Microstructure and magnetic properties of Fe(x)Ni(1-x) alloy nanoplatelets

Plate-like nanoparticles (or nanoplatelets) of Fe(x)Ni(1-x) (x = 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6) alloy were successfully synthesized through a simple sonochemical method. The shapes of the alloy nanoplatelets with different Fe atom contents are almost same. Their average diameters are about 50 nm, and their average thicknesses are several nanometers. The obtained Fe(x)Ni(1-x) alloy nanoplatelets are single-phased and have a face-centered cubic (FCC) crystal structure. The lattice constants of the alloy nanoplatelets are larger than the corresponding bulk value and increase with increasing Fe content. The surface oxidation of the alloy nanoplatelets leads to the lattice expansion. The alloy nanoplatelet powders are all ferromagnetic, and their saturation magnetizations are slightly lower than the corresponding bulk value. The saturation magnetic field and the coercivity increase with increasing Fe content. Magnetic hysteresis loops along the directions deviating different angles from the nanoplatelets plane are obviously different, indicating that the easy-axis is in the in-plane direction and the magnetization reversal is incoherent mode. The micromagnetic simulation results for the array composed of thirty-six Fe0.6Ni0.4 alloy nanoplatelets fit well with the measured data.     

Ni doped Fe3O4 magnetic nanoparticles

In this work, the effect of nickel doping on the structural and magnetic properties of Fe3O4 nanoparticles is analysed. Ni(x)Fe(3-x)O4 nanoparticles (x = 0, 0.04, 0.06 and 0.11) were obtained by chemical co-precipitation method, starting from a mixture of FeCl2 x 4H2O and Ni(AcO)2 x 4H2O salts. The analysis of the structure and composition of the synthesized nanoparticles confirms their nanometer size (main sizes around 10 nm) and the inclusion of the Ni atoms in the characteristic spinel structure of the magnetite Fe3O4 phase. In order to characterize in detail the structure of the samples, X-ray absorption (XANES) measurements were performed on the Ni and Fe K-edges. The results indicate the oxidation of the Ni atoms to the 2+ state and the location of the Ni2+ cations in the Fe2+ octahedral sites. With respect to the magnetic properties, the samples display the characteristic superparamagnetic behaviour, with anhysteretic magnetic response at room temperature. The estimated magnetic moment confirms the partial substitution of the Fe2+ cations by Ni2+ atoms in the octahedral sites of the spinel structure.     

Ni(2+) and H(2)PO(4)(-) uptake properties of compounds in the CaTiO(3)-CaFeO(2.5) system

A batch method was used to investigate the uptake of heavy metal cations and anions by the compounds in the CaTiO(3)-CaFeO(2.5) system, in which a series of oxygen vacancies was systematically introduced into a perovskite structure as the x-value of Ca(Fe(x)Ti(1-x))O(3-x/2) was increased. Samples of CaTiO(3), CaFe(0.1)Ti(0.9)O(2.95), CaFe(0.5)Ti(0.5)O(2.75), CaFe(0.67)Ti(0.33)O(2.67) and CaFeO(2.5) were prepared by solid mixing (SM), co-precipitation (CP) and gel evaporation (GE) methods. The resulting samples were calcined at temperatures between 400 and 1000 °C. The target crystalline phases differed according to the preparation method, but in most cases were formed at 700-800 °C. The Ni(2+) sorption isotherms of all the samples were fitted better by the Langmuir model than by the Freundlich model, while in the case of H(2)PO(4)(-) sorption isotherms, these were better fitted by the latter model. The uptake ability increased with increasing x value of the samples. The maximum values for the saturated sorption of Ni(2+) (Q(0)(Ni(2+)) = 2.83 mmol/g) and H(2)PO(4)(-) (K(F)(H(2)PO(4)(-)) = 2.95 mmol/g) were achieved for x = 1 (i.e. CaFeO(2.5)) sample.     

