research article synthesis, electrical conductivity,...

Hindawi Publishing CorporationInternational Journal of Polymer ScienceVolume 2013 Article ID 307525 7 pageshttpdxdoiorg1011552013307525

Research ArticleSynthesis Electrical Conductivity and Dielectric Behavior ofPolyanilineV2O5 Composites

Shama Islam1 G B V S Lakshmi2 Azher M Siddiqui1 M Husain1 and M Zulfequar1

1 Department of Physics Jamia Millia Islamia New Delhi 110025 India2Material Science Group Inter University Accelerator Centre New Delhi 110025 India

Correspondence should be addressed to M Zulfequar mzulferediffmailcom

Received 31 March 2013 Accepted 12 June 2013

Academic Editor Enrique Vigueras-Santiago

Copyright copy 2013 Shama Islam et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Conducting polymer composites of polyanilinevanadium pentaoxide PANIV2O5(with different initial weight percentage of

V2O5) has been synthesized by in situ polymerization method DC conductivity of compressed pellets has been analyzed in the

temperature range 300ndash550K and was found to increase with V2O5doping This increase in conductivity is mainly due to band

conduction It has also been observed that the dielectric constant and dielectric loss increase with the level of doping of V2O5but

remain independent of the frequency (50KHzndash1MHz) X-ray diffraction pattern shows some order of crystallinity of compositesdue to interaction of polyaniline with V

2O5 UV-visible spectroscopy shows an increase in the optical band gap with doping

1 Introduction

The conducting polymers have emerged as a new class ofmaterials because of their unique electrical optical andchemical properties By proper doping the conductivityof these materials can be varied from semiconducting tometallic regime which offers new concept of charge transportmechanism Among different conducting polymers conduc-tive polyaniline (PANI) has been studied extensively becauseof its ease of synthesis in aqueous media its environmentalstability special electrical and other properties PANI andits derivatives have received much attention because of theirvarious technological applications reversible proton dopinghigh electrical conductivity and ease of bulk synthesis PANIis also a suitable candidate for a variety of technologicalapplications such as solar cells electromagnetic shieldingelectrodes for rechargeable batteries and sensors [1ndash11]

Many authors have studied the progress of chemical poly-merization and doping of aniline and its derivatives Theeffort was to correlate mechanisms of oxidation of anilinesand properties of PANI such as electrical conductivitymolec-ular weight and crystallinity However when they were takenin the composite form their electrical as well as dielectricproperties alter from those of basic materials A number of

groups had reported on the electrical conductivity and dielec-tric properties of composites of a variety of conducting poly-mers [12ndash15] Recently heterogeneous conducting polymercomposites especially organic-inorganic composites becamethe subject of extensive study Among the basematerials usedpolyaniline (PANI) is one of the most extensively studiedconducting polymer Ever since its discovery in a pioneeringwork by Mc Diarmid et al [16ndash21] The DC conductivityof a conjugated polymer depends on the doping level andfor a given dopant in a particular polymer the conductivityincreases up to a certain level and then saturates

The vanadium oxygen system (V2O5and VO

2) has been

widely studied because the system shows metal semicon-ductor transitions which imply an abrupt change in theiroptical and electrical properties For example VO

2exhibits

a change in electrical resistivity in the order of 105Ω cm overa temperature change of 01 at 68∘C in a single crystal Thisoxide is therefore used in thermal sensing and switchingSimilarly V

2O5has been a subject of several theoretical and

applied studies due to its industrial importance for manytechnological applications such as heterogeneous catalystV2O5also plays the role of active electrode in a rechargeable

lithium battery High electrochemical activity high stabilityand ease of thin film formation by numerous deposition

2 International Journal of Polymer Science

techniques led to its use as a highly promising intercalationmaterial in solid statemicrobattery applications It is themoststable oxide in the VndashO system with an energy gap of sim22 eVand shows a semiconductor-metal transition at about 250∘C[22ndash26]

In the present study composites of PANIV2O5have

been synthesized by in situ polymerization of aniline usingammonium persulphate ((NH

4) S2O8) as oxidizing agent in

the presence of V2O5 The V

2O5concentrations were varied

from0 to 40weightThe composites obtained have differentconcentrations of V

2O5

In present work electrical conductivity by two-probemethod and dielectric behavior by LCR methods of thesesynthesized composites have been studied X-ray diffraction(XRD) and UV-visible absorption spectroscopy have beencarried out to characterize these samples

2 Experimental

All chemicals used were of analytical reagent (AR) gradeThe monomer aniline was doubly distilled prior to useAmmonium persulphate ((NH

4) S2O8) hydrochloric acid

(HCl) and vanadium pentoxide V2O5were used as received

in the present studyPolyaniline has been synthesized by in situ oxidative poly-

merization of aniline hydrochloric acid (HCl) and ammo-nium persulphate ((NH

4) S2O8) as oxidant The oxidant

monomer ratio is 1 125 Aniline (125M) has been dissolvedin 10mL of HCl (1M) taken in 200mL round bottom flaskand stirred well Further finely ground V

2O5powder taken

in different (20 30 and 40) wt with respect to anilineconcentration has been added to the previous mixture undervigorous stirring in order to keep V

2O5powder suspended

in solution The reaction mixture has been cooled up to 5∘Cand the precooled solution of ammoniumpersulfate (1M) hasbeen slowly added drop by drop over a period of 30minThereaction has been allowed to proceed for 6ndash8 h The mixturewas further cooled down to 4∘C for 24ndash36 hours It was thenfiltered and washed with ammonia until filtrate was colorlessThe dark colored polymer powder so obtained was driedthoroughly in an oven at 100∘C until constant weight wasattained then grinded and sieved PANI has been synthesizedin the same manner in the absence of V

