research article structural and magnetic properties of

Research ArticleStructural and Magnetic Properties of Microwave AssistedSol-Gel Synthesized La09Sr01MnO3 Manganite Nanoparticles

Mahin Eshraghi1 and Parviz Kameli2

1 Department of Physics Payame Noor University Tehran 19395-3697 Iran2Department of Physics Isfahan University of Technology Isfahan 84156-83111 Iran

Correspondence should be addressed to M Eshraghi mahin eshraghiyahoocom

Received 24 November 2013 Accepted 31 December 2013 Published 10 February 2014

Academic Editors G F Goya and L Suber

Copyright copy 2014 M Eshraghi and P Kameli This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

The structural and magnetic properties of nanoparticles of La09Sr01MnO3 (LSMO) were studied using powder X-ray diffraction(XRD) transmission electron microscope (TEM) and magnetic measurements The XRD refinement result indicates that samplescrystallize in the rhombohedral structure with R-3C space groupThe dcmagnetizationmeasurements revealed that samples exhibitno hysteretic behavior at room temperature symptomatic of the superparamagnetic (SPM) behavior The results of ac magneticsusceptibility measurements show that the susceptibility data are not in accordance with the Neel-Brownmodel for SPM relaxationbut fit well with conventional critical slowing down model which indicates that the dipole-dipole interactions are strong enough tocause superspin-glass-like phase in LSMO samples

1 Introduction

Magnetic nanoparticles are currently the subject of intenseresearch because of their potential applications in highdensity magnetic storage and biomedical applications [1ndash3]The perovskite manganite with the formula La

1minus119909A119909MnO3

(A = Sr Ca Ba or vacancies) has attracted considerableattention due to the discovery of the phenomenon of colossalmagnetoresistance (CMR) and its potential application [4ndash7] The properties of these materials are explained by doubleexchange theory of Zener [7] and electron lattice interaction[8] By varying the composition 119909 and consequently tuningthe Mn3+Mn4+ ratio the compound La

1minus119909A119909MnO3reveals

various electronic magnetic and structural phase transitionsat different temperatures These phase transitions have beenattributed to strong coupling among spin charge orbitaldegree of freedom and lattice vibrations

It is well known that the magnetic and transport prop-erties of these materials strongly depend on the parti-cle size due to the influence of structural and magneticdisorders at the grain boundaries [9ndash13] The size effects

and the large surface area ofmagnetic nanoparticles intenselychange some of the magnetic properties compared to bulkcounter parts Manganite nanoparticles display features likelower values of magnetization [14] higher values of lowfield magnetoresistance [15] exhibiting superparamagnetic(SPM) phenomena [16] and so forth SPM nanoparticleswith single domain microstructure have a high potentialas carriers for biomedical applications According to theStoner-Wohlfarth theory the magnetocrystalline anisotropyenergy 119864

119886 of a single-domain particle can be approximated

by 119864119886= 119870119881 sin 2120579 where 119870 is the magnetocrystalline

anisotropy constant119881 is the volume of the nanoparticle and120579 is the angle between the magnetization direction and theeasy axis of the nanoparticle119864

119886serves as an energy barrier for

blocking the flips of magnetic moments When 119864119886becomes

comparable with thermal activation energy 119870119861119879 with 119870

119861as

the Boltzmann constant thermal activation can overcomethe anisotropy energy barrier This state occurs above theblocking temperatures119879

119861 called SPM state At blocking tem-

perature thermal energy is equal to the anisotropy energyThe absence of hysteresis almost incalculable coercivity

Hindawi Publishing CorporationISRN NanotechnologyVolume 2014 Article ID 867139 6 pageshttpdxdoiorg1011552014867139

2 ISRN Nanotechnology

20 30 40 50 60 70 80

134208036

220116

300024

006

110In

tens

ity (a

u)

S1

S4

S3

S2

012

2120579 (deg)

(a)In

tens

ity (a

u)

20 30 40 50 60 70 80

ExpCal

Exp-calBraggrsquos position

2120579 (deg)

(b)

Figure 1 (a) The XRD pattern of S1 S2 S3 and S4 samples at room temperature (b) The observed and calculated (Rietveld analysis) XRDpatterns of S3 sample at room temperature

and remanence and the nonachievement of saturation evenat high magnetic field are the typical characteristics of SPMbehavior [17]

