Enhancement in dielectric and magnetic properties of Ni–Zn ferrites prepared by sol–gel method

Nasir, S.; Saleemi, Awais Siddique; Zahra, Fatima Tuz; Anis-ur-Rehman, M.

doi:10.1016/j.jallcom.2013.03.160

Cited by 34 publications

(7 citation statements)

References 23 publications

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“…This might be one reason why XRD patterns increased and sharpened gradually with the increase of calcination temperature. A positive trend between crystallite size and XRD peak intensity has been previously reported for the preparation of the Cu x Mg 1−x Al 2 O 4 spinel oxides and Ni-Zn ferrites [16,20]. The change was also accompanied by the appearance of additional Fe 2 O 3 (JCPDS 01-089-0596) phases.…”

Section: Resultssupporting

confidence: 72%

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Degradation of polychlorinated biphenyls using mesoporous iron-based spinels

Huang¹,

Su²,

Zhang³

et al. 2013

Journal of Hazardous Materials

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h i g h l i g h t s• The NiFe 2 O 4 had the highest activity in degradation of CB-209, followed by Fe 3 O 4 .• Hydroxyl species, organic acids, PCBs and chlorobenzenes were identified as products.• Three degradation reactions and one combination reaction competitively occurred.• Hydrodechlorination of CB-209 was more favored over Fe 3 O 4 than NiFe 2 O 4 .• Oxidation reaction of CB-209 was more favored over t r a c tA series of mesoporous iron-based spinel materials were synthesized to degrade polychlorinated biphenyls (PCBs), with CB-209 being used as a model compound. The materials were characterized by X-ray powder diffraction (XRD), pore structure analysis, and X-ray photoelectron spectroscopy (XPS). A comparison of the dechlorination efficiencies (DEs) of the materials revealed that NiFe 2 O 4 had the highest DE, followed by Fe 3 O 4 . Newly produced polychlorinated biphenyls, chlorinated benzenes, hydroxyl species and organic acids were detected by gas chromatography-mass spectrometry, high performance liquid chromatography-mass spectrometry and ion chromatograph. Identification of the intermediate products indicates that three degradation pathways, hydrodechlorination, the breakage of C C bridge bond and oxidative reaction, accompanied by one combination reaction, are competitively occurring over the iron-based spinels. The relative amounts of produced three NoCB isomers were illustrated by the C Cl BDEs of CB-209 at meta-, para-and ortho-positions, and their energy gap between HOMO and LUMO. The consumption of the reactive oxygen species caused by the transformation of Fe 3 O 4 into Fe 2 O 3 in the Fe 3 O 4 reaction system, and the existence of the highly reactive O 2 −• species in the NiFe 2 O 4 reaction system, could provide a reason why the oxidation reaction was more favored over NiFe 2 O 4 than Fe 3 O 4 .

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Section: Resultssupporting

confidence: 72%

“…In inverse spinels, half of B cations occupy the tetrahedral sites. Spinels have high thermostability and high hardness, and some of them exhibit extraordinary electric and magnetic properties [14][15][16][17]. Recently, spinel oxides are increasingly being investigated as catalysts to remove environmental pollutants.…”

Section: Introductionmentioning

confidence: 99%

Degradation of polychlorinated biphenyls using mesoporous iron-based spinels

Huang¹,

Su²,

Zhang³

et al. 2013

Journal of Hazardous Materials

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“…In comparison with sol-gel method, simplified sol-gel method offers greater phase purity as surfactants are not used in this method [8]. Initial precursors for bismuth cobaltite synthesis used were bismuth oxide, calcium chloride, neodymium Temperature of hot plate was then set at 80-90 • C to start the reaction with continuous magnetic stirring.…”

Section: Methodsmentioning

confidence: 99%

Introducing Rare Earth Dopants for Controlled Conductivity in Thermoelectric Cobaltites

Ahmed

Munir

Saqib

et al. 2014

J Supercond Nov Magn

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The conversion of waste heat into electrical energy plays a key role in our current challenge to develop alternative energy technologies to reduce our dependence on fossil fuels. Thermoelectric (TE) materials are the first choice to handle this subject. In TE materials, cobaltites are the material of interest, due to their nontoxic properties. Cobaltites exhibits large TE power, low resistivity, and relatively small thermal conductivity at room temperature. TE material (BiCa 2−x R x CoO y ) where R is for rare earth like Nd, (x = 0.0, 0.2) was synthesized in nanoregime by simplified sol-gel method. Simplified sol-gel method was chosen because it gives maximum phase purity and tunable parameters for desired properties. The mechanism used to enhance thermoelectric properties is to reduce thermal conductivity of the material and increase electrical conductivity of the material using nanostructures. Material characterizations were done for structural studies using X-ray diffraction (XRD). XRD revealed monoclinic crystal structure. Temperature-dependent electrical conductivity showed an increase with increase in temperature. Thermal conductivity was also measured. Both electrical resistivity and thermal conductivity decrease as a result of neodymium doping which enhanced its importance as thermoelectric material. The different parameters were correlated to understand the conduction mechanism.

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“…3 Over the past decades, different methods have been developed to synthesize various spinel ferrites, such as coprecipitation, mechanical alloying, hydrothermal and solvothermal reactions, sol-gel synthesis, auto-combustion, and sonochemical synthesis. [4][5][6][7][8] However, to find a facile synthetic method for ferrite nanoparticles with well-controlled magnetic properties is still a challenge.…”

mentioning

confidence: 99%

Microstructure and magnetic properties of MFe2O4 (M = Co, Ni, and Mn) ferrite nanocrystals prepared using colloid mill and hydrothermal method

Wang

Ding

Zhao

et al. 2015

Journal of Applied Physics

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Three kinds of spinel ferrite nanocrystals, MFe2O4 (M = Co, Ni, and Mn), are synthesized using colloid mill and hydrothermal method. During the synthesis process, a rapid mixing and reduction of cations with sodium borohydride (NaBH4) take place in a colloid mill then through a hydrothermal reaction, a slow oxidation and structural transformation of the spinel ferrite nanocrystals occur. The phase purity and crystal lattice parameters are estimated by X-ray diffraction studies. Scanning electron microscopy and transmission electron microscopy images show the morphology and particle size of the as-synthesized ferrite nanocrystals. Raman spectrum reveals active phonon modes at room temperature, and a shifting of the modes implies cation redistribution in the tetrahedral and octahedral sites. Magnetic measurements show that all the obtained samples exhibit higher saturation magnetization (Ms). Meanwhile, experiments demonstrate that the hydrothermal reaction time has significant effects on microstructure, morphologies, and magnetic properties of the as-synthesized ferrite nanocrystals.

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Enhancement in dielectric and magnetic properties of Ni–Zn ferrites prepared by sol–gel method

Cited by 34 publications

References 23 publications

Degradation of polychlorinated biphenyls using mesoporous iron-based spinels

Degradation of polychlorinated biphenyls using mesoporous iron-based spinels

Introducing Rare Earth Dopants for Controlled Conductivity in Thermoelectric Cobaltites

Microstructure and magnetic properties of MFe2O4 (M = Co, Ni, and Mn) ferrite nanocrystals prepared using colloid mill and hydrothermal method

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