2O5

TheDC conductivity of pure PANI and PANIV2O5com-

posites wasmeasured by using two-probemethod in the tem-perature range 300ndash550KThe powder was made into pelletsof 1 cm diameter and different thickness for PANIV

2O5

composites The bulk DC conductivity was measured bymounting between two steel electrodes inside a speciallydesigned metallic sample holder [22] The temperature wasmeasured with a calibrated copper-constantan thermocouplemounted near the electrodes The samples were annealedat a temperature of 100∘C to avoid any effect of moistureabsorption These measurements were made at a pressureof about 10minus3 Torr A stabilized voltage of 15 V was appliedacross the sample and the resultant current was measuredwith a picoammeter

In order to get information about the crystallinity X-ray diffraction patterns of all samples are recorded at roomtemperature by using a Panalytical (PW 3710) X-ray powderdiffractometer with Cu K120572 radiation All the samples werescanned in angular range of 0ndash90∘ with scan speed of 001∘sunder the similar conditions UV-visible spectroscopy hasbeen carried out using Camspec M550 double beam UV-visible spectrophotometer [22ndash26]

3 Results and Discussion

31 Temperature DC Conductivity Studies The variation ofDC conductivity with temperature for pure PANI and thePANIV

2O5composites (with different wt) is shown in

Figure 1 Arrhenius plot of DC conductivity shows straightline behavior The DC conductivity of pure PANI increasedexponentially with doping exhibiting semiconductor charac-teristicsThe conductivity as a function of temperature can berepresented by the relation [27]

120590DC = 1205900exp (minusΔ119864

119896119879) (1)

where (ΔE) is the activation energy for the DC conductionmechanism ldquo119896rdquo is the Boltzmann constant and ldquo120590

0rdquo is the

preexponential factor The activation energy (Δ119864) has beencalculated from the slope of Figure 1 for pure PANI andthe PANIV

2O5 The DC conductivity of undoped PANI

is measured to be 358 times 10minus9 Scm After doping withdifferent weight of V

2O5the conductivity was found to

change from 10minus7 to 10minus9 Scm attaining a maximum valueat 30 weight of V

2O5and then reduced at 40 weight

of V2O5 The doping of conducting polymers implies

charge transfer the associated insertion of a counter ionand the simultaneous control of Fermi level or chemicalpotential Through doping electronic and optical propertiesof conducting polymers can be controlled over a long rangeThe electrical conductivity of conducting polymers resultsfrommobile charge carriers introduced into the 120587-electronicsystem through doping At low doping levels these chargecarriers are self-localized and form nonlinear configurationsBecause of large interchain transfer integrals the transportof charge is believed to be principally along the conjugatedchains with interchain hopping as a necessary secondarycondition [28ndash31] When the polymer is heavily doped (40weight ) the wave functions are delocalized over manylattice constants along the polymer chain In PANI sincethere are nearly degenerate ground states the dominatingcharge carriers are polarons and bipolarons [32] WhenPANI is doped with V

2O5hydrochloric acid the charge

carriers form nonlinear configurations and as a result theconductivity does not change substantially The nonlinearformation may be more in the case of heavy doping of 40weight of V

2O5 due to which it exhibits lesser conductivity

than 30 weight doped polymerThe activation energy ΔE DC conductivity 120590DC and

preexponential factor 1205900of pure PANI and PANIV

2O5

composites have been measured and tabulated in Table 1

International Journal of Polymer Science 3

22 24 26 28 30 32 34minus220

minus215

minus210

minus205

minus200

minus195

minus190

20 21 22 23 24 25 26minus180minus175minus170minus165minus160minus155minus150minus145minus140minus135

15 20 25 30 35minus16

minus15

minus14

minus13

minus12

minus11

minus10

150 155 160 165 170 175 180 185 190 195minus19

minus18

minus17

minus16

minus15

minus14

Pure PANI Initial 20 weight

Initial 30 weight Initial 40 weight

1000T (Kminus1)1000T (Kminus1)

1000T (Kminus1) 1000T (Kminus1)

ln 120590 d

c(o

hmminus1cm

minus1)

ln 120590 d

c(o

hmminus1cm

minus1)

ln 120590 d

c(o

hmminus1cm

minus1)

ln 120590 d

c(o

hmminus1cm

minus1)

Figure 1 Temperature dependence of DC conductivity in the temperature range (300ndash550K) for pure PANI and PANIV2O5composites

(different weight )

Table 1 Electrical and dielectric parameters of pure PANI and PANIV2O5 composite (different weight )

Sample 120590dc (Ωminus1 cmminus1) Δ119864 (eV) 120590

0(Ωminus1 cmminus1)

119879 = 302K and 119891 = 850KHz1205761015840

12057610158401015840

PANI 358 times 10minus9 022 299 times 10

minus6 759 17343PANIV2O5 20wt 620 times 10

minus8 061 200 times 10minus1 835 315835

PANIV2O5 30wt 248 times 10minus6 017 110 times 10



32 Dielectric Parameters as a Function of Frequency andTemperature Dielectric parameters as a function of fre-quency and temperature are calculated using the values of theequivalent parallel capacitance 119862

119875 dissipation factor119863 and

parallel equivalent resistance 119877119875 recorded by the LCRmeter

(Model Wayne Kerr) at selected frequencies range Tempera-ture dependence of the dielectric constant (1205761015840) and dielectricloss (12057610158401015840) is studied for PANI and PANIV

2O5composites in

the different range of temperature (300ndash320K) and frequencyrange from 50 kHz to 1MHz Dielectric parameters have beencalculated using the following equations