Phase Transformation and Magnetostriction of (R-Pr)(Fe-T)_2 (R=Dy Tb; T=Co, Ni)

1. IntroductionMuch attention has been focused onmagnetostrictive materials RFe2, particularly,Tbo.zv~o.sDyo.vs~o.vFez (Terfenol-D), due to theirexcellellt magnetoelastic properties for the transducer deviceslll. Clark et al. firstly suggestedthat the pseudobinary compounds combined byTb, Dy and Fe could be constructed in an effortto reduce the anisotropy while maintaining largemagnetostrictionlZ]. Clark et al. also found in thecompensated system Tbl--.Pr.FeZ that (Tb, Pr)Fe3phase appea…     

Fabrication and magnetic property of BaSm(x)Fe(12-x)O19 (x < or = 0.4) nanofibers

BaSm(x)Fe(12-x)O19 (x < or = 0.4) ferrite nanofibers were prepared by sol-gel method from starting reagents of metal salts and citric acid. These nanofibers were characterized by TG-DTA, FTIR, SEM, XRD and VSM. These results show that the BaSm(x)Fe(12-x)O19 (x < or = 0.4) ferrite nanofibers were obtained subsequently from calcination at 750 degrees C for 1 h. The BaSm(x)Fe(12-x)O19 (x < or = 0.4) microstructure and magnetic property are mainly influenced by chemical composition and heat-treatment temperature. The grain sizes of BaSm0.3Fe11.7O19 ferrite nanofibers are in a nanoscale from 40 nm to 62 nm corresponding to the calcination temperature from 750 degrees C to 1050 derees C. The saturation magnetization of BaSm(x)Fe(12-x)O19 ferrite nanofiber calcined at 950 degrees C for 1 h initially decreases with the Sm content from 0 to 0.3 and then increases with a further Sm content, while the coercivity exhibits a continuous increase from 348 kA x m(-1) (x = 0) to 427 kA x m(-1) (x = 0.4). The differences of magnetic properties are attributed to lattice distortion and enhancement for the anisotropy energy.     

Atomically controlled processing in silicon-based CVD epitaxial growth

One of the main requirements for Si-based ultrasmall device is atomic-order control of process technology. Here, we show the concept of atomically controlled processing for group IV semiconductors based on atomic-order surface reaction control in Si-based CVD epitaxial growth. Self-limiting formation of 1-3 atomic layers of group IV or related atoms after thermal adsorption and reaction of hydride gases on Si(1-x)Gex(100) (x = 0-1) surface are generalized based on the Langmuir-type model. Moreover, Si-based epitaxial growth on N, P or C atomic layer formed on Si(1-x)Gex(100) surface is achieved at temperatures below 500 degrees C. N atoms of about 4 x 10(14) cm(-2) are buried in the Si epitaxial layer within about 1 nm thick region. In the Si(0.5)Ge(0.5) epitaxial layer, N atoms of about 6 x 10(14) cm(-2) are confined within about 1.5 nm thick region. The confined N atoms in Si(1-x)Gex preferentially form Si-N bonds. For unstrained Si cap layer grown on top of the P atomic layer formed on Si(1-x)Gex(100) with P atomic amount of below about 4 x 10(14) cm(-2) using Si2H6 instead of SiH4, the incorporated P atoms are almost confined within 1 nm around the heterointerface. It is found that tensile-strain in the Si cap layer growth enhances P surface segregation and reduces the incorporated P atomic amount around the heterointerface. Heavy C atomic-layer doping suppresses strain relaxation as well as intermixing between Si and Ge at the nm-order thick Si(1-x)Gex/Si heterointerface. These results open the way to atomically controlled technology for ULSIs.     

微波多元醇法制备单分散Ni1-xZnxFe2O4/MWCNTs与磁性能

以多壁碳纳米管(MWCNTs)为模板,三乙二醇(TREG)为溶剂,采用微波多元醇法制备MWC-NTs负载组成可控的Ni1-xZnxFe2O4(x=0.4、0.5、0.6)纳米复合材料Ni1-xZnxFe2O4/MWCNTs。其结构和形貌通过XRD、SEM、TEM和EDX进行表征,用VSM测试样品的磁性,并探讨了微波功率、微波时间对镍锌铁氧体负载的影响。结果表明立方系尖晶石结构的单分散Ni1-xZnxFe2O4磁性纳米粒子均匀负载在碳纳米管表面,平均粒径约为6nm;其磁性能与镍锌铁氧体的组成有关,随着Zn含量的增加,饱和磁化强度(Ms)先增大后减小,当x=0.5时Ms达到最大值。矫顽力(Hc)都比较小,在室温下表现为超顺磁性。     

