Electrical Properties of Nanophase Ferrites Doped with Rare Earth Ions

Mahalakshmi, S.; SrinivasaManja, K.; Nithiyanantham, S.

doi:10.1007/s10948-014-2551-y

Cited by 71 publications

(29 citation statements)

References 29 publications

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“…This increase lattice constant can be attributed to larger ionic radiuses of Cu 2+ (0.72Å) relative to Ni 2+ (0.69Å); this is consistent with [18][19][20][21]. The lattice parameter increases more in Cu 2+ substitution in the synthesized nanocrystals.…”

Section: Structural Characterizationsupporting

confidence: 76%

Structural and Morphological Studies of Copper-Doped Nickel Ferrite

Mahalakshmi

Manja

Nithiyanantham

2015

J Supercond Nov Magn

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Ferrite nanocrystals are an interesting material due to their rich physical properties. Here we add non-magnetic dopant Cu to nickel ferrite nanocrystals, Ni 1−x M x Fe 2 O 4 (x = 0.2, 0.4, and 0.6) M = Cu, and study how relevant properties of the samples are modified accordingly. The grain size and the surface morphology were studied by scanning electron microscopy (SEM).Basically, these doping cause a rearrangement of Fe +3 ions into the two preexisting octahedral and tetrahedral sites. In fact, this, we show, induces pertinent magnetic properties of the doped samples. In the case of Cu doping, the Jahn-Teller effect also emerges, which we identify through the Fourier transform infrared spectroscopy of the samples. Moreover, we show an increase in the lattice parameters of the doped samples, as well a superparamagnetic behavior for the doped samples, while the Jahn-Teller effect precludes a similar behavior in the CuFe 2 O 4 nanocrystals.

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Section: Structural Characterizationsupporting

confidence: 76%

Structural and Morphological Studies of Copper-Doped Nickel Ferrite

Mahalakshmi

Manja

Nithiyanantham

2015

J Supercond Nov Magn

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“…Hopping mechanism successfully explains conducting behavior in Cl0.5Zn0.5Fe1-xRxO4 (x=0.4 and x=1); (R=La, Nd, Sm, Gd and Dy) [87], Mg1−xNixFe2−ySmyO4 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0; y = 0.0, 0.05, 0.1) [88], RE doped NixFe(3−x)O4 [89]. As discussed earlier, RE 3+ diffuse towards grain boundaries in ferrite, this causes formation of non conducting layers in grain boundaries.…”

Section: Electrical and Dielectric Propertiesmentioning

confidence: 80%

Solubility limit, magnetic interaction and conduction mechanism in rare earth doped spinel ferrite

Singh¹,

Kumar²,

Srivastava³

et al. 2016

Appl. Sci. Lett.

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In present review we have focused various issues like solubility limit, magnetic interaction and conduction mechanism of rare earth doped ferrite. Cumulative effects of valence state, magnetic moments of rare earth ions, weakening/strengthening of exchange interaction and magnetic ordering in rare earth ion doped ferrite are responsible for magnetic behavior. It is proposed that characterization techniques based on synchrotron radiation like X-ray absorption spectroscopy and X-ray magnetic circular dichroism can open pathways to prove these assumptions.Keywords: Rare earth, ferrites, magnetic interaction, valence state 1.INTRODUCTIONSpinel ferrites are ferrimagnetic material which have numerous technological applications [1][2][3]. Moreover, nanoparticles of these ferrites are being utilized in high-density magnetic information storage, magnetic resonance imaging, drug delivery etc. [4][5][6]. These several applications are based on magnetic and electrical behavior of ferrites [1][2][3][4][5][6]. These properties depend on various factors like, ionic radii, nature of hybridization, presence of doped atom in host lattice apart from the particle size [7][8][9][10]. Thus, research is being carried out for doped ferrite systems in order to understand the altered behavior and to optimize them for different applications [11][12][13][14][15]. In recent years, rare earth (RE) doped ferrites become interesting due to their superiority for various applications over other doped ferrite systems [17][18][19][20][21][22]. These systems become radioactive and exhibit potentential for biomedical applications [19] along-with efficient tumor passive targeting [23]. Improved capability of dye removal [24], waste water treatment [25], degradation of organic pollutants through photocatalytic activity [26] are other important fields of utilization of these ferrites. These ferrites exhibit enhanced magneto optical kerr (MOKE) effect [20] and excellent microwave absorption properties [21,22]. Thus, these ferrites cover a wide range of applications chiefly based on their magnetic characteristics [17][18][19][20][21][22][23][24][25]. However, there is lack of understanding of magnetic interaction, conduction mechanism inside these ferrites [15,16]. Thus purpose of this review article is to discuss these issues and to give prospects for future research in this direction. SPINEL FERRITEThe general formula for spinel ferrite is MO:Fe2O3 where, M is a divalent transition metal ion. Spinel name is given due to resemblance of structure of these ferrites with mineral spinel MgO.Al2O3. In this structure, oxygen ions are packed quite close together in face centred cubic arrangement and metal ions occupy spaces between them (Fig. 1). These spaces are categorized as tetrahedral (A) and octahedral (B) sites when surrounded by four and six oxygen ions respectively (Fig. 1).In a unit cell of spinel ferrite, there exists 64 and 32 A and B-sites respectively. Only 1/8 th and 1/2 th of A and B-sites are occupied [27]. Metal ions are distributed among A a...

