibrating sample magnetometer measurements reveal an enhancement in the ferromagnetic properties with increasing ferrite ratio. The prominent anisotropic shift in the M-H hysteresis loop was discussed as a consequence of interfacial magnetic interactions between LaSrCo manganite and CuCd ferrite grains. Correlation between the measured magnetic parameters and ferrite/manganite ratio is reported and discussed.

Ahmed, M. A.; Bishay, Samiha T.; Salem-Gaballah, S. M.

2013-05-01

419

Effect of high-energy ball milling time on structural and magnetic properties of nanocrystalline cobalt ferrite powders  

NASA Astrophysics Data System (ADS)

Cobalt ferrite nanocrystals synthesized by conventional and size-controlled coprecipitation methods were treated by high-energy ball milling, HEBM, in order to study the effect of crystal size reduction and/or strain on the resulting magnetic properties. Processed nanocrystals were characterized by X-ray diffraction, Brunauer, Emmett, and Teller surface area analysis, transmission electron microscopy (TEM), and vibrating sample magnetometry. The cobalt ferrite nanocrystals exhibited crystal size reduction from initial values (average crystallite sizes of 12±1 nm and 18±3 nm, respectively) down to 10 nm after HEBM for 10 h. The specific surface area was decreased by milling (from 96.5 to 59.4 m2/g; for the 12 nm cobalt ferrite nanocrystals), due to particles aggregation. TEM analyses corroborated the aggregation of the nanoparticles at such long milling times. The same cobalt ferrite nanocrystals exhibited a rise in coercivity from 394 to 560 Oe after 5 h ball milling which was attributed to the introduction of strain anisotropy, namely point defects, as suggested by the systematic shift of the diffraction peaks towards higher angles. In turn, the magnetic characterization of the starting 18 nm-nanocrystals reported a drop in coercivity from 4506 Oe to 491 Oe that was attributed predominantly to size reduction within the single domain region. A correlation between particle size, cationic distribution, and HEBM processing conditions became evident.

Cedeño-Mattei, Yarilyn; Perales-Pérez, Oscar; Uwakweh, Oswald N. C.

2013-09-01

420

EFFECTS OF MANGANESE ON THYROID HORMONE HOMEOSTASIS  

PubMed Central

Manganese (Mn) is an essential trace nutrient that is potentially toxic at high levels of exposure. As a constituent of numerous enzymes and a cofactor, manganese plays an important role in a number of physiologic processes in mammals. The manganese-containing enzyme, manganese superoxide dismutase (Mn-SOD), is the principal antioxidant enzyme which neutralizes the toxic effects of reactive oxygen species. Other manganese-containing enzymes include oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases and glutamine synthetase. Environmental or occupational exposure to high levels of manganese can cause a neuropathy resembling idiopathic Parkinson’s disease, commonly referred to as manganism. Manganism and Parkinson’s disease are both characterized by motor deficits and damage to nuclei of the basal ganglia, particularly the substantia nigra, with altered dopamine (and its metabolites) contributing to these disorders. Dopamine, a major neurotransmitter plays a crucial role in the modulation of the cognitive function, working memory and/or attention of the prefrontal cortex and the hippocampus. Dopamine is also a known inhibitory modulator of thyroid stimulating hormone (TSH) secretion. The involvement of dopamine and dopaminergic receptors in neurodevelopment, as well as TSH modulation, led us to hypothesize that excessive manganese exposure may lead to adverse neurodevelopmental outcomes due to the disruption of thyroid homeostasis via the loss of dopaminergic control of TSH regulation of thyroid hormones. This disruption may alter thyroid hormone levels, resulting in some of the deficits associated with gestational exposure to manganese. While the effects of manganese in adult populations are relatively well documented, comprehensive data on its neurodevelopmental effects are sparse. Given the importance of this topic, we review the potential participation of thyroid hormone dyshomeostasis in the neurodevelopmental effects of manganese positing the hypotheses that manganese may directly or indirectly affect thyroid function by injuring the thyroid gland or dysregulating dopaminergic modulation of thyroid hormone synthesis.

Soldin, OP; Aschner, M

2007-01-01

421

Manganese poisoning and the attack of trivalent manganese upon catecholamines.  

PubMed

Human manganese poisoning or manganism results in damage to the substantia nigra of the brain stem, a drop in the level of the inhibitory neurotransmitter dopamine, and symptoms resembling those of Parkinson's disease. Manganic (Mn3+) manganese ions were shown to be readily produced by O-2 in vitro and spontaneously under conditions obtainable in the human brain. Mn3+ as its pyrophosphate complex was shown to rapidly and efficiently carry out four-electron oxidations of dopamine, its precursor dopa (3,4-dihydroxyphenylalanine), and its biosynthetic products epinephrine and norepinephrine. Mn3+-pyrophosphate was shown to specifically attack dihydroxybenzene derivatives, but only those with adjacent hydroxyl groups. Further, the addition of Mn2+-pyrophosphate to a system containing a flux of O2- and dopamine greatly accelerated the oxidation of dopamine. The oxidation of dopamine by Mn3+ neither produced nor required O2, and Mn3+ was far more efficient than Mn2+, Mn4+ (MnO2), O2-, or H2O2 in oxidizing the catecholamines. A higher oxidation state, Mn(OH)3, formed spontaneously in an aqueous Mn(OH)2 precipitate and slowly darkened, presumably being oxidized to MnO2. Like reagent MnO2, it weakly catalyzed dopamine oxidation. However, both MnO2 preparations showed dramatically increased abilities to oxidize dopamine in the presence of pyrophosphate due to enhancement of the spontaneous formation of the Mn3+ complex. These results strongly suggest that the pathology of manganese neurotoxicity is dependent on the ease with which simple Mn3+ complexes are formed under physiological conditions and the efficiency with which they destroy catecholamines. PMID:3039917

Archibald, F S; Tyree, C

1987-08-01

422

Efficient hypersonic wave excitation [ferrite film systems  

Microsoft Academic Search

Bulk acoustic waves (AW) magnetostrictive excitation in ferrite film-dielectric substrate structures have been considered theoretically and experimentally in the 2.5-10 GHz frequency range. Insertion losses of 7 dB have been achieved in the 2.5-10 GHz frequency range

A. S. Bugaev; V. B. Gorsky

1995-01-01

423

Boric Acid Corrosion of Ferritic Reactor Components.  

