Effect of (CoO) Nanoparticles on Someoptical Properties of (PVA- Paam) Composite

Effect of (CoO) Nanoparticles on Someoptical Properties of (PVA- Paam) Composite

*Majeed Ali Habeeb, *Hiader Mohammed Mohssen

• University of Babylon,College of Education for pure sciences, Department of Physics.Iraq

  **Raheem Gaayid Kadhim

  ** University of Babylon, College of Sciences, Department of Physics. Iraq

  AbstractIn the present work, many samples have been prepared by adding different weight percentages of cobalt oxide nanoparticles (3, 6, 9, and 12)wt. %.hese samples were prepared by casting method. The absorptionspectrum has been recorded in the wavelength range (200-1100)nm and calculated energy gap of the indirect allowed and forbidden transitionas well asoptical constant such as(refractive index, extinction coefficient and read and imaginary dielectric constants).

  Keywords(PVA-PAAm) Composites, Cobalt Oxide

  Nanoparticles, Optical Properties

  I INTRODUCTION

  and optical properties of polymers have attracted much attention in view of their application in electronic and optical devices. Electrical conduction in polymers has been studied aiming to understand the nature of the charge transport prevalent in these materials while the optical properties are aimed at achieving better reflection, antireflection, interference and polarization properties[1].Although many people probably do not realize it, everyone is familiar with polymers. They are all around in everyday use, in rubber, plastics, resins , in adhesives and adhesive tapes, their common structural feature is the presence of long covalently bonded chains of atoms. They are an extraordinarily versatile class of materials, with properties of a given type often having enormously different values for different polymers and even sometimes for the same polymer in different physical states[2].Optical properties of polymers constitute an important aspects in study of electronic transition and the possibility of their application as optical filters, a cover in solar collection, selection surfaces and green house. The information about the electronic structure of crystalline and amorphous semiconductors has been mostly accumulated from the studies of optical properties in wide frequency range. The significance of amorphous semiconductors is in its energy gap [3]. Polyvinyl alcohol (PVA) is a potential material having a very high dielectric strengthgood charge storage capacity and dopant-dependent electrical and opticalproperties[3]. So the wide range of applications of PVA can be even more extended byincorporation of dopant into PVA matrix [4].The advantage of poly vinyl alcohol that has the ability to blend into the water which is resistant to do solvents, oils, and has the ability exceptional adhesion

  materials cellulosic so uses his wide is used in making paper and textile industries in the manufacture of membranes resistance to oxygen in the coating photographic film,[5] also polyvinylalcohol semi-amorphous [6].Polyacrylamide (PAAm) is crystal solid very stable that viscosity in 25C its between(10-5000)*10-3 (Poise)by used method sedimentation in the ultracentrifuge .(PAAm) are polymers dissolved in water and these no similar the monomer anther non-baneful. For contain on nitrogen theoretical 19.7% but technological its 15.8% to 16.8% and inform percentage contain on hydrogen 3.6 and this last given him properties many a polarization and have application width of fieldsthe industry,livingand medicine[7] .Further, polymers, on doping with noble metal nanoparticles, show novel and distinctive properties obtained from unique combination of the inherent characteristics of polymers and properties of metal nanoparticles [8].The inorganic or organic nanoparticles doping into the polymer matrix an provide high-performance novel materials that findapplications in many industrial fields[9].The oxides of transition metals, such as copper, iron, nickel, cobalt, and zinc, have received many important applications, including magnetic storage media, solar energy transformation, electronic, semiconductor, varistor, catalysis, and electrical and optical switching devices[10].(CoO) nanoparticles in the 20-30nm rang. Have been prepared by thermal decomposition the particles were characterized to be pyramid shape with hexagonal close-packed structure [11] has cubic rock-salt structure and received considerable attention over last few years due to its importance in technological applications catalytic properties [12].