1205761015840=119862119875

1198620

12057610158401015840=

1205761015840

120596119862119875119877119875

= 1205761015840119863

(2)

where 1198620= (008854At) pf is the geometrical capacitance of

vacuum of the same dimensions as that of the sampleA and 119905are the area and thickness of the sample respectively119862

119875is the

capacitance measured in pf 120596 = 2120587119891 and 119863 = tan 120575 with 120575being the phase angle The 1205761015840 and 12057610158401015840 are respectively the realand imaginary parts of the complex dielectric constant 120576(119891)which are represented by the relation

120576 (119891) = 1205761015840(119891) minus 119894120576

10158401015840(119891) (3)

Thedielectric constant of amaterial consists of ionic elec-tronic and dipolar polarizations Temperature dependence ofthe dielectric constant (1205761015840) and dielectric loss (12057610158401015840) is shownin Figures 2 and 3 It is clear that dielectric constant (1205761015840)and dielectric loss (12057610158401015840) remain constant with temperaturefor pure PANI and 20 weight of PANIV

2O5 whereas a

slightly increase is observed in (1205761015840) for 30 and 40 dopedsamples and (12057610158401015840) slightly increases for 40 weight Figures4 and 5 show variation of dielectric constant and dielectricloss as a function of frequency for pure polyaniline andV2O5composite (different wt) The results show constant

behavior with frequency their value increases with dopingof V2O5(different wt) At 850KHz the dielectric constant

for the composite samples with 40 weight of oxide is about


300 302 304 306 308 310 312 314 316 318 3200

50

100

150

200

250

300

350

PANIInitial 20 weight

Initial 30 weightInitial 40 weight

Temperature (K)

f = 850kHz

120576998400

Figure 2 Dielectric constant (1205761015840) versus temperature at fixed fre-quency for pure polyaniline and PANIV

2O5composites (different

weight )

300 302 304 306 308 310 312 314 316 318 3200

200

400

600

800

Temperature (K)



f = 850kHz

120576998400998400

times10minus2

Figure 3 Dielectric loss (12057610158401015840) versus temperature at fixed frequencyfor pure polyaniline and PANIV

2O5composites (different weight

)

24234 This value decreases to about 835 for the compositesamples having 20 weight of oxide On the other handthe value of the dielectric constant for pure PANI at thisfrequency is about 759 The corresponding dielectric loss forthe composite samples with 40 weight of oxide is about8568281 at 850KHz frequency The value decreases to about315835 for the composite with 20weightof oxide Similarlythe value of dielectric loss for pure PANI is about 17343 atsame frequency Similar trend in the dielectric behaviour ofPPyFe

3O4composites has been reported [33 34] Higher

dielectric constant and dielectric loss observed with highdoping of oxide

The dielectric loss consists of two contributions one fromthe dielectric polarization processes and the other from DCconduction To study the origin of the dielectric loss in theoperating temperature range the DC conduction loss wascalculated using the relation

12057610158401015840

DC =120590DC1205760120596 (4)

000

50

100

150

200

250

Frequency (Hz)



2000 k 4000 k 6000 k 8000 k 10 M

T = 425K

120576998400

Figure 4 Dielectric constant (1205761015840) versus frequency at fixed tem-perature (302K) for pure polyaniline and PANIV

2O5composites

(different weight )

The DC conduction loss is small compared to the observeddielectric loss (12057610158401015840) It can also be noted that the DC con-duction loss increases with increasing dopantrsquos concentrationdue to the increase of polarons and bipolarons Variousother workers have also observed such type of behavior[35 36] Polaron formation depends upon the viscosity ofthe medium The theories based on charged defect centersserve as basis for understanding the dielectric response andconduction mechanisms of such materials In the correlatedbarrier hoppingmodel of Elliott (CBH) [37 38] two electronsare assumed to transfer between charged defect sites (119863+ and119863minus) by hopping over a potential barrier separating them

The maximum value of the potential barrier separating thecharged defect sites (119882

119898) can be approximately equated to the

band gap of the material Based on the same model of Elliott[38] the slope obtained from Figure 6 can be written as

(119898) =minus4119896119879

119882119898

(5)

where119898 is defined here as 119904 minus 1 and119898 is in line with 119879 As anoutcome of CBH model the value of 119904 decreases from unitywith increasing temperature and 119904 is a band gap-dependentproperty [39 40] The values of 119898 are calculated from theslopes of these straight lines in Figure 6 The values of 119898are negative and the magnitude of119898 decreases linearly withincreasing weight of V

2O5 Thus these results indicate

that the observed dielectric dispersion is recognized mainlyto dipolar type dispersion in the present study The DCconduction loss and numerical value of power (119898) are givenin Table 2

33 Powder X-Ray Diffraction Analysis XRD patterns of allthe four samples pure PANI PANIV

2O5composites (with

different weight ) show similar structure of amorphousnature in Figure 7 In undoped powder an intense hump near19∘ndash24∘ is found which is shifted towards lower angle side at14ndash18∘ in doped samples There are other three small peaksappearing in 20weight V

2O5doped samples near 15∘ (200)

20∘ (001) and at 26∘ (110) which conform the concentration


0100200300400500600700800900



T = 425K

00 2000 k 4000 k 6000 k 8000 k 10 MFrequency (Hz)

120576998400998400

times10minus2

Figure 5 Dielectric loss (12057610158401015840) versus frequency at fixed temperature(302K) for pure PANI and PANIV


)

125 130 135 140 145 150 155 160minus11minus10minus9minus8minus7minus6minus5minus4minus3



ln(120596) (kHz)

ln(120576

998400998400)

Figure 6 ln(12057610158401015840) versus ln(120596) at fixed temperature for pure PANIand PANIV

2O5(different wt)

Table 2 Temperature dependence of slope (119898) and DC conductionloss of pure PANI and PANIV2O5 composites (different weight )

