Synthesis and magnetic characterization of nickel ferrite nanoparticles prepared by co-precipitation route

Magnetic nanoparticles of nickel ferrite (NiFe2O4) have been synthesized by co-precipitation route using stable ferric and nickel salts with sodium hydroxide as the precipitating agent and oleic acid as the surfactant. X-ray diffraction (XRD) and transmission electron microscope (TEM) analyses confirmed the formation of single-phase nickel ferrite nanoparticles in the range 8-28 nm depending upon the annealing temperature of the samples during the synthesis. The size of the particles (d) was observed to be increasing linearly with annealing temperature of the sample while the coercivity with particle size goes through a maximum, peaking at similar to 11 nm and then decreases for larger particles. Typical blocking effects were observed below similar to 225 K for all the prepared samples. The superparamagnetic blocking temperature (T-B) was found to be increasing with increasing particle size that has been attributed to the increased effective anisotropy energy of the nanoparticles. The saturation moment of all the samples was found much below the bulk value of nickel ferrite that has been attributed to the disordered surface spins or dead/inert layer in these nanoparticles. (c) 2008 Elsevier B. V. All rights reserved.

Structural analysis of nickel doped cobalt ferrite nanoparticles prepared by coprecipitation route

Magnetic nanoparticles of nickel substituted cobalt ferrite (NixCo1-xFe2O4:0 <= x <= 1) have been synthesized by co-precipitation route. Particles size as estimated by the full width half maximum (FWHM) of the strongest X-ray diffraction (XRD) peak and transmission electron microscopy (TEM) techniques was found in the range 18-28 +/- 4 nm. Energy dispersive X-ray (EDX) analysis confirms the presence of Co, Ni, Fe and oxygen as well as the desired phases in the prepared nanoparticles. The selective area electron diffraction (SAED) analysis confirms the crystalline nature of the prepared nanoparticles. Data collected from the magnetization hysteresis loops of the samples show that the prepared nanoparticles are highly magnetic at room temperature. Both coercivity and saturation magnetization of the samples were found to decrease linearly with increasing Ni-concentration in cobalt ferrite. Superparamagnetic blocking temperature as determined from the zero field cooled (ZFC) magnetization curve shows a decreasing trend with increasing Ni-concentration in cobalt ferrite nanoparticles. (C) 2009 Elsevier B.V. All rights reserved.

Calibration of a solid-state copper ion-selective electrode in cupric ion buffers containing chloride

It is shown that near-Nernstian calibration slopes can be obtained with a Cu1.8Se electrode in a range of cupric ion buffers in spite of a high chloride content. Best results are obtained with the ligands ethylenediamine, glycine and histidine. The onset of cupric ion toxicity towards marine organisms falls within the pCu calibration range obtained with glycine, and the Cu1.8Se electrode could, therefore, be useful for monitoring cupric ion activity in bioassays in sea-water media.

zero point of charge of cupric hydroxide and surface area determination by dye adsorption

zero point of charge of freshly precipitated cu(oh)2 has been determined to lie at pH 7.7 by means of microclectrophoresis technique. Day aged hydroxide shows an acid zpc shift to pH 7.3. these experimental values approximate the equivalence points of cu+ and oh_ ,which can be estimated from the solubility diagram constructed fo gu(oh)2 and cuo.

Facile synthesis of poly(o-phenylenediamine) microfibrils using cupric sulfate as the oxidant

A rapid, templateless, surfactantless approach is proposed to prepare microfibrils by simply mixing of aqueous cupric sulfate and o-phenylenediamine (oPD) solutions at room temperature. The as-prepared poly(o-phenylenediamine) (PoPD) microfibrils have been characterized by optical microscope, transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis) and X-ray diffraction (XRD).

Studies on the magnetism of cobalt ferrite nanocrystals synthesized by hydrothermal method

Fe-Co/CoFe2O4 nanocomposite and CoFe2O4 nanopowders were prepared by the hydrothermal method. The structure of magnetic powders were characterized by X-ray diffraction diffractometer (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), thermal gravity analysis (TGA) and differential thermal analysis (DTA) analysis, X-ray photoelectron spectrometry (XPS), and Fourier transform infrared spectra (FTIR) techniques, while magnetic properties were determined by using a vibrating sample magnetometer (VSM) at room temperature.

Preparation of ferrite MFe2O4 (M = Co, Ni) ribbons with nanoporous structure and their magnetic properties

Spinel ferrite, MFe2O4 (M = Co, Ni), ribbons with nanoporous structure were prepared by electrospinning combined with sol-gel technology. The ribbons were formed through the agglomeration of magnetic nanoparticles with PVP as the structure directing template. The length of the polycrystalline ribbons can reach millimeters, and the width of the ribbons can be tuned from several micrometers to several hundred nanometers by changing the concentration of precursor. The nanoporous structure was formed during the decomposition of PVP and inorganic salts.