National Technical Information Service (NTIS)

An increasing amount of nuclear industry reports have indicated corrosion of ferritic steel components by reactor primary coolant. A literature survey produced information regarding corrosion of AISI 4135 steel in both H3BO3 and H3BO3 + KOH solutions at 7...

C. Czajkowski

1982-01-01

424

A Study of a Ferrite Phase Shifter.  

National Technical Information Service (NTIS)

A study of a DOFL-type phase shifter was conducted at S-band. This phase shifter was capable of operation at power levels above 10 kw peak power. Phase shift and loss were determined as a function of several parameters: ferrite width and height, waveguide...

M. L. Reuss

1964-01-01

425

Microwave reciprocal latching ferrite phase shifters  

Microsoft Academic Search

The report describes analytical and experimental investigations carried out on dual-mode, reciprocal, latching ferrite phase shifters, with special emphasis placed on low insertion loss and low potential cost for production quantities. Analytical work has been directed at providing design limit and tradeoff information that may be of value to the system designer as well as to the phase shifter designer.

C. R. Boyd Jr.

1975-01-01

426

Modeling a stripline ferrite phase shifter  

Microsoft Academic Search

A model is proposed for the behavior of transmission lines on ferrite substrates. This may be the first time a model has correctly described the absorption below the gyromagnetic resonant frequency corresponding to the magnetization at saturation, or ?4?Ms . This new model should allow accurate prediction of impedances and propagation constants for frequencies operating close to this cutoff frequency,

Steven N. Stitzer

1997-01-01

427

The design of reciprocal ferrite phase shifters  

Microsoft Academic Search

The design of a reciprocal ferrite phase shifter in a rectangular waveguide, using perturbation theory with a quasi-stationary approximation for the field perturbation of the system is considered. The theoretical results are compared with experimental data and with a design carried out without using the quasi-stationary approximation [5], The simplicity of the proposed method and the good agreement between the

N. S. Pechurkin; L. V. Bychkova; A. N. Elsukov

1966-01-01

428

An Accurate Analog Ferrite Phase Shifter  

Microsoft Academic Search

An analog ferrite phase shifter has been developed for applications requiring an accurate relationship between phase shift and control current. A prototype unit is described that operates over a 1.3 GHz. range at X-band with VSWR under 1.2:1, loss under 1 dB., hysteresis at ±1 degree, and negligible frequency dispersion of phase shift.

C. R. Boyd

1971-01-01

429

Practical millimeter-wave ferrite phase shifters  

Microsoft Academic Search

The performance of latching ferrite phase shifters is examined. For a dual-mode phase shifter, modified transmission line techniques were used to determine the phase shifter and nonreciprocal polarizer lengths in circular waveguide, constrained in diameter such that the TE(21) mode was nonpropagating. For the nonreciprocal toroid phase shifter, the transverse resonance method was used, with the waveguide height taken as

C. R. Boyd Jr.

1982-01-01

430

Low Temperature Thermal Expansion of Barium Ferrite.  

National Technical Information Service (NTIS)

The linear thermal expansion of polycrystalline barium ferrite, BaFe12O19, was measured from 76 to 293 K both parallel and perpendicular to the magnetization direction. An anisotropy of about 15-20% was observed. The results match well the available data ...

A. F. Clark W. M. Haynes V. A. Deason R. J. Trapani

1975-01-01

431

Rapid Solidification of Candidate Ferritic Steels.  

National Technical Information Service (NTIS)

HT-9 and 9Cr-1Mo steels were rapidly solidified by the liquid dynamic compaction process and 2-1/4Cr-1Mo steel was prepared by the ultrasonic gas atomization process. The consolidation was performed in the ferritic temperature range in order to minimize s...

J. Megusar C. A. Craven G. Kohse O. K. Harling J. Runkle

1985-01-01

432

Thermodynamic studies on lithium ferrites  

SciTech Connect

Thermodynamic studies on ternary oxides of Li-Fe-O systems were carried out using differential scanning calorimetry, Knudsen effusion mass spectrometry, and solid-state electrochemical technique based on fluoride electrolyte. Heat capacities of LiFe{sub 5}O{sub 8}(s) and LiFeO{sub 2}(s) were determined in the temperature range 127-861 K using differential scanning calorimetry. Gibbs energies of formation of LiFe{sub 5}O{sub 8}(s) and LiFeO{sub 2}(s) were determined using Knudsen effusion mass spectrometry and solid-state galvanic cell technique. The combined least squares fits can be represented as {Delta}{sub f}G{sub m}{sup o}(LiFe{sub 5}O{sub 8},s,T)/kJ mol{sup -1} ({+-}6)=-2341+0.6764(T/K) (588{<=}T/K{<=}971) {Delta}{sub f}G{sub m}{sup o}(LiFeO{sub 2},s,T)/kJ mol{sup -1} ({+-}3)=-708+0.1656(T/K) (569{<=}T/K{<=}1021) The temperature independent term of the above equations represents {Delta}{sub f}H{sup o}{sub m}(T{sub av}) and temperature dependent term represents negative change in entropy of the respective compounds. Thermodynamic analysis shows that LiFe{sub 5}O{sub 8}(s) is more stable compared to LiFeO{sub 2}(s). -- Graphical abstract: Comparison of {Delta}{sub f}G{sub m}{sup o}(T) of lithium ferrites determined using different techniques. Display Omitted Highlights: {yields} Thermodynamic studies on Li-Fe-O system using DSC, KEQMS and galvanic cell. {yields} Heat capacities of LiFe{sub 5}O{sub 8}(s) and LiFeO{sub 2}(s) were determined using DSC 127-861 K. {yields} {Delta}{sub f}G{sup o}{sub m} of these compounds were determined and compared. {yields} Thermodynamic tables for LiFe{sub 5}O{sub 8}(s) and LiFeO{sub 2}(s) were constructed.