Sample 12057610158401015840

dc (119898) Indirect bandgap 119864

119892(eV)

PANI 29 times 10minus3

minus02 322PANIV2O5 20wt 15 times 10

minus3minus003 327

PANIV2O5 30wt 128 minus0009 331PANIV2O5 40wt 48 times 10

minus3minus00034 332

of V2O5in the compositesThese peaks continued to be up to

40 weight doped samplesThus V2O5dopant is interacting

well with PANI this explains the continuous increase in theconductivity as well as crystallinity of composites Sharpnessof the peaks also shows increase in the crystallinity ofcomposites [41 42]

34 Optical Properties The optical parameters of the purePANI and PANIV

2O5composites have been calculated by

0 10 20 30 40 50 60 70 80

PANI

Cou

nts

s

Initial 20 weight

Initial 40 weight

Initial 30 weight

2120579 (deg)

Figure 7 XRD of pure PANI and PANIV2O5composites (different

weight )

using the UV-spectrophotometer (190ndash1100 nm) In amor-phous materials the optical band gap between the valenceband and the conduction band [43] is given by

120572ℎ] = 119861(ℎ] minus 119864119892)119898

(6)

where ldquo119864119892rdquo is the optical band gap and ldquo119861rdquo is band tailing

parameter related constant At the fundamental edge ofamorphous materials two types of optical transitions cantake place In both types of optical transitions the photoninteracts with the electron in the valence band and raises itto the conduction band There is no interaction with latticein the direct transition and the photon interacts with latticein indirect transition In the given equation ldquo119898rdquo decides thetransition for119898 = 12 the transition is direct allowed119898 = 2

for indirect allowed transition119898 = 3 for indirect forbiddenand 119898 = 32 for direct forbidden band gap After applyingall values of 119898 the composites 119898 = 2 (indirect transition)is found most suitable to calculate band gap Extinctioncoefficient (119870) is calculated by using the relation [44]

119870 =120572120582

4120587 (7)

where ldquo120572rdquo is the absorption coefficient and ldquo120582rdquo is thewavelength of photonThe extinction coefficient is a measureof fractional loss due to absorption and scattering per unitdistance of the medium participating [45ndash47] Figure 8 givesthe (120572ℎ])12 dependence on energy for composites Theintercept of slope on 119909-axis gives the value of optical bandgap The optical band gap measured for pure PANI andPANIV

2O5is given inTable 2which is found to increasewith

the increase of the concentration of V2O5 Due to the increase

in the band gap with V2O5concentration the disorderliness

reduces and defect state density decreases With the additionof V2O5 the unsaturated defects decrease in composites and

a number of saturated bonds are produced The density oflocalized states decreases with the reduction in the numberof unsaturated defects According to the Davis and Mott


310 315 320 325 330 335 340 345 350

60

80

100

120

140

160

180

200

h (eV)

Pure PANIPANIV2O5 initial 20 weight

PANIV2O5 initial 30 weightPANIV2O5 initial 40 weight

(120572h)

12

(cm

minus1eV

)12

Figure 8 (120572ℎ])12 versus photon energy of pure PANI andPANIV

2O5composites (different weight )

model [48] of density of states the width of the localizedstates near the mobility edge depends on defects and degreeof disorder present in amorphous structure It is known thatwith saturated bonds some unsaturated bonds are producedas a result of some insufficient numbers of atoms depositedin the amorphous materials The high concentration of theselocalized states is responsible for the low value of opticalband gap The addition of V

2O5in the PANI decreases the

unsaturated defects producing a number of saturated bondsThis reduction in the unsaturated bonds or defects decreasesthe density of localized states in band structure increasing theoptical band gap

4 Conclusion

A series of PANIV2O5composites have been prepared by in

situ polymerizationwith different weight percentage of V2O5

XRD study reveals the encapsulation of oxide particles bypolymer and some degree of crystallinityTheDC conductiv-ity of polyaniline and PANIV

2O5composites together with

the dielectric constant and dielectric loss measurements havebeen determined from the measured values of capacitancein the frequency range from 50KHz to 1MHz and in thetemperature range of 300ndash550K The conductivity measuredis in the range 10minus7ndash10minus9 Scm at a temperature 302K Theconductivity increasedwith doping aswell as the crystallinityincreased when compared to undoped sample This increasein conductivity of composites at dielectric constant anddielectric loss results indicates that the observed dielectricdispersion is recognized mainly to dipolar type dispersionin the present study and shows independent behavior offrequency Indirect transition (119898 = 2) is found most suitableto calculate band gap The optical band gap (119864

119892) increases

as the concentration of V2O5increases it shows that the

disorderliness reduces and defect state density decreasesDielectric behavior is possible for application in conductivepaints rechargeable batteries sensors MOS devices and soforth

References

[1] J Aguilar-Hernandez and K Potje-Kamloth ldquoEvaluation ofthe electrical conductivity of polypyrrole polymer compositesrdquoJournal of Physics D Applied Physics vol 34 no 11 pp 1700ndash1711 2001

[2] A Dey A De and S K De ldquoElectrical transport and dielectricrelaxation in Fe

3O4-polypyrrole hybrid nanocompositesrdquo Jour-

nal of Physics Condensed Matter vol 17 no 37 pp 5895ndash59102005

[3] C J Mathai S Saravanan M R Anantharaman S Venkitacha-lam and S Jayalekshmi ldquoCharacterization of low dielectricconstant polyaniline thin film synthesized by ac plasma poly-merization techniquerdquo Journal of Physics D Applied Physics vol35 no 3 pp 240ndash245 2002

[4] T K Vishnuvardhan V R Kulkarni C Basavaraja and S CRaghavendra ldquoSynthesis characterization and ac conductivityof polypyrroleY

