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Manuscript Details
Manuscript number CJPH_2017_86
Title Effect of Gamma irradiation on some electrical and Dielectric properties of Ce+3substituted Ni-Zn nano ferrites
Short title Electrical properties of Ferrites on gamma irradiation
Article type Research Paper
Abstract
Cerium substituted Nickel Zinc nano ferrites of compositions 0 ≥x≤1, y=0.1 is synthesized by employing non-conventional nitrate gel technique at 6000 C sintering temperature. The structural studies through Powder XRD carriedout for all the samples without irradiation it reflects that there is no significant impurity peaks were observed and thecrystallite size is 8nm-37nm and also the linear variation of Porosity on concentrations of Zn+2 ions. The influence ofgamma irradiation emitted by Co60 source with constant dose rate 4.97kilo Gray (5 Mega rad) on electrical anddielectric Properties was studied as a function of frequency. It attributes the significant alteration in the dielectricproperties at 50Hz-10KHz. This is may be dipole polarization between two equivalent equilibrium positions isimplicated and Porosity of the samples changing the polarization of the dipoles. Comparatively, DC resistivity value ofirradiated ferrite may decrease five times this effect is due to Fe2+ ions hopping at B-site.
Keywords Ni-Zn Ferrite; Irradiation studies; Dielectric Properties; Electrical Properties.
Manuscript category Condensed Matter: Structure, etc.
Corresponding Author Santhosh Kumar Melanayakanakatte Veerabhadrappa
Corresponding Author'sInstitution
Jain Institute of Technology
Order of Authors Santhosh Kumar Melanayakanakatte Veerabhadrappa, N Chandamma, G.JShankarmurthy, Dr Melagiriyappa Eswarappa, Nagaraja Kodihalli Kireeti
Suggested reviewers manab kundu, GOPALU KARUNAKARAN, Poornesh P.
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From, Mr. Santhosh Kumar M V
Asst. Professor, Dept of Physics Jain institute of Technology,
Davangere, Karnataka, India
To, The Editor- in- chief,
Chinese Journal of Physics
Dear Sir, Subject: Submission of manuscript to the Journal of Magnetism and Magnetic Materials
I submit herewith the manuscript entitled “Effect of Gamma irradiation on some electrical and Dielectric properties of Ce+3 substituted Ni-Zn nano ferrites” authored by N. Chandamma, G J Shankarmurthy, E. Melagiriyappa, and Nagaraj K K for publication in Journal of Solid State Ionics, kindly consider it favorably. On behalf of co-authors, I declare that the work is original and unpublished, is being submitted only to this editor and is not being considered at any other journal for publication.
Thank you
Yours Sincerely Mr. Santhosh Kumar M. V Davangere 09-12-2016
Effect of Gamma irradiation on some electrical and Dielectric properties of Ce+3 substituted Ni-Zn nano ferrites
N. Chandamma1, Santhosh Kumar M. V.1*, G. J. Shankarmurthy2, E.
Melagiriyappa3, K. K. Nagaraja4*
1Govt. First Grade College, Davangere 577002, India
1*Dept of Physics, Jain institute of Technology, Davangere 577003, India
2University BDT College of Engineering, Davangere 577002, India
3Dept of Science, SJM Polytechnic, Chitradurga 577502, India
4*National University of Science and Technology “MISiS”, Leninskii pr. 4, Moscow 119049 Russia
Email:1* [email protected]
Abstract:
Cerium substituted Nickel Zinc nano ferrites of compositions , is synthesized by 0 ≥ x ≤ 1 y = 0.1
employing non-conventional nitrate gel technique at 6000 C sintering temperature. The structural
studies through Powder XRD carried out for all the samples without irradiation it reflects that there is
no significant impurity peaks were observed and the crystallite size is 8nm-37nm and also the linear
variation of Porosity on concentrations of Zn+2 ions. The influence of gamma irradiation emitted by
Co60 source with constant dose rate 4.97kilo Gray (5 Mega rad) on electrical and dielectric Properties
was studied as a function of frequency. It attributes the significant alteration in the dielectric
properties at 50Hz-10KHz. This is may be dipole polarization between two equivalent equilibrium
positions is implicated and Porosity of the samples changing the polarization of the dipoles.
Comparatively, DC resistivity value of irradiated ferrite may decrease five times this effect is due to
Fe2+ ions hopping at B-site.
Key Words: Ni-Zn Ferrite; Irradiation studies; Dielectric Properties; Electrical Properties.
