research article dielectric studies on fe nanodoped...

Research ArticleDielectric Studies on Fe3O4 Nanodoped119901-119899-Alkyloxybenzoic Acids

S Sreehari Sastry1 L Tanuj Kumar1 T Vishwam2 V R K Murthy3

S Lakshminaryana4 and Ha Sie Tiong5

1 Department of Physics Acharya Nagarjuna University Nagarjuna Nagar 522510 India2Department of Physics Gitam University Hyderabad Campus Rudraram 502329 India3 Department of Physics Indian Institute of Technology Chennai 600036 India4Department of Electronics and Communication Engineering KL University Greenfields Vaddeswaram GunturAndhra Pradesh 522002 India

5 Departmant of Chemical Science Faculty of Science Universiti Tunku Abdul Rahman Jalan Universiti Bandar Barat31900 Kampar Perak Malaysia

Correspondence should be addressed to S Sreehari Sastry sreeharisastryyahoocom

Received 20 January 2014 Accepted 16 May 2014 Published 16 June 2014

Academic Editor Victor V Moshchalkov

Copyright copy 2014 S Sreehari Sastry et al 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 stability of phase transition temperatures and textural changes for thermotropic pure and nanodoped 119901-119899-alkyloxybenzoicacid mesogens were aimed to study at considerable time periods Frequency and temperature dependent dielectric constant anddielectric loss for the pure and nanodoped liquid crystals were carried out Significant anomalies in dielectric studies were observednear phase transitions when dielectric constant and dielectric loss had been measured as a function of temperature and frequencyChanges in dielectric constant and loss were observed and there were no apparent changes at high frequencies instead maintainingconstant values The variations in conductivity activation energy and relaxation times had also been studied in the nematic andsmectic phasesThe temperature dependent dielectric constant stability (temperature coefficient of dielectric constant 120591

120576) had shown

shift in the observed frequency range of thermotropic liquid crystals corresponding to the change in the dielectric constant values

1 Introduction

Nanodoped liquid crystal (LC) research has emerged animportant potential area in scientific and technological appli-cations especially in liquid crystal displays [1] The liquidcrystalline materials doped with nanoparticles have indeedattracted much scientific and technological interest mainlybecause the incorporation of nanomaterials enhances thephysical properties of the liquid crystal itself [2] Low dopingconcentrations (lt3 by weight) are usually preferred toget a more stable and for an even distribution in the LCwhich will lower the interaction forces between particles [34] 119901-119899-alkyloxybenzoic acids are extensively studied earlierand gained interesting results [5ndash8] Various experimentaltechniques are being done on these alkyloxybenzoic acidson individual members and on mixed compounds [6 8ndash10]

Dielectric spectroscopy [11 12] is an effective experimentaltool to understand the doping of nanoparticles in liquidcrystals It all depends on intrinsic properties of chargedmaterial distribution in molecules and also the intermolec-ular interactions The LC anisotropy is proven to havesubstantially increased due to introduction of nanoparticles(magnetic nanoparticles basically ferric oxides) [13] How-ever enhancement of the electrooptical properties of LC isdependent on the size type concentration and intrinsiccharacteristics of nanoparticles that are used for doping [1415]

The present study aims to examine the stable conditionsfor the properties of textural phase transitions and dielectricproperties from room temperature to more than its isotropictemperatures on nanodoped 119901-119899-alkyloxybenzoic acids

Hindawi Publishing CorporationAdvances in Condensed Matter PhysicsVolume 2014 Article ID 639259 12 pageshttpdxdoiorg1011552014639259

2 Advances in Condensed Matter Physics

2 Materials and Methods

119901-119899-Alkyloxybenzoic acids (119899OBA) from 119899 = 3 to 10 and 12are procured from Frinton Laboratories Inc USAThe ferricoxides (Fe

3O4) nanoparticles of 20 nm size are procured

from Indian Institute of Technology Chennai Magnetite(Fe3O4) nanoparticles of 01 are doped through continuous

stirring for nearly 3 hours in their isotropic phase of 119901-119899-alkyloxybenzoic acids and after cooling the nanodoped 119901-119899-alkyloxybenzoic acids (N119899OBA) are subjected to study

Textural and phase transition temperatures are measuredusing a Meopta polarising optical microscope (POM) withhot stage as described by Gray [16] The pure and nanodis-persed thermotropic LCs are filled in LC1 ITOcoated cells for90∘ twist aligned (5mm times 5mm times 6 120583m) which are obtainedfromMs Instec Inc USAThe compounds in their isotropicstate are filled in these cells through capillary action methodTextural and phase transition temperatures are studied afterpreparation of the sample and observations are made againafter a gap of period to understand the stability of Fe

3O4

nanoparticlesThe temperature and frequency dependence of capaci-

tance 119862 resistance 119877 and inductance 119871 were measured byusing Newtonrsquos 4th Ltd LCR meter model PM1700 Thecells filled with pure and nanodoped samples are placedin an Instec hot and cold stage (HCS 302) equipped withmicroscope (Olympus BX50) having DP10 camera setupThe temperature is monitored and controlled through acomputer by a software program to an accuracy of plusmn01∘CThe sample is heated to isotropic state and held until attainingthermal equilibrium The data of 119862 119871 and 119877 is taken duringcooling processThemeasuring signal is the square formwithamplitude of 2V The frequency range of measurement isfrom 100Hz to 1MHzThe accuracy of dielectric constant andloss are estimated to the error of 1 and 2 respectively

3 Results and Discussion

31 Textures and Phase Transition Temperatures The phasesand their transition temperatures shown in Table 1 areobtained from POM for nanodoped 119901-119899-alkyloxybenzoicacids which exhibit enantiotropic behavior

The phase transition temperatures for different series ofthose pure 119901-119899-alkyloxybenzoic acids [17] recorded immedi-ately after preparation of N119899OBA are not similar as shownin Table 1 The clearing temperatures have decreased fornanodoped liquid crystals when compared to pure liquidcrystals [18] This decrease is due to increase in the vander Waals attraction among nanoparticles that disturbedthe orientational properties of director in the LCs mediumHence the interaction among them excluding the neighbour-hoodmolecules has formed strong anchoring conditions thatinfluenced the specific orientation to the director resulting intopological defects [19 20]

The nanoparticles appeared to be stabilized after manyinteractions among themselves within the liquid crystalmediumThemobility of these nanoparticles in liquid crystalmedium is limited forming stable dispersions in alkyloxyben-zoic acids It means the surface anchoring properties became

Table 1 Phase transition temperatures of nanoalkyloxy benzoicacids

S number CompoundN119899OBA n= Textures Transition

temperatures (∘C)1 3 I-N-Cr 1472ndash13132 4 I-N-Cr 1422ndash12773 5 I-N-Cr 1418ndash11584 6 I-N-SC-Cr 1392ndash1153ndash9315 7 I-N-SC-Cr 1332ndash937ndash8586 8 I-Ch-Cr 1282ndash88 97 9 I-N-SC-Cr 1318ndash1062ndash8728 10 I-SA-SB-Cr 958ndash828ndash6729 12 I-N-SC-Cr 1188ndash1075ndash878Note I = isotropic N = nematic Ch = cholesteric SA = smectic A SB =smectic B and SC = smectic C

weak such that there is no director distortion in the liquidcrystal phase On the other hand these features reveal clearlythat the elastic energy dominates the magnetic one as longas the orientation of director is fixed [21] The textures ofnematic and smectic phases of pure and doped samples areshown in Figure 1 All the 119899OBA samples have exhibited boththreaded nematic and smectic C [22] from 119899 = 7 to 10 and 12whereas 119899 = 3 to 6 samples show only threaded nematic Inaddition the observed nanodoped 119899OBA liquid crystals havedisplayed threaded nematic and Sm C for 119899 = 6 7 9 and 12and cholesteric phase in nanodoped 8OBA and the phases ofSm A and Sm B in nanodoped 10OBA

These changes can be attributed to the increase in chainlength surface anisotropy and even-odd effect which arecommonly existing in homologous series [23] The texturalchanges start playing into effect in nanodoped samples for119899 = 6 This is a self-explanatory showing the effect of chainlength increase on texturesThe existence of cholesteric phasein N8OBA particularly is due to electroconvection that isusually existing in nematic liquid crystals of short rangeSm C order [24] Comparatively among all in the selectedhomologous series of 119899OBA the 8OBA has displayed shortrange Sm C (from 905∘C to 985∘C) Hence only in 8OBAthe presence of nano has made it modified to cholestericWith the order of chain length increase the nanoparticleseffect the alignment of LC molecules and try to bring theminto layering which is identified as Sm A and Sm B Thesetextures corresponding to different phases are shown inFigures 1(e)ndash1(g)