In this paper we have studied the effect of annealingtemperature on the structural and magnetic properties of themicrowave-assisted sol-gel grown La

09Sr01MnO3(LSMO)

manganite samples

2 Experimental

The LSMO manganite samples were prepared by themicrowave-assisted combustion method using a domesticLG microwave oven operating at frequency of 245GHzwith the output power of 1000W Stoichiometric amounts ofLa(NO

3)3sdot6H2O(Merck 99) n(NO

3)2 sdot 4H

2O(Merck 99)

and Sr(NO3) (Merck 95)were dissolved inwater andmixed

with ethylene glycol and citric acid forming a stable solutionThe mixture was then kept in a microwave oven with 60 ofoutput power This mixture undergoes dehydration followedby decomposition and spontaneous combustion with theevolution of voluminous gases The obtained final product isin the form of a foamy powder and is calcined at 450∘C (S1)for 6 h Different packages of powder were sintered at 550∘C(S2) 575∘C (S3) and 600∘C (S4) for 6 h to obtain powderswith different particle sizes

Phase formation and crystal structure of the powderswere checked by XRD pattern using CuK120572 radiation sourcein the 2120579 scan range from 20∘ to 80∘ The average particlesizes of the samples were estimated from TEM micrographsThe ac magnetic susceptibility has been measured versustemperature at different frequencies in the selected range of33ndash1000Hz and using a Lake Shore ac susceptometer model7000 The dc magnetization was carried out as a function

of magnetic field at 295K using a Meghnatis Daghigh Kavirvibrating sample magnetometer (VSM)

3 Results and Discussion

Figure 1 shows the XRD patterns at room temperature forsamples Figure 1(a) shows that S1 sample is amorphous andits crystal structure is not formed By sintering the powderat higher temperatures 550∘C to 600∘C the perovskitecrystal structure is formed The Rietveld analyses of theXRD pattern of the samples have been carried out usingFULLPROFprogram [18] Figure 1(b) shows the XRDpatternwith Rietveld analysis of the S3 sampleThe estimated averagelattice parameters are 119886 = 119887 = 5511 A and c = 13352 Awhich are found in close agreement with reported values[19] Typically the TEM micrograph of S3 sample is shownin Figure 2 TEM micrograph shows that the mean particlesize of the S3 sample is about 50 nm Also the selected areadiffraction patterns of sample S3 confirms the crystallinenature of this sample

To study the magnetic response of samples to an externalfield wemeasured field dependentmagnetization using VSMat room temperature Figure 3 shows the room temperaturehysteresis curves of the samples sintered at different tem-peratures It can be seen that by increasing the sinteringtemperature the magnetization (119872) increases slightly Anincrease in magnetization with the sintering temperature canbe attributed mainly due to the enhancement of grain sizeThe increase of magnetization by increasing the grain sizecould be ascribed to the lower surface area of larger grainsThis is because of the magnetically disordered state in thesurface In the case of nanometric-size grains defects areexpected to occur to a higher extent due to the vacanciesmicrostrain and dislocations Since the sizes of samples

ISRN Nanotechnology 3

Figure 2 TEM micrograph of sample S3 Upper panel shows theselected area diffraction pattern of sample S3

are within the superparamagnetic and single domain limitsthese samples are SPM in nature with zero coercivity andnonsaturated magnetization

To further study the SPM behavior of samples we haveperformed ac susceptibility measurements on sample S3Figure 4 shows the real 1205941015840(119879) and imaginary 12059410158401015840(119879) partsof ac magnetic susceptibility as function of temperature inan ac field of 10Oe and frequencies of 33 111 333 666 and1000Hz It is evident that by decreasing the temperature the120594

1015840(119879) and 12059410158401015840(119879) show a peak related to the blockingfreezing

temperature (119879119861) of the SPMspin glass systems [20ndash22]

Above 119879119861 the nanoparticles considered being in the SPM

regime and below which the nanoparticles are in the so-called blockedfreezed regime 119879