Introduction:
Ferrites are very attractive materials for novel technological applications in recent years due to their
combined properties as magnetically a ferromagnetic material and electrically an insulator.
Polycrystalline phase ferrite, are having applications ranging from microwave frequencies to radio
frequencies they are very good dielectric materials [1-2]. It is influenced by the factors sintering
conditions, chemical composition, crystallite size, cation distribution in the tetrahedral (A) and
octahedral [B] lattice sites and including the method of preparation [3]. Zn-Ni ferrites have
applications as soft magnetic materials with high frequency due to high electrical resistivity and low
eddy-current loss effects of rare earth elements substitution in ferrites have been investigated.[4,6]
Rare-earth substituted soft nickel spinel ferrites have attracted great attention in the field of
materials science owing to they're enhanced magnetic and electrical properties [7].The substitution
of rare-earth ions into spinel ferrites and the occurrence of 4f–3d couplings in ferrites can improve
the magnetic and electrical transport properties of NiFe2O4 ferrites.[8] The recent studies of
frontiers of research on the impact of irradiation on its structural, electrical, magnetic and other
properties may give the significant changes. It was found that due to γ -irradiation, both of lattice
parameter and porosity were influenced and leads to structural inhomogeneity. The values of
magnetization and initial permeability were decreased as a result of irradiation [9] many researchers
have effectively synthesized Ni ferrite [10], Ni-Zn [11] and Ni-Cu-Zn [12] ferrites by employing
the auto combustion technique and studied their magnetic and electrical properties. In the present
work, the authors aimed to blend the soft nickel Zinc ferrite substituted with Ce+3 through auto
combustion technique and to study the effect of composition on structural properties and also the
effect of Co60 irradiation on the dielectric and electrical property as a function of frequency and
composition.
Experimental methods and materials:
Cerium substituted nano nickel-zinc ferrite crystals of compositions and is prepared 0 ≥ x ≤ 1 y = 0.1
via non-conventional solution combustion method using the analytical Reagent Grade of metal nitrates
and Urea. The quantitative stoichiometric ratio of nitrates are dissolved in a minimum quantity of de-
ionized water with constant stirring about 2 hours and maintained the temperature at 800C then after
homogeneous mixture, it kept in the muffle furnace for 4 hours with 5000C temperature then burnt
powder is pressed into pellets.
The structural characterization of all the samples was carried out by PXRD by PANalytical
X’pert PRO MPD Instrument with graphite-filtered Cu Kα radiation source λ=1.541Å, Germany. The
surface morphology of the pellets (samples) is examined by a JEOL.JSM-6390LV SEM operated at
200 kV, and also EDAX is carried out to know relative abundance of the element in the sample. Later
the samples are irradiated with 1.33MeV energy gamma radiation by Co60 source for 6 hours with a
dose rate of 4.97 kiloGray (5M Rad). Then A.C. response measurements were done at room
temperature using Hioki model 3532-50 programmable Computer interfaced with a digital LCR meter
(Japan) in the selected frequency range of 50Hz to 5MHz before and after irradiation. And
compositional dependence of DC resistivity of the samples studied at room temperature.
Results and discussion:
1. Structural studies:
The analysis of the powder XRD patterns was done and used to determine the respective planes of
the face-centered cubic structure of the ferrites. The well-resolved peaks in the Powder XRD pattern
clearly indicated that the single phase nature of the samples. The diffraction patterns and relative
intensities of all the diffraction peaks are matched well with those of JCPDS card 22-1086 and the ‘Ce’
diffraction peaks matched well with those of JCPDS card 34-0394. The appeared peaks were indexed
to the crystal plane of spinel ferrite (220), (311), (400), (422), (333) and (440) respectively except this
there are no much significant impurity peaks in the obtained pattern [13]. The patterns of the peaks are
matches with the spinal crystalline phase. Then crystallite size is determine using Scherrer’s
Relation[14], it shows the crystallite size decreases with Zn+2 concentrations and it is due to more
lattice strain created by rare Ce+3 and ionic radius Zn+2 at B- site (Table 1). And lattice parameters are
determined by using Bragg’s relation [15]
The variation of porosity of the ferrite sample with the composition of zinc is obtained by plotting
Porosity against Zn+2 concentrations. The porosity seems to be linearly dependent on Zn+2
concentrations in the present method of synthesis It is due to the more ionic radius of Zn+2 (0.82 Å)
and influence of the small quantity of rare-earth ions can alter the structure of ferrites due to its large
ionic radius.[16]. Through, y –intercept of the linear fit we obtained the 48% of threshold porosity.