The aggregation of magnetite nanoparticles appearingin the textures shown in Figure 2 is attributed to a largecontribution to the magnetic anisotropy which is likely tobe located on the particle surface by overcoming randomlyoriented molecules with uniaxial symmetry of mesophases

TheUV-visible spectroscopic studies have also confirmedthe presence of magnetite nanoparticles in the lattice ofsamples

The UV-visible spectra of pure and nanodoped 7OBAmesogen samples are shown in Figure 3 It is observed thatthe spectrum for pure 7OBA does not exhibit any absorption

Advances in Condensed Matter Physics 3

(a) (b)

(c) (d) (e)

(f) (g)

Figure 1 Textures of 119899OBA (a) Threaded nematic (b) Smectic C and typical nanodoped 119899OBA (c) Nematic (d) Smectic C (e) Cholestericin N8OBA (f) Smectic A (g) Smectic B in N10BA

peaks in the wavelength range of 200 nmndash2000 nmHoweverthe spectrum of nanodoped 7OBA shows three significantpeaks at 418 nm 681 nm and 821 nmwhich are the character-istic peaks of Fe3+ ion [25] So the UV-visible spectral studyconfirms the presence of Fe

3O4nanoparticles in the prepared

nanodoped mesogens

32 Dielectric Spectral Studies for Series of Pure andNanodoped 119901-119899-Alkyloxybenzoic Acids

321 Frequency Dependence of Dielectric Constant and Tem-perature Coefficient of Dielectric Constant 120591

120576 The dielec-

tric constant of a material is numerically the ratio of thecapacitance of a capacitor containing that material to thecapacitance of the same electrode system with vacuum

Using (1) the dielectric constant (1205761) for series of pure andnanoalkyloxybenzoic acids is calculated

1205761

=(119862119901minus 119862119900) 119889

120576119900119860

+ 1 (1)

where 119860 = area of the cell 119889 = thickness of the cell 1205760=

permittivity of free space 885 times 10minus12 Fmminus1119862119901= capacitance

with sample and 119862119900= capacitance without sample

The temperature coefficient of dielectric constant (120591120576) is

calculated using (2) Values of 120591120576can be positive or negative

indicating an increasing or decreasing dielectric constantrespectively with an increasing temperature [26] As theseare thermotropic liquid crystals their temperature stabilitywith respect to other materials is low [26] To determine120591120576 the measured dielectric constant at isotropic temperature

considered as reference temperature is compared with thevalues recorded at both initial and final phases given fortemperature range of liquid crystal Consider

120591120576=

(120576 (119879final) 120576 (119879ref)) minus (120576 (119879initial) 120576 (119879ref))

119879final minus 119879initial

lowast 106

[ppm∘C]

(2)

where 119879initial = initial LC phase temperature value 119879final =final LC phase temperature value 120576(119879initial) 120576(119879final) = thecorresponding dielectric constant and 120576(119879ref) = dielectric


(a) (b)

Figure 2 The aggregation of Fe3O4nanoparticles in nanodoped 12OBA (brown color shade)

400 600 800

04

06

08

Abso

rptio

n (

)

Wavelength (nm)

7OBA

(a)

Abso

rptio

n (

)

400 600 800Wavelength (nm)

06

N7 OBA

821nm

681nm

418nm

(b)

Figure 3 UV-visible spectrum of (a) pure and (b) nanodoped samples of 7OBA mesogens

constant at reference temperature (50∘C) The 120591120576value has

units of parts per million per degree Celsius [ppm∘C]Figure 4 represents the calculated 120576

1 variation using (1)as a function of frequency (119891) for pure and nanodoped LCscompounds in different phases 119899OBA and N119899OBA serieshave shown the same path in the graphical chart showinga decrease in 120576

1 at low frequencies and almost constant1205761 at high frequencies It infers that doping ferroelectricnanoparticles to liquid crystal for a small amount (01) hasaffected slightly the dielectric properties of the system at lowfrequencies

At high frequency both compounds exhibit constant 1205761and also show lower values These are associated with thelowest electrical loss characteristics The high orientationof liquid crystal molecules in isotropic phase shows highvalue of 1205761 when compared with another phase On dopingnanoparticles the strong anchoring forces developed among

nanoparticles and liquid crystal molecules caused decrease indielectric permittivity Fixed orientations of molecules havebrought low values in liquid crystalline phase

More stability in the dielectric constant at temperaturesfor high frequencies is significantly relative to low frequenciesfor both compounds as shown in Figure 5 120591

120576is the product

of thermal and dielectric constant properties of the resultsproduced by 120591

120576as a function of frequency are corresponding

to variations in dielectric constant and structural propertiesThe lower values of 120591

120576closer to zero indicate stable

dielectric constant with temperature While compared withdielectric constant variation of pure and nano LCs the 120591

120576

variation is high since it consists of important role of thermaland alignment stabilities with respect to applied field FromFigure 5 (119899 = 3 and 8) the instability thermal propertiesshowing high value of 120591

120576are observed for 119899 = 3 to 6

(both 119899OBA and N119899OBA) mesogens at lower frequenciesThe high transition temperatures and orientational order of


0

20

40

60

80

100

102 103 104 105 106

At 423K (LC phase)5OBA5OBA nano

f (Hz)

1205761

(a)

0

20

40

60

80

100

120

102 103 104 105 106

At 433K (Isotropic phase)5OBA5OBA nano

f (Hz)

1205761(b)

Figure 4 Frequency dependence of 1205761 for pure and nanodoped LCs (01) in LC and isotropic phases

the nematic molecules are attributed to that property as aresult of the dominating frequency applied With increasingchain length the smectic translation order decreased in thetransition temperatures Surface anchoring by nanoparticleswould also bring instability in thermal and dielectric prop-erties resulting in decrease for owing molecules aligned withrespect to applied high frequencies

322 Frequency Dependence of Dielectric Loss Conductivityand Activation Energy The simplest model for a capacitorwith a lossy dielectric is the capacitor with a perfect dielectricin parallel with a resistor giving power dissipation Thedielectric loss angle (tan 120575) values are directly measuredfrom the experimental technique and the imaginary part ofpermittivity (dielectric loss 12057611) is calculated using (3) for thechosen series

12057611

= 1205761 tan 120575 (3)

Based on 12057611 data the sample conductivity 120590 (siemens

per meter) is estimated using (4) Changes in electricalconductivity and charge transferring for low concentrationdispersion of Fe

3O4nanodoped in alkyloxybenzoic acids and

for pure compounds are studied At different temperaturesand isotropic phase the ac conductivity in the LC region ismeasured from (4) from 1 kHz to 1MHz frequencies

120590ac = 212058712057611990012057611

119891 (4)

where 1205760= permittivity of free space 885 times 10minus12 Fmminus1 119891 =

corresponding frequency in Hz and 12057611 = dielectric loss

Themost widely adopted form of the Arrhenius equation[27] to study for the effect of temperature on conductivity isshown in (5) The activation energy is viewed as an energetic

threshold for a fruitful electric field production generated bythe LC molecules orientation or by dispersed nanoparticlesstructure It is possible to calculate activation energy with theArrhenius equation simply by using the conductivity at twotemperatures It would be more realistic and reliable if moredata of conductivity is taken at different temperatures Henceby using the ac conductivity values calculated from (4) in theLC temperature region from 1 kHz to 1MHz the activationenergy (119882) is calculated by following

120590ac = 120590119900exp (minus 119882

119870119879) (5)

where 119882 = activation energy KJmol 119870 = Boltzmannconstant in eVK119879= temperature relative to the conductivityvalue calculated using a reference temperature and the tem-perature values at corresponding phases 120590ac = conductivityin LC phase and 120590

119900= conductivity in the isotropic phase at

different frequenciesFigure 6 has indicated the dielectric loss for nanodoped

system that is increased when compared to pure compounds(LC phase) because of more conducting nature in nanodopedparticles Low dielectric loss at high frequencies has shownsimilarity with the variation of dielectric constant (Figure 4)owing to smaller angle of rotation The loss factor onfrequency dependent is also the same behavior in a similarway as the dielectric constant (which is known when theloss experimental data is analyzed) The positional variationof relaxation peaks within the frequency range studied isobserved only for a particular compound of even series of119899OBA and N119899OBA

