scholarly journals FTIR and Electrical Study of Dysprosium Doped Cobalt Ferrite Nanoparticles

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Hemaunt Kumar ◽  
Jitendra Pal Singh ◽  
R. C. Srivastava ◽  
P. Negi ◽  
H. M. Agrawal ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Spinel Structure ◽  
Room Temperature ◽  
Cobalt Ferrite ◽  
Spinel Phase ◽  
Ferrite Nanoparticles ◽  
Absorption Bands ◽  
Octahedral Sites ◽  
Electrical Study

We have studied the role of Dy3+ doping on the XRD, TEM, FTIR, and dielectric and electrical properties of CoFe2O4 at room temperature. Cubic spinel phase of CoFe2−xDyxO4 (x = 0.00, 0.05, 0.10, and 0.15) was synthesized by using different sintering temperatures (300, 500, 700, and 900°C). The two absorption bands ν1 and ν2 are observed in Fourier transform infrared spectroscopy (FTIR) spectra corresponding to the tetrahedral and octahedral sites, which show signature of spinel structure of the sample. For the sample sintered at 300°C, the dielectric constant is almost unchanged with the frequency at the particular concentrations of x = 0.00 and 0.05. Similar result is obtained for the sample sintered at 500°C (x = 0.10, 0.15), 700°C (x = 0.05, 0.10, and 0.15), and 900°C (x = 0.05, 0.10). An increase in the dielectric constant was observed for the undoped cobalt ferrite sintered at 500, 700, and 900°C. The values of electrical resistivity of the materials vary from ~105 to 109 Ω-cm.

scholarly journals Epitaxial growth and structure of cobalt ferrite thin films with large inversion parameter on Ag(001)

2019 ◽  
Vol 75 (1) ◽  
pp. 8-17 ◽  
Author(s):  
Maurizio De Santis ◽  
Aude Bailly ◽  
Ian Coates ◽  
Stéphane Grenier ◽  
Olivier Heckmann ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Spinel Structure ◽  
Room Temperature ◽  
Cobalt Ferrite ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
Step Method ◽  
X Ray ◽  
Octahedral Sites

Cobalt ferrite ultrathin films with the inverse spinel structure are among the best candidates for spin filtering at room temperature. High-quality epitaxial CoFe2O4 films about 4 nm thick have been fabricated on Ag(001) following a three-step method: an ultrathin metallic CoFe2 alloy was first grown in coherent epitaxy on the substrate and then treated twice with O2, first at room temperature and then during annealing. The epitaxial orientation and the surface, interface and film structure were resolved using a combination of low-energy electron diffraction, scanning tunnelling microscopy, Auger electron spectroscopy and in situ grazing-incidence X-ray diffraction. A slight tetragonal distortion was observed, which should drive the easy magnetization axis in-plane due to the large magneto-elastic coupling of such a material. The so-called inversion parameter, i.e. the Co fraction occupying octahedral sites in the ferrite spinel structure, is a key element for its spin-dependent electronic gap. It was obtained through in situ resonant X-ray diffraction measurements collected at both the Co and Fe K edges. The data analysis was performed using FDMNES, an ab initio program already extensively used to simulate X-ray absorption spectroscopy, and shows that the Co ions are predominantly located on octahedral sites with an inversion parameter of 0.88 (5). Ex situ X-ray photoelectron spectroscopy gives an estimation in accordance with the values obtained through diffraction analysis.

The Effect of Yttrium and Indium Doping on the Structure and Electrical Properties of Zinc-Ferrite Nanoparticles

2007 ◽  
Vol 128 ◽  
pp. 101-106 ◽  
Author(s):  
Marija Maletin ◽  
Evagelia G. Moshopoulou ◽  
Stevan Jankov ◽  
Srdjan Rakic ◽  
Vladimir V. Srdic
Keyword(s):  
Electrical Conductivity ◽  
Spinel Structure ◽  
Zinc Ferrite ◽  
Single Phase ◽  
Spinel Phase ◽  
Ferrite Nanoparticles ◽  
Second Phase ◽  
Indium Doping ◽  
Yttrium Concentration

Yttrium- and indium-doped zinc-ferrite nanoparticles were prepared by a coprecipitation method. The influence of doping level on the structure and the conductivity of the samples obtained was investigated. It was found that Y-doped zinc-ferrite nanoparticles, with a single spinel phase and a size of a few nanometers, are formed in the whole range of yttrium concentration. However, In-doped zinc-ferrite nanoparticles were formed for all investigated indium cooncentrations, but only the samples InxZn1-xFe2O4 with x.≤ 0.15 are single-phase (for x ≥ 0.20 a second phase - cubic In(OH)3, is formed). The decrease and increase of the electrical conductivity with yttrium and indium doping respectively are explained by taking into consideration the different role of these ions in the spinel structure and the electron hopping mechanism.

A Magnetically Ordered Non-Stoichiometric Zinc Ferrite for the Oxidative Dehydrogenation Reactions.