119861is frequency dependent

and shifted to higher temperature with increasing frequencyThe frequency dependence of the acmagnetic susceptibility isa characteristic of SPMspin glass systems There are severalmodels to interpret the ac susceptibility behavior of themagnetic nanoparticles In the noninteracting SPM systemthe frequency dependence of blocking temperature followsthe Neel-Brown model [23]

120591 = 1205910exp( 119870119881119896119861119879119861

) (1)

where 120591 is related to measuring frequency (120591 = 1119891) and1205910is related to the jump attempt frequency of the magnetic

moment of nanoparticle between the opposite directions ofthe magnetization easy axis For SPM systems 120591

0is in the

range of 10minus9ndash10minus13 s Blocking temperature is the one thatthe thermal energy overcomes to anisotropy energy Whenthe energy of the potential barrier is comparable to thermalenergy the magnetization direction of the nanoparticlesstarts to fluctuate and goes through a rapid SPM relax-ation Above 119879

119861the magnetization direction of nanoparticles

can follow the direction of the applied field Below theblocking temperature the thermal energy is less than theanisotropy energy hence the direction of magnetization ofeach nanoparticle whichmay lie in the direction of easy axis isblocked Since the nanoparticles and consequently their easyaxes are randomly oriented by decreasing the temperaturethe total magnetic susceptibility is reduced The linear plotof ln(119891) versus the reciprocal of blocking temperature (1119879

119861)

is shown in Figure 5 The (119870119881119896119861) and 120591

0can be obtained

from the slope and intercept of the plot By fitting theexperimental data we have found an unphysical small 120591

0sim

126 times 10

minus90 in comparison to the values of 10minus9ndash10minus13 s forSPM systems As expected this result simply indicates thatthere exists strong interaction between nanoparticles of S3sample The interactions between nanoparticles affected theblockingfreezing temperature via modifying the energy bar-rier On the other hand the Vogel-Fulcher law describes thebehavior of magnetically interacting (medium interaction)nanoparticles as follows [20]

120591 = 1205910exp( 119870119881

119896119861(119879119861minus 1198790)

) (2)

In this model 1198790is an effective temperature representing the

existence of the interaction between nanoparticles and 1205910is

a time-scale constant typically on the order of 10minus9ndash10minus13 sFitting result with the Vogel-Fulcher law is given in Figure 6According to Dormann et al studies [20] the Vogel-Fulcherlaw is valid only if 119879

0≪ 119879119861 In our work 119879

0is 199K while the

average value of 119879119861is 202K This point revealed that Vogel-

Fulcher law cannot explain the behavior of the sampleTwo criteria have often been used to compare the fre-

quency sensitivity of peak temperature in different samplesand to distinguish between canonical spin glasses otherdisordered magnetic compounds where the freezing is pro-gressive and fine particles They are given as [20]

1198881= (

Δ119879119891

119879119891Δ (log

10119891)

)

1198882= (

119879119891minus 1198790

119879119891

)

(3)

where Δ119879119891is the difference between 119879

119891measured at the

frequency Δ(log10119891) interval Δ119879

119891= 119879119891(119891 = 1000Hz) minus 119879

119891

(119891 = 33Hz) and 119879119891is the mean value of blockingfreezing

temperature in the range of experimental frequencies and 1198790

is the characteristic temperature of the Vogel-Fulcher law(2) The value of 119888

1 which is independent of any model

represents the relative shift of blocking temperature perdecade of frequencyThe value of 119888

2can be useful to compare

the 119879119891variation between various systems The experimental

values of 1198881and 1198882depend on the interaction strength between

magnetic nanoparticles Dormann et al distinguish threedifferent types of dynamical behavior based on the values of1198881and 1198882 (1) for noninteracting particles 01 lt 119888

1lt 013

and 1198882= 1 (2) for weak interaction regime (inhomogeneous

freezing) 003 lt 1198881lt 006 and 03 lt 119888

2lt 06 and

in the medium to strong interaction regime (homogeneousfreezing) 0005 lt 119888

1lt 002 and 007 lt 119888

2lt 03 [17] Both

1198881and 1198882decrease with increasing the interactions between

nanoparticles The calculated values of 1198881and 119888

2for our

sample are 001 and 0015 respectively By comparing the 1198881

and 1198882values with values just given above one can claim that

there is a strong interaction between LSMO nanoparticlesIn the case of strong interaction between nanoparticles

magnetic nanoparticles indicate superspin glass behavior


0 5000 10000

0

2

4 S2

minus10000 minus5000

minus2

minus4

M(e

mu

gr)