Rakshit, S.K., E-mail: swarup_kr@rediffmail.co [Product Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Parida, S.C.; Naik, Y.P.; Chaudhary, Ziley Singh [Product Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Venugopal, V. [Radiochemistry and Isotope Group, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

2011-05-15

433

Low temperature synthesis, structural, and magnetic characterization of manganese sillenite Bi12MnO20  

NASA Astrophysics Data System (ADS)

A low temperature (~393 K) soft chemical route under refluxing conditions has been followed to prepare polycrystalline manganese sillenites, Bi12MnO20 (BMO). X-ray diffraction and scanning electron microscopy show a cubic BMO pure phase with a=10.206 A?, homogeneous morphology, and nanoparticle size. A detailed study of the magnetic properties is presented. The zero-field-cooled and field-cooled magnetization curves show a typical nanoparticle behavior with blocking temperature TB~18 K. The ac susceptibility measured at different frequencies gives an Arrhenius behavior compatible with the superparamagnetic nanoparticle relaxation processes but with an unusually small relaxation time. The relaxation time is shown to be field dependent due to strong interparticle interaction.

de Oliveira, L. A. S.; Sinnecker, J. P.; Vieira, M. D.; Pentón-Madrigal, A.

2010-05-01

434

The magnetism of metallic manganese alloys  

SciTech Connect

The magnetic excitations in antiferromagnetic manganese-copper and manganese-iron alloys are characterized by high spin-wave velocities, and energy gap at long wavelengths and wavelength dependent damping. There are strong elastic constant anomalies above T[sub N] as well as magnetoelastic distortions below T[sub N]. The theoretical explanation of these effects is reviewed.

Holden, T.M. (Atomic Energy of Canada Ltd., Chalk River, ON (Canada)); Mikke, K. (Institute of Atomic Energy, Otwock-Swierk (Poland)); Fawcett, E. (Toronto Univ., ON (Canada)); Fernandez-Baca, J.A. (Oak Ridge National Lab., TN (United States))

1992-01-01

435

The magnetism of metallic manganese alloys  

SciTech Connect

The magnetic excitations in antiferromagnetic manganese-copper and manganese-iron alloys are characterized by high spin-wave velocities, and energy gap at long wavelengths and wavelength dependent damping. There are strong elastic constant anomalies above T{sub N} as well as magnetoelastic distortions below T{sub N}. The theoretical explanation of these effects is reviewed.

Holden, T.M. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada); Mikke, K. [Institute of Atomic Energy, Otwock-Swierk (Poland); Fawcett, E. [Toronto Univ., ON (Canada); Fernandez-Baca, J.A. [Oak Ridge National Lab., TN (United States)

1992-12-31

436

Manganese potentiates nitric oxide production by microglia.  

PubMed

Manganese toxicity has been associated with clinical symptoms of neurotoxicity which are similar to the symptoms observed in Parkinson's disease. Earlier reports indicated that reactive microglia was present in the substantia nigra of patients with Parkinson's disease. Using N9 microglial cells, the current study was designed to determine whether high levels of manganese were associated with microglial activation. Results indicated that manganese significantly increased the bacterial lipopolysaccharide-induced nitric oxide production. This potent activity of manganese was not shared by other transition metals tested, including iron, cobalt, nickel, copper and zinc. Immunohistochemical staining and Western blot analysis indicated that manganese increased the cellular production of inducible nitric oxide synthase. Northern blot analysis indicated that manganese likely increased iNOS gene transcription since this agent increased the mRNA level of the inducible nitric oxide synthase. In contrast to other transition metals tested, manganese did not appear to be cytotoxic to microglial cells. These results suggested that manganese could induce sustained production of neurotoxic nitric oxide by activated microglial cells, which might cause detrimental consequences to surrounding neurons. PMID:10320780

Chang, J Y; Liu, L Z

1999-05-01

437

High coercivity induced by mechanical milling in cobalt ferrite powders  

NASA Astrophysics Data System (ADS)

In this work we report a study of the magnetic behavior of ferrimagnetic oxide CoFe2O4 treated by mechanical milling with different grinding balls. The cobalt ferrite nanoparticles were prepared using a simple hydrothermal method and annealed at 500 °C. The non-milled sample presented coercivity of about 1.9 kOe, saturation magnetization of 69.5 emu/g, and a remanence ratio of 0.42. After milling, two samples attained coercivity of 4.2 and 4.1 kOe, and saturation magnetization of 67.0 and 71.4 emu/g respectively. The remanence ratio MR/MS for these samples increase to 0.49 and 0.51, respectively. To investigate the influence of the microstructure on the magnetic behavior of these samples, we used X-ray powder diffraction (XPD), transmission electron microscopy, and vibrating sample magnetometry. The XPD analysis by the Williamson-Hall plot was used to estimate the average crystallite size and strain induced by mechanical milling in the samples.

Ponce, A. S.; Chagas, E. F.; Prado, R. J.; Fernandes, C. H. M.; Terezo, A. J.; Baggio-Saitovitch, E.