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“…17,21,28 Recently, substitution for Fe 3+ in spinel ferrites has been gaining tremendous importance to design materials for utilization in high-density magnetic recording, enhanced memory storage, magnetic fluids, and catalyst applications. 2,6,9,[12][13][14][15][16][17][18][19][26][27][28] In general, the chemical and physical nature of the ion/dopant into CFO matrix allows tuning the final magnetic, dielectric and electrical characteristics. [13][14][15][16][17][18][19][20][21][22][23][24][25] Specifically, the degree of modification that can result in the properties and phenomena of CFO depends on the ionic radius, the electronic configuration of the substituting ion, its site preference (A versus B site), and the extent of distribution at the specific sites within the spinel structure.…”

Section: Introductionmentioning

confidence: 99%

Effect of Molybdenum Incorporation on the Structure and Magnetic Properties of Cobalt Ferrite

et al. 2017

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Melendez, A.; Manadhar, S.; Singamaneni, S. R.; Reddy, Kongara M.; Gandha, Kinjal H.; Niebedim, I. C.; and Ramana, C. V., "Effect of Molybdenum Incorporation on the Structure and Magnetic Properties of Cobalt Ferrite" (2017). Ames Laboratory Accepted Manuscripts. 61. AbstractWe report on the effect of molybdenum (Mo) incorporation on the crystal structure, surface morphology, Mo chemical valence state, and magnetic properties of cobalt ferrite (CoFe2O4, referred to CFO). Molybdenum incorporated cobalt ferrite (CoFe2-xMoxO4, referred to CFMO) ceramics were prepared by the conventional solid-state reaction method by varying the Mo concentration in the range of x = 0.0-0.3. X-ray diffraction studies indicate that the CFMO materials crystallize in inverse spinel cubic phase. Molybdenum incorporation induced lattice parameter increase from 8.322 to 8.343 Å coupled with a significant increase in density from 5.4 to 5.7 g/cm3 was evident in structural analyses. Scanning electron microscopy imaging analyses indicate that the Mo incorporation induces agglomeration of particles leading to larger particle size with increasing x(Mo) values. Detailed X-ray photoelectron spectroscopic (XPS) analyses indicate the increasing Mo content with increasing x from 0.0 to 0.3. XPS confirms that the chemistry of Mo is complex in these CFMO compounds; Mo ions exist in the lower oxidation state (Mo4+) for higher x while in a mixed chemical valence state (Mo4+, Mo5+, Mo6+) for lower x values. From the temperature-dependent magnetization, the samples show ferrimagnetic behavior including the pristine CFO. From the isothermal magnetization measurements, we find almost 2-fold decrease in coercive field (Hc) from 2143 to 1145 Oe with the increase in Mo doping up to 30%. This doping-dependent Hc is consistently observed at all the temperatures measured (4, 100, 200, and 300 K). Furthermore, the saturation magnetization estimated at 4 K and at 1.5 T (from M-H loops) goes through a peak at 92 emu/g (at 15% Mo doping) from 81 emu/g (pristine CFO), and starts decreasing to 79 emu/g (at 30% Mo doping). The results demonstrate that the crystal structure, microstructure, and magnetic properties can be tuned by controlling the Mo-content in the CFMO materials. ABSTRACTWe report on the effect of molybdenum (Mo) incorporation on the crystal structure, surface morphology, Mo chemical valence state and magnetic properties of cobalt ferrite (CoFe2O4, referred to CFO). Molybdenum incorporated cobalt ferrite (CoFe2-xMoxO4, referred to CFMO) ceramics were prepared by the conventional solid-state reaction method by varying the Mo concentration in the range of x=0.0-0.3. X-ray diffraction studies indicate that the CFMO materials crystallize in inverse spinel cubic phase. Molybdenum incorporation induced lattice parameter increase from 8.322 to 8.343 Å coupled with a significant increase in density from 5.4 to 5.7 g/cm 3 was evident in structural analyses. Scanning electron microscopy imaging analysis indicate that the Mo incorporation induces agglomeration of pa...

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Electrical Properties of Nanophase Ferrites Doped with Rare Earth Ions

Cited by 71 publications

References 29 publications

Structural and Morphological Studies of Copper-Doped Nickel Ferrite

Structural and Morphological Studies of Copper-Doped Nickel Ferrite

Solubility limit, magnetic interaction and conduction mechanism in rare earth doped spinel ferrite

Effect of Molybdenum Incorporation on the Structure and Magnetic Properties of Cobalt Ferrite

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