Figure 7 represents the conductivity variation with tem-perature from isotropic to crystal at specific frequenciesand shows the results for 12OBA and N12OBA as a repre-sentative case The other members of 119899OBA and N119899OBA


00

times105

minus40

40

80

120

160

200

101 103102 104 105 106

f (Hz)

3OBA3 OBA nano

120591120576

(ppm

∘C)

(a)

00

times105

minus20

20

40

60

80

101 103102 104 105 106

f (Hz)

120591120576

(ppm

∘C)

8OBA8OBA nano

(b)

Figure 5 Frequency dependence of thermal coefficient of dielectric constant 120591120576for pure and nanodoped LCs

0

10

20

30

102 103 104 105 106

f (Hz)


12057611

(a)

0

10

20

30

40

50

102 103 104 105 106

f (Hz)At 410K (Isotropic phase)

10OBA10OBA nano

12057611

(b)

Figure 6 Frequency dependence of 12057611 for pure and (01) nanodoped LCs

mesogens have been shown in a similar pattern but witha different magnitude For the frequency increased from123Hz to 1MHz the conductivity rapidly increased Hencethe variation at lower frequencies is not significant in thegraph However the low frequencies variation is prominentfor both 12OBA and N12OBA compounds as depicted onright side graph The conductivity has increased with theincreased frequency of 1MHz The maximum conductivityvalues studied at 1MHz are 125 times 10minus4 (Sm) in isotropic

state for nanodoped LCs N3OBA and 107 times 10minus4 (Sm) for3OBA Having the lowest carbon chain length in the seriesthemobility ofmolecular rotation in 3OBAhas led to increasein flow of current in anisotropic LCs matrix compared tothat in other compounds upon their gradual increased chainlengths in the series The presence of higher conductivityfor nanodoped LCs than pure compounds is known throughthe higher dielectric constant recorded for pure LCs thanfor nanodoped as shown in Figure 4


00022 00024 00026 00028

00

20

40

60

80

12OBA

Tminus1 (Kminus1)

times10minus5

120590(S

m)

(a)

00022

05

00

20

25

10

15

12OBA

00024 00026 00028

Tminus1 (Kminus1)

times10minus6

120590(S

m)

(b)

12OBA nano

00022 00024 00026 00028Tminus1 (Kminus1)

00

20

40

60

80times10minus5

115 kHz

11kHz105 kHz

126Hz121Hz

1MHz

120590(S

m)

(c)

00

20

40

60

80

100

12OBA nano

00022 00024 00026 00028Tminus1 (Kminus1)

times10minus6

115 kHz11kHz105 kHz

120590(S

m)

(d)

Figure 7 Relative conductivity 120590 (Ssdotmminus1) versus inverse temperature 1119879 (1K) for pure and nanodoped LCs of 12OBA ((a) and (c)) at variousfrequencies and ((b) and (d)) for the variations at low frequencies

The anomalies at near transition temperatures areobserved A nearly invariant temperature affecting ac con-ductivity is noticed in the smectic to crystal transition Asharp decrease in nematic phase is observed with respectto increase in inverse temperature As discussed earlierthe high conductivity value is exhibited at high frequencytherefore for pure and nanodoped LCs high frequencyrelative conductivity dominates than other lower frequencies

The calculated activation energy (119882) for conduction inentire LC region by using (5) as function of frequency at LC

temperatures for nematic and smectic regions is shown inFigure 8 The results shown here are representing 5OBA and8OBA and their nanocomplexes as a case study and conclu-sions are drawn for other members of 119899OBA mesogens

The activation energy also showed similar tendencies inthe nanodispersed samples that is decreasing with increasingfrequency in the smectic and solid phases Figure 8 indicatesthat there are three levels present in the frequency rangein nematic phase Firstly the frequency increased with theincrease of activation energy secondly on further increase


0

100

200

300

400

500

5OBA nano

Frequency (Hz)

minus100

W(k

Jmol

)

102 103 104 105 106

Nematic drops (433 K) Nematic (428 K)Nematic (423 K)

Nematic (418 K)Nematic (413 K)Solid (393)

(a)

5OBA

0

40

80

120

160

Frequency (Hz)

minus40

W(k

Jmol

)

102 103 104 105 106

Nematic (428 K)Nematic (418 K)


(b)

0

50

100

150

200

2508OBA nano

Nematic (418 K)Nematic (413 K)Nematic (403 K)

Nematic (393 K)Smectic (383 K)Solid (363 K)

minus50

W(k

Jmol

)

Frequency (Hz)102 103 104 105 106

(c)

0

20

40

60

80 8OBA


Nematic (393 K)Smectic (373 K)

minus60

minus40

minus20

Frequency (Hz)102 103 104 105 106

W(k

Jmol

)

(d)

Figure 8 Frequency dependence of activation energy in nematic and smectic phases for (a) nanodoped and (b) pure LCs of 5OBA and (c)nanodoped 8OBA and pure 8OBA

in frequency there exists a broad frequency region wherethe activation energy is nearly constant and finally starteddecreasing until approaching 0 (KJmol) This effect is raiseddue to the role of the surface activity of dispersed particles inlocal order of the liquid crystal as a result of elastic distortionsassociated with the liquid crystal on following increasedfrequencies

By analyzing the activation energy results it can be con-cluded that the energy values for both compounds in nematicphase are in the range from minus100 to 250 (KJmol) The valuesof activation energy in smectic phase at a particular frequency

region are more than 250 (KJmol) which is similar to therelative conductivity (120590) that showed steep slope in nematicas in smectic phaseThis can be explained by considering tworeasons while using long and short molecular axis rotationin the liquid crystal matrix in the presence or absence ofthe suspended nanoparticles with respect to applied fieldFirstly at low frequencies the increase in activation energy innematic phase for 119899 = 3 to 6 (both pure and nano) has led torestricted mobility of charged carriers resulting in low con-ductivity (Figure 7) At higher frequencies the decrease inthe activation energy (Figure 8) is related to high mobility of


360 380 400 420 440

0

20

40

60

80 1 kHz

Temperature (K)

1205761

(a)

0

20

40

60

80 1 kHz

360 380 400 420 440

Temperature (K)1205761

1

(b)

360 380 400 420 440

Temperature (K)

20

22

24

26

28 1 MHz

1205761

8OBA8OBA nano

(c)

360 380 400 420 440

Temperature (K)

06

08

10

12

14

161 MHz

12057611

8OBA8OBA nano

(d)

Figure 9 Temperature dependence of 1205761 and 12057611 for (a) nanodoped and (b) pure 8OBA at 1 kHz and (c) nanodoped and (d) pure at 1MHz

charged transports This is confirmed by correlating the highconductivity (Figure 7) and low temperature coefficient ofdielectric constant (Figure 5) at higher frequencies There-fore the distortion in rotation and in alignment of LCmolecules with respect to the field will bring on increase inthe conductivity on lowering its active potential energy

323 Temperature Dependence of Dielectric Constant and Lossfor Pure andNanodoped Alkyloxybenzoic Acids Temperaturedependent dielectric studies for the prepared 119899OBA nan-odoped particles are carried out to analyze its response toan applied low ac voltage (2V) The variations in dielectric

constant and loss with temperature at various frequencies areshown in Figure 9 Increase in the ionization of the samplewith temperature increases the processes of conductivity anddissipation factor simultaneously and it is vice versa in caseof higher frequencies

A nearly similar trend of dielectric constant with temper-ature is also observed in dielectric loss These different varia-tions at low and high frequencies due to temperature may beattributed to conformational vibrations of mobile molecularfragments like vibrations of flexible alkyloxy groups andvibrations of the benzene rings together of 119899OBA mesogensFrom Figure 9(a) (1 kHz) it is observed that an increase


0 20 40 60 80 100 1200

20

40

60

80

5OBA nano (433 K)Semicircle fittingNematic

U V

12057611

1205761

120579

(a)

U V

0

20

40

60

80

12057611

0 20 40 60 80 100 120


1205761

(b)

Smectic

0 20 40 60 80

Semicircle fitting

1205761

1205790

20

40

60

12057611

10OBA nano (388K)

U V

(c)

U V

0

20

40

60

12057611

Smectic

0 20 40 60

Semicircle fitting

1205761

10OBA nano (378K)

120579

(d)