2O3compositesrdquo Bulletin of Materials Science

vol 29 no 1 pp 77ndash83 2006[5] W Chen L Xingwei X Gi W Zhaoquang and Z Wenquing

ldquoMagnetic and conducting particles preparation of polypyrrolelayer on Fe

3O4nanospheresrdquo Applied Surface Science vol 218

no 1ndash4 pp 216ndash222 2003[6] S D Patil S C Raghavendra M Revansiddappa P Narsimha

and M V N A Prasad ldquoSynthesis transport and dielectricproperties of polyanilineCo

3O4compositesrdquo Bulletin of Mate-

rials Science vol 30 no 2 pp 89ndash92 2007[7] C Li and G Shi ldquoSynthesis and electrochemical applications

of the composites of conducting polymers and chemicallyconverted graphenerdquo Electrochimica Acta vol 56 no 28 pp10737ndash10747 2011

[8] Y Chen C Xu and Y Wang ldquoViscoelasticity behaviors oflightly cured natural rubberzinc dimethacrylate compositesrdquoPolymer Composites vol 33 pp 1206ndash1214 2012

[9] T Matsunaga H Daifuku T Nakajima and T Gawa-goeldquoDevelopment of polyaniline-lithium secondary batteryrdquo Poly-mers for Advanced Technologies vol 1 no 1 pp 33ndash39 1990

[10] G Gustafsson Y Cao G M Treacy F Klavetter N Colaneriand A J Heeger ldquoFlexible light-emitting diodes made fromsoluble conducting polymersrdquo Nature vol 357 no 6378 pp477ndash479 1992

[11] A Olcani M Abe M Ezoe T Doi T Miyata and A MiyakeldquoSynthesis and properties of high-molecular-weight solublepolyaniline and its application to the 4MB-capacity bariumferrite floppy diskrsquos antistatic coatingrdquo Synthetic Metals vol 57p 3969 1993

[12] J Yang J Hou W Zhu M Xu and M Wan ldquoSubstitutedpolyaniline-polypropylene film composites preparation andpropertiesrdquo Synthetic Metals vol 80 no 3 pp 283ndash289 1996

[13] C O Yoon M Reghu D Moses Y Cao and A J HeegerldquoTransports in blends of conducting polymersrdquo Synthetic Met-als vol 69 no 1-3 pp 255ndash258 1995

[14] R Murugesan and E Subramanian ldquoCharge dynamics inconducting polyaniline-metal oxalate compositesrdquo Bulletin ofMaterials Science vol 26 no 6 pp 529ndash535 2003

[15] C Brosseau P Queffelec and P Talbot ldquoMicrowave characteri-zation of filled polymersrdquo Journal of Applied Physics vol 89 no8 article 4532 2001

[16] A G Mac Diarmid J C Chiang M Halpern et al ldquoldquoPolyani-linerdquo interconversion of metallic and insulating formsrdquo Molec-ular Crystals and Liquid Crystals vol 121 no 1ndash4 pp 173ndash1801985


[17] S P Armes and J F Miller ldquoOptimum reaction conditions forthe polymerization of aniline in aqueous solution by ammo-nium persulphaterdquo Synthetic Metals vol 22 no 4 pp 385ndash3931988

[18] M LGautu andP J G Romero ldquoSynthesis and characterizationof intercalate phases in the organic-inorganic polyanilineV

2O5

systemrdquo Journal of Solid State Chemistry vol 147 no 2 pp 601ndash608 1999

[19] W Jia E Segal D Kornemandel Y Lamhot M Narkis and ASiegmann ldquoPolyaniline-DBSAorganophilic clay nanocompos-ites synthesis and characterizationrdquo Synthetic Metals vol 128no 1 pp 115ndash120 2002

[20] S J Su and N Kuramoto ldquoProcessable polyaniline-titaniumdioxide nanocomposites effect of titanium dioxide on theconductivityrdquo Synthetic Metals vol 114 no 2 pp 147ndash153 2000

[21] S Wang Z Tan Y Li L Sun and T Zhang ldquoSynthesischaracterization and thermal analysis of polyanilineZrO

2com-

positesrdquoThermochimica Acta vol 441 no 2 pp 191ndash194 2006[22] M A M Khan M Zulfequar A Kumar and M Husain

ldquoConduction mechanism in amorphous Se75In25-xPb x filmsrdquoMaterials Chemistry and Physics vol 87 no 1 pp 179ndash183 2004

[23] G T Kim JMuster V Krstic et al ldquoField-effect transistormadeof individual V

2O5nanofibersrdquo Applied Physics Letters vol 76

no 14 pp 1875ndash1877 2000[24] Q H Wu A Thissen W Jaegermann and M Liu ldquoPhotoelec-

tron spectroscopy study of oxygen vacancy on vanadium oxidessurfacerdquo Applied Surface Science vol 236 no 1ndash4 pp 473ndash4782004

[25] C V Ramana R J Smith O M Hussain C C Chusuei and CM Julien ldquoCorrelation between growth conditionsmicrostruc-ture and optical properties in pulsed-laser-depositedV

2O5thin

filmsrdquo Chemistry of Materials vol 17 no 5 pp 1213ndash1219 2005[26] G B V S Lakshmi V Ali A M Siddiqui P K Kulriya andM

Zulfequar ldquoOptical studies of SHI Irradiated poly(o-toluidine)-PVC blendsrdquo The European Physical JournalmdashApplied Physicsvol 39 no 3 pp 251ndash255 2007

[27] Z H Khani M M Malik M Zulfequar and M HusainldquoElectrical conduction mechanism in a-Se

80minus119909Te119909Ga20

films(0ltor=xltor=20)rdquo Journal of Physics Condensed Matter vol 7no 47 pp 8979ndash8991 1995

