Opto-Mechanical studies of Polymer-Nanocomposites
Kamal Kumar Kushwah1, 2, Nitendra Kumar Gautam2, Pranav Singh2, and M.Ramrakhiani2
Rani Durgavati Vishwavidhyalaya, Jabalpur (M.P.), India
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The nanocomposite films of CdSe and ZnSe nanocrystals in polyvinyl alcohol (PVA) matrix were synthesized by environmental friendly chemical method. These composites were characterized by X-ray diffraction which indicates the hexagonal crystalline structure of CdSe as well as ZnSe with particle size up to a few nm. The Particle size is found to decrease by increasing PVA Concentration. The photoluminescence properties of these composite films with varying concentreation of PVA have been investigated.
The PL peak of CdSe and ZnSe were observed at 510 nm and 465 nm respectively. The higher intensity is observed by increasing PVA content in CdSe and ZnSe nanocomposite films without any change in position of PL peak. The PL emission may be attributed due to band to band transition which is greater than bulk band gap of ZnSe /CdSe. The blue shift could be attributed to size reduction of PVA matrix to ZnSe/CdSe nanoparticles. Due to proper passivation of surface states non-radiative transition are reduced which enhance the PL intensity. The polymer matrix acts to stabilize the nano particle. Due to the PL peak in green and blue region these composite films are promising materials for optical display devices.
Optically transparent ZnSe/PVA composite Samples of comparatively larger thickness were prepared and obtained in thin film form. All prepared films exhibit excellent optical transparency in the visible region. The Refractive index of these composites was measured at sodium line with the help of Abee’s refractometer and was found in the range of 1.695-1.730. It is seen that refractive index varies with polymer concentration. This may be useful for their potential application in anti-reflection coating, display devices and optical sensors.
Micro Hardness of these nanocomposites was also measured by Vicker hardness tester and its dependence with varying load and mechanical behavior of samples was discussed.