2. FESEM -EDAX Analysis:
The surface morphology and microstructure of the samples studied through JEOL.JSM-6390LV
SEM operated at 20 kV Figure 2. And it shows the well-defined spinal structure with some
agglomeration in the grains and existing of two phases formed by Ce+3 rare earth element. The grain
size is decreasing with the concentration of Zn+2 ion the average grain size is calculated for all
compositions of Zn+2 ion is varies from 0.3 to 1µm in size. EDAX spectra of one of the sample
figure 3. it suggests that well distribution of all chemical elements in the tetrahedral and octahedral
site Ce+3 and Fe+3 ions are found in between 6 to 7 k eV and Zn+2 8 to 9 k eV Ni+3-Ce+3-Zn+2at 1k
eV In all the samples.
3. Dielectric Studies and AC Conductivity:
The dielectric behavior has been studied by measuring the dielectric constant and Dielectric
loss tangent (tan δ) at room temperatures with frequency range 50Hz-1MHz; it reveals that
dispersion due to Maxwell-Wagner type interfacial polarization in agreement with Koop’s
phenomenological theory for unirradiated and irradiated samples [17]. It is clear in figure 5
dielectric constant is significantly altered after irradiation with gamma radiation, due to the
microstructural defects and disorder, which affect the electrical and dielectric properties of
polycrystalline and single crystal nanoparticles of magnetic metal oxides like ferrites. In electric
properties are very sensitive to the irradiation-induced defects which results in a significant alter in
the dielectric constant [18]. Dielectric polarization in the samples with contains the rare earth
element the exchange of electronic charge Fe2+⇔Fe3++e, between tetrahedral and octahedral sites
which produce the local displacement in the opposite direction of applied fields [19]. The
preferential sites of Ni–Zn ions in the crystalline phase is octahedral and tetrahedral sites can be
explained by the Verwey and de Boer mechanism in which electron exchange between ions of the
same element present in more than one valence state takes place [20] These displacements
determine the polarization as well as dielectric properties. The valence exchange between iron ions
is responsible for the polarization which increases dielectric constant (ε’) comparatively with
unirradiated samples. The γ- radiation causes the effect on its homogeneity leads to create the
resistive and conductive boundary; hence frequency of applied alternating field increases the
interfacial polarization [21, 23].
Figure 6 shows the variation of dielectric loss with the frequency of irradiated and
unirradiated samples. In the unirradiated samples, the maximum dielectric loss is at a lower
frequency. It reveals the Koop’s theory this fact is explained with the facts the high resistive grain
boundaries effect is maximum this leads to the energy required to exchange Fe+2 to Fe+3 ions
located at the grain boundaries at higher frequencies it requires low energy for hopping hence low
loss at higher frequencies[22]. in the irradiated sample, resonance peak is observed around 4-5 kHz
for the composition the alternating frequency make the hopping of ions between A and B Site when
the frequency applied equal is to the natural frequency electrical energy transfer to the oscillating
ions according to Debye relaxation theory. The Relaxation time factor is i.e. , Where ‘E’ 𝜏 = 𝜏0 𝑒- 𝐸
𝐾 𝑇
activation energy of the electrons [24].
Figure 7 shows the Variation of AC Conductivity (σac) with frequency 50Hz to 1MHz range at first
it shows increases at higher frequency region it starts to increase rapidly due to hooping of carriers
thereby increase in the conductivity at higher frequencies the carriers the theory of this explained in
the Koop’s model at low frequency the grain boundaries effect at higher frequency it turns to the
conductive grains this variation is higher rate of transportation of carriers [25]. AC conductivity
increases at higher frequencies due to small poloran conduction they are associated with frequency
as well as temperature which breaks the barrier of non-conductive resistive grains and enters to the
conductive grains. The possibility of small polarons due to defective grain boundaries creates the
large number of small polorons. Hence after irradiation conductivity seems to be increases but in
the literature shows less effects on the rare earth element substituted samples and Fe2+⇔Fe3
Hopping between A-B sites and also concentration of Zn+2 in the A site and Ni+3 at B site similar
observation is made them for sample Prepared by sol-gel method by author Sabah M Ali Ridha
[26].