Figure 10 Cole-Cole plots of 1205761 and 12057611 for nematic and smectic phases of N119899OBA at different temperatures N5OBA (nematic (a) and (b))

and N10OBA (smectic (c) and (d)) compounds

in dielectric constant on increasing temperature has sug-gested that the dipoles are oriented perpendicularly towardsthe director at high temperatures whereas in Figure 9(b)(1MHz) nearly constant is observed at high temperaturesThe difference in dielectric constant and loss of pure andnanodoped LCs as shown in Figure 9 is due to variations inthermal transition temperatures

324 Cole-Cole Plots of 1205761 and 12057611 for Nematic and Smectic

Phases between 1 kHz to 1MHz for Pure and Nanodoped 119901-119899-Alkyloxybenzoic Acids By using the dielectric data (dielectricconstant and loss) from LCR meter the Cole-Cole plots [28]are drawn for different temperatures The relaxation time 120591(Sec) can be found from the arc plot by using

120596 = (V119906)

1(1minus120572)

(6)


where 120572 = 12057990 (distribution parameter) 120596 = 2Π119891 (angularfrequency Hz) and 119906 V values are determined from thedrawn Cole-Cole plots

Figure 10 (as representative case) illustrates a few char-acteristic results showing typical Cole-Cole plots at severaltemperatures (in LC region) The symbols used in it arerepresenting the experimental data and the solid line isrepresenting the semicircle fitting Table 2 provides the subsetrelaxation time values at different frequencies and phasesSame relaxation times are observed to all frequencies onsemicircle curvature at a particular temperature on varied119906 V values From Figure 10 conclusions are drawn that thedielectric dispersions (curvature) for nanodoped LCs areexhibited better at the frequency studied when comparedto pure composites These plots are drawn to analyze thedielectric dispersion spectra of the LC phases with respectto isotropic phase relaxation times and variations in dipolesorientation variation as a function of temperature Eventhough there is a fixed temperature and having same nematicor smectic order with same molecular structure in theseseries there are different relaxation times observed at differ-ent relaxation frequencies for variation in their carbon chainlength Table 2 shows the calculated values of relaxation timesusing Cole-Cole plots in isotropic nematic and smecticphases at particular temperatures

Among all these series the pure 7OBA compound doesnot show any relaxation but the 7OBAnanodoped compoundshows relaxation This phenomenon is reversed in the caseof 4OBA compound as given in Table 2 It is concludedthat the Fe

3O4particles hindered the free rotations in the

liquid crystal matrix and showed better relaxation times atstudied frequencies when compared to pure compoundsIn some cases of pure and nanodoped LCs have displayednearly equal dispersions and relaxation times as that ofthe isotropic phase [12] and showing the reorientation ofmolecular dipoles dominating the ordering in LC phasesThepresence of nano not only effected the molecular orderingbut also influenced the dielectric parameters like 120576

1015840 12057610158401015840 120591and activation energy These changes can be attributed to thedipole moment contribution of magnetite nanoparticles tothe liquid crystal molecules [29 30]

4 Conclusions

The dielectric spectrum of frequency dependent dielectricconstant and the loss for both pure and nanodoped alky-loxybenzoic acids in perpendicular alignment are analyzedThe sharp changes in measured dielectric parameters inthe temperature region are corresponding to the respectivephase transitions in the liquid crystal materials Two regionsof dispersion observed on dielectric charts that is one atlow frequency dispersion and the other at high-frequencyare related to the rotation of molecules about the shortaxis in the former case and about the long axis in thelatter case In addition the variation in activation energy atdifferent regions of temperature corresponds to conductivityas a function of frequency The strong interaction betweenthe Fe

3O4nanoparticles and the liquid crystal anisotropic

Table 2 Subset values of relaxation time (Sec) with temperaturevariation at different frequencies for 119899OBA

Phases Relaxation times (frequency (Hz)) (Sec)

Propyloxybenzoic acids Nanopropyloxybenzoicacids

Isotropic 0185 times 10minus3 (869 times 102) 0191 times 10minus4 (110 times 103)Nematic 0116 times 10minus4 (146 times 104) 0311 times 10minus2 (869 times 102)

Butyloxybenzoic acids Nanobutyloxybenzoicacids

Nematic 0227 times 10minus3 (115 times 103) mdash

Pentyloxybenzoic acids Nanopentyloxybenzoicacids


Hexyloxybenzoic acids Nanohexyloxybenzoicacids


Heptyloxybenzoic acids Nanoheptyloxybenzoicacids

Isotropic mdash 0562 times 10minus3 (281 times 102)Nematic mdash 0125 times 10minus2 (221 times 102)

Octyloxybenzoic acids Nanooctyloxybenzoicacids

Isotropic 0138 times 10minus3 (202 times 103) 0308 times 10minus3 (869 times 102)Nematic 0227 times 10minus3 (115 times 103) 0131 times 10minus2 (121 times 102)Smectic 0131 times 10minus2 (121 times 102) 0130 times 10minus2 (314 times 102)

Nonyloxybenzoic acids Nanononyloxybenzoicacids

Isotropic 0995 times 10minus3 (160 times 102) 0563 times 10minus3 (212 times 102)Nematic mdash 0131 times 10minus2 (121 times 102)Smectic mdash mdash

Decyloxybenzoic acids Nanodecyloxybenzoicacids


Dodecyloxybenzoicacids

Nanododecyloxybenzoicacids


matrix has brought obvious effects on thermal transitionbehavior and dielectric properties of LCs Therefore whenthe nanoparticles are dispersed in the anisotropic liquidcrystallinemedium the particle resonance depending on theangle of the director and the surface reactivity is identifiable

Conflict of Interests

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


Acknowledgments

The authors gratefully acknowledge UGC DRS LEVEL IIIProgram no F5301DRS2009 (SAP-I) dated September 022009 and DST FIST Program no DSTFSTPSI - 0022011dated December 20 2011 New Delhi for providing financialassistance to the Department of Physics ANU

References

[1] X Liu Z Zhong Y Tang and B Liang ldquoReview on thesynthesis and applications of Fe

3O4nanomaterialsrdquo Journal of

Nanomaterials vol 2013 Article ID 902538 7 pages 2013[2] E SaievarIranizad Z Dehghani and M Nadafan ldquoMea-

surement of ferronematic liquid crystal using a single beammethodrdquo International Journal of Engineering Research andScience and Technology vol 3 no 2 pp 1043ndash1047 2014

[3] J Mazo-Zuluaga J Restrepo and J Mejıa-Lopez ldquoSurfaceanisotropy of a Fe

3O4nanoparticle a simulation approachrdquo

Physica B Condensed Matter vol 398 no 2 pp 187ndash190 2007[4] R M Cornell and U Schwertmann The Iron Oxides VCH

mbH Weinheim Germany 1996[5] M Ramakrishna N Rao P V D Prasad and V G K M

Pisipati ldquoOrientational order parameter in alkoxy benzoicacidsmdashoptical studiesrdquo Molecular Crystals and Liquid Crystalsvol 528 pp 49ndash63 2010

[6] H P Hinov and M Petrov ldquoObservations of Sm C layerundulations and Sm C edge-dislocations in NOBA filmsrdquoMolecular crystals and liquid crystals vol 100 no 3-4 pp 223ndash251 1983

[7] V N Vijayakumar K Murugadass and M L N MadhuMohan ldquoInter hydrogen bonded complexes of hexadecylanilineand alkoxy benzoic acids a study of crystallization kineticsrdquoBrazilian Journal of Physics vol 39 no 3 pp 600ndash605 2009

[8] T Chitravel and M L N M Mohan ldquoOccurrence of ambienttemperature and reentrant smectic ordering in an intermolecu-lar hydrogen bonding between alkyl aniline and alkoxy benzoicacidsrdquoMolecular Crystals and Liquid Crystals vol 524 no 1 pp131ndash143 2010

[9] P A Kumar V G K M Pisipati A V Rajeswari and SS Sastry ldquoInduced smectic-G phase through intermolecularhydrogen bondingmdashpart XII thermal and phase behaviour ofp-aminobenzonitrile p-n-alkoxybenzoic acidsrdquo Zeitschrift furNaturforschung A Journal of Physical Sciences vol 57 no 3-4pp 184ndash188 2002

[10] L Bata and G Molnar ldquoDielectric dispersion measurements ina nematic liquid crystal mixturerdquo Chemical Physics Letters vol33 no 3 pp 535ndash539 1975