H (Oe)

(a)

S3

0 5000 10000minus10000 minus5000

0

2

4

minus2

minus4

M(e

mu

gr)

H (Oe)

(b)

S4

0 5000 10000minus10000 minus5000

0

2

4

minus2

minus4

M(e

mu

gr)

H (Oe)

(c)

Figure 3 Room temperature magnetization versus magnetic field of the S2 S3 and S4 samples

50 100 150 200 250 300

015

030

045

060

07533Hz

1000Hz

times10minus3

X998400

(cumiddot

mk

g)

T (K)

(a)

50 100 150 200 250 300

0000

0005

0010

0015

33Hz

1000Hz

times10minus3

X998400

(cumiddot

mk

g)

T (K)

(b)

Figure 4 Frequency dependence of real and imaginary parts of ac susceptibility for sample S3 in frequencies of 33ndash1000Hz and ac field of10Oe


30

35

40

45

50

55

60

65

70

000486 000489 000492 000495 0004981TB (Kminus1)

Ln(f

)

Figure 5 The best fits of ac magnetic susceptibility data for sampleS3 using Neel-Brown model

30

35

40

45

50

55

60

65

70

010 015 020 025 030 035 040 045 0501(TB minus T0) (Kminus1)

Ln(f

)

Figure 6 The best fits of ac magnetic susceptibility data for sampleS3 using Vogel-Fulcher model

[24] The possibility of presence of a spinglass behavior wasexamined by the critical slowing downmodel [24] as follows

120591 = 1205910(

119879119891

119879119892

minus 1)

minus119911120592

(4)

where 119879119891is the freezing temperature and 119879

119892is the glass-

transition temperature The exponent depends on the lawgoverning the phase transition 120591

0is related to the relaxation

time of the individual particle magnetic moment 120592 is thecritical exponent of correlation length 120585 = (119879

1198911198790minus 1)

minus120592and 119911 relates 120591 and 120585 as 120591 sim 120585119911 The parameter 119911120592 as adynamic critical exponent shows interactions strength andvaries between 4 and 12 and 120591

0is in the range of 10minus9ndash10minus13 s

for frustrated three-dimensional systems such as spin glassesreentrant spin glasses and superspin glasses (SSG) [25 26]Figure 7 shows the best fits of ac magnetic susceptibility

2

3

4

5

6

7

8

minus50 minus45 minus40 minus35

Ln[(Tf minus Tg) minus 1)]

Ln(f

)

Figure 7 The best fits of ac magnetic susceptibility data for sampleS3 using critical slowing down model

data using the critical slowing down model The obtainedvalues of 120591

0and 119911120592 are 417 times 10minus11 and 48 respectively

Based on the calculated values of 119911120592 and 1205910 the behavior of

our sample is consistent with those expected for spin glasssystems and could suggest the existence of a phase transitionto a SSG state below the peak temperature This type ofSSG-like behavior has been reported elsewhere for differentsamples For example Fiorani et al reported the values of1205910sim 10

minus11 and 119911120592 = 76 for interacting nanoparticles of120574-Fe2O3[27] Also the SSG-like behavior has been reported

in oleic acid-coatedMn05Zn05Fe2O4ferrite nanoparticles by

Parekh and Upadhyay [28]

4 Conclusions

The La09Sr01MnO3(LSMO) manganite nanoparticles could

be synthesized successfully in nanocrystalline form by themicrowave-assisted sol-gel auto-combustion method Theestimated negligible coercivity and remanent magnetizationindicate superparamagnetic behavior for these nanoparticlesamples Spin dynamics analysis using ac magnetic suscep-tibility measurements showed that these nanoparticles havesuperspin glass behaviorwith strongly interacting superspins

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors would like to thank the Payame Noor Universityfor supporting this work


References

[1] M Todorovic S Schuttz J Wong and A Scherer ldquoWritingand reading of single magnetic domain per bit perpendicularpatterned mediardquo Applied Physics Letters vol 74 p 2516 1999

