Polymer composite of polyvinyl alcohol (PVA), nickel nitrate  have been prepared by solution cast method for different doping concentrations of nickel nitrate. The optical characterization has been done by analyzing the absorption spectra in the spectral region 200–800 nm. It was found that the optical energy gap decreases with increasing NiNO3 content.  The refractive index (n), extinction coefficient (k), static dielectric constant have been calculated for the investigated films. The optical constants are changing with increase the weight percentages of nickel nitrate. Key words: composite, polymer,  optical constants, nickel nitrate 

Ahmed, Hind

Hakim, Hussein

Hashim, Ahmed

Rabee, Bahaa H.

Salman, Saba R.

English

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Advances in Physics Theories and Applications                                                                                                  www.iiste.org ISSN 2224-719X (Paper) ISSN 2225-0638 (Online) Vol.20, 2013          152 Preparation and Study of Optical Properties of (Polymer-Nickel Nitrate) Composite  Hind Ahmed, Bahaa H. Rabee, Hussein Hakim, Ahmed Hashim , Saba R. Salman     Babylon University, College of Education, Department of Physics, Iraq E-Mail: ahmed_taay@yahoo.com  ABSTRACT Polymer composite of polyvinyl alcohol (PVA), nickel nitrate  have been prepared by solution cast method for different doping concentrations of nickel nitrate. The optical characterization has been done by analyzing the absorption spectra in the spectral region 200–800 nm. It was found that the optical energy gap decreases with increasing NiNO3 content.  The refractive index (n), extinction coefficient (k), static dielectric constant have been calculated for the investigated films. The optical constants are changing with increase the weight percentages of nickel nitrate. Key words: composite, polymer,  optical constants, nickel nitrate    1. INTRODUCTION       The doped polymers may present useful applications in integrated optics or in real time holography. In order to tailor materials with improved properties within the doped polymer class, it is necessary to understand and control the electronic mechanisms involved in the optical behavior[1]. The physical properties of polymers may be affected by doping, the certain structural, optical, mechanical, electrical and magnetic properties of the selected polymer can be controllably modified owing to the type of the doping, concentration, and the way in which it penetrates and interacts with the chains of the polymer[2]. Polyvinyl Alcohol offers a combination of excellent film forming and binder characteristics, along with insolubility in cold water and organic solvents. This combination of characteristics is useful in a variety of applications . Moreover, it contains a carbon backbone with hydroxyl groups attached to methane carbons. These hydroxyl groups can be a source of hydrogen bonding, hence the assistance in the formation of polymer blends [3]. Recently, we focused our research on studying the optical properties of PVA filled with (NiNO3) fillers.  2. MATERIALS AND METHODS   PVA and NiNO3 used as received. The experiment was carried out at room temperature (25oC). Different weight percentages of PVA and NiNO3 are dissolved completely in 30ml (weight of each sample 1 gm and the concentrations of nickel nitrate are 0, 0.5, 1, 1.5 wt.%) distilled under constant stirring for 1hour while the mixture was heated up till 90oC then the mixture was let to cool down to room temperature (25oC) while the stirring of the mixture was carried out to ensure a homogenous composition. To cast the film, the mixture for each NiNo3 concentrations was poured in a casting glass plate and let it dry at room temperature for 120 hours. At the expiry of this time, the films were ready which were peeled off the casting glass plate and cut into pieces for characterization by measuring optical properties using double-beam spectrophotometer.  3. RESULTS AND DISCUSSION          The absorption spectra of the composite with different concentrations of nickel nitrite is shown in Fig. 1.  Advances in Physics Theories and Applications                                                                                                  www.iiste.org ISSN 2224-719X (Paper) ISSN 2225-0638 (Online) Vol.20, 2013          153  Fig. 1: Absorbance  of NiNO3 /PVA composite with different concentrations of nickel nitrite.      It is clear from Fig 1 that as the concentration of the NiNO3 component in the polymer composition increases the absorption         Fig.2 shows the variation of absorption coefficient  for composite with  various photon energy. The absorption coefficient (α) of composite depends on optical absorbance (A) and thickness of film (d) which is evaluated using the relation [4]: )1......(........../303.2 dA=α   Fig.2 absorption coefficient  for composite with  various photon energy  The optical energy gap (Eg) of the thin films has been determined from absorption coefficient data as a function of photon energy. According to the generally accepted non-direct transition model for amorphous semiconductors proposed by Tauc [5],  )2....(..........)( rgEhBh −= υυα  Where B is a constant related to the properties of the valance band and conduction band, hυ is the photon energy , Eg is the optical energy band gap, r=2,or3 for indirect allowed and indirect forbidden transition .From the linear plots of (α h ν) l/r against (h ν), the optical energy gap has been determined from the intercepts of extrapolations to zero with the photon energy axis (αhν)1/r → 0 . From the results obtained it is seen that an decrease of concentration of NiNO3 in the system leads to an increase in the optical band gap. The increase in band gap with decrease in concentration can be due to the decrease in cluster size of the parent solution. It is found that as the 00.511.522.533.54200 300 400 500 600 700 800Wavelength(nm)Absorbancepure0.5 wt.%1 wt.%1.5 wt.%0246810121 2 3 4 5 6 7Photon energy(eV)pure0.5 wt .%1 wt .