4. DC Resistivity (ρdc):
Figure 8 gives the compositional dependence of DC Resistivity of the Nix Zn1-x Fe2-y O4(x= 0, 0.2,
0.4, 0.6, 0.8, 1 & y=0.1) unirradiated and irradiated samples. it shows a little decrease in the DC
Resistivity with increases in the Zn+2 concentration, it makes the interaction between Zn+2 and Fe+3
at octahedral site and increases in the Zn+2 concentration decreases in the iron ion content the Zn+2
occupies the B site leads to decreases in A-B, B-B interaction and decrease in Fe2+–Fe3+ hopping
[27, 28, 29]. Gamma irradiation enhances the electronic mobility and electrical conduction it is
mainly due to the number of Fe2+ at the B-sites it may play a dominant role in the increase of the
DC conductivity due to the gamma irradiation thereby decrement in the DC resistivity [30].
5. Conclusion:
Ni-Zn ferrites substituted with rare earth element Ce+3(Ni1-xZnxCeyFe2-yO4; x= 0.2, 0.4, 0.6, 0.8, 1,
& y= 0.1) were synthesized by no conventional solution combustion method. Powder XRD studies
reveal that ferrites were crystallized in spinel structure and there is no significant impurities phase
in the prepared samples. The crystallite size found to be varying with the Zn2+ concentration. The
SEM analysis shows the dual grain formation is observed for the entire sample. The AC Properties
are significantly altered due to the irradiation effect. And also we noticed that the irradiation effect
may also influence by the porosity of the samples; it was not reported in any previous papers.
Acknowledgement
The authors are thankful to University Grants Commission, New Delhi for the financial support.
And also express their gratefulness to Principal of Govt. First Grade College, Davangere, and
Principal of SJM Science College, Chitradurga, Dr. Ravindrachari, Mangalore, University, for their
help in providing instrumentation. Mr. SMV acknowledges the Dr. Jagadeesh M.R, Jain Institute of
Technology Davangere.
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Figure 1
Powder X-ray Diffraction pattern of Ni1-x Zn xCey Fe2-y O4 (x=0, 0.2, 0.4, 0.6, 0.8, 1, & y= 0.1)
Figure 2: Porosity Versus Zn+2 Concentration and Porosity Linear fit.
Figure 3. FE SEM micrographs of Ni1-x Zn x Cey Fe2-y O4 (x=0, 0.2, 0.4, 0.6, 0.8, 1, & y= 0.1)
Figure 4 EDAX spectra of one of the sample obtained up to 9KeV shows the presence of Ni, Zn, Ce, Fe, and O
Figure 5 Dependence of Dielectric Constant on frequency of the samples (x=0.2, 0.4, 0.6, 0.8, 1 &y=0.1)
Figure 6 Dependence of Dielectric loss on frequency of the samples (x=0.2, 0.4, 0.6, 0.8, 1 &y=0.1)
Figure 7 Dependence of AC Electrical conductivity on frequency of samples (x=0.2, 0.4, 0.6, 0.8, 1 &y=0.1)
Figure 8 DC Electrical Resistivity of the samples (x=0.2, 0.4, 0.6, 0.8, 1 &y=0.1)
Table 1
Bulk density, X -ray density, Crystallite size, Lattice Strain & lattice Constant of the Samples.
SamplesBulk
Density(dexp)
gm/cm3
X ray density(dx)
gm/cm3
Porosity(P)%
Crystallite Size(D)nm
LatticeStrain
Lattice Constant (a)
Å
Ni Ce0.1Fe1.9O4 2.763 5.364 48.49 31.76 0.0072 8.34817
Ni0.8Ce0.1 Zn0.2Fe1.9O4 2.706 5.355 49.47 37.53 0.0061 8.37114
Ni0.6Ce0.1 Zn0.4Fe1.9O4 2.690 5.442 50.58 37.53 0.0061 8.33918
Ni0.4Ce0.1 Zn0.6Fe1.9O4 2.450 5.394 54.57 29.48 0.0078 8.37553
Ni0.2Ce0.1 Zn0.8Fe1.9O4 2.415 5.404 55.32 27.51 0.0084 8.39397
Zn Ce0.1 Fe1.9O4 2.511 5.394 53.43 8.481 0.0273 8.40752
The following Novelty work which is not been reported by any of author in any journals
crystallite size is decreases with Zn+2 concentrations 48% of threshold porosity of the samples. SEM analysis -spinal structure with some agglomeration in the grains and existing
of two phases formed by Ce+3 rare earth element Significant changes in the Dielectric studies DC resistance decreases due to gamma irradiation