[2] T D Schladt K Schneider H Schild andW Tremel ldquoSynthesisand bio-functionalization of magnetic nanoparticles for medi-cal diagnosis and treatmentrdquo Dalton Transactions vol 40 no24 pp 6315ndash6343 2011

[3] L Zhang and T J Webster ldquoNanotechnology and nanomate-rials promises for improved tissue regenerationrdquo Nano Todayvol 4 no 1 pp 66ndash80 2009

[4] S Jin T H Tiefel M McCormack R A Fastnacht RRamesh and L H Chen ldquoThousandfold change in resistivityin magnetoresistive La-Ca-Mn-O filmsrdquo Science vol 264 no5157 pp 413ndash415 1994

[5] A Asamitsu YMoritomo Y Tomioka T Arima andY TokuraldquoA structural phase transition induced by an external magneticfieldrdquo Nature vol 373 no 6513 pp 407ndash409 1995

[6] Y TokuraColossalMagnetoresistive Oxides Gordon and BreachScience Singapor 2000

[7] C Zener ldquoInteraction between the d-shells in the transitionmetals II Ferromagnetic compounds of manganese with per-ovskite structurerdquo Physical Review B vol 82 no 3 pp 403ndash4051951

[8] A J Millis and P B Shramin ldquoDouble exchange alone doesnot explain the resistivity of La

1minus119909Sr119909MnO

3rdquo Physical Review

Letters vol 74 no 25 pp 5144ndash5147 1995[9] R D Sanchez J Rivas C Vazquez et al ldquoGiant magnetore-

sistance in fine particle of La067

Ca033

MnO3synthesized at low

temperaturesrdquo Applied Physics Letters vol 68 p 134 1996[10] N Zhang W Ding W Zhong D Xing and Y Du ldquoTunnel-

type giant magnetoresistance in the granular perovskiteLa085

Sr015

MnO3rdquo Physical Review B vol 56 p 8138 1997

[11] K Wang W Song T Yu B Zhao M Pu and Y Sun ldquoColos-sal magnetoresistance in fine particle of layered-perovskiteLa2minus2119909

Ca2+2119909

Mn2O7(x = 03) synthesized at low temperaturesrdquo

Physica Status Solidi A vol 171 no 2 pp 577ndash582 1999[12] A Rostamnejadi H Salamati P Kameli and H Ahmadvand

ldquoSuperparamagnetic behavior of La067

Sr033

MnO3nanoparti-

cles prepared via sol-gel methodrdquo Journal of Magnetism andMagnetic Materials vol 321 no 19 pp 3126ndash3131 2009

[13] S Daengsakul C Thomas C Mongkolkachit and S MaensirildquoEffects of crystallite size on magnetic properties of thermal-hydro decomposition prepared La


3nanocrystalline

powdersrdquo Solid State Sciences vol 14 no 9 pp 1306ndash1314 2012[14] P Kameli H Salamati and A Aezami ldquoEffect of particle size

on the structural and magnetic properties of la08Sr02MnO

3rdquo

Journal of Applied Physics vol 100 no 5 Article ID 0539142006

[15] D G Kuberkar R R Doshi P S Solanki et al ldquoGrainmorphology and size disorder effect on the transport and mag-netotransport in sol-gel grown nanostructured manganitesrdquoApplied Surface Science vol 258 no 22 pp 9041ndash9046 2012

[16] A Rostamnejadi H Salamati and P Kameli ldquoMagnetic prop-erties of interacting La

067Sr033

MnO3nanoparticlesrdquo Journal of

Superconductivity and Novel Magnetism vol 25 no 4 pp 1123ndash1132 2012

[17] J L Dormann D Fiorani and E Tronc ldquoOn the modelsfor interparticle interactions in nanoparticle assemblies com-parison with experimental resultsrdquo Journal of Magnetism andMagnetic Materials vol 202 no 1 pp 251ndash267 1999

[18] J Rodrıguez-Carvajal ldquoRecent advances in magnetic structuredetermination by neutron powder diffractionrdquo Physica B vol192 no 1-2 pp 55ndash69 1993

[19] K P Shinde S S Pawar and S H Pawar ldquoInfluence of anneal-ing temperature on morphological and magnetic properties ofLa09Sr01MnO

