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* santhukphysics@gmail.com

4* nrajkk@gmail.com

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