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Opto-Mechanical studies of Polymer Nano-composites films. Kamal Kumar Kushwah1,2, Nitendra Kumar Gautam2, Pranav Singh2 and M.Ramrakhiani2
1. Department of Applied Physics, Jabalpur Engineering College, Jabalpur, M.P., India. 2. Department of Post Graduate Studies and Research in Physics and Electronics Rani Durgavati Vishwavidhyalaya, Jabalpur (M.P.) E-mail:kamal_kushwah2005@yahoo.com
1. INTRODUCTION 1. Polymer- inorganic nanocomposites have attracted much attention recently due to their unique size dependent chemical and physical properties [1]. 2. ZnSe & CdSe nanocomposites exhibit size dependent tunable photoluminescence [2]. 3. Studies have been under taken to prepare ZnSe and CdSe nanoparticles in PVA matrix and investigate their Photo luminescence.
2. EXPERIMENTAL 1. ZnSe/PVA,CdSe/PVA Nanocomposites were prepared by chemical method. 2. First PVA solution was prepared in distilled water and then 1 ml ZnCl2 solution was added to it for ZnSe/PVA and CdCl2 solution was added for CdSe/PVA separately. 3. After setting the pH by NH3 solution at 10, 1 ml of freshly prepared Na2SeSO3 solution was added and stirred for 90 minutes to obtain ZnSe/PVA and CdSe/PVA nanocomposite separately and solution was spread on glass plates and on solvent evaporation nanocomposites films were obtained. 4. A number of samples were prepared with different PVA concentration and subjected to X-ray diffraction and Photoluminescence, Refractive Index and Microhardness investigations.
3. RESULT AND DISCUSSION 1. XRD pattern reveals cubic structure for ZnSe/PVA and hexagonal for CdSe/PVA Nanocomposite films . 2. Three Peaks are obtained at 2θ=27.57˚, 45.59˚, 53.27˚ indicating reflection from (111), (220), (311) planes for ZnSe/PVA. 3. The peak corresponding to 2θ=20˚ represents PVA matrix.
4. The Particles size of samples computed from Debye Scherrer formula are obtained up to 20nm.
5. The Particle size is found to decrease by increasing PVA Concentration. 6. PVA is acting as capping agent and by increasing its concentration smaller ZnSe/CdSe particles are formed in its matrix.
7. The microhardness was found to increase with decreasing nanoparticle size of ZnSe/ CdSe in PVA polymer. 8. ZnSe/PVA films were found more harder than CdSe/PVA nanocomposite films.
Fig.1. XRD pattern of ZnSe/PVA
9. Photoluminescence (PL) spectra of ZnSe/PVA samples excited by 230 nm UV light are shown in fig.2. 10. A single peak is obtained at 465 nm for ZnSe/PVA and the higher intensity is observed by increasing PVA content in ZnSe nanocomposite films without any change in position of PL peak. 11. Higher intensity is obtained for smaller ZnSe particles in PVA matrix. 12. The emission may be attributed to band to band transition of which is greater than bulk band gap of ZnSe. 13. The oscillator strength is increased by reducing the size which enhances the PL intensity. 14. Due to proper passsivation of surface states non radiative transitions are not increased which enhance the PL intensity.
S5 S4 S3 S2 S1
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Fig.2 Photoluminescence Spectra of ZnSe/PVA Samples.
4. CONCLUSION 1. Thus ZnSe/PVA and CdSe/PVA Nanocomposites synthesized by very simple chemical route.
can
be
2. XRD analysis revealed that, increasing PVA concentration in ZnSe/PVA and CdSe/PVA composites, particle size is reduced. 3.
PL intensity is increased with reduction in particle size, due to enhanced oscillator strength.
4. The polymer matrix acts to stabilize the nano particle and incorporation of ZnSe/CdSe nanoparticles make these films harder than PVA.
5. This may be useful for their potential application in anti-reflection coating, display devices and optical sensors. 6. Due to the PL peak in green and blue region these composite films are promising materials for optical display devices.
ACKNOWLEDGEMENT The authors gratefully acknowledge the valuable assistant provided by Inter University consortium (IUC) Indore for characterizing samples by XRD and also very much thankful to Department of Nanotechnology, MAINAT, Bhopal for PL Studies.
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