[11] A V Kovalchuk ldquoRelaxation processes and charge transportacross liquid crystal-electrode interfacerdquo Journal of PhysicsCondensed Matter vol 13 no 46 pp 10333ndash10345 2001

[12] A V Kovalchuk ldquoLow-frequecy dielectric relaxation at thetunnel charge transfer across the liquidelectrode interfacerdquoFunctional Materials vol 8 no 4 pp 690ndash693 2001

[13] O P Gornitska A V Kovalchuk T N Kovalchuk et alldquoDielectric properties of nematic liquid crystals with Fe

3O4

nanoparticles in direct magnetic fieldrdquo Semiconductor PhysicsQuantum Electronics and Optoelectronics vol 12 no 3 pp 309ndash314 2009

[14] H H Liang and J Y Lee ldquoEnhanced electro-optical prop-erties of liquid crystals devices by doping with ferroelectric

nanoparticlesrdquo in FerroelectricsmdashMaterial Aspects M LallartEd chapter 10 InTech Rijeka Croatia 2011

[15] M J Park and O O Park ldquoAlignment of liquid crystals on atopographically nano-patterned polymer surface prepared by asoft-imprint techniquerdquoMicroelectronic Engineering vol 85 no11 pp 2261ndash2265 2008

[16] G W Gray Molecular Structure and the Properties of LiquidCrystals Academic Press New York NY USA 1962

[17] R PavlisKansas USA edition ofMicscapeMagazine MicroscopyUK Front Page 2006

[18] S S Sastry S S Begum T V Kumari V R K Murthy and ST Ha ldquoEffect of magnetite nano particles on p-n-alkyl benzoicacid mesogensrdquo E-Journal of Chemistry vol 9 no 4 pp 2462ndash2471 2012

[19] H Stark ldquoPhysics of colloidal dispersions in nematic liquidcrystalsrdquo Physics Report vol 351 no 6 pp 387ndash474 2001

[20] R W Ruhwandl and E M Terentjev ldquoLong-range forces andaggregation of colloid particles in a nematic liquid crystalrdquoPhysical Review EmdashStatistical Physics Plasmas Fluids andRelated Interdisciplinary Topics vol 55 no 3 pp 2958ndash29611997

[21] F S Y Yeung Y L JHo YW Li andH S Kwok ldquoLiquid crystalalignment layer with controllable anchoring energiesrdquo Journalof Display Technology vol 4 no 1 pp 24ndash27 2008

[22] K Vijayalakshmi Induced smectic phases through hydrogenbonded mesogenic systems [PhD thesis] Acharya NagarjunaUniversity Andhra Pradesh India 2009

[23] S Deepthi and C R S Kumar ldquoMolecular dynamics ofmesogenic p-n-alkoxy benzoic acidrdquo International Journal ofAdvanced Research vol 2 no 2 pp 30ndash34 2014

[24] M Petrov E Keskinova and B Katranchev ldquoThe electrocon-vection in the nematic liquid crystals with short range smecticC orderrdquo Journal of Molecular Liquids vol 138 no 1ndash3 pp 130ndash138 2008

[25] A K Mishra and D Das ldquoInvestigation on Fe-doped ZnOnanostructures prepared by a chemical routerdquoMaterials Scienceand Engineering B Solid-State Materials for Advanced Technol-ogy vol 171 no 1ndash3 pp 5ndash10 2010

[26] D C Thompson M M Tentzeris and J PapapolymerouldquoPackaging of MMICs in multilayer LCP substratesrdquo IEEEMicrowave and Wireless Components Letters vol 16 no 7 pp410ndash412 2006

[27] S Arrhenius ldquoUber die reaktionsgeschwindigkeit bei derinversion von rohrzucker durch saurenrdquo Journal of PhysicalChemistry vol 4 pp 226ndash248 1889

[28] K S Cole and R H Cole ldquoDispersion and absorption indielectrics I Alternating current characteristicsrdquo Journal ofChemical Physics vol 9 no 4 pp 341ndash351 1941

[29] A Thanassoulas E Karatairi C George et al ldquoCdSe nanopar-ticles dispersed in ferroelectric smectic liquid crystals effectsupon the smectic order and the smectic-A to chiral smectic-Cphase transitionrdquo Physical Review EmdashStatistical Nonlinear andSoft Matter Physics vol 88 Article ID 032504 8 pages 2013

[30] M Petrov B Katranchev P M Rafailov et al ldquoPhase andproperties of nanocomposites of hydrogen bonded liquid crys-tals and carbon nanotubesrdquo Physical Review EmdashStatisticalNonlinear and Soft Matter Physics vol 88 Article ID 04250311 pages 2013

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


FluidsJournal of

Atomic and Molecular Physics

Journal of



Advances in Condensed Matter Physics

OpticsInternational Journal of



AstronomyAdvances in

International Journal of


Superconductivity


Statistical MechanicsInternational Journal of


GravityJournal of


AstrophysicsJournal of


Physics Research International


Solid State PhysicsJournal of

Computational Methods in Physics

Journal of



Soft MatterJournal of

Hindawi Publishing Corporationhttpwwwhindawicom

AerodynamicsJournal of

Volume 2014


PhotonicsJournal of


Journal of

Biophysics


ThermodynamicsJournal of


2 Materials and Methods

119901-119899-Alkyloxybenzoic acids (119899OBA) from 119899 = 3 to 10 and 12are procured from Frinton Laboratories Inc USAThe ferricoxides (Fe

3O4) nanoparticles of 20 nm size are procured

from Indian Institute of Technology Chennai Magnetite(Fe3O4) nanoparticles of 01 are doped through continuous

stirring for nearly 3 hours in their isotropic phase of 119901-119899-alkyloxybenzoic acids and after cooling the nanodoped 119901-119899-alkyloxybenzoic acids (N119899OBA) are subjected to study

Textural and phase transition temperatures are measuredusing a Meopta polarising optical microscope (POM) withhot stage as described by Gray [16] The pure and nanodis-persed thermotropic LCs are filled in LC1 ITOcoated cells for90∘ twist aligned (5mm times 5mm times 6 120583m) which are obtainedfromMs Instec Inc USAThe compounds in their isotropicstate are filled in these cells through capillary action methodTextural and phase transition temperatures are studied afterpreparation of the sample and observations are made againafter a gap of period to understand the stability of Fe

3O4

nanoparticlesThe temperature and frequency dependence of capaci-

tance 119862 resistance 119877 and inductance 119871 were measured byusing Newtonrsquos 4th Ltd LCR meter model PM1700 Thecells filled with pure and nanodoped samples are placedin an Instec hot and cold stage (HCS 302) equipped withmicroscope (Olympus BX50) having DP10 camera setupThe temperature is monitored and controlled through acomputer by a software program to an accuracy of plusmn01∘CThe sample is heated to isotropic state and held until attainingthermal equilibrium The data of 119862 119871 and 119877 is taken duringcooling processThemeasuring signal is the square formwithamplitude of 2V The frequency range of measurement isfrom 100Hz to 1MHzThe accuracy of dielectric constant andloss are estimated to the error of 1 and 2 respectively

3 Results and Discussion

31 Textures and Phase Transition Temperatures The phasesand their transition temperatures shown in Table 1 areobtained from POM for nanodoped 119901-119899-alkyloxybenzoicacids which exhibit enantiotropic behavior

The phase transition temperatures for different series ofthose pure 119901-119899-alkyloxybenzoic acids [17] recorded immedi-ately after preparation of N119899OBA are not similar as shownin Table 1 The clearing temperatures have decreased fornanodoped liquid crystals when compared to pure liquidcrystals [18] This decrease is due to increase in the vander Waals attraction among nanoparticles that disturbedthe orientational properties of director in the LCs mediumHence the interaction among them excluding the neighbour-hoodmolecules has formed strong anchoring conditions thatinfluenced the specific orientation to the director resulting intopological defects [19 20]

The nanoparticles appeared to be stabilized after manyinteractions among themselves within the liquid crystalmediumThemobility of these nanoparticles in liquid crystalmedium is limited forming stable dispersions in alkyloxyben-zoic acids It means the surface anchoring properties became

