Room temperature ferromagnetism of Co doped CeO2−δ diluted magnetic oxide: Effect of oxygen and anisotropy

Vodungbo, Boris; Zheng, Y.; Vidal, Franck; Demaille, Dominique; Etgens, V. H.; Mosca, D. H.

doi:10.1063/1.2472520

Cited by 100 publications

(72 citation statements)

References 20 publications

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“…At the beginning of the reaction, the concentration of monomer is the highest during the course of particle precipitation. Anisotropic Ce(OH) 3 nuclei are formed once the Ce 3+ ions are mixed with the MOH solution. NO 17 Rod-like particles with an aspect ratio of about 10 were obtained at 120 C. The concentration of monomer is depleted by nucleation and growth of the rods.…”

Section: Effect Of Alkali Metal Hydroxides On the Morphological Develmentioning

confidence: 99%

“…[1][2][3] Therefore, synthetic methods have been developed to tailor the morphology of these particles making them useful in practical applications. In particular, there is an increasing interest in preparation of cerium oxide (ceria) that has recently been used in various fields such as an oxygen ion conductor in solid-oxide fuel cells 4 and as an oxygen pump due to its high oxygen ion conductivity.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Alkali Metal Hydroxides on the Morphological Development and Optical Properties of Ceria Nanocubes Under Hydrothermal Conditions

Kepenekci¹,

Emirdag‐Eanes²,

Demir³

2011

J. Nanosci. Nanotech.

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Nanocrystalline cerium(IV) oxide (CeO 2 , ceria) particles were produced via the hydrothermal treatment of cerium nitrate hexahydrate with various alkali metal hydroxides (MOH: M = Li, Na, K). Experimental conditions such as [MOH], reaction temperature, and reaction time were studied. Particle morphology as well as size of crystallites was precisely controlled by choice of experimental conditions. While rod-shaped particles were obtained at 120 C, well-defined nanocubes were formed at higher temperatures regardless of the choice of MOH. Examination of particle growth kinetics, in the final stages of crystallization, showed that particle growth rate is controlled by two different mechanisms. Grain boundary diffusion controls the particle growth in the presence of NaOH with an activation energy of 113.8 kj/mol and surface diffusion for LiOH ad KOH with the activation energy of 43.0-150.9 kj/mol, respectively. In addition, the particles exhibit strong violet and blue emissions at 400 nm and 370 nm. The former emission originates from excitation of a wide band gap of CeO 2 . The latter one is attributed to the trivalency of the cerium ion and appears to be sensitive to all the experimental conditions studied. Both extending reaction time and increasing temperature reduce the intensity of the 370 nm emission and increase the intensity of the 400 nm emission.

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Section: Effect Of Alkali Metal Hydroxides On the Morphological Develmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Alkali Metal Hydroxides on the Morphological Development and Optical Properties of Ceria Nanocubes Under Hydrothermal Conditions

Kepenekci¹,

Emirdag‐Eanes²,

Demir³

2011

J. Nanosci. Nanotech.

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“…The CeO 2 is often used as oxygen storage media due to its oxygen storage capacity via Ce 4+ /Ce 3+ redox cycles [13][14][15]. Early work on CeO 2 -based O-DMSs was focused on thin films [5][6][7] and only a little work has been carried out on powders, bulk, and nanocrystalline form [10][11][12]16]. Tiwari et al [5] first discovered RT-FM in Ce 1-x Co x O 2-δ (x ≤ 0.05) films deposited on a LaAlO 3 (001) substrate by a pulsed laser deposition (PLD) technique.…”

Section: Introductionmentioning

confidence: 99%

Structure and Magnetic Properties of Monodisperse Fe3+-doped CeO2 Nanospheres

2013

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Abstract:This work reports the study concerning the structure and magnetic properties of undoped CeO2 and Fe-doped CeO2 (Ce1−xFexO2, 0.01 ≤ x ≤ 0.07) nanospheres with diameters of 100∼200 nm prepared by hydrothermal method using polyvinylpyrrolidone (PVP) as surfactant. The prepared samples were studied by using X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray absorption near-edge structure (XANES), and vibrating sample magnetometry (VSM). The XRD results showed that Fe-doped CeO2 was single-phased with a cubic structure, and with Fe 3+ successfully substituting in Ce 4+ sites. Raman spectra showed a redshift of F2g mode that caused by the Fe doping. The samples of both undoped CeO2 and Fe-doped CeO2 exhibited room temperature ferromagnetism, and the saturated magnetization (Ms) increased with increasing Fe content until x = 0.05, and then the samples displayed ferromagnetic loops as well as paramagnetic behavior. The roles of Ce 3+ and Fe 3+ spin electrons are discussed for the ferromagnetism in the Fe-doped CeO2.

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“…In addition to oxygen vacancies, TM doping has been shown to increase the RTFM of ceria NPs (6)(7)(8)(9)(10)(11)(12)(13). There are at least two possible mechanisms for RTFM enhancement by TM doping: creation of oxygen vacancies by introduction of a different-valance dopant into the host lattice and ferromagnetic ordering of a TM dopant.…”

Section: Introductionmentioning

confidence: 99%

Concentration dependence of magnetic moment in Ce1-xFexO2

Beausoleil

Thurber

Rao

et al. 2012

Journal of Applied Physics

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In this study, we examined the impact of iron doping on the structural, chemical, and magnetic properties of ceria (Ce 1-x Fe x O 2 ). Samples were produced in triplicate through a coprecipitation approach in a forced hydrolysis synthesis that yielded consistently sized nanocrystals, using three different cerium precursors: cerium chloride, cerium ammonium nitrate and cerium nitrate. Particles were characterized by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), electron paramagnetic resonance (EPR) spectroscopy and vibrating sample magnetometry (VSM). XRD showed the average crystallite size to be 4.4 ± 1.2 nm, which agreed well with TEM data. XPS and EPR data shows iron to be in the Fe 3+ state and confirms the nominal dopant concentration. The moment per Fe ion found was largest at the lowest dopant concentrations, with values of 0.078 and 0.055 µ B /Fe ion for 0.1 and 0.5% Fe, respectively, which quickly decreased as the concentration was increased. We used XPS to estimate Ce 3+ /Ce 4+ ratio to be in the 0.2-0.3 range and observed a linear relation between the saturation magnetization and the Ce 3+ /Ce 4+ ratio.Introduction:

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Room temperature ferromagnetism of Co doped CeO2−δ diluted magnetic oxide: Effect of oxygen and anisotropy

Cited by 100 publications

References 20 publications

Effect of Alkali Metal Hydroxides on the Morphological Development and Optical Properties of Ceria Nanocubes Under Hydrothermal Conditions

Effect of Alkali Metal Hydroxides on the Morphological Development and Optical Properties of Ceria Nanocubes Under Hydrothermal Conditions

Structure and Magnetic Properties of Monodisperse Fe3+-doped CeO2 Nanospheres

Concentration dependence of magnetic moment in Ce1-xFexO2

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