[28] P M Grant and I P Batra ldquoBand structure of polyacetylene(CH)xrdquo Solid State Communications vol 29 no 3 pp 225ndash2291979

[29] J Fink and G Leising ldquoMomentum-dependent dielectric func-tions of oriented trans-polyacetylenerdquo Physical Review B vol34 no 8 pp 5320ndash5328 1986

[30] P Dutta S Biswas M Ghosh S K De and S Chatterjee ldquoThedc and ac conductivity of polyaniline-polyvinyl alcohol blendsrdquoSynthetic Metals vol 122 no 2 pp 455ndash461 2001

[31] S De A Dey and S K Dea ldquoCharge transport mechanism ofvanadium pentoxide xerogel-polyaniline nanocompositerdquo TheEuropean Physical Journal vol 46 pp 355ndash361 2005

[32] A J Heeger S Kivelson J R Schrieffer andW-P Su ldquoSolitonsin conducting polymersrdquoReviews ofModern Physics vol 60 no3 pp 781ndash850 1988




[34] N NMallikarjuna S KManohar P V Kulkarni A Venkatara-man and T M Aminabhavi ldquoNovel high dielectric con-stant nanocomposites of polyaniline dispersed with 120574-Fe

2O3

nanoparticlesrdquo Journal of Applied Polymer Science vol 97 no5 pp 1868ndash1874 2005

[35] R Singh R P Tandon V S Panwar and S Chandra ldquoLow-frequency ac conduction in lightly doped polypyrrole filmsrdquoJournal of Applied Physics vol 69 no 4 pp 2504ndash2511 1991

[36] N Musahwar M A Majeed Khan M Husain and M Zulfe-quar ldquoDielectric and electrical properties of Se-S glassy alloysrdquoPhysica B Condensed Matter vol 396 no 1-2 pp 81ndash86 2007

[37] S R Elliott ldquoA theory of ac conduction in chalcogenideglassesrdquo Philosophical Magazine vol 36 no 6 pp 1291ndash13041977

[38] S R Elliott ldquoTemperature dependence of ac conductivity ofchalcogenide glassesrdquoPhilosophicalMagazine B vol 37 pp 553ndash560 1978

[39] J C Giuntini J V Zanchetta D Jullien R Eholie and PHouenou ldquoTemperature dependence of dielectric losses inchalcogenide glassesrdquo Journal of Non-Crystalline Solids vol 45no 1 pp 57ndash62 1981

[40] W K Lee J F Liu and A S Nowick ldquoLimiting behavior of acconductivity in ionically conducting crystals and glasses a newuniversalityrdquo Physical Review Letters vol 67 no 12 pp 1559ndash1561 1991

[41] H K Chaudhari and D S Kekler ldquoX-ray diffraction study ofdoped polyanilinerdquo Journal of Applied Polymer Science vol 62no 1 pp 15ndash18 1996

[42] B P Barbero and L E Cadus ldquoV2O5-SmVO

4mechanical mix-

ture oxidative dehydrogenation of propanerdquo Applied CatalysisA General vol 237 no 1-2 pp 263ndash273 2002

[43] J I PankoveOptical processes in Semiconductors Prentice-HallEnglewood Cliffs NJ USA 1971

[44] A Abdel-Aal ldquoDielectric relaxation in Cd119909InSe9minus119909

chalco-genide thin filmsrdquo Egyptian Journal of Solids vol 29 p 2932006

[45] G D Cody C R Wronski B Abeles R B Stephens and BBrooks ldquoOptical characterization of amorphous silicon hydridefilmsrdquo Solar Cells vol 2 no 3 pp 227ndash243 1980

[46] J Tauc Amorphous and Liquid Semiconductors Plenum PressNewYork NY USA 1974

[47] E Marquez J Ramirez-Malo P Villares R Jimenez-GarayP J S Ewen and A E Owen ldquoCalculation of the thicknessand optical constants of amorphous arsenic sulphide filmsfrom their transmission spectrardquo Journal of Physics D AppliedPhysics vol 25 no 3 pp 535ndash541 1992

[48] N F Mott and E A Davis Electronics Processes in Non-Crystalline Materials Clarendon Oxford UK 1979

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


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


techniques led to its use as a highly promising intercalationmaterial in solid statemicrobattery applications It is themoststable oxide in the VndashO system with an energy gap of sim22 eVand shows a semiconductor-metal transition at about 250∘C[22ndash26]

In the present study composites of PANIV2O5have

been synthesized by in situ polymerization of aniline usingammonium persulphate ((NH

4) S2O8) as oxidizing agent in

the presence of V2O5 The V

2O5concentrations were varied

from0 to 40weightThe composites obtained have differentconcentrations of V

2O5

In present work electrical conductivity by two-probemethod and dielectric behavior by LCR methods of thesesynthesized composites have been studied X-ray diffraction(XRD) and UV-visible absorption spectroscopy have beencarried out to characterize these samples

2 Experimental

All chemicals used were of analytical reagent (AR) gradeThe monomer aniline was doubly distilled prior to useAmmonium persulphate ((NH

4) S2O8) hydrochloric acid

(HCl) and vanadium pentoxide V2O5were used as received

in the present studyPolyaniline has been synthesized by in situ oxidative poly-

merization of aniline hydrochloric acid (HCl) and ammo-nium persulphate ((NH

4) S2O8) as oxidant The oxidant

monomer ratio is 1 125 Aniline (125M) has been dissolvedin 10mL of HCl (1M) taken in 200mL round bottom flaskand stirred well Further finely ground V

2O5powder taken

in different (20 30 and 40) wt with respect to anilineconcentration has been added to the previous mixture undervigorous stirring in order to keep V