  1. MATERIALS AND METHODS

     The composite of polymers which consisting of PVA and PAAm were prepare by dissolved the polymers in 30ml of distilled water by using magnetic stirrer used to mixing process to get solution more homogeneous at heat (75C) for (1hour) with ratios (8:2)of PVA and PAAm then the CoO nanoparticles was added slowly to the composite polymers with different concentrations are (3,6,9and12)wt.% The resultsolution was stirred continuously until the solution mixture became a homogeneous viscous appearance at room temperature for times (15-30) minutes. (PVA-PAAm- CoO)nanocomposite membranes are obtained by leaving the mixture solution in a petre dish diameter (5.5cm)at room

     temperature.

     The absorption spectra of (PVA-PAAm-CoO) nanocompositeshave been recording in the length range (200-1100) nm by using (UV-1800) Shimadzu spectrophotometer, theabsorption coefficient () was calculated from the following equation:[13]

     =2.303 A\d (1)

     Where A is absorbance and d is the thickness sample.

     The optical energy gap has been calculated by using this equation.[15]

     h= B (h Eg)r .(2)

     Where:h is the energy of photon B is proportionality constantEgoptical energy gap and ris an index having the values of (r=2) this indicates an allowed indirect transition. When the value of (r=3), this indicates forbidden indirect transition.

     The extinction coefficient (k) is directly proportional to the absorption coefficient (). [14] k=/4…(3)

     Where is the wavelength of light.

     The refractive index has been calculated by using this equation. [16]

     n= [4R/(R-1)2-k2]1/2-(R+1/R-1) …. (4)

     The parameter 1 is the real part ofdielectric constant;2 is theimaginary part of dielectricconstant calculated from these equations. [17]

     1 =n2-k2………………… (5)

     2=2nk . (6)

  2. RESULTS AND DISCUSSION

Absorbance

The relationship between the absorbance and wavelength of the incident light for (PVA-PAAm-CoO)nanocomposites at room temperature shown in Fig(1).From this figure note that intensity of the peak increases as a result of increasing concentration of (CoO) nanoparticles and no shift in the peak position. The increase of absorbance with increase of weight percentage of the (CoO) nanoparticles, is due to absorb the incident light by free electrons [18].

1

0.8

0.6

pure

3%a 6%a 9%a

0.4

0.2

0

200 300 400 500 600 700 800 900

nm

Fig(1):Variation of optical absorbance for (PVA-PAAm-CoO) nanocomposites with wavelength.

Fig(2).shows the relation between the absorption coefficient and photon energy of the (PVA-PAAm-CoO) nanocomposites.We note that the change in the absorption coefficient is small at low energies this indicates the possibility of electronic transitions is a few. At high energy, the change of absorption coefficient is large. The results showed that the values of absorption coefficient of the( PVA- PAAm- CoO)nanocomposites is low(<104cm-1) which indicates the indirect electronic transition. [16]

pure 3% 6%

9%

500

400

(cm)-1

300

200

100

0

1 1.5 2 2.5 3 3.5 4 4.5 5 5.5

photon energy (ev)

Fig(2): Absorption coefficient for(PVA-PAAm- CoO)nanocomposites with various photon energy.

The relation between (h)1/2 (cm .ev)1/2and photon energy of nanocomposites shown in Fig (3).From this figure we note that the value of optical energy gap decrease by increasing of weight percentage of (CoO) nanoparticles, also the transition which occurs in the samples is allowed indirect transition.This attributed to the creation of site levels in the forbidden energy gap; the transition in this case is conducted in two stages that involve the transition of electron from the valence band to the local levels to the conduction band as a result of increasing the cobalt oxide nanoparticles weight percentage. Thisbehavior is attributed to the fact that nanocomposites are of heterogeneous type (i.e. the electronic conduction depends on added concentration), the increase of the added rate provides paths in the polymer which facilitate the crossing of electron from the valence band to the conduction band, this explains the decrease of energy gap with increase (CoO) nanoparticles. [19]

(h) 1/2(cm-1.ev) 1/2

.