Table 1 Phase transition temperatures of nanoalkyloxy benzoicacids

S number CompoundN119899OBA n= Textures Transition

temperatures (∘C)1 3 I-N-Cr 1472ndash13132 4 I-N-Cr 1422ndash12773 5 I-N-Cr 1418ndash11584 6 I-N-SC-Cr 1392ndash1153ndash9315 7 I-N-SC-Cr 1332ndash937ndash8586 8 I-Ch-Cr 1282ndash88 97 9 I-N-SC-Cr 1318ndash1062ndash8728 10 I-SA-SB-Cr 958ndash828ndash6729 12 I-N-SC-Cr 1188ndash1075ndash878Note I = isotropic N = nematic Ch = cholesteric SA = smectic A SB =smectic B and SC = smectic C

weak such that there is no director distortion in the liquidcrystal phase On the other hand these features reveal clearlythat the elastic energy dominates the magnetic one as longas the orientation of director is fixed [21] The textures ofnematic and smectic phases of pure and doped samples areshown in Figure 1 All the 119899OBA samples have exhibited boththreaded nematic and smectic C [22] from 119899 = 7 to 10 and 12whereas 119899 = 3 to 6 samples show only threaded nematic Inaddition the observed nanodoped 119899OBA liquid crystals havedisplayed threaded nematic and Sm C for 119899 = 6 7 9 and 12and cholesteric phase in nanodoped 8OBA and the phases ofSm A and Sm B in nanodoped 10OBA

These changes can be attributed to the increase in chainlength surface anisotropy and even-odd effect which arecommonly existing in homologous series [23] The texturalchanges start playing into effect in nanodoped samples for119899 = 6 This is a self-explanatory showing the effect of chainlength increase on texturesThe existence of cholesteric phasein N8OBA particularly is due to electroconvection that isusually existing in nematic liquid crystals of short rangeSm C order [24] Comparatively among all in the selectedhomologous series of 119899OBA the 8OBA has displayed shortrange Sm C (from 905∘C to 985∘C) Hence only in 8OBAthe presence of nano has made it modified to cholestericWith the order of chain length increase the nanoparticleseffect the alignment of LC molecules and try to bring theminto layering which is identified as Sm A and Sm B Thesetextures corresponding to different phases are shown inFigures 1(e)ndash1(g)

The aggregation of magnetite nanoparticles appearingin the textures shown in Figure 2 is attributed to a largecontribution to the magnetic anisotropy which is likely tobe located on the particle surface by overcoming randomlyoriented molecules with uniaxial symmetry of mesophases

TheUV-visible spectroscopic studies have also confirmedthe presence of magnetite nanoparticles in the lattice ofsamples

The UV-visible spectra of pure and nanodoped 7OBAmesogen samples are shown in Figure 3 It is observed thatthe spectrum for pure 7OBA does not exhibit any absorption


(a) (b)

(c) (d) (e)

(f) (g)




nanodoped mesogens



120576 The dielec-



1205761

=(119862119901minus 119862119900) 119889

120576119900119860

+ 1 (1)








120591120576=



lowast 106

[ppm∘C]

(2)



(a) (b)


400 600 800

04

06

08

Abso

rptio

n (

)

Wavelength (nm)

7OBA

(a)

Abso

rptio

n (

)


06

N7 OBA

821nm

681nm

418nm

(b)















120576





0

20

40

60

80

100

102 103 104 105 106


f (Hz)

1205761

(a)

0

20

40

60

80

100

120

102 103 104 105 106


f (Hz)

1205761(b)




12057611

= 1205761 tan 120575 (3)





120590ac = 212058712057611990012057611

119891 (4)





120590ac = 120590119900exp (minus 119882

119870119879) (5)







00

times105

minus40

40

80

120

160

200

101 103102 104 105 106

f (Hz)

3OBA3 OBA nano

120591120576

(ppm

∘C)

(a)

00

times105

minus20

20

40

60

80

101 103102 104 105 106

f (Hz)

120591120576

(ppm

∘C)

8OBA8OBA nano

(b)


0

10

20

30

102 103 104 105 106

f (Hz)


12057611

(a)

0

10

20

30

40

50

102 103 104 105 106


10OBA10OBA nano

12057611

(b)





00022 00024 00026 00028

00

20

40

60

80

12OBA

Tminus1 (Kminus1)

times10minus5

120590(S

m)

(a)

00022

05

00

20

25

10

15

12OBA

00024 00026 00028

Tminus1 (Kminus1)

times10minus6

120590(S

m)

(b)

12OBA nano

00022 00024 00026 00028Tminus1 (Kminus1)

00

20

40

60

80times10minus5

115 kHz

11kHz105 kHz

126Hz121Hz

1MHz

120590(S

m)

(c)

00

20

40

60

80

100

12OBA nano

00022 00024 00026 00028Tminus1 (Kminus1)

times10minus6

115 kHz11kHz105 kHz

120590(S

m)

(d)







0

100

200

300

400

500

5OBA nano

Frequency (Hz)

minus100

W(k

Jmol

)

102 103 104 105 106



(a)

5OBA

0

40

80

120

160

Frequency (Hz)

minus40

W(k

Jmol

)

102 103 104 105 106



(b)

0

50

100

150

200

2508OBA nano



minus50

W(k

Jmol

)

Frequency (Hz)102 103 104 105 106

(c)

0

20

40

60

80 8OBA



minus60

minus40

minus20

Frequency (Hz)102 103 104 105 106

W(k

Jmol

)

(d)






360 380 400 420 440

0

20

40

60

80 1 kHz

Temperature (K)

1205761

(a)

0

20

40

60

80 1 kHz

360 380 400 420 440


1

(b)

360 380 400 420 440

Temperature (K)

20

22

24

26

28 1 MHz

1205761

8OBA8OBA nano

(c)

360 380 400 420 440

Temperature (K)

06

08

10

12

14

161 MHz

12057611

8OBA8OBA nano

(d)







0 20 40 60 80 100 1200

20

40

60

80


U V

12057611

1205761

120579

(a)

U V

0

20

40

60

80

12057611

0 20 40 60 80 100 120


1205761

(b)

Smectic

0 20 40 60 80

Semicircle fitting

1205761

1205790

20

40

60

12057611

10OBA nano (388K)

U V

(c)

U V

0

20

40

60

12057611

Smectic

0 20 40 60

Semicircle fitting

1205761

10OBA nano (378K)

120579

(d)






120596 = (V119906)

1(1minus120572)

(6)








4 Conclusions




























Acknowledgments


References


















3O4






[17] R PavlisKansas USA edition ofMicscapeMagazine MicroscopyUK Front 006



















FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




(a) (b)

(c) (d) (e)

(f) (g)




nanodoped mesogens



120576 The dielec-



1205761

=(119862119901minus 119862119900) 119889

120576119900119860

+ 1 (1)








120591120576=



lowast 106

[ppm∘C]

(2)



(a) (b)


400 600 800

04

06

08

Abso

rptio

n (

)

Wavelength (nm)

7OBA

(a)

Abso

rptio

n (

)


06

N7 OBA

821nm

681nm

418nm

(b)















120576





0

20

40

60

80

100

102 103 104 105 106


f (Hz)

1205761

(a)

0

20

40

60

80

100

120

102 103 104 105 106


f (Hz)

1205761(b)




12057611

= 1205761 tan 120575 (3)





120590ac = 212058712057611990012057611

119891 (4)





120590ac = 120590119900exp (minus 119882

119870119879) (5)







00

times105

minus40

40

80

120

160

200

101 103102 104 105 106

f (Hz)

3OBA3 OBA nano

120591120576

(ppm

∘C)

(a)

00

times105

minus20

20

40

60

80

101 103102 104 105 106

f (Hz)

120591120576

(ppm

∘C)

8OBA8OBA nano

(b)


0

10

20

30

102 103 104 105 106

f (Hz)


12057611

(a)

0

10

20

30

40

50

102 103 104 105 106


10OBA10OBA nano

12057611

(b)





00022 00024 00026 00028

00

20

40

60

80

12OBA

Tminus1 (Kminus1)

times10minus5

120590(S

m)

(a)

00022

05

00

20

25

10

15

12OBA

00024 00026 00028

Tminus1 (Kminus1)

times10minus6

120590(S

m)

(b)

12OBA nano

00022 00024 00026 00028Tminus1 (Kminus1)

00

20

40

60

80times10minus5

115 kHz

11kHz105 kHz

126Hz121Hz

1MHz

120590(S

m)

(c)

00

20

40

60

80

100

12OBA nano

00022 00024 00026 00028Tminus1 (Kminus1)

times10minus6

115 kHz11kHz105 kHz

120590(S

m)

(d)







0

100

200

300

400

500

5OBA nano

Frequency (Hz)

minus100

W(k

Jmol

)