2013-10-01

438

Structural Features of Manganese Precipitating Bacteria  

NASA Astrophysics Data System (ADS)

Studies of biological communities of the past (and their associated activities) are usually dependent upon preservation of fossil material. With bacteria this rarely occurs because of the absence of sufficient fossilizable cellular material. However, some bacteria deposit metabolic products that can, conditions allowing, be preserved indefinitely. In particular, manganese and iron depositing bacteria have the capacity to form preservable microfossils. In order to better understand these microfossils of the past, we have examined present day morphologies of manganese oxidizing bacteria. These bacteria are highly pleomorphic, depending on the growth medium, the age of the culture, and the extent of manganese oxidation. Transmission electron microscopy indicates that manganese may be deposited either intra-or extra-cellularly. The prognosis of the use of morphological information for the interpretation of ancient and modern manganese deposits is discussed.

Nealson, Kenneth H.; Tebo, Bradley

1980-06-01

439

Harnessing microbial subsurface metal reduction activities to synthesise nanoscale cobalt ferrite with enhanced magnetic properties  

SciTech Connect

Nanoscale ferrimagnetic particles have a diverse range of uses from directed cancer therapy and drug delivery systems to magnetic recording media and transducers. Such applications require the production of monodisperse nanoparticles with well-controlled size, composition, and magnetic properties. To fabricate these materials purely using synthetic methods is costly in both environmental and economical terms. However, metal-reducing microorganisms offer an untapped resource to produce these materials. Here, the Fe(III)-reducing bacterium Geobacter sulfurreducens is used to synthesize magnetic iron oxide nanoparticles. A combination of electron microscopy, soft X-ray spectroscopy, and magnetometry techniques was employed to show that this method of biosynthesis results in high yields of crystalline nanoparticles with a narrow size distribution and magnetic properties equal to the best chemically synthesized materials. In particular, it is demonstrated here that cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles with low temperature coercivity approaching 8 kOe and an effective anisotropy constant of {approx} 10{sup 6} erg cm{sup -3} can be manufactured through this biotechnological route. The dramatic enhancement in the magnetic properties of the nanoparticles by the introduction of high quantities of Co into the spinel structure represents a significant advance over previous biomineralization studies in this area using magnetotactic bacteria. The successful production of nanoparticulate ferrites achieved in this study at high yields could open up the way for the scaled-up industrial manufacture of nanoparticles using environmentally benign methodologies. Production of ferromagnetic nanoparticles for pioneering cancer therapy, drug delivery, chemical sensors, catalytic activity, photoconductive materials, as well as more traditional uses in data storage embodies a large area of inorganic synthesis research. In particular, the addition of transition metals other than Fe into the structure of magnetite (Fe{sub 3}O{sub 4}) has been shown to greatly enhance the magnetic properties of the particles, tailoring them to different commercial uses. However, synthesis of magnetic nanoparticles is often carried out at high temperatures with toxic solvents resulting in high environmental and energy costs. Additionally, these ferrite nanoparticles are not intrinsically biocompatible, and to make them suitable for insertion into the human body is a rather intricate task. A relatively unexplored resource for magnetic nanomaterial production is subsurface Fe(III)-reducing bacteria, as these microorganisms are capable of producing large quantities of nanoscale magnetite (Fe{sub 3}O{sub 4}) at ambient temperatures. Metal-reducing bacteria live in environments deficient in oxygen and conserve energy for growth through the oxidation of hydrogen or organic electron donors, coupled to the reduction of oxidized metals such as Fe(III)-bearing minerals. This can result in the formation of magnetite via the extracellular reduction of amorphous Fe(III)-oxyhydroxides causing the release of soluble Fe(II) and resulting in complete recrystallization of the amorphous mineral into a new phase. Some previous studies have reported altering the composition of biogenic magnetite produced by Fe(III)-reducing bacteria for industrial and environmental applications. However, research into the commercial exploitation of bacteria to form magnetic minerals has focused primarily on magnetotactic bacteria which form magnetosomal magnetite internally using very different pathways to those bacteria forming magnetite outside the cell. Magnetotactic bacteria live at the sediment-water interface and use internal nanomagnets to guide them to their preferred environmental niche using the Earth's magnetic field. Since magnetotactic bacteria generally grow optimally under carefully controlled microaerobic conditions, the culturing processes for these organisms are challenging and result in low yields of nanomagnetite. Despite these limitations, magnetotactic bacteria have bee

Coker, Victoria S.; Telling, Neil D.; van der Laan, Gerrit; Pattrick, Richard A.D.; Pearce, Carolyn I.; Arenholz, Elke; Tuna, Floriana; Winpenny, Richard E.P.; Lloyd, Jonathan R.

2009-03-24

440

Manganese regulates expression of manganese peroxide by Phanerochaete chrysosporium  

SciTech Connect

The appearance of manganese peroxidase (MnP) activity in nitrogen-limited cultures of Phanerochaete chrysosporium is dependent on the presence of manganese. Cultures grown in the absence of Mn developed normally and produced normal levels of the secondary metabolite veratryl alcohol but produced no MnP activity. Immunoblot analysis indicated that appearance of MnP protein in the extracellular medium was also dependent on the presence of Mn. Intracellular MnP protein was detectable only in cells grown in the presence of Mn. MnP mRNA was detected by Northern (RNA) blot analysis only in cells grown in the presence of Mn. If Mn was added to 4-day-old nitrogen-limited Mn-deficient cultures, extracellular MnP activity appeared after 6 h and reached a maximum after 18 h. Both actinomycin D and cycloheximide inhibited the induction of MnP activity by Mn. These results indicate that Mn, the substrate of the enzyme, is involved in the transcriptional regulation of the MnP gene.