2O5powder suspended

in solution The reaction mixture has been cooled up to 5∘Cand the precooled solution of ammoniumpersulfate (1M) hasbeen slowly added drop by drop over a period of 30minThereaction has been allowed to proceed for 6ndash8 h The mixturewas further cooled down to 4∘C for 24ndash36 hours It was thenfiltered and washed with ammonia until filtrate was colorlessThe dark colored polymer powder so obtained was driedthoroughly in an oven at 100∘C until constant weight wasattained then grinded and sieved PANI has been synthesizedin the same manner in the absence of V

2O5

TheDC conductivity of pure PANI and PANIV2O5com-

posites wasmeasured by using two-probemethod in the tem-perature range 300ndash550KThe powder was made into pelletsof 1 cm diameter and different thickness for PANIV

2O5

composites The bulk DC conductivity was measured bymounting between two steel electrodes inside a speciallydesigned metallic sample holder [22] The temperature wasmeasured with a calibrated copper-constantan thermocouplemounted near the electrodes The samples were annealedat a temperature of 100∘C to avoid any effect of moistureabsorption These measurements were made at a pressureof about 10minus3 Torr A stabilized voltage of 15 V was appliedacross the sample and the resultant current was measuredwith a picoammeter

In order to get information about the crystallinity X-ray diffraction patterns of all samples are recorded at roomtemperature by using a Panalytical (PW 3710) X-ray powderdiffractometer with Cu K120572 radiation All the samples werescanned in angular range of 0ndash90∘ with scan speed of 001∘sunder the similar conditions UV-visible spectroscopy hasbeen carried out using Camspec M550 double beam UV-visible spectrophotometer [22ndash26]

3 Results and Discussion

31 Temperature DC Conductivity Studies The variation ofDC conductivity with temperature for pure PANI and thePANIV

2O5composites (with different wt) is shown in

Figure 1 Arrhenius plot of DC conductivity shows straightline behavior The DC conductivity of pure PANI increasedexponentially with doping exhibiting semiconductor charac-teristicsThe conductivity as a function of temperature can berepresented by the relation [27]

120590DC = 1205900exp (minusΔ119864

119896119879) (1)

where (ΔE) is the activation energy for the DC conductionmechanism ldquo119896rdquo is the Boltzmann constant and ldquo120590

0rdquo is the

preexponential factor The activation energy (Δ119864) has beencalculated from the slope of Figure 1 for pure PANI andthe PANIV

2O5 The DC conductivity of undoped PANI

is measured to be 358 times 10minus9 Scm After doping withdifferent weight of V

2O5the conductivity was found to

change from 10minus7 to 10minus9 Scm attaining a maximum valueat 30 weight of V

2O5and then reduced at 40 weight

of V2O5 The doping of conducting polymers implies

charge transfer the associated insertion of a counter ionand the simultaneous control of Fermi level or chemicalpotential Through doping electronic and optical propertiesof conducting polymers can be controlled over a long rangeThe electrical conductivity of conducting polymers resultsfrommobile charge carriers introduced into the 120587-electronicsystem through doping At low doping levels these chargecarriers are self-localized and form nonlinear configurationsBecause of large interchain transfer integrals the transportof charge is believed to be principally along the conjugatedchains with interchain hopping as a necessary secondarycondition [28ndash31] When the polymer is heavily doped (40weight ) the wave functions are delocalized over manylattice constants along the polymer chain In PANI sincethere are nearly degenerate ground states the dominatingcharge carriers are polarons and bipolarons [32] WhenPANI is doped with V

2O5hydrochloric acid the charge

carriers form nonlinear configurations and as a result theconductivity does not change substantially The nonlinearformation may be more in the case of heavy doping of 40weight of V

2O5 due to which it exhibits lesser conductivity

than 30 weight doped polymerThe activation energy ΔE DC conductivity 120590DC and

preexponential factor 1205900of pure PANI and PANIV

2O5

composites have been measured and tabulated in Table 1


22 24 26 28 30 32 34minus220

minus215

minus210

minus205

minus200

minus195

minus190


15 20 25 30 35minus16

minus15

minus14

minus13

minus12

minus11

minus10

150 155 160 165 170 175 180 185 190 195minus19

minus18

minus17

minus16

minus15

minus14





ln 120590 d

c(o

hmminus1cm

minus1)

ln 120590 d

c(o

hmminus1cm

minus1)

ln 120590 d

c(o

hmminus1cm

minus1)

ln 120590 d

c(o

hmminus1cm

minus1)


(different weight )




119879 = 302K and 119891 = 850KHz1205761015840

12057610158401015840











2O5composites in


1205761015840=119862119875

1198620

12057610158401015840=

1205761015840

120596119862119875119877119875

= 1205761015840119863

(2)



119875is the


120576 (119891) = 1205761015840(119891) minus 119894120576

10158401015840(119891) (3)


2O5 whereas a





300 302 304 306 308 310 312 314 316 318 3200

50

100

150

200

250

300

350



Temperature (K)

f = 850kHz

120576998400



weight )

300 302 304 306 308 310 312 314 316 318 3200

200

400

600

800

Temperature (K)



f = 850kHz

120576998400998400

times10minus2



)





12057610158401015840

DC =120590DC1205760120596 (4)

000

50

100

150

200

250

Frequency (Hz)



2000 k 4000 k 6000 k 8000 k 10 M

T = 425K

120576998400


2O5composites

(different weight )





(119898) =minus4119896119879

119882119898

(5)





2O5composites (with





0100200300400500600700800900



T = 425K


120576998400998400

times10minus2



)




ln(120596) (kHz)

ln(120576

998400998400)


2O5(different wt)