102 103 104 105 106



(a)

5OBA

0

40

80

120

160

Frequency (Hz)

minus40

W(k

Jmol

)

102 103 104 105 106



(b)

0

50

100

150

200

2508OBA nano



minus50

W(k

Jmol

)

Frequency (Hz)102 103 104 105 106

(c)

0

20

40

60

80 8OBA



minus60

minus40

minus20

Frequency (Hz)102 103 104 105 106

W(k

Jmol

)

(d)






360 380 400 420 440

0

20

40

60

80 1 kHz

Temperature (K)

1205761

(a)

0

20

40

60

80 1 kHz

360 380 400 420 440


1

(b)

360 380 400 420 440

Temperature (K)

20

22

24

26

28 1 MHz

1205761

8OBA8OBA nano

(c)

360 380 400 420 440

Temperature (K)

06

08

10

12

14

161 MHz

12057611

8OBA8OBA nano

(d)







0 20 40 60 80 100 1200

20

40

60

80


U V

12057611

1205761

120579

(a)

U V

0

20

40

60

80

12057611

0 20 40 60 80 100 120


1205761

(b)

Smectic

0 20 40 60 80

Semicircle fitting

1205761

1205790

20

40

60

12057611

10OBA nano (388K)

U V

(c)

U V

0

20

40

60

12057611

Smectic

0 20 40 60

Semicircle fitting

1205761

10OBA nano (378K)

120579

(d)






120596 = (V119906)

1(1minus120572)

(6)








4 Conclusions




























Acknowledgments


References


















3O4

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




(a) (b)


400 600 800

04

06

08

Abso

rptio

n (

)

Wavelength (nm)

7OBA

(a)

Abso

rptio

n (

)


06

N7 OBA

821nm

681nm

418nm

(b)















120576





0

20

40

60

80

100

102 103 104 105 106


f (Hz)

1205761

(a)

0

20

40

60

80

100

120

102 103 104 105 106


f (Hz)

1205761(b)




12057611

= 1205761 tan 120575 (3)





120590ac = 212058712057611990012057611

119891 (4)





120590ac = 120590119900exp (minus 119882

119870119879) (5)







00

times105

minus40

40

80

120

160

200

101 103102 104 105 106

f (Hz)

3OBA3 OBA nano

120591120576

(ppm

∘C)

(a)

00

times105

minus20

20

40

60

80

101 103102 104 105 106

f (Hz)

120591120576

(ppm

∘C)

8OBA8OBA nano

(b)


0

10

20

30

102 103 104 105 106

f (Hz)


12057611

(a)

0

10

20

30

40

50

102 103 104 105 106


10OBA10OBA nano

12057611

(b)





00022 00024 00026 00028

00

20

40

60

80

12OBA

Tminus1 (Kminus1)

times10minus5

120590(S

m)

(a)

00022

05

00

20

25

10

15

12OBA

00024 00026 00028

Tminus1 (Kminus1)

times10minus6

120590(S

m)

(b)

12OBA nano

00022 00024 00026 00028Tminus1 (Kminus1)

00

20

40

60

80times10minus5

115 kHz

11kHz105 kHz

126Hz121Hz

1MHz

120590(S

m)

(c)

00

20

40

60

80

100

12OBA nano

00022 00024 00026 00028Tminus1 (Kminus1)

times10minus6

115 kHz11kHz105 kHz

120590(S

m)

(d)







0

100

200

300

400

500

5OBA nano

Frequency (Hz)

minus100

W(k

Jmol

)

102 103 104 105 106



(a)

5OBA

0

40

80

120

160

Frequency (Hz)

minus40

W(k

Jmol

)

102 103 104 105 106



(b)

0

50

100

150

200

2508OBA nano



minus50

W(k

Jmol

)

Frequency (Hz)102 103 104 105 106

(c)

0

20

40

60

80 8OBA



minus60

minus40

minus20

Frequency (Hz)102 103 104 105 106

W(k

Jmol

)

(d)






360 380 400 420 440

0

20

40

60

80 1 kHz

Temperature (K)

1205761

(a)

0

20

40

60

80 1 kHz

360 380 400 420 440


1

(b)

360 380 400 420 440

Temperature (K)

20

22

24

26

28 1 MHz

1205761

8OBA8OBA nano

(c)

360 380 400 420 440

Temperature (K)

06

08

10

12

14

161 MHz

12057611

8OBA8OBA nano

(d)







0 20 40 60 80 100 1200

20

40

60

80


U V

12057611

1205761

120579

(a)

U V

0

20

40

60

80

12057611

0 20 40 60 80 100 120


1205761

(b)

Smectic

0 20 40 60 80

Semicircle fitting

1205761

1205790

20

40

60

12057611

10OBA nano (388K)

U V

(c)

U V

0

20

40

60

12057611

Smectic

0 20 40 60

Semicircle fitting

1205761

10OBA nano (378K)

120579

(d)






120596 = (V119906)

1(1minus120572)

(6)








4 Conclusions




























Acknowledgments


References


















3O4

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




0

20

40

60

80

100

102 103 104 105 106


f (Hz)

1205761

(a)

0

20

40

60

80

100

120

102 103 104 105 106


f (Hz)

1205761(b)




12057611

= 1205761 tan 120575 (3)





120590ac = 212058712057611990012057611

119891 (4)





120590ac = 120590119900exp (minus 119882

119870119879) (5)







00

times105

minus40

40

80

120

160

200

101 103102 104 105 106

f (Hz)

3OBA3 OBA nano

120591120576

(ppm

∘C)

(a)

00

times105

minus20

20

40

60

80

101 103102 104 105 106

f (Hz)

120591120576

(ppm

∘C)

8OBA8OBA nano

(b)


0

10

20

30

102 103 104 105 106

f (Hz)


12057611

(a)

0

10

20

30

40

50

102 103 104 105 106


10OBA10OBA nano

12057611

(b)





00022 00024 00026 00028

00

20

40

60

80

12OBA

Tminus1 (Kminus1)

times10minus5

120590(S

m)

(a)

00022

05

00

20

25

10

15

12OBA

00024 00026 00028

Tminus1 (Kminus1)

times10minus6

120590(S

m)

(b)

12OBA nano

00022 00024 00026 00028Tminus1 (Kminus1)

00

20

40

60

80times10minus5

115 kHz

11kHz105 kHz

126Hz121Hz

1MHz

120590(S

m)

(c)

00

20

40

60

80

100

12OBA nano

00022 00024 00026 00028Tminus1 (Kminus1)

times10minus6

115 kHz11kHz105 kHz

120590(S

m)

(d)







0

100

200

300

400

500

5OBA nano

Frequency (Hz)

minus100

W(k

Jmol

)

102 103 104 105 106



(a)

5OBA

0

40

80

120

160

Frequency (Hz)

minus40

W(k

Jmol

)

102 103 104 105 106



(b)

0

50

100

150

200

2508OBA nano



minus50

W(k

Jmol

)

Frequency (Hz)102 103 104 105 106

(c)

0

20

40

60

80 8OBA



minus60

minus40

minus20

Frequency (Hz)102 103 104 105 106

W(k

Jmol

)

(d)






360 380 400 420 440

0

20

40

60

80 1 kHz

Temperature (K)

1205761

(a)

0

20

40

60

80 1 kHz

360 380 400 420 440


1

(b)

360 380 400 420 440

Temperature (K)

20

22

24

26

28 1 MHz

1205761

8OBA8OBA nano

(c)

360 380 400 420 440

Temperature (K)

06

08

10

12

14

161 MHz

12057611

8OBA8OBA nano

(d)







0 20 40 60 80 100 1200

20

40

60

80


U V

12057611

1205761

120579

(a)

U V

0

20

40

60

80

12057611

0 20 40 60 80 100 120


1205761

(b)

Smectic

0 20 40 60 80

Semicircle fitting

1205761

1205790

20

40

60

12057611

10OBA nano (388K)

U V

(c)

U V

0

20

40

60

12057611

Smectic

0 20 40 60

Semicircle fitting

1205761

10OBA nano (378K)

120579

(d)






120596 = (V119906)

1(1minus120572)

(6)








4 Conclusions




























Acknowledgments


References


















3O4

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




00

times105

minus40

40

80

120

160

200

101 103102 104 105 106

f (Hz)

3OBA3 OBA nano

120591120576

(ppm

∘C)

(a)