Brown, J.A.; Glenn, J.K.; Gold, M.H. (Oregon Graduate Institute of Science and Technology, Beaverton (USA))

1990-06-01

441

Thermal expansion of manganese carbonate  

Microsoft Academic Search

Precision lattice parameters of manganese carbonate have been determined at different temperatures by the X-ray powder method\\u000a in the temperature range 28 to 265 C. The data has been used to evaluate, by a graphical method, the two coefficients of\\u000a thermal expansion,?\\u000a ? along thec-axis and?\\u000a ? at right-angles to thec-axis. The temperature-dependence of the coefficients is represented by the

K. V. Krishna Rao; K. Satyanaryana Murthy

1970-01-01

442

Manganese partitioning in low carbon manganese steel during annealing  

SciTech Connect

For 6Mn16 steel experimental soft annealing at 625 deg. C for periods from 1 h to 60 h and modeling with Thermo-Calc were performed to estimate the partitioning of alloying elements, in particular Mn, between ferrite, cementite and austenite. Using transmission electron microscopy and X-ray analysis it was established that the increase of Mn concentration in carbides to a level 7%-11.2% caused a local decrease of the Ac{sub 1} temperature and led to the presence of austenite around the carbides. Thus, after cooling, small bainite-martensite or bainite-martensite-retained austenite (BM-A) islands were observed. A dispersion of carbides and a coarsening process were observed. The measured amount of Mn in the carbides was in good agreement with theoretical predictions.

Lis, J. [Institute of Materials Engineering, Czestochowa University of Technology, 19 Armii Krajowej, 42-200 Czestochowa (Poland); Lis, A. [Institute of Materials Engineering, Czestochowa University of Technology, 19 Armii Krajowej, 42-200 Czestochowa (Poland)], E-mail: lis@mim.pcz.czest.pl; Kolan, C. [Institute of Materials Engineering, Czestochowa University of Technology, 19 Armii Krajowej, 42-200 Czestochowa (Poland)

2008-08-15

443

The Structural Stability of Manganese Oxide Electrodes for Lithium Batteries  

Microsoft Academic Search

Manganese oxides are of interest as insertion electrodes for rechargeable 3 V and 4 V lithium batteries. During discharge, lithium ions are inserted into the manganese oxide host structure with a concomitant reduction of the manganese ions; the reverse process occurs on charge. The cycle life of these batteries is critically dependent on the ability of the manganese oxide structure

Michael M. Thackeray

1997-01-01

444

Preparation and Magnetic Properties of NiFe2O4 Nanoparticles by Modified Pechini Method  

Microsoft Academic Search

Nickel ferrite (NiFe2O4) nanoparticles have been synthesized by modified Pechini method in the presence of surfactant and certain amount of concentrated nitric acid. The obtained foamed gel precursors were characterized by TG\\/DTA to determine the thermal decomposition and subsequently were calcined at different temperatures in the range of 500–800°C for 2 h to obtain NiFe2O4 nanoparticles which were characterized by X-ray

Xian-ming Liu; Wen-Liang Gao

2011-01-01

445

Preparation and Magnetic Properties of NiFe2O4 Nanoparticles by Modified Pechini Method  

Microsoft Academic Search

Nickel ferrite (NiFe2O4) nanoparticles have been synthesized by modified Pechini method in the presence of surfactant and certain amount of concentrated nitric acid. The obtained foamed gel precursors were characterized by thermogravimetry-differential thermal analysis (TG-DTA) to determine the thermal decomposition and subsequently calcined at different temperatures in the range of 500--800°C for 2 h to obtain NiFe2O4 nanoparticles, which were characterized

Xian-ming Liu; Wen-Liang Gao

2012-01-01

446

Ethanol Gas Sensing of Mn-Doped CoFe$_{2}$O $_{4}$ Nanoparticles  

Microsoft Academic Search

Undoped and Mn-doped cobalt ferrite (CoFe O ) nanoparticles were synthesized and characterized for thermal conductivity and magnetic properties. Room temperature ferro- magnetism and an increase in saturation magnetization due to Mn doping (65.4 emu\\/g for 3 at.% of Mn and 20.8 emu\\/g for undoped CoFe O nanoparticles) are observed. The ethanol gas sensitivity of undoped and Mn-doped (3 at.%)

P. Indra Devi; N. Rajkumar; B. Renganathan; D. Sastikumar; K. Ramachandran

2011-01-01

447

TOPICAL REVIEW: Synthesis and applications of magnetic nanoparticles for biorecognition and point of care medical diagnostics  

Microsoft Academic Search

Functionalized magnetic nanoparticles are important components in biorecognition and medical diagnostics. Here, we present a review of our contribution to this interdisciplinary research field. We start by describing a simple one-step process for the synthesis of highly uniform ferrite nanoparticles (d = 20-200 nm) and their functionalization with amino acids via carboxyl groups. For real-world applications, we used admicellar polymerization

Adarsh Sandhu; Hiroshi Handa; Masanori Abe

2010-01-01

448

Manganese metallurgy review. Part I: Leaching of ores\\/secondary materials and recovery of electrolytic\\/chemical manganese dioxide  

Microsoft Academic Search

The world rapidly growing demand for manganese has made it increasingly important to develop processes for economical recovery of manganese from low grade manganese ores and other secondary sources. Part I of this review outlines metallurgical processes for manganese production from various resources, particularly focusing on recent developments in direct hydrometallurgical leaching and recovery processes to identify potential sources of

Wensheng Zhang; Chu Yong Cheng

2007-01-01

449

Preparation of high-permeability NiCuZn ferrite*  

PubMed Central

Appropriate addition of CuO/V2O5 and the reduction of the granularity of the raw materials particle decrease the sintering temperature of NiZn ferrite from 1200 °C to 930 °C. Furthermore, the magnetic properties of the NiZn ferrite prepared at low temperature of 930 °C is superior to that of the NiZn ferrite prepared by sintering at high temperature of 1200 °C because the microstructure of the NiZn ferrite sintered at 930 °C is more uniform and compact than that of the NiZn ferrite sintered at 1200 °C. The high permeability of 1700 and relative loss coefficient tan?/?i of 9.0×10?6 at 100 kHz was achieved in the (Ni0.17Zn0.63Cu0.20)Fe1.915O4 ferrite.