3rdquo Applied Surface Science vol 257 no 23 pp

9996ndash9999 2011[20] J L Dormann D Fiorani and E Tronc ldquoMagnetic relaxation

in fine-particle systemsrdquo Advances in Chemical Physics vol 98pp 283ndash494 1997

[21] M Suzuki S I Fullem I S Suzuki L Wang and C ZhongldquoObservation of superspin-glass behavior in Fe

3O4nanoparti-

clesrdquo Physical Review B vol 79 no 2 Article ID 024418 7 pages2009

[22] B Aslibeiki P Kameli I Manouchehri and H SalamatildquoStrongly interacting superspins in Fe

3O4nanoparticlesrdquo Cur-

rent Applied Physics vol 12 no 3 pp 812ndash816 2012[23] M Tadic V Kusigerski D Markovic M Panjan I Milosevic

and V Spasojevic ldquoHighly crystalline superparamagnetic ironoxide nanoparticles (SPION) in a silicamatrixrdquo Journal of Alloysand Compounds vol 525 pp 28ndash33 2012

[24] B Aslibeiki P Kameli H Salamati M Eshraghi and TTahmasebi ldquoSuperspin glass state in MnFe

2O4nanoparticlesrdquo

Journal of Magnetism and Magnetic Materials vol 322 no 19pp 2929ndash2934 2010

[25] J Mydosh ldquoDisordered magnetism and spin glassesrdquo Journal ofMagnetism and Magnetic Materials vol 157-158 pp 606ndash6101996

[26] M Thakur M Patra S Majumdar and S Giri ldquoCoexistence ofsuperparamagnetic and superspin glass behaviors in Co

50Ni50

nanoparticles embedded in the amorphous SiO2hostrdquo Journal

of Applied Physics vol 105 no 7 Article ID 073905 2009[27] D Fiorani A M Testa F Lucari F DrsquoOrazio and H Romero

ldquoMagnetic properties of maghemite nanoparticle systems sur-face anisotropy and interparticle interaction effectsrdquo Physica BCondensed Matter vol 320 no 1ndash4 pp 122ndash126 2002

[28] K Parekh and R V Upadhyay ldquoStatic and dynamic magneticproperties of monodispersed Mn

05Zn05Fe2O4nanomagnetic

particlesrdquo Journal of Applied Physics vol 107 no 5 Article ID053907 2010

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



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CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


20 30 40 50 60 70 80

134208036

220116

300024

006

110In

tens

ity (a

u)

S1

S4

S3

S2

012

2120579 (deg)

(a)In

tens

ity (a

u)

20 30 40 50 60 70 80

ExpCal

Exp-calBraggrsquos position

2120579 (deg)

(b)

Figure 1 (a) The XRD pattern of S1 S2 S3 and S4 samples at room temperature (b) The observed and calculated (Rietveld analysis) XRDpatterns of S3 sample at room temperature

and remanence and the nonachievement of saturation evenat high magnetic field are the typical characteristics of SPMbehavior [17]

In this paper we have studied the effect of annealingtemperature on the structural and magnetic properties of themicrowave-assisted sol-gel grown La

09Sr01MnO3(LSMO)

manganite samples

2 Experimental

The LSMO manganite samples were prepared by themicrowave-assisted combustion method using a domesticLG microwave oven operating at frequency of 245GHzwith the output power of 1000W Stoichiometric amounts ofLa(NO

3)3sdot6H2O(Merck 99) n(NO

3)2 sdot 4H

2O(Merck 99)

and Sr(NO3) (Merck 95)were dissolved inwater andmixed

with ethylene glycol and citric acid forming a stable solutionThe mixture was then kept in a microwave oven with 60 ofoutput power This mixture undergoes dehydration followedby decomposition and spontaneous combustion with theevolution of voluminous gases The obtained final product isin the form of a foamy powder and is calcined at 450∘C (S1)for 6 h Different packages of powder were sintered at 550∘C(S2) 575∘C (S3) and 600∘C (S4) for 6 h to obtain powderswith different particle sizes