Crystallization mechanisms of phase change (GeSbSn)(100-x)Co(x) optical recording films

In this study, the (GeSbSn)(100-x0Co(x) films (x = 0-13.3) were deposited on natural oxidized silicon wafer and glass substrate by dc magnetron co-sputtering of GeSbSn and Co targets. The ZnS-SiO2 films were used as protective layers. The thicknesses of the (GeSbSn)(100-x)Co(x) films and protective layer were 100 nm and 30 nm, respectively. We investigated the effects of Co addition on the thermal property, crystallization kinetics, and crystallization mechanism of the GeSbSn recording film. The crystallization temperatures of (GeSbSn)(100-x)Co(x) films were decreased with Co content. It was found that the activation energy of the (GeSbSn)(100-x)Co(x) films will decrease from 1.53 eV to 0.55 eV as Co content increased from 0 at.% to 13.3 at.%.     

Electrochemical and thermal behaviour of Li[Li(x)(Ni0.3Co0.1Mn0.6)1 - x]O2 (x = 0.09, 0.11) cathode Materials for lithium rechargeable batteries

High rate capable Mn-rich layered Li[Li(x)(Ni0.3Co0.1Mn0.6)1-x]O2 (x = 0.09, 0.11) cathode materials that are fully charged are investigated with respect to stability. Differential scanning calorimetry is used to determine the thermal stability of cathode material compositions together with PVdF binder and a conductive agent by heating from 30 degrees C to 400 degrees C at 10 degrees C/min. In the Li[Li(x)(Ni0.3Co0.1Mn0.6)1-x]O2 (x = 0.09, x = 0.11) cathode materials, the exothermic reaction started at 100 degrees C. Due to thermal runway, a sharp peak was observed at 279.25 degrees C for the material of x = 0.09 with exothermic heat generation of 168.4 J/g. For the Mn-rich cathode material, where x = 0.11, two relatively smaller peaks appeared at 250.72 degrees C and 268.60 degrees C with heat evolution of 71.49 J/g and 93.67 J/g, respectively. These layered cathode materials are thermally stable. The x = 0.09 composition shows huge heat flow occurrence when compared to the x = 0.11. It is concluded from a heat generation analysis that the two Mn-rich cathode materials are thermally stable for lithium rechargeable batteries.     

Gas sensing property of perovskite SrTi(1-x)Fe(x)O3_delta fabricated by thick film planar technology

Planar sensor of SrTi(1-x)Fe(x)O3-delta, x = 0.4 and 0.6, with perovskite structure was fabricated on alumina substrate using thick film technology. Electrical resistance was measured as a function of thermal treatment conditions, atmosphere, time and temperature. Sensing property was also measured as a function of temperature and the gases of O2, CH4, CO, CO2, NO and NO2. The resistance of SrTi(1-x)Fe(x)O3-delta is lower than those of SrTiO3 or SrFeO3. TCR (temperature coefficient of resistance) of zero over 550 degrees C was measured for the composition of SrTi(1-x)Fe(x)O3-delta after thermal treatment at 1100 degrees C in air atmosphere only. The perovskite SrTi(1-x)Fe(x)O3-delta didn't show any response to CH4, CO, CO2, NO and NO2, but an excellent response and recovery characteristics with oxygen concentration.     

Non-basic solution eco-routes to nano-scale NiO with different shapes: Synthesis and application

The assembly of NiO nanodiscs (namely nanoflowers) as well as the dispersed NiO nanodiscs have been successfully synthesized via the thermal decomposition of Ni(OH)₂ obtained from different Ni sources in non-basic solution. The route is environment-friendly. The materials were characterized by X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM) and N₂ adsorption–desorption. The porous structures with pore size around 6 nm can be observed on the single NiO disc. The nanoflowers exhibit better performance than nanodiscs in the electrochemical test and water treatment experiments, due to much more available surface areas and spaces formed in the NiO nanoflowers.     

