AC conductivity and dielectric studies on nickel ferrite nano-particles synthesized by sol gel technique

2012 ◽  
Author(s):  
S. Omprakash ◽  
A. P. Gnana Prakash ◽  
P. S. Naik
2020 ◽  
Vol 49 (7) ◽  
pp. 4186-4194
Author(s):  
I. B. T. Silva ◽  
A. G. D’assunção ◽  
J. B. L. Oliveira ◽  
J. R. F. Guerra ◽  
C. H. N. Cordeiro

2007 ◽  
Vol 25 (2) ◽  
pp. 199-203 ◽  
Author(s):  
Qiang Zhen ◽  
Ruifang Chen ◽  
Kai Van ◽  
Rong Li

2013 ◽  
Vol 209 ◽  
pp. 177-181 ◽  
Author(s):  
Ram S. Barkule ◽  
D.V. Kurmude ◽  
A.V. Raut ◽  
N.N. Waghule ◽  
K.M. Jadhav ◽  
...  

Abstract: The magnetic nano-particles of nickel ferrite were synthesized successfully by sol-gel auto-combustion method using high purity metal nitrates and citric acid as chelating agent. The as prepared powder of nickel ferrite was sintered at 5500C for 5 hr to obtain good crystalline phase and was used for further study. The X-ray diffraction technique was employed to confirm the single phase formation of nickel ferrite nano-particles. The X-ray diffraction pattern shows the Bragg’s peak which belongs to cubic spinel structure. The values of lattice constant, X-ray density, oxygen parameter and radii of tetrahedral and octahedral sites were calculated from XRD data. The average crystallite size was estimated using Scherrer’s formula and found to be 6 nm. The temperature dependence of the electrical conductivity plot shows the kink, which can be attributed to ferromagnetic-paramagnetic transition. The activation energy obtained from resistivity plots in paramagnetic region is found to be more than that in ferrimagnetic region. The conduction mechanism in these nickel ferrite nano-particles has been discussed on the basis of hopping of electrons.


2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
I. G. Blanco-Esqueda ◽  
G. Ortega-Zarzosa ◽  
J. R. Martínez ◽  
A. L. Guerrero

Magnetic composites with silver nanoparticles bonded to their surface were successfully prepared using a simple chemical method. By means of a sol-gel technique, nickel ferrite nanoparticles have been prepared and coated with silica to control and avoid their magnetic agglomeration. The structural and magnetic properties of the nanoparticles were studied in function of the annealing temperature. Then, silver nanoparticles were incorporated by hydrolysis-condensation of tetraethyl orthosilicate, which contains silver nitrate on the surface of the nickel ferrite-SiO2core/shell. Samples were characterized using X-ray diffraction, IR spectroscopy, SEM, and magnetometry. Results show that the silica covered the nickel ferrite nanoparticles and the silver nanoparticles remain stable in the surface of the composite.


2010 ◽  
Vol 11 ◽  
pp. 25-34 ◽  
Author(s):  
Noorhana Yahya ◽  
Hanita Daud ◽  
Nurulhuda Ali Tajuddin ◽  
Hasnah Mohd Daud ◽  
Afza Shafie ◽  
...  