Preparation of nanocrystalline NiZnCu ferrite particles by sol-gel method and their magnetic properties

Polyvinyl alcohol (PVA) was first used as chelating agent and metal nitrates as precursor of ferrite in the fabrication of nanocrystalline Ni0.65Zn0.35Cu0.1Fe1.9O4 particles by the sol-gel method. The thermal decomposition process of dried gel was studied by thermogravimetry (TG), differential thermal analysis (DTA) and infrared spectra (IR). The structural and magnetic properties of resultant particles were investigated by X-ray diffraction (XRD), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and Mossbauer spectroscopy. The dependence of the decomposition of dried gel, the formation of spinel structured NiZnCu ferrite, the sizes of annealed particles, the saturation magnetization and coercivity of annealed particles on annealing temperature is presented.

A study of NiZnCu-ferrite/SiO2 nanocomposites with different ferrite contents synthesized by sol-gel method

Ni0.65Zn0.35Cu0.1Fe1.9O4/SiO2 nanocomposites with different weight percentages of NiZnCu-ferrite dispersed in silica matrix were successfully fabricated by the sol-gel method using tetraethylorthosilicate (TEOS) as a precursor of silica, and metal nitrates as precursors of NiZnCu ferrite. The thermal decomposition process of the dried gel was studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The obtained Ni0.65Zn0.35Cu0.1Fe1.9O4/SiO2 nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), Mossbauer spectroscopy and vibrating sample magnetometry (VSM). The formation of stoichiometric NiZnCu-ferrite dispersed in silica matrix is confirmed when the weight percentage of ferrite is not more than 30%. Samples with higher ferrite content have small amount of alpha-Fe2O3. The transition from the paramagnetic to the ferromagnetic state is observed as the ferrite content increases from 20 to 90wt%.

Preparation of magnetic and conductive NiZn ferrite-polyaniline nanocomposites with core-shell structure

Magnetic and conductive NiZn ferrite-polyaniline nanocomposites with novel core-shell structure have been fabricated by microemulsion process. The samples were characterized by XRD, TEM, SEM, IR, UV-vis, voltage/current detector and SQUID magnetometry. The core-shell structure of nanocomposites was observed by TEM. The changes of the magnetic and conductive properties after polyaniline coating were investigated.

Cupric hexacyanoferrate nanoparticle modified carbon ceramic composite electrodes

Graphite powder-supported cupric hexacyanoferrate (CuHCF) nanoparticles were dispersed into methyltrimethoxysilane based gels to produce a conducting carbon ceramic Composite, which was used as electrode material to fabricate surface- renewable CuHCF-modified electrodes. Electrochemical behavior of the CuHCF-modifled carbon ceramic composite electrodes was characterized using cyclic and square-wave voltammetry. Cyclic voltammograms at various scan rates indicated that peak currents were surface-confined at low scan rates. In the presence of glutathione, a clear electrocatalytic response was observed at the CuHCF-modified composite electrodes. In addition, the electrodes exhibited a distinct advantage of reproducible surface-renewal by simple mechanical polishing on emery paper, as well as ease of preparation, and good chemical and mechanical stability in a flowing stream.

Study of cupric hexacyanoferrate-modified platinum electrodes using probe beam deflection and electrochemical quartz crystal microbalance techniques

The ion exchange mechanism accompanying the oxidation/reduction processes of cupric hexacyanoferrate-modified platinum electrodes in different aqueous electrolyte solutions has been studied by means of in situ probe beam deflection and the electrochemical quartz crystal microbalance technique. The results demonstrate that the charge neutrality of the film during the reoxidation/reduction process is accomplished predominantly by the movement of cations, but anions and/or solvent are also participator(s). Moreover, in KHC8H4O4 (potassium biphthalate) solution, the EQCM data obtained from chronoamperometry experiment are more complicated than those in KCl and K2SO4 solutions. (C) 1997 Elsevier Science Ltd.

Fractal roughness characterization of super-ground Mn-Zn ferrite single crystals

The surface of superground Mn-Zn ferrite single crystal may be identified as a self-affine fractal in the stochastic sense. The rms roughness increased as a power of the scale from 10(2) nm to 10(6) nm with the roughness exponent alpha = 0.17 +/- 0.04, and 0.11 +/- 0.06, for grinding feed rate of 15 and 10 mu m/rev, respectively. The scaling behavior coincided with the theory prediction well used for growing self-affine surfaces in the interested region for magnetic heads performance. The rms roughnesses increased with increase in the feed rate, implying that the feed rate is a crucial grinding parameter affecting the supersmooth surface roughness in the machining process.

Cupric (II)-2,2 '-Biquinoline Transfer Across the Liquid/Liquid Interface and Kinetics of Complexation

Cupric (II) ion transfer across the water/nitrobenzene interface facilitated by 2,2'-biqulnoline was investigated by cyclic voltammtry. Transfer process was controlled by diffusion. At [BQ](NB)>>[Cu2+](W), transfer ion was found to be 1:2 Cu2+-biquinoline