%1.5 wt.%α(cm)-1Advances in Physics Theories and Applications                                                                                                  www.iiste.org ISSN 2224-719X (Paper) ISSN 2225-0638 (Online) Vol.20, 2013          154 concentration of the   NiNO3 decreases there is a red shift in band edge and a change in the slope of absorption spectra[6] as shown in figures (3a.and 3b.).   Fig..3a. the relationship between (αhυ)1/2(cm-1.eV)1/2 and photon energy of  composites.  Fig..3b. the relationship between (αhυ)1/3(cm-1.eV)1/3 and photon energy of  composites.      Fig.4 shows the variation of extinction coefficient  for composite with  various wavelength. The extinction coefficient K, is related to the absorption coefficient α  can be calculated by using the relation[6]: )3.....(..............................4/ παλ=K   05101520253035400 1 2 3 4 5 6 7Photon energy(eV)pure0.5 wt.%1 wt.%1.5 wt.% (αhυ)1/2(cm-1.eV)1/20246810120 1 2 3 4 5 6 7Photon energy(eV)pure0.5 wt.%1 wt .%1.5 wt.%(αhυ)1/3(cm-1.eV)1/3Advances in Physics Theories and Applications                                                                                                  www.iiste.org ISSN 2224-719X (Paper) ISSN 2225-0638 (Online) Vol.20, 2013          155  Fig.4 extinction coefficient  for  composite with  various wavelength  The refractive index as a function of wavelength can be determined from the reflection coefficient data R and the extinction coefficient k using equation ( as shown in figure 5)[6]: )4.(..........)1()1())1(4( 2/122−+−−−=RRKRRn   Fig.5 the relationship between refractive index for  composite with wavelength         The decrease in the extinction coefficient with an increase in wavelength shows that the fraction of light lost due to scattering[6]. The high refractive index values of these composites are advantageous for strong optical confinement and enhance the optical intensities for nonlinear interactions. The real part of the dielectric constant is associated with the term that shows how much it will slow down the speed of light in the material ,can be calculated by using the relation[6]:  )5(..........221 kn −=ε   and imaginary part of the dielectric constant can be calculated by using the relation[7]:  ε2 =2nk      ...… …....(6)  1.E-071.E-061.E-051.E-04200 300 400 500 600 700 800kpure0.5 wt.%1 wt.%1.5 wt.%λ(nm)11.21.41.61.822.22.42.62.83200 300 400 500 600 700 800npure0.5 wt.%1 wt.%1.5 wt.%λ(nm)Advances in Physics Theories and Applications                                                                                                  www.iiste.org ISSN 2224-719X (Paper) ISSN 2225-0638 (Online) Vol.20, 2013          156  Fig.6 variation of real part of dielectric constant of composite with wavelength  Fig.7 variation of imaginary part of dielectric constant of composite with wavelength  The imaginary part shows how a dielectric absorbs energy from an electric field due to dipole motion. The dielectric constant (ε1) and dielectric loss (ε2) have been determined from [7].  4. CONCLUSIONS   1. The absorbance increases with increase the concentration of  nickel nitrite. 2. The absorption coefficient, extinction coefficient, refractive index and real and imaginary parts of dielectric constants are increasing with increase the weight  percentages of  nickel nitrite.  REFERENCES [1] M. Bulinski, V. Kuncser, D. Cristea, C. Plapcianu, S. Krautwald, H. Franke, F. E. Wagner, G. Filoti,"OPTICAL AND ELECTRONIC PROPERTIES OF METAL DOPED POLYMERS FOR INTEGRATED OPTICS, J.  of  Optoelectronics and Advanced Materials Vol. 5, No. 1, pp. 331 - 335(2003). [2] Omed Ghareb Abdullah and Sarkawt Abubakr Hussen, "Variation of Optical Band Gap Width of PVA films Doped with Aluminum Iodide”. 2010 International  Conference on Manufacturing Science and Technology (ICMST 2010). [3] A. Bhattacharya, P. Ray, “Studies on Surface Tension of Poly(Vinyl Alcohol): Effect of Concentration, Temperature, and Addition of Chaotropic Agents” Received 30  September 2003; accepted 16 December 2003. [4] C. Mwolfe, N. Holouyak and G. B. Stillman, "Physical properties of Semiconductor", prentice Hall, New York, (1989). 0123456789200 300 400 500 600 700 800pure0.5 wt.%1 wt.%1.5 wt.%ε 1λ(nm)0.E+002.E-054.E-056.E-058.E-051.E-041.E-041.E-04200 300 400 500 600 700 800pure0.5 wt.%1 wt.%1.5 wt.%ε 2λ(nm)Advances in Physics Theories and Applications                                                                                                  www.iiste.org ISSN 2224-719X (Paper) ISSN 2225-0638 (Online) Vol.20, 2013          157 [5]Abd El-Raheem M M, J. Phys. Condens. Matter. 19, 216209 (2007). [6] R Tintu , Nampoori V P , Radhakrishnan P and Sheenu Thomas J. Appl. Phys. 108, 073525(2010). [7]  R Tintu, K. Saurav, K.Sulakshna,Vpn.Nampoori,Pradhakrishnan and Sheenu thomas .” Ge28Se60Sb12 /PVA composite films for photonic application”. Journal of Non-  Oxide Glasses Vol. 2, No 4, , p. 167-174, 2010.   This academic article was published by The International Institute for Science, Technology and Education (IISTE).  The IISTE is a pioneer in the Open Access Publishing service based in the U.S. and Europe.  The aim of the institute is Accelerating Global Knowledge Sharing.  More information about the publisher can be found in the IISTE’s homepage:  http://www.iiste.org  CALL FOR PAPERS The IISTE is currently hosting more than 30 peer-reviewed academic journals and collaborating with academic institutions around the world.  There’s no deadline for submission.  Prospective authors of IISTE journals can find the submission instruction on the following page: http://www.iiste.org/Journals/ The IISTE editorial team promises to the review and publish all the qualified submissions in a fast manner. 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Preparation and Study of Optical Properties of (Polymer-Nickel Nitrate) Composite

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Preparation and Study of Optical Properties of (Polymer-Nickel Nitrate) Composite

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