Phase formation and crystal structure of the powderswere checked by XRD pattern using CuK120572 radiation sourcein the 2120579 scan range from 20∘ to 80∘ The average particlesizes of the samples were estimated from TEM micrographsThe ac magnetic susceptibility has been measured versustemperature at different frequencies in the selected range of33ndash1000Hz and using a Lake Shore ac susceptometer model7000 The dc magnetization was carried out as a function

of magnetic field at 295K using a Meghnatis Daghigh Kavirvibrating sample magnetometer (VSM)

3 Results and Discussion

Figure 1 shows the XRD patterns at room temperature forsamples Figure 1(a) shows that S1 sample is amorphous andits crystal structure is not formed By sintering the powderat higher temperatures 550∘C to 600∘C the perovskitecrystal structure is formed The Rietveld analyses of theXRD pattern of the samples have been carried out usingFULLPROFprogram [18] Figure 1(b) shows the XRDpatternwith Rietveld analysis of the S3 sampleThe estimated averagelattice parameters are 119886 = 119887 = 5511 A and c = 13352 Awhich are found in close agreement with reported values[19] Typically the TEM micrograph of S3 sample is shownin Figure 2 TEM micrograph shows that the mean particlesize of the S3 sample is about 50 nm Also the selected areadiffraction patterns of sample S3 confirms the crystallinenature of this sample

To study the magnetic response of samples to an externalfield wemeasured field dependentmagnetization using VSMat room temperature Figure 3 shows the room temperaturehysteresis curves of the samples sintered at different tem-peratures It can be seen that by increasing the sinteringtemperature the magnetization (119872) increases slightly Anincrease in magnetization with the sintering temperature canbe attributed mainly due to the enhancement of grain sizeThe increase of magnetization by increasing the grain sizecould be ascribed to the lower surface area of larger grainsThis is because of the magnetically disordered state in thesurface In the case of nanometric-size grains defects areexpected to occur to a higher extent due to the vacanciesmicrostrain and dislocations Since the sizes of samples











120591 = 1205910exp( 119870119881119896119861119879119861

) (1)



0is in the




119861)


0can be obtained


0sim

126 times 10


120591 = 1205910exp( 119870119881

119896119861(119879119861minus 1198790)

) (2)




0≪ 119879119861 In our work 119879

0is 199K while the




1198881= (

Δ119879119891

119879119891Δ (log

10119891)

)

1198882= (

119879119891minus 1198790

119879119891

)

(3)




119891= 119879119891(119891 = 1000Hz) minus 119879

119891










1lt 013



2lt 06 and


1lt 002 and 007 lt 119888

2lt 03 [17] Both



2for our






0 5000 10000

0

2

4 S2


minus2

minus4

M(e

mu

gr)

H (Oe)

(a)

S3

0 5000 10000minus10000 minus5000

0

2

4

minus2

minus4

M(e

mu

gr)

H (Oe)

(b)

S4

0 5000 10000minus10000 minus5000

0

2

4

minus2

minus4

M(e

mu

gr)

H (Oe)

(c)


50 100 150 200 250 300

015

030

045

060

07533Hz

1000Hz

times10minus3

X998400

(cumiddot

mk

g)

T (K)

(a)

50 100 150 200 250 300

0000

0005

0010

0015

33Hz

1000Hz

times10minus3

X998400

(cumiddot

mk

g)

T (K)

(b)



30

35

40

45

50

55

60

65

70

000486 000489 000492 000495 0004981TB (Kminus1)

Ln(f

)


30

35

40

45

50

55

60

65

70

010 015 020 025 030 035 040 045 0501(TB minus T0) (Kminus1)

Ln(f

)



120591 = 1205910(

119879119891

119879119892

minus 1)

minus119911120592

(4)


119892is the glass-




1198911198790minus 1)




2

3

4

5

6

7

8



Ln(f

)









4 Conclusions





Acknowledgment



References













Ca033




Sr015



Ca2+2119909




Sr033

MnO3nanoparti-




3nanocrystalline



3rdquo




067Sr033










3O4nanoparti-











50Ni50














CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials













120591 = 1205910exp( 119870119881119896119861119879119861

) (1)



0is in the




119861)


0can be obtained


0sim

126 times 10


120591 = 1205910exp( 119870119881

119896119861(119879119861minus 1198790)

) (2)