Adsorption and aggregation of Fe(III)-hydroxy complexes during the photodegradation of phenol using the iron-added-TiO(2) combined system

The behavior of Fe(III) aquacomplexes in TiO(2) suspensions in the degradation of phenol has been investigated. The most active Fe(OH)(2+) species adsorbed on the surface of TiO(2) retards the conversion of Fe(OH)(2+) into oligomers and therefore increases the percentage of Fe(OH)(2+) with irradiation time, with a consequent enhancement in the catalytic cycle of Fe(III)/Fe(II) and excited charge traps by Fe(III) in the iron-TiO(2) system. The influence of iron addition on TiO(2) was obtained when the regeneration of [Fe(OH)(2+)] remained continuous with irradiation time. In an optimum TiO(2) suspension (0.5g/L) with the addition of 0.1mM Fe(III), the measured k(obs) values for phenol degradation were enhanced for the higher adsorption of Fe(OH)(2+) on the reactive surface of TiO(2) at a specified irradiation time.     

Synthesis and Magnetostriction of (CexTb1-x)0.5Pr0.5Fe2 Compounds

1. IntroductionBased on the single-ion model predictionl'], thecubic Laves phase compound PrFeZ possesses a gialltmagnetostrictive value due to its large second--orderStevens' factor ioJ, the ground state angular momentum J and the average radius squared < re, > ofthe 4f electron shell for the Pr3+ ion. And it is apotelltial candidate for giant magnetostrictive materials. However, previous researches showed that theradius of Prc+ ion is very large and the cubic PrFeZhas not been synthesiz…     

Synthesis of ferrites obtained from heavy metal solutions using wet method

Wet method was employed to the treatment of heavy metal-contaminated wastewater, and Zn(x)Fe(3-x)O(4), Ni(x)Fe(3-x)O(4) and Cr(x)Fe(3-x)O(4) (0Cr(3+) and the influence of the three ions on sample thermostability is Zn(2+)>Ni(2+)>Cr(3+).     

Diameter-dependent composition of vapor-liquid-solid grown Si(1-x)Ge(x) nanowires

Diameter-dependent compositions of Si(1-x)Ge(x) nanowires grown by a vapor-liquid-solid mechanism using SiH(4) and GeH(4) precursors are studied by transmission electron microscopy and X-ray energy dispersive spectroscopy. For the growth conditions studied, the Ge concentration in Si(1-x)Ge(x) nanowires shows a strong dependence on nanowire diameter, with the Ge concentration decreasing with decreasing nanowire diameter below approximately 50 nm. The size-dependent nature of Ge concentration in Si(1-x)Ge(x) NWs is strongly suggestive of Gibbs-Thomson effects and highlights another important phenomenon in nanowire growth.     

Simultaneous removal of perchlorate and arsenate by ion-exchange media modified with nanostructured iron (hydr)oxide

Hybrid ion-exchange (HIX) media for simultaneous removal of arsenate and perchlorate were prepared by impregnation of non-crystalline iron (hydr)oxide nanoparticles onto strong base ion-exchange (IX) resins using two different chemical treatment techniques. In situ precipitation of Fe(III) (M treatment) resulted in the formation of sphere-like clusters of nanomaterials with diameters of approximately 5nm, while KMnO4/Fe(II) treatments yielded rod-like nanomaterials with diameters of 10-50nm inside the pores of the media. The iron content of most HIX media was >10% of dry weight. The HIX media prepared via the M treatment method consistently exhibited greater arsenate adsorption capacity. The fitted Freundlich adsorption intensity parameters (q=K x C(E)(1/n)) for arsenate (1/n<0.6) indicated favorable adsorption trends. The K values ranged between 2.5 and 34.7mgAs/gdry resin and were generally higher for the M treated media in comparison to the permanganate treated media. The separation factors for perchlorate over chloride (alpha(Cl-)(ClO4-)) for the HIX media were lower than its untreated counterparts. The HIX prepared via the M treatment, had higher alpha(Cl-)(ClO4-) than the HIX obtained by the KMnO(4)/Fe(II) treatments suggesting that permanganate may adversely impact the ion-exchange base media. Short bed adsorber (SBA) tests demonstrated that the mass transport kinetics for both ions are adequately rapid to permit simultaneous removal using HIX media in a fixed bed reactor.     