2001 ◽  
Vol 676 ◽  
Author(s):  
J. A. Toledo ◽  
N. Nava ◽  
X. C. Sun ◽  
X. Bokhimi
Keyword(s):  
Catalytic Activity ◽  
Oxidative Dehydrogenation ◽  
Spinel Structure ◽  
Zinc Ferrite ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Octahedral Sites ◽  
Tetrahedral Sites ◽  
Dehydrogenation Reactions ◽  
Hydrothermal Reduction

ABSTRACTZnFe2O4 nanoparticles were prepared by hydrothermal reduction approach. A considerable amount of α-Fe2O3 was segregated in the as-synthesized sample, which diffused into the tetrahedral and octahedral sites of the ZnFe2O4 spinel structure with increasing the annealing temperature. The introduction of Fe3+ into the tetrahedral positions was observed by Mössbauer spectra. Magnetization measurements showed an unusual ferrimagnetic behavior of the ZnFe2O4 phase, even at room temperature, confirming the introduction of Fe3+ into the tetrahedral sites of the spinel structure. Catalytic activity measured in the oxidative dehydrogenation of 1-butene reaction increased with increasing annealing temperature, indicating that those interactions of Fe3+ in tetrahedral and octahedral positions also promotes the activity and selectivity to butadiene formation.

Design optimization and stability enhancement of modified inter-digital capacitive humidity transducer with cobalt ferrite nanoparticles as dielectric

2019 ◽  
Vol 42 (4) ◽  
pp. 917-923
Author(s):  
Jiss Paul ◽  
Jacob Philip
Keyword(s):  
Recovery Time ◽  
Room Temperature ◽  
Cobalt Ferrite ◽  
Dynamic Range ◽  
Ferrite Nanoparticles ◽  
Sensitive Layer ◽  
Humidity Transducer ◽  
The Stability ◽  
Stability Enhancement ◽  
Sensing Characteristics

A modified inter-digital capacitive (IDC) transducer for relative humidity (RH) measurement is fabricated by coating a thick film of polyvinyl alcohol (PVA) on the structure. The effective capacitance of the sensor, measured at 1MHz, increases with RH at room temperature. The RH sensing characteristics of PVA coated IDC transducer are analysed in terms of its sensitivity, dynamic range, frequency response, repeatability and recovery time. It is found that the stability of such a PVA based RH transducer improves remarkably by diffusing nanoparticles of CoFe2O4 in the PVA layer. A standard deviation of ± 0.05 and ± 0.01 for a sensitive layer with pure PVA and PVA-CoFe2O4 combination respectively results in a measurement error of ± 0.005 and ± 0.003.

The Role of Niobium in (Ca, Si, Ce, Nb)-Doped TiO2 Varistors

2007 ◽  
Vol 280-283 ◽  
pp. 297-300 ◽  
Author(s):  
Shao Hua Luo ◽  
Zi Long Tang ◽  
Hong Yun Li ◽  
Zhong Tai Zhang ◽  
Xi Zhou Xiong
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Room Temperature ◽  
Structural Characteristics ◽  
Nonlinear Coefficient ◽  
The Other ◽  
Optimal Composition ◽  
Low Loss ◽  
Nb Addition

The present work attempted to investigate the effect of Nb addition on the electrical properties of the (Ca,Si,Ce,Nb)-doped TiO2 ceramics. The content of added niobium is in the range 0.1-1.0mol %, while that of the other additives keeps constant. The results showed that an optimal composition doped with 0.8mol% Nb2O5, followed by sintering at 1350°C, was obtained with low V1 mA of 7.22V, high nonlinear coefficient of 5.76, ultrahigh dielectric constant (er = 86000) as well as relatively low loss (tgd = 0.52) in room temperature at 1 kHz. SEM studies show that change of niobium had significant influence on grain growth and micro structural characteristics of the sintered samples.

scholarly journals Role of Zn2+ Substitution on the Magnetic, Hyperthermic, and Relaxometric Properties of Cobalt Ferrite Nanoparticles

2019 ◽  
Vol 123 (10) ◽  
pp. 6148-6157 ◽  
Author(s):  
Martin Albino ◽  
Elvira Fantechi ◽  
Claudia Innocenti ◽  
Alberto López-Ortega ◽  
Valentina Bonanni ◽  
...  
Keyword(s):  
Cobalt Ferrite ◽  
Ferrite Nanoparticles ◽  
Cobalt Ferrite Nanoparticles

Dielectric and Magnetic Properties of Sintered Cobalt Ferrite Derived from Nanocrystalline Powders

2012 ◽  
Vol 476-478 ◽  
pp. 726-729 ◽  
Author(s):  
Liang Neng Wu ◽  
Li Zhen Jiang ◽  
Fang Yu Hong
Keyword(s):  
Dielectric Constant ◽  
Magnetic Properties ◽  
Hysteresis Loop ◽  
Loss Tangent ◽  
Room Temperature ◽  
Cobalt Ferrite ◽  
Relative Dielectric Constant ◽  
Nanocrystalline Powders ◽  
Magnetic Characteristics ◽  
Dielectric Constant And Loss

A kind of Cobalt ferrite ceramics were successfully prepared by using nanocrystalline powders synthesized by citrate gel method. The relative dielectric constant and loss tangent of the ceramic as a function of frequency (100 Hz - 1 MHz) was investigated at room temperature. Both of them decrease with increase in frequency showing dispersion. Hysteresis loop magnetization was measured and the ceramic show good magnetic characteristics at room temperature.

The role of terbium cation substitution on the magnetic properties of cobalt ferrite nanoparticles

2013 ◽  
Vol 330 ◽  
pp. 169-173 ◽  
Author(s):  
Tahmineh Sodaee ◽  
Ali Ghasemi ◽  
Ebrahim Paimozd ◽  
Andrea Paesano ◽  
Akimitsu Morisako
Keyword(s):  
Magnetic Properties ◽  
Cobalt Ferrite ◽  
Ferrite Nanoparticles ◽  
Cation Substitution ◽  
Cobalt Ferrite Nanoparticles
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