Zinc oxide (ZnO) has found many important applications such as optoelectronic devices, sensors and varistors. The challenging part however is synthesizing ZnO nanoparticles and its utilisation as EM detectors. Sol-gel and self-combustion techniques were chosen in this study due to the ability to produce single phase and nano-size samples. The starting mixture consists of 10 grams of zinc (II) nitrate, Zn(NO3)2.6H2O salt which was dissolved in 50 mL of nitric acid, HNO3.The solution was stirred at 250 rpm continuously for 1 day. The mixture was then gradually heated for every 15 minutes until it combusted at 110oC for the self-combustion technique. For the sol-gel technique, the dissolved mixture was heated at 40oC, 50oC, 60oC and 70oC until the gelatine was formed. After the drying process, the as-prepared samples were annealed at 100oC and 200 oC for 1 hour for each technique. Characterizations were performed by using X-Ray Diffraction (XRD), Raman Spectra and Scanning Electron Microscopy (SEM).The XRD analysis showed a major peak of [101] plane at 2Ө for the self-combustion technique and the sol-gel technique. Raman results for the samples prepared via sol-gel and self-combustion techniques had shown the major peak of ZnO that is located at the Raman shifts of 437.67 cm-1. Using the Scherrer equation, single crystal nano particle of ZnO was successfully obtained in the range of 38.49 nm to 50.70 nm for the sample prepared via the sol gel technique. By the self-combustion technique, the average dimension of the as-prepared sample is in the range of 34-49 nm. Further heat treatment resulted in a major change of the Raman shift corresponding to the single phase ZnO nano particles. The best samples were used as electromagnetic (EM) detectors. The EM detectors are polymer based composite which were prepared using a casting technique.


2020 ◽  
Vol 7 ◽  

Gadolinium doped SrTiO3-δ i.e. Sr1-xGdxTiO3-δ for various values of ‘x’ have been successfully synthesized using sol gel technique in the reported work. XRD patterns of the obtained ceramics are found to be sharp and well defined having no impurity phases for all the compositions. Lattice parameter ‘a’ decreases with increase in the amount of Gadolinium. XRD, FESEM and EDX studies confirm the formation of Sr1-xGdxTiO3-δ ceramics with required cubic structure. FESEM/EDX analysis reveals that ceramics possess high density with marginal inter-granular porosity. The dielectric studies show that the synthesized samples possess high dielectric constants, high ac conductivity and low loss factors which further improve with gadolinium doping


2016 ◽  
Vol 846 ◽  
pp. 318-325
Author(s):  
Taifunisyam Taib ◽  
Souad A. Mohamad ◽  
Mohd Rafie bin Johan ◽  
Wan Jefrey Basiron ◽  
Chin Kim Ming ◽  
...  

Silver-silica nanocomposites (Ag-SiO2NCs) with various compositions were synthesized through sol-gel technique. The morphology, optical and thermal stability of the nanocomposite were investigated and was compared with pure sol-gel to determine the effects of the nanoparticles. Transmission electron microscopy (TEM) confirmed that SiO2 was encapsulated Ag with mean size of 30 nm. Uv-vis spectroscopy shows that the surface plasmon resonance (SPR) peak show Ag-SiO2 NCs were greatly reduce due to the SiO2 particles. The permittivity and refractive index were decreased as the composition of Ag was increased at composition of 60% silver. The real permittivity is negative along the visible region. The trend stability of Ag-SiO2NCs were increased with the increased amount of silver.


Crystals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 384 ◽  
Author(s):  
Jinpei Lin ◽  
Yun He ◽  
Xianglin Du ◽  
Qing Lin ◽  
Hu Yang ◽  
...  

The present study envisages the preparation of chromium substituted Nickel ferrite NiCrxFe2−xO4 (x = 0~1.0) powders by a sol-gel auto-combustion method. X-ray diffraction analysis (XRD) showed that the specimens with x > 0.2 exhibited a single-phase spinel structure, and that more content of Cr within a specimen is favorable for the synthesis of pure Ni-Cr ferrites. The lattice parameter decreased with an increase in the Cr concentration. The sample without calcining exhibited a good crystallinity. Scanning Electron Microscopy (SEM) showed the formation of ferrite powders nano-particles, and that the substitution of Cr weakened the agglomeration between the particles. Mössbauer spectra of NiCrxFe2−xO4 showed two normal Zeeman-split sextets that displayed a ferrimagnetic behavior. Furthermore, the spectra indicated that iron was in the Fe3+ state, and the magnetic hyperfine field at the tetrahedral tended to decrease with an increase in the Cr substitution. The saturation magnetization decreased by the Cr3+ ions, and reached a minimum value (Ms = 4.46 emu/g). With an increase in the annealing temperature, the coercivity increased initially, which later decreased.


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