Hu, Jun; Yan, Mi

2005-01-01

450

Ferritization treatment of copper in soil by electrokinetic remediation.  

PubMed

The usefulness of the combined use of the electrokinetic (EK) remediation and a ferrite treatment zone (FTZ) was demonstrated for a treatment of the contaminated soil with heavy metal ions. Copper ions in contaminated soil were transferred into the FTZ by the EK technology and were ferritized in this system. The distribution of copper in a migration chamber after EK treatment with FTZ for 48h showed the large difference in the total and eluted concentration of copper. This indicated that copper ions transferred by EK into the FTZ were ferritized there with ferrite reagent in soil alkalified by EK process. The copper-ferrite compound, which was not dissolved with diluted acid, was retained in the FTZ and accumulated there. The ratio of the ferritized amount of copper against total copper was 92% in the EK process with FTZ after 48 h. PMID:17374444

Kimura, Tomoyuki; Takase, Ken-Ichi; Terui, Norifumi; Tanaka, Shunitz

2007-01-09

451

Ferrite-Piezoelectric Layered Composites: Synthesis and Magnetoelectric Characterization  

NASA Astrophysics Data System (ADS)

The observation of strong magnetoelectric effects is reported in thick film bilayers and multilayers of ferrite-lead titanate zirconate (PZT). The ferrites used in our studies included pure and zinc substituted cobalt-, nickel- and lithium ferrites. Samples were prepared by sintering 10-40 mm thick films obtained by tape-casting. Measurements of ME voltage coefficients at 10-1000 Hz indicated a giant ME effect in nickel ferrite-PZT, but a relatively weak coupling in other ferrite-PZT systems. Evidence was found for enhancement in ME coefficients when Zn was substituted in ferrites. The Zn-assisted increase was attributed to low anisotropy and high permeability that resulted in favorable magneto-mechanical coupling in the composites. G. Srinivasan, E. T. Rasmussen, and R. Hayes, Phys. Rev. B 67, 014418 (2003) Supported by NSF and ARO grants.

Hayes, R. W.; Srinivasan, G.

2004-10-01

452

Design of ferrite-tuned accelerator cavities using perpendicular-biased high-Q ferrites  

SciTech Connect

Microwave ferrites with dc bias fields perpendicular to the rf fields exhibit magnetic and dielectric quality factors 1 order of magnitude above that of ferrites used in ferrite-tuned synchrotron accelerating cavities built in the past. For the LAMPF II project, these ferrites appear to allow the design of synchrotron cavities with high gap voltages and high efficiency. A simple coaxial quarter-wave-resonator geometry, first considered only as a model for preliminary studies, turned out to be a good basis for the solution of most technical problems such as generation of the bias field, cooling of the ferrites, and installation of a generous high-voltage gap design. Two quarter-wave resonators combined to form one accelerating unit of about 2.5-m length and 0.6-m diameter should be capable of delivering 120 kV of accelerating voltage in the tuning range 50-60 MHz, up to 200 kV in the range 59-60 MHz. The main advantage of the given resonator design is its full rotational symmetry, which allows calculation and optimization of all electrical properties with maximum reliability.

Kaspar, K.

1984-11-01

453

The reduction and oxidation behaviour of manganese oxides  

Microsoft Academic Search

The reduction of manganese oxides with methane was studied to investigate the suitability of manganese as an oxygen storage compound. Manganese oxides are reduced by CH4 to a lower-valent manganese oxide, producing CO2 and water. Once the manganese oxide is reduced, it can be regenerated, i.e. reoxidised. By integrating this exothermic oxidation cycle with endothermic methane reforming, a new setup

E. R. Stobbe; B. A. de Boer; J. W. Geus

1999-01-01

454

Structure of Widmanstatten crystals of ferrite and cementite  

Microsoft Academic Search

Structural analysis of Widmanstatten crystals in ?8, 10, and 5? carbon steel shows that Widmanstatten ferrite is first deposited\\u000a at the austenite grain boundaries in cast 50? steel. The intervals are filled with polyhedral ferrite. The plates of Widmanstatten\\u000a ferrite and cementite are laminar in structure. The layer thickness is ?10 3 nm or less. Analysis of the fine structure

I. A. Bataev; A. A. Bataev; V. G. Burov; Ya. S. Lizunkova; E. E. Zakharevich

2008-01-01

455

Recrystalised grain morphology in 9Cr 1Mo ferritic steel  

Microsoft Academic Search

Grain morphology in cold rolled, recrystallize-annealed 9Cr 1Mo commercial grade ferritic steel has been investigated. The recrytallization-annealing up to 100h at 1100K exhibited carbide particles embedded in ?-ferrite grain matrix. The resulted grain sizes were much smaller than those of virgin sample. The heat treatment more than 100h resulted in dual phase ferrite-martensite morphology. The recrystallization-annealing at 1300 and 1350K

M. N. Mungole; Gadadhar Sahoo; S. Bhargava; R. Balasubramaniam

2008-01-01

456

Cryogenic X-band ferrite phase shifter\\/attenuator  

Microsoft Academic Search

A cryogenic ferrite phase shifter\\/attenuator (PSA) has been developed which is biased with persistent supercurrents to facilitate the precision adjustment of the amplitude and phase of X-band signals. The PSA is constructed in stripline and uses two slabs of TT2-113 ferrite (35x3x1.6 mm) slightly rounded at the ends. Quarter-wavelength matching transformers are used to broadband-match the ferrite loaded line over