1200

1000

800

600

400

200

0

pure

%wt3

%wt6

%wt9

1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6

photon energ (ev)

Fig(3):The relationship between (h)1/2(cm-1.ev)1/2and photon energyof (PVA-PAAm-CoO)nanocomposites

pure

%wt3

%wt6

%wt9

(h)1/3(cm-1.ev)1/3

Fig(4).shows the relationship between (h)1/3 (cm-1. ev)1/3 and photon energy of nanocomposites ,we can see from this figure the value of forbidden energy gap also decreases by increasing weight percentage of (CoO)nanoparticlesas well as this value of forbidden indirect transition is less than the one value which is represent allowed indirect transition.[19]Theforbiddenenergy gab valuesdependence in general on the crystal structure of the nanocomposites and on thearrangement and distribution way of atoms in the crystal lattice, also the decreaseenergy band gap due to decease the distance between the valance band and conduction band withincrease the concentration of (CoO)nanoparticles.[22]

800

700

600

500

400

300

200

100

0

1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6

photon energy (ev)

Fig(4): The relationship between (h)1/3(cm -1ev)1/3and photon energy of(PVA-PAAm-CoO)nanocomposites

1

0.5

0

Refractive index

The behavior of refractive index with photon energy of (PVA- PAAm-CoO)nanocompositesshown in Fig(5). This figure shows that the refractive index of (PVA- PAAm- CoO)nanocompositesincrease with increasesconcentration of the(CoO)nanoparticles,The reason of this result is, the increase of the (CoO) concentration leads to increase the density of the nanocomposites.[20]

2.5

2

1.5

n pure

%w3 n

%w6n

%w9 n

1

3

photon energy (ev)

5

Fig (5): The variation between refractive index and photon energy of(PVA- PAAm-CoO)nanocomposites

The variation between extinction coefficient of (PVA- PAAm-CoO)nanocomposites with photon energy shown in Fig (6). This figure shows that the extinction coefficient has

low values at (UV-region) and with little concentration as well as it is increased with increasing additive concentrations of (CoO)nanoparticles because of increasing in absorption coefficient, but at visible region we note that the extinction coefficient is very low because of the low absorption at this region. [21]

.1E-03

.9E-04

.8E-04

.7E-04

.6E-04

.5E-04

.4E-04

.3E-04

.2E-04

.1E-04

.0E+00

1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6

photon energy (ev)

9%k

6%k

3%k

pure

Extinction coefficient

Fig (6): The relationship between extinction coefficient and photon energy of (PVA-PAAm-CoO)nanocomposites.

Real dielectric constant

Figs(7,8).show the variation of real and imaginary parts of dielectric constant of (PVA-PAAm-CoO) nanocomposites.This concluded that the variation of 1mainly depends on (n2) because of small values of the (k2), while the 2 mainly depends on the (k) values which are related to thevariation of absorption coefficient. [17]

5

4.5

4

3.5

3

2.5

2

1.5

1

0.5

0

pure

%w3

%w6

%w9

1

2

3

4

5

photon energy (ev)

Fig (7):Variation of real part of dielectric constant with photon energy of (PVA-PAAm-CoO)nanocomposites

2.50E-03

2.00E-03

1.50E-03

pure

%w3

%w6

%w9

1 1.5 2 2.5 3 3.5 4 4.5 5 5.5

photon energy (ev)

1.00E-03

5.00E-04

0.00E+00

imaginary dielectric constant

Fig (8):Variation of imaginary part of dielectric constant with photon energy of (PVA-PAAm-CoO)nanocomposites

CONCLUSION

1. The absorption coefficient for all (PVA-PAAm- CoO) nanocomposites increases with increasing of CoO wt. %nanoparticles.

2. The energy gap of indirect transition decreases with increasing of CoO wt. %nanoparticles.

3. Extinction coefficient, refractive index and dielectric constant (real and imaginary) increased with increasing of concentration.

REFERENCES

1. Althues. H, Henley J andKaskel S, 2007,"(Functional inorganic nanofillers for transparent polymers)",ChemSoc Rev; 36: 1454_6550.