0≪ 119879119861 In our work 119879

0is 199K while the




1198881= (

Δ119879119891

119879119891Δ (log

10119891)

)

1198882= (

119879119891minus 1198790

119879119891

)

(3)




119891= 119879119891(119891 = 1000Hz) minus 119879

119891










1lt 013



2lt 06 and


1lt 002 and 007 lt 119888

2lt 03 [17] Both



2for our






0 5000 10000

0

2

4 S2


minus2

minus4

M(e

mu

gr)

H (Oe)

(a)

S3

0 5000 10000minus10000 minus5000

0

2

4

minus2

minus4

M(e

mu

gr)

H (Oe)

(b)

S4

0 5000 10000minus10000 minus5000

0

2

4

minus2

minus4

M(e

mu

gr)

H (Oe)

(c)


50 100 150 200 250 300

015

030

045

060

07533Hz

1000Hz

times10minus3

X998400

(cumiddot

mk

g)

T (K)

(a)

50 100 150 200 250 300

0000

0005

0010

0015

33Hz

1000Hz

times10minus3

X998400

(cumiddot

mk

g)

T (K)

(b)



30

35

40

45

50

55

60

65

70

000486 000489 000492 000495 0004981TB (Kminus1)

Ln(f

)


30

35

40

45

50

55

60

65

70

010 015 020 025 030 035 040 045 0501(TB minus T0) (Kminus1)

Ln(f

)



120591 = 1205910(

119879119891

119879119892

minus 1)

minus119911120592

(4)


119892is the glass-




1198911198790minus 1)




2

3

4

5

6

7

8



Ln(f

)









4 Conclusions





Acknowledgment



References













Ca033




Sr015



Ca2+2119909




Sr033

MnO3nanoparti-




3nanocrystalline



3rdquo




067Sr033










3O4nanoparti-











50Ni50














CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




0 5000 10000

0

2

4 S2


minus2

minus4

M(e

mu

gr)

H (Oe)

(a)

S3

0 5000 10000minus10000 minus5000

0

2

4

minus2

minus4

M(e

mu

gr)

H (Oe)

(b)

S4

0 5000 10000minus10000 minus5000

0

2

4

minus2

minus4

M(e

mu

gr)

H (Oe)

(c)


50 100 150 200 250 300

015

030

045

060

07533Hz

1000Hz

times10minus3

X998400

(cumiddot

mk

g)

T (K)

(a)

50 100 150 200 250 300

0000

0005

0010

0015

33Hz

1000Hz

times10minus3

X998400

(cumiddot

mk

g)

T (K)

(b)



30

35

40

45

50

55

60

65

70

000486 000489 000492 000495 0004981TB (Kminus1)

Ln(f

)


30

35

40

45

50

55

60

65

70

010 015 020 025 030 035 040 045 0501(TB minus T0) (Kminus1)

Ln(f

)



120591 = 1205910(

119879119891

119879119892

minus 1)

minus119911120592

(4)


119892is the glass-




1198911198790minus 1)




2

3

4

5

6

7

8



Ln(f

)









4 Conclusions





Acknowledgment



References













Ca033




Sr015



Ca2+2119909




Sr033

MnO3nanoparti-




3nanocrystalline



3rdquo




067Sr033










3O4nanoparti-











50Ni50














CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




30

35

40

45

50

55

60

65

70

000486 000489 000492 000495 0004981TB (Kminus1)

Ln(f

)


30

35

40

45

50

55

60

65

70

010 015 020 025 030 035 040 045 0501(TB minus T0) (Kminus1)

Ln(f

)



120591 = 1205910(

119879119891

119879119892

minus 1)

minus119911120592

(4)


119892is the glass-




1198911198790minus 1)




2

3

4

5

6

7

8



Ln(f

)









4 Conclusions





Acknowledgment



References













Ca033




Sr015



Ca2+2119909




Sr033

MnO3nanoparti-




3nanocrystalline



3rdquo




067Sr033










3O4nanoparti-











50Ni50














CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




References













Ca033




Sr015



Ca2+2119909




Sr033

MnO3nanoparti-




3nanocrystalline



3rdquo




067Sr033










3O4nanoparti-











50Ni50














CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



research article structural and magnetic properties of

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