L. D. Mann; D. G. Blair

1983-01-01

457

Practical millimeter-wave ferrite phase shifters  

NASA Astrophysics Data System (ADS)

The performance of latching ferrite phase shifters is examined. For a dual-mode phase shifter, modified transmission line techniques were used to determine the phase shifter and nonreciprocal polarizer lengths in circular waveguide, constrained in diameter such that the TE(21) mode was nonpropagating. For the nonreciprocal toroid phase shifter, the transverse resonance method was used, with the waveguide height taken as that of a standard waveguide in each frequency band calculated, and the toroid dimensions and waveguide width adjusted for a uniform phase shift vs. frequency characteristic. Perturbational methods were used in both cases to determine the contributions of waveguide wall loss and material dielectric and magnetic losses to the total predicted insertion loss of the shifter. Computations were carried out in the 10, 35, 60, and 94 GHz regions. The superior efficiency of the dual-mode type's use of ferrite results in a superior performance with regard to losses. Practical 35 GHz units are discussed.

Boyd, C. R., Jr.

1982-12-01

458

Peats and ferrites for heavy metal removal  

SciTech Connect

Peat is a relatively inexpensive material which processes a native cation exchange capacity. Efforts to utilize peat have been hampered by its low permeability to water and its tendency to severely leach in water at pH>6. These disadvantages have been significantly minimized by treating the peat with concentrated sulfuric acid. The acid treatment also increases the cation exchange capacity of the peat. Results of both column batch studies of the modified peat for use as an actinide adsorbent will be presented. Ferrites are mixed valence iron compounds having metal sorptive and magnetic properties. A naturally occurring ferrite material is magnetite. We have studied activation techniques to give magnetite a high capacity for removing heavy metals and actinides from aqueous process waste solutions. The solution can then be magnetically filtered to removal magnetite sorbed metals from solution. results of the experiments will be described. 18 refs.

Navratil, J.D.

1986-01-01

459

Conventional and microwave hydrothermal synthesis of monodispersed metal oxide nanoparticles at liquid-liquid interface  

EPA Science Inventory

Monodispersed nanoparticles of metal oxide including ferrites MFe2O4 (M=, Ni, Co, Mn) and ¿-Fe2O3, Ta2O5 etc. have been synthesized using a water-toluene interface under both conventional and microwave hydrothermal conditions. This general synthesis procedure uses readily availab...

460

Investigation of surface passivation process on magnetic nanoparticles by Raman spectroscopy  

Microsoft Academic Search

A detailed study of the surface passivation process in superparamagnetic cobalt ferrite nanoparticles has been carried out using micro Raman spectroscopy. In addition to Raman spectroscopy, X-ray diffraction and atomic absorption spectroscopy were also used to investigate passivated and non-passivated samples. The data were discussed in terms of changes in the structural characteristics of the samples considering the introduction of

T. F. O. Melo; S. W. da Silva; M. A. G. Soler; E. C. D. Lima; P. C. Morais

2006-01-01

461

Influence of Aluminum Alloying and Heating Rate on Austenite Formation in Low Carbon-Manganese Steels  

NASA Astrophysics Data System (ADS)

This investigation focuses on the austenite formation process during continuous heating, over a wide range of heating rates (0.05 to 20 K/s), in three low carbon-manganese steels alloyed with different levels of aluminum (0.02, 0.48, and 0.94, wt pct Al). High resolution dilatometry, combined with metallographic observations, was used to determine the starting ( Ac 1) and finishing ( Ac 3) temperatures of this transformation. It is shown that both the aluminum content and the applied heating rate have a strong influence on this process. During fast heating (>1 K/s), the pearlite phase present in the initial microstructure remains almost unaffected up to temperature Ac 1. On the contrary, during slow heating, cementite lamellas inside pearlite partially dissolve, this dissolution effect being more pronounced for the lower carbon and higher aluminum content steels. The changes in the initial microstructure during slow heating affect the austenite nucleation and growth processes. Furthermore, in the aluminum alloyed steels, slow heating conditions shift the Ac 3 temperature to higher values. This shift is suggested to be due to aluminum partitioning from austenite to ferrite, which stabilizes ferrite and delays its transformation to higher temperatures. Thermodynamic calculations carried out with MTDATA software seem to support some of the experimental observations carried out under very low heating conditions close to equilibrium (0.05 K/s).

San Martín, D.; Palizdar, Y.; García-Mateo, C.; Cochrane, R. C.; Brydson, R.; Scott, A. J.

2011-09-01

462

Tunable polarity of the Casimir force based on saturated ferrites  

SciTech Connect

We study the polarity of the Casimir force between two different parallel slabs separated by vacuum when the saturated ferrite materials under the influence of an external magnetic field are taken into consideration. Between the ordinary dielectric slab and the ferrite slab, repulsive Casimir force may be observed by adjusting the applied magnetic field. For the ferrite material, we consider the frequency dependence of the permeability modified by the external magnetic field to analyze the formation of the repulsive Casimir force. The restoring force, which means the transition of the force polarity from repulsion to attraction with the increasing slab separation, can also be obtained between two different ferrite slabs.

Zeng Ran [School of Telecommunication, Hangzhou Dianzi University, Hangzhou 310018 (China); Yang Yaping [Department of Physics, Tongji University, Shanghai 200092 (China); Beijing Computational Science Research Center, Beijing 100084 (China)

2011-01-15

463

Ferrite microwave electronics Citations from the NTIS data base  

NASA Astrophysics Data System (ADS)

Research reports on single crystals, thin films, dielectrics, semiconductor devices, integrated circuits, phase shifters, and waveguide components are cited. Studies on the microwave properties of ferrites are included.

Reed, W. E.

