ABSTRACT
Synthesized in Cases I And II ............................................................................ 36 2.5 Conclusion ......................................................................................................... 38 Keywords ................................................................................................................... 39 Acknowledgment ....................................................................................................... 39 References .................................................................................................................. 39
2.1 INTRODUCTION
There are the novel chemical synthesis of silver nanoparticles (NPs) of different size and shapes, like nanorod, nanospindle, nanocube, nanosphere, nanoellipsoid, and
some plate like structures. Here silver nitrate (AgNO3) has been used as the precursor, polyvinyl pyrolidone (PVP) as the stabilizer and benzoic acid as the reducing agent and the temperature of the reaction has been varied from 60 to 120°C at 10°C interval to obtain different nanostructures of silver. It has been found that by taking the higher value of the ratio between AgNO3 and PVP but with the same amount of benzoic acid, different shapes of silver NPs, such as spherical, triangular, pentagonal, hexagonal, and some elongated shapes are produced. The nanostructures of the samples are characterized using scanning electrons and transmission electron microscopes. The UVvisible spectra of all the samples are collected and the absorption spectra of the first set of synthesized samples exhibit two absorption peaks, one in visible region (transverse) and another in near infrared region (longitudinal) but longitudinal band is absent for the second set of samples that is with higher AgNO3 and PVP ratio. It is found that as the temperature increases; the longitudinal peak wavelength is blue shifted. So both temperature and the AgNO3 and PVP ratio have dominant roles in producing different morphologies, size and shape of the silver NPs. The photoluminescence (PL) emissions in the UV-visible region have been obtained from the second set of samples and it is found that the intensity of the most intense PL peak at 345 nm reduces with the increase in the temperature of synthesis.