Sample 12057610158401015840


119892(eV)



minus3minus003 327








0 10 20 30 40 50 60 70 80

PANI

Cou

nts

s

Initial 20 weight

Initial 40 weight

Initial 30 weight

2120579 (deg)


weight )


120572ℎ] = 119861(ℎ] minus 119864119892)119898

(6)




119870 =120572120582

4120587 (7)








310 315 320 325 330 335 340 345 350

60

80

100

120

140

160

180

200

h (eV)



(120572h)

12

(cm

minus1eV

)12






4 Conclusion






119892) increases



References




























2O5





2com-








2O5thin




80minus119909Te119909Ga20











2O3










4mechanical mix-
















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




22 24 26 28 30 32 34minus220

minus215

minus210

minus205

minus200

minus195

minus190


15 20 25 30 35minus16

minus15

minus14

minus13

minus12

minus11

minus10

150 155 160 165 170 175 180 185 190 195minus19

minus18

minus17

minus16

minus15

minus14





ln 120590 d

c(o

hmminus1cm

minus1)

ln 120590 d

c(o

hmminus1cm

minus1)

ln 120590 d

c(o

hmminus1cm

minus1)

ln 120590 d

c(o

hmminus1cm

minus1)


(different weight )




119879 = 302K and 119891 = 850KHz1205761015840

12057610158401015840











2O5composites in


1205761015840=119862119875

1198620

12057610158401015840=

1205761015840

120596119862119875119877119875

= 1205761015840119863

(2)



119875is the


120576 (119891) = 1205761015840(119891) minus 119894120576

10158401015840(119891) (3)


2O5 whereas a





300 302 304 306 308 310 312 314 316 318 3200

50

100

150

200

250

300

350



Temperature (K)

f = 850kHz

120576998400



weight )

300 302 304 306 308 310 312 314 316 318 3200

200

400

600

800

Temperature (K)



f = 850kHz

120576998400998400

times10minus2



)





12057610158401015840

DC =120590DC1205760120596 (4)

000

50

100

150

200

250

Frequency (Hz)



2000 k 4000 k 6000 k 8000 k 10 M

T = 425K

120576998400


2O5composites

(different weight )





(119898) =minus4119896119879

119882119898

(5)





2O5composites (with





0100200300400500600700800900



T = 425K


120576998400998400

times10minus2



)




ln(120596) (kHz)

ln(120576

998400998400)


2O5(different wt)


Sample 12057610158401015840


119892(eV)



minus3minus003 327








0 10 20 30 40 50 60 70 80

PANI

Cou

nts

s

Initial 20 weight

Initial 40 weight

Initial 30 weight

2120579 (deg)


weight )


120572ℎ] = 119861(ℎ] minus 119864119892)119898

(6)




119870 =120572120582

4120587 (7)








310 315 320 325 330 335 340 345 350

60

80

100

120

140

160

180

200

h (eV)



(120572h)

12

(cm

minus1eV

)12






4 Conclusion






119892) increases



References




























2O5





2com-








2O5thin




80minus119909Te119909Ga20











2O3










4mechanical mix-
















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




300 302 304 306 308 310 312 314 316 318 3200

50

100

150

200

250

300

350



Temperature (K)

f = 850kHz

120576998400



weight )

300 302 304 306 308 310 312 314 316 318 3200

200

400

600

800

Temperature (K)



f = 850kHz

120576998400998400

times10minus2



)





12057610158401015840

DC =120590DC1205760120596 (4)

000

50

100

150

200

250

Frequency (Hz)



2000 k 4000 k 6000 k 8000 k 10 M

T = 425K

120576998400


2O5composites

(different weight )





(119898) =minus4119896119879

119882119898

(5)





2O5composites (with





0100200300400500600700800900



T = 425K


120576998400998400

times10minus2



)




ln(120596) (kHz)

ln(120576

998400998400)


2O5(different wt)


Sample 12057610158401015840


119892(eV)



minus3minus003 327








0 10 20 30 40 50 60 70 80

PANI

Cou

nts

s

Initial 20 weight

Initial 40 weight

Initial 30 weight

2120579 (deg)


weight )


120572ℎ] = 119861(ℎ] minus 119864119892)119898

(6)




119870 =120572120582

4120587 (7)








310 315 320 325 330 335 340 345 350

60

80

100

120

140

160

180

200

h (eV)



(120572h)

12

(cm

minus1eV

)12






4 Conclusion






119892) increases



References




























2O5





2com-








2O5thin




80minus119909Te119909Ga20











2O3










4mechanical mix-
















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




0100200300400500600700800900



T = 425K


120576998400998400

times10minus2



)




ln(120596) (kHz)

ln(120576

998400998400)


2O5(different wt)


Sample 12057610158401015840


119892(eV)



minus3minus003 327








0 10 20 30 40 50 60 70 80

PANI

Cou

nts

s

Initial 20 weight

Initial 40 weight

Initial 30 weight

2120579 (deg)


weight )


120572ℎ] = 119861(ℎ] minus 119864119892)119898

(6)




119870 =120572120582

4120587 (7)








310 315 320 325 330 335 340 345 350

60

80

100

120

140

160

180

200

h (eV)



(120572h)

12

(cm

minus1eV

)12






4 Conclusion






119892) increases



References




























2O5





2com-








2O5thin




80minus119909Te119909Ga20











2O3










4mechanical mix-
















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




310 315 320 325 330 335 340 345 350

60

80

100

120

140

160

180

200

h (eV)



(120572h)

12

(cm

minus1eV

)12






4 Conclusion






119892) increases



References




























2O5





2com-








2O5thin




80minus119909Te119909Ga20











2O3










4mechanical mix-
















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






2O5





2com-








2O5thin




80minus119909Te119909Ga20











2O3










4mechanical mix-
















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 synthesis, electrical conductivity,...

Documents