1980-07-01

464

Nanosized copper ferrite materials: Mechanochemical synthesis and characterization  

SciTech Connect

Nanodimensional powders of cubic copper ferrite are synthesized by two-steps procedure of co-precipitation of copper and iron hydroxide carbonates, followed by mechanochemical treatment. X-ray powder diffraction, Moessbauer spectroscopy and temperature-programmed reduction are used for the characterization of the obtained materials. Their catalytic behavior is tested in methanol decomposition to hydrogen and CO and total oxidation of toluene. Formation of nanosized ferrite material is registered even after one hour of milling time. It is established that the prolonging of treatment procedure decreases the dispersion of the obtained product with the appearance of Fe{sub 2}O{sub 3}. It is demonstrated that the catalytic behavior of the samples depends not only on their initial phase composition, but on the concomitant ferrite phase transformations by the influence of the reaction medium. -- Graphical abstract: It is demonstrated that the catalytic behavior of the obtained copper ferrites depends not only on their initial phase composition, but on the concomitant phase transformations by the influence of the reaction medium. Display Omitted Highlights: {yields} Two-step co-precipitation-ball-milling procedure for copper ferrites preparation. {yields} The phase composition of ferrites depends on the milling duration. {yields} Ferrites transforms under the reaction medium, which affects their catalytic behavior. {yields} Ferrites decompose to magnetite and carbides during methanol decomposition. {yields} Agglomeration and further crystallization of ferrite occur during toluene oxidation.

Manova, Elina [Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 11, 1113 Sofia (Bulgaria); Tsoncheva, Tanya, E-mail: tsoncheva@orgchm.bas.b [Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 9, 1113 Sofia (Bulgaria); Paneva, Daniela [Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 11, 1113 Sofia (Bulgaria); Popova, Margarita [Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 9, 1113 Sofia (Bulgaria); Velinov, Nikolay; Kunev, Boris; Tenchev, Krassimir; Mitov, Ivan [Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 11, 1113 Sofia (Bulgaria)

2011-05-15

465

CHARACTERIZING AND MODELING FERRITE-CORE PROBES  

SciTech Connect

In this paper, we accurately and carefully characterize a ferrite-core probe that is widely used for aircraft inspections. The characterization starts with the development of a model that can be executed using the proprietary volume-integral code, VIC-3D(c), and then the model is fitted to measured multifrequency impedance data taken with the probe in freespace and over samples of a titanium alloy and aluminum. Excellent results are achieved, and will be discussed.

Sabbagh, Harold A.; Murphy, R. Kim; Sabbagh, Elias H. [Victor Technologies LLC, Bloomington, IN 47401 (United States); Aldrin, John C. [Computational Tools, Gurnee, IL 60031 (United States)

2010-02-22

466

Preparation of TEM samples of ferritic alloys.  

SciTech Connect

We describe techniques for electropolishing irradiated ferritic specimens for examination under the TEM in situations where the foil quality is of utmost importance. First, we describe some modifications to the standard technique for making plan-view specimens aimed at optimizing the foil quality. Second, we describe a technique for making plan-view specimens from a region of buried damage in a specimen irradiated with 2 MeV Fe{sup +} ions.

Yao, Z.; Xu, S.; Jenkins, M. L.; Kirk, M. A.; Materials Science Division; Univ. of Oxford

2008-01-01

467

Cold worked ferritic alloys and components  

DOEpatents

This invention relates to liquid metal fast breeder reactor and steam generator precipitation hardening fully ferritic alloy components which have a microstructure substantially free of the primary precipitation hardening phase while having cells or arrays of dislocations of varying population densities. It also relates to the process by which these components are produced, which entails solution treating the alloy followed by a final cold working step. In this condition, the first significant precipitation hardening of the component occurs during high temperature use.

Korenko, Michael K. (Wexford, PA)

1984-01-01

468

Rapid solidification of candidate ferritic steels  

SciTech Connect

HT-9 and 9Cr-1Mo steels were rapidly solidified by the liquid dynamic compaction process and 2-1/4Cr-1Mo steel was prepared by the ultrasonic gas atomization process. The consolidation was performed in the ferritic temperature range in order to minimize segregation. These alloys will be tested at ORNL using 1/3 CVN test specimens and the results will be compared with those for conventially processed alloys.

Megusar, J.; Craven, C.A.; Kohse, G.; Harling, O.K.; Runkle, J.

1985-01-01

469

Superconductor ferrite phase shifters and circulators  

Microsoft Academic Search

We have previously demonstrated high-Tc superconductor\\/ferrite nonreciprocal microwave phase shifters that avoid dc magnetic-flux penetration of the superconductor through a novel design of the magnetic circuit, and thus operate with very low loss. Recently, a simplified magnetic structure has been introduced, and devices with approximately 0.1 dB insertion loss with 500 degrees of phase shift (figure of merit 5000 deg\\/dB)

D. E. Oates; G. F. Dionne; D. H. Temme; J. A. Weiss

1997-01-01

470

Ferrite Phase Shifter for the UHF Region  

Microsoft Academic Search

An extremely compact, low-loss, ferrite phase shifter has been developed for the 200 to 800-mc region. It consists of a folded stripline structure approximately 61\\/2 inches long and less than 1 inch square in cross section. The device requires a longitudinal magnetic field of sufficient intensity to place the operating region above resonance. For field swings of about 900 oersteds

C. M. Johnson

1959-01-01

471

Zinc-ferrite pigment for corrosion protection  

Microsoft Academic Search

Zinc-ferrite pigment was prepared by solid-state reaction. A mixture of ?-Fe2O3 and ZnO in a molar ratio of 1:1 was fired at 1,200°C. X-ray diffraction measurements proved that the reacted material crystallized into a spinal structure. Measurement of the pigment specification and properties were carried out according to standard international methods. The pigment extract and the extract of the pigment-linseed

Y. M. Abu Ayana; S. M. El-Sawy; S. H. Salah

1997-01-01