Finite size effect and influence of temperature on electrical properties of nanocrystalline Ni–Cd ferrites

Batoo, Khalid Mujasam; Kumar, Shalendra; Lee, Chan Gyu; Alimuddin, Alimuddin

doi:10.1016/j.cap.2008.12.002

Cited by 91 publications

(44 citation statements)

References 25 publications

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“…Many authors [1,16,17] have considered ferrites samples to be formed of different regions with different conductivities and studied the overall ferrites conductivity which increases with frequency by considering space charge polarization and Koop's two-layer model [18], known to be suitable to describe heterogeneous structures, where the ferrite is assumed to be made up of well conducting grains separated by poor conducting layers or grain boundaries. Since as mentioned above conduction takes place by the hopping mechanism through the interaction Fe 2 þ -O-Fe 3 þ and Ni 2 þ -O-Ni 3 þ over the octahedral B-sites, the electrons reaching the grain boundary through hopping will pile up there due to its higher resistivity, thereby producing space charge polarization [16].…”

Section: The Ac Conductivity Behaviormentioning

confidence: 99%

“…Due to the potential applications of ferrites and the interesting physics involved in their field of research, even after so many decades, scientists, researchers and engineers are still interested in the design of various types of ferrite materials, substituted with different cations, and prepared by different techniques [1]. Recently, the synthesis of spinel nanoferrites had the greatest interest where nanoferrites have unique electrical and magnetic properties as compared with the bulk.…”

Section: Introductionmentioning

confidence: 99%

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Dielectric behavior of nano-structured and bulk Li Ni Zn ferrite samples

Saafan

Assar

2012

Journal of Magnetism and Magnetic Materials

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Section: The Ac Conductivity Behaviormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dielectric behavior of nano-structured and bulk Li Ni Zn ferrite samples

Saafan

Assar

2012

Journal of Magnetism and Magnetic Materials

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“…1a, confirming the single phase and pure Li 0.5 Mn 0.75−x/2 Cd x/2 Fe 2 O 4 (0.00 ≤ x ≤ 0.80) formation without any impurity or extra plane. The crystallite sizes are calculated using the standard Scherer formula [12],…”

Section: X-rays and Sem Analysismentioning

confidence: 99%

Effect of Dopants Mn2+ and Cd2+ Concentration on Electrical and Magnetic Properties of Li-Mixed Spinel Nanoferrites

Faraz

Ahmad

2011

J Supercond Nov Magn

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Spinel mixed Li-ferrites with incorporation of various dopants (Cd 2+ and Ni 2+ ) concentration in ranges 0.00 ≤ x ≤ 0.80 are prepared using sol-gel technique. The various phases, lattice constant/parameter, X-ray density and crystallite size are confirmed using X-ray diffraction (XRD). The particle size and lattice parameters are found in the range 15-33 nm and 8.35-8.66 Å. This confirmed that incorporating dopant strongly influences the material structure and an increase is observed in lattice parameter and particle size with increase in dopant concentration. The structure is influenced by the dopant position, at the octahedral (B) and tetrahedral (A) sites. The decrease in activation energy (E) is observed with increase in dopant concentration. Furthermore, analysis of the crystallite size and morphology is done using scanning electron microscopy (SEM), which confirmed that the observed particle size is comparable with the X-ray diffraction (XRD) results. The dopant affects electrical properties such as dc electrical resistivity and drift mobility. The observed trend for drift mobility and dc electrical resistivity confirmed the semiconducting behavior of the synthesized material. The magnetic parameters saturation magnetization (M s ), remanence (M r ) and coercivity (H c ) are strongly affected by dopant concentration. A sudden increase in magnetic parameters M r and M s is observed A. Faraz ( ) Thermal Transport Laboratory (TTL), School of chemical and materials Engineering (by incorporating a small amount of dopant up to x = 0.40 and with further incorporation cause a decrease in the values of these parameters due to the non-magnetic behavior of incorporating dopant Cd 2+ ions. These decreases in values can be explained using the spin canted model and cations positioning at tetrahedral (A) and octahedral (B) sites. The decrease in Curie temperature, observed with increase in dopant incorporation, is due to the decrease/weakening interaction between tetrahedral (A) and octahedral (B) sites.

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“…But it is to be noted that grain boundaries are more effective at low frequencies and grains are effective at high frequencies [19]. The high value of dielectric constant at low frequencies can be explained on the basis of space charge polarization produced by the electron accumulation at grain boundaries owing to their high resistance [21,22]. As the frequency increases, the conducting grains come into action, decreasing the space charge polarization and thereby decreasing dielectric permittivity rapidly.…”

Section: Real Part Of Dielectric Permittivity (E R )mentioning

confidence: 95%

“…The poorly conducting grain boundaries which are effective at low frequencies are responsible for the low value of AC conductivity when the applied frequency is low. But as frequency increases the hopping conduction increases which is due to increase in effectiveness of the conducting grains at higher frequencies [21]. But with further increase in frequency, the hopping of charge carriers could not follow the applied field which results in decrease of the AC conductivity values.…”

Section: Ac Conductivitymentioning

confidence: 98%

Effect of Gd3+ substitution on the structural and electrical properties of Mg0.75Zn0.25Fe2O4 nanoparticles

Sebastian¹,

Mohammed²

2016

Indian J Phys

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Nanoparticles of gadolinium substituted Mg-Zn ferrite, Mg 0.75 Zn 0.25 Gd x Fe 2-x O 4 (where x = 0.00, 0.05, 0.10, 0.15) have been prepared by the sol-gel technique. The lattice constant is found to increase with increase in the Gd 3? ion concentration. The observed variation of dielectric constant with frequency is explained on the basis of the MaxwellWagner two layer model and the electron hopping mechanism. The dielectric constant and dielectric loss decrease with Gd 3? ion substitution. The variation of AC conductivity with frequency suggests that the conduction is due to small polaron hopping. It is also noticed that the dielectric constant and the AC conductivity increase with temperature and it is explained in terms of the thermally enhanced drift mobility of the charge carriers. The observed low value of dielectric constant and also the dielectric loss factor obtained for gadolinium substituted ferrites make them desirable for high frequency applications.

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Finite size effect and influence of temperature on electrical properties of nanocrystalline Ni–Cd ferrites

Cited by 91 publications

References 25 publications

Dielectric behavior of nano-structured and bulk Li Ni Zn ferrite samples

Dielectric behavior of nano-structured and bulk Li Ni Zn ferrite samples

Effect of Dopants Mn2+ and Cd2+ Concentration on Electrical and Magnetic Properties of Li-Mixed Spinel Nanoferrites

Effect of Gd3+ substitution on the structural and electrical properties of Mg0.75Zn0.25Fe2O4 nanoparticles

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