00

times105

minus20

20

40

60

80

101 103102 104 105 106

f (Hz)

120591120576

(ppm

∘C)

8OBA8OBA nano

(b)


0

10

20

30

102 103 104 105 106

f (Hz)


12057611

(a)

0

10

20

30

40

50

102 103 104 105 106


10OBA10OBA nano

12057611

(b)





00022 00024 00026 00028

00

20

40

60

80

12OBA

Tminus1 (Kminus1)

times10minus5

120590(S

m)

(a)

00022

05

00

20

25

10

15

12OBA

00024 00026 00028

Tminus1 (Kminus1)

times10minus6

120590(S

m)

(b)

12OBA nano

00022 00024 00026 00028Tminus1 (Kminus1)

00

20

40

60

80times10minus5

115 kHz

11kHz105 kHz

126Hz121Hz

1MHz

120590(S

m)

(c)

00

20

40

60

80

100

12OBA nano

00022 00024 00026 00028Tminus1 (Kminus1)

times10minus6

115 kHz11kHz105 kHz

120590(S

m)

(d)







0

100

200

300

400

500

5OBA nano

Frequency (Hz)

minus100

W(k

Jmol

)

102 103 104 105 106



(a)

5OBA

0

40

80

120

160

Frequency (Hz)

minus40

W(k

Jmol

)

102 103 104 105 106



(b)

0

50

100

150

200

2508OBA nano



minus50

W(k

Jmol

)

Frequency (Hz)102 103 104 105 106

(c)

0

20

40

60

80 8OBA



minus60

minus40

minus20

Frequency (Hz)102 103 104 105 106

W(k

Jmol

)

(d)






360 380 400 420 440

0

20

40

60

80 1 kHz

Temperature (K)

1205761

(a)

0

20

40

60

80 1 kHz

360 380 400 420 440


1

(b)

360 380 400 420 440

Temperature (K)

20

22

24

26

28 1 MHz

1205761

8OBA8OBA nano

(c)

360 380 400 420 440

Temperature (K)

06

08

10

12

14

161 MHz

12057611

8OBA8OBA nano

(d)







0 20 40 60 80 100 1200

20

40

60

80


U V

12057611

1205761

120579

(a)

U V

0

20

40

60

80

12057611

0 20 40 60 80 100 120


1205761

(b)

Smectic

0 20 40 60 80

Semicircle fitting

1205761

1205790

20

40

60

12057611

10OBA nano (388K)

U V

(c)

U V

0

20

40

60

12057611

Smectic

0 20 40 60

Semicircle fitting

1205761

10OBA nano (378K)

120579

(d)






120596 = (V119906)

1(1minus120572)

(6)








4 Conclusions




























Acknowledgments


References


















3O4

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




00022 00024 00026 00028

00

20

40

60

80

12OBA

Tminus1 (Kminus1)

times10minus5

120590(S

m)

(a)

00022

05

00

20

25

10

15

12OBA

00024 00026 00028

Tminus1 (Kminus1)

times10minus6

120590(S

m)

(b)

12OBA nano

00022 00024 00026 00028Tminus1 (Kminus1)

00

20

40

60

80times10minus5

115 kHz

11kHz105 kHz

126Hz121Hz

1MHz

120590(S

m)

(c)

00

20

40

60

80

100

12OBA nano

00022 00024 00026 00028Tminus1 (Kminus1)

times10minus6

115 kHz11kHz105 kHz

120590(S

m)

(d)







0

100

200

300

400

500

5OBA nano

Frequency (Hz)

minus100

W(k

Jmol

)

102 103 104 105 106



(a)

5OBA

0

40

80

120

160

Frequency (Hz)

minus40

W(k

Jmol

)

102 103 104 105 106



(b)

0

50

100

150

200

2508OBA nano



minus50

W(k

Jmol

)

Frequency (Hz)102 103 104 105 106

(c)

0

20

40

60

80 8OBA



minus60

minus40

minus20

Frequency (Hz)102 103 104 105 106

W(k

Jmol

)

(d)






360 380 400 420 440

0

20

40

60

80 1 kHz

Temperature (K)

1205761

(a)

0

20

40

60

80 1 kHz

360 380 400 420 440


1

(b)

360 380 400 420 440

Temperature (K)

20

22

24

26

28 1 MHz

1205761

8OBA8OBA nano

(c)

360 380 400 420 440

Temperature (K)

06

08

10

12

14

161 MHz

12057611

8OBA8OBA nano

(d)







0 20 40 60 80 100 1200

20

40

60

80


U V

12057611

1205761

120579

(a)

U V

0

20

40

60

80

12057611

0 20 40 60 80 100 120


1205761

(b)

Smectic

0 20 40 60 80

Semicircle fitting

1205761

1205790

20

40

60

12057611

10OBA nano (388K)

U V

(c)

U V

0

20

40

60

12057611

Smectic

0 20 40 60

Semicircle fitting

1205761

10OBA nano (378K)

120579

(d)






120596 = (V119906)

1(1minus120572)

(6)








4 Conclusions




























Acknowledgments


References


















3O4

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




0

100

200

300

400

500

5OBA nano

Frequency (Hz)

minus100

W(k

Jmol

)

102 103 104 105 106



(a)

5OBA

0

40

80

120

160

Frequency (Hz)

minus40

W(k

Jmol

)

102 103 104 105 106



(b)

0

50

100

150

200

2508OBA nano



minus50

W(k

Jmol

)

Frequency (Hz)102 103 104 105 106

(c)

0

20

40

60

80 8OBA



minus60

minus40

minus20

Frequency (Hz)102 103 104 105 106

W(k

Jmol

)

(d)






360 380 400 420 440

0

20

40

60

80 1 kHz

Temperature (K)

1205761

(a)

0

20

40

60

80 1 kHz

360 380 400 420 440


1

(b)

360 380 400 420 440

Temperature (K)

20

22

24

26

28 1 MHz

1205761

8OBA8OBA nano

(c)

360 380 400 420 440

Temperature (K)

06

08

10

12

14

161 MHz

12057611

8OBA8OBA nano

(d)







0 20 40 60 80 100 1200

20

40

60

80


U V

12057611

1205761

120579

(a)

U V

0

20

40

60

80

12057611

0 20 40 60 80 100 120


1205761

(b)

Smectic

0 20 40 60 80

Semicircle fitting

1205761

1205790

20

40

60

12057611

10OBA nano (388K)

U V

(c)

U V

0

20

40

60

12057611

Smectic

0 20 40 60

Semicircle fitting

1205761

10OBA nano (378K)

120579

(d)






120596 = (V119906)

1(1minus120572)

(6)








4 Conclusions




























Acknowledgments


References


















3O4

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




360 380 400 420 440

0

20

40

60

80 1 kHz

Temperature (K)

1205761

(a)

0

20

40

60

80 1 kHz

360 380 400 420 440


1

(b)

360 380 400 420 440

Temperature (K)

20

22

24

26

28 1 MHz

1205761

8OBA8OBA nano

(c)

360 380 400 420 440

Temperature (K)

06

08

10

12

14

161 MHz

12057611

8OBA8OBA nano

(d)







0 20 40 60 80 100 1200

20

40

60

80


U V

12057611

1205761

120579

(a)

U V

0

20

40

60

80

12057611

0 20 40 60 80 100 120


1205761

(b)

Smectic

0 20 40 60 80

Semicircle fitting

1205761

1205790

20

40

60

12057611

10OBA nano (388K)

U V

(c)

U V

0

20

40

60

12057611

Smectic

0 20 40 60

Semicircle fitting

1205761

10OBA nano (378K)

120579

(d)






120596 = (V119906)

1(1minus120572)

(6)








4 Conclusions




























Acknowledgments


References


















3O4

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




0 20 40 60 80 100 1200

20

40

60

80


U V

12057611

1205761

120579

(a)

U V

0

20

40

60

80

12057611

0 20 40 60 80 100 120


1205761

(b)

Smectic

0 20 40 60 80

Semicircle fitting

1205761

1205790

20

40

60

12057611

10OBA nano (388K)

U V

(c)

U V

0

20

40

60

12057611

Smectic

0 20 40 60

Semicircle fitting

1205761

10OBA nano (378K)

120579

(d)






120596 = (V119906)

1(1minus120572)

(6)








4 Conclusions




























Acknowledgments


References


















3O4

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics










4 Conclusions




























Acknowledgments


References


















3O4

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




Acknowledgments


References


















3O4

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics








FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics



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