2. David, 2002, "(Introduction to physical polymer)", new Cambridge university press.

3. P.Gabriel and A-KMaaroufi, 2011, "(Critical filler concentration for electro conductive polymer composites)",Society of Plastics Engineers (SPE),10.1002/spepro.00352,P 3/3.

4. O.G.Abdullah and S.A.Hussein,2010,"(Variation of optical band Gap width of PVA films Doped with Aluminum iodide)", Inter conference onManufacturingSci and Tech(ICMST).

5. J. E. Mark, 1999,"(Polymer Data Hand Book)", Oxford University Press.

6. M. Abdelaziz and E.M. Abdelrazek, 2006,"(Effect of dopant mixture on structural, optical and electron spin resonance properties of polyvinyl alcohol)",Physica. doi:10.1016/j.physb.07.67.

7. R.H.Abaas,2006,"(Study the effect ofgamma raysinthe physical properties(electrical ,

   opticalandrheological)ofmaterialpolyacrylamide(PAAm)dissolved indistilledwater", theses, College of Education,Al-Mustansiryah University ,Iraq.

8. A.Gautam and S. Ram, 2010,"(Preparation and thermochemical properties of Ag-PVA nanocomposite films)", Mater. Chem. Phys. 119: 266-271.

9. I.A .Latifand H .M .Abdullah, 2012,"(Dielectric Constant properties of Poly (vinyl acetal)/PVA Dispersed with ZnO Nanoparticles)", Second scientific coference-TikritUniversity.

10. W. Wang and G .Zhang, 2009,"Synthesis and optical properties of high-parity CoO nanowires prepared by an environ mentally friendly molten salt route ", J, of crystal Growth 311:4275-4280.

11. X .He and H.shi,2011,"synthesis and anomalous magnetic properties of hexagonal CoO Nanoparticles ",material .Res Bull,46:1692-1697.

12. C. Xu, Y. Liu, G. Xu and G. Wang, 2002,"(Fabrication of CoO. nanorods Via thermal decomposition of CoC2O4 precursor)", Chemical physical Letters 366: 567571.

13. F.L.Rashed,A.Hashim,M.A.Habeeb,S.R.Salman and H.Ahmed,2013,"(preparation of PS-PMMA copolymer and study the effect of sodium fluoride on its optical properties)",journal of Engineering and Applied Sciences,8(5):137-139.

14. R Tintu, K. Saurav, K. Sulakshna, Vpn. Nampoori, Pradhakrishna and Sheenuthomas,2010,"(Ge28Se60Sb12 /PVA composite films for photonic application)", Journal of Non-Oxide Glasses, 2( 4):167-174.

15. G. Sami Salman .2005."(Optical and structural properties of SnO2 membranes Tinged by fluorosis and gamma-ray irradiated)", Master, Faculty of Sciences, University of Baghdad.

16. A.Hashim,H.Hakim and M.Ali,2013,"(Optical Constants for (PVA- PEG-Al2(SO4)3 Composites)", Chemical and Materials Engineering 2(2): 47-49.

17. M.A.Habeeb, 2011,"(Effect of rate of deposition on the 0ptical parameters of GaAs films)",European journal of Scientific Research,57(3):478-484. [18] P.U. Asogwa,2011,"(Band gap shift and optical characterization of PVA Capped PbO thin films: Effect of thermal annealing)", ChalcogenideLetters, 8(3):163-170.

1. M. Dahshan, 2002, "(Introduction to material science and Engineering)", 2nd ed.

2. Ahmad A.H., Awatif A.M. and Zeid Abdul-Majied N., 2007, "Dopping Effect On Optical Constants of Polymethylmethacrylate (PMMA)", J. of Eng.& Technology, 25(4).

[21 ]K. Bula1, T. Jesionowski and S. Borysiak,2011,"(Proceedings of the Conference of Multiphase Polymers and Polymer Composites: From Nan scale to Macro Composites)", Paris-Est., Creteil University, June, France.

[22] Abd El-Raheem M.M, 2007, J. Phys. Condens. Matter. 19, 216209.