Synthesis, characterization and magnetic properties of Zn substituted Li-Ni nano ferrites

Nanosized Li-Ni-Zn ferrites with general chemical formula Li0.5 Ni(0.75-x/2) Zn(x/2) Fe2O4 (0 < x < 1) were synthesized from a simple polymer matrix based precursor solution. The solution was composed of metal nitrates, polymer (PVA) and disaccharide (sucrose). Thermolysis/flame pyrolysis of the precursor mass in an external temperature resulted in the oxide phase formation. X-ray diffraction studies confirm the formation of single phase ferrites. The microstructural analysis was carried out by scanning electron microscopy (SEM). The average grain diameter was estimated by the Scherrer method and grain diameter is found to vary from 16 nm to 33 nm. The saturation magnetization was studied as a function of composition.     

Synthesis and photoluminescence of nano-sized (Gd,Y)PO4:Eu3+ by solution combustion method

We synthesized (Gd(1-x)Yx)(0.94)PO4:Eu(0.06) (0 < or = x < or = 1.0) phosphor powders of an ultra-fine size (approximately 23 nm), smooth surface, and spherical and regular morphologies by the solution combustion method. The crystallite sizes of the annealed (Gd(1-x)Yx)(0.94)PO4:Eu(0.06) phosphors with x = 0, 0.25, 0.5, 0.75, and 1.0 were 63.3, 62.3, 49.9, 45.1, and 43.3 nm, respectively. The photoluminescent characteristics of the phosphors were studied under vacuum ultraviolet excitation, depending on the Y3+ concentration. The intensity of the peaks corresponding to the red emission increased with increases in the Y3+ concentration. The Y(0.94)PO4:Eu(0.06) phosphor emitted the strongest intensity and the purest red color.     

Synthesis of hierarchical Ni(OH)(2) and NiO nanosheets and their adsorption kinetics and isotherms to Congo red in water

Ni(OH)(2) and NiO nanosheets with hierarchical porous structures were synthesized by a simple chemical precipitation method using nickel chloride as precursors and urea as precipitating agent. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy and nitrogen adsorption-desorption isotherms. Adsorption of Congo red (CR) onto the as-prepared samples from aqueous solutions was investigated and discussed. The pore structure analyses indicate that Ni(OH)(2) and NiO nanosheets are composed of at least three levels of hierarchical porous organization: small mesopores (ca. 3-5 nm), large mesopores (ca. 10-50 nm) and macropores (100-500 nm). The equilibrium adsorption data of CR on the as-prepared samples were analyzed by Langmuir and Freundlich models, suggesting that the Langmuir model provides the better correlation of the experimental data. The adsorption capacities for removal of CR was determined using the Langmuir equation and found to be 82.9, 151.7 and 39.7 mg/g for Ni(OH)(2) nanosheets, NiO nanosheets and NiO nanoparticles, respectively. Adsorption data were modeled using the pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetics equations. The results indicate that pseudo-second-order kinetic equation and intra-particle diffusion model can better describe the adsorption kinetics. The as-prepared Ni(OH)(2) and NiO nanosheets are found to be effective adsorbents for the removal of Congo red pollutant from wastewater as a result of their unique hierarchical porous structures and high specific surface areas.     

Morphology and magnetic properties of diluted magnetic semiconductor 1D nanostructure Ni(x)Sn(1-x)O(2-delta)

SnO2 and Ni(x)Sn(1-x)O(2-delta) (x = 0.007-0.043) 1D nanostructures are fabricated using a catalyzer assisted chemical vapor deposition (CVD). The morphology of the 1D nanostructure is sensitive to the fabrication conditions. As the Ar flux rate is decreased from 50 sccm to 40 sccm, the 1D nanostructure changes from nanowire to nanobelt. All of the Ni(x)Sn(1-x)O(2-delta) 1D nanostructures exhibit room temperature ferromagnetism (RTFM). With the increasing x, magnetic moment per Ni ion increases at first, reaches a maximum of 3.33 microB in x = 0.025, then decreases. The results of annealing in vacuum and oxidizing atmospheres reveal that oxygen vacancies play a crucial role in introducing ferromagnetism, which implies that the origin of RTFM can be understood by the bound magnetic polaron model (BMP).