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Optical limiting characteristics of core-shell nanoparticles
, A. Ramalingam
Published in
Volume: 64
Pages: 694 - 696
TiO 2 nanoparticles were synthesized by hydrothermal method at 180°C from TiOSO 4 aqueous solution with1m/l concentration. The obtained products were coated with silica by means of a seeded polymerization technique for a coating time of 1440 minutes to obtain well defined TiO 2@SiO 2 core-shell structure. The uncoated and coated nanoparticles were characterized by using X-Ray diffraction technique (XRD), Fourier Transform Infrared Spectroscopy (FT-IR) to study their physico-chemical properties. Evidence from XRD and FTIR results show that SiO2 is homogenously coated on the surface of titania particles. FTIR spectra show that there exists an interaction between TiO 2 and SiO 2 and results in the formation of Ti-O-Si chemical bonds at the interface of TiO 2 particles and SiO 2 coating layer. The non linear optical limiting properties of TiO2 and TiO 2@SiO 2 nanoparticles dispersed in ethylene glycol were studied at 532nm using 5ns Nd:YAG laser pulses. Three-photon absorption is responsible for optical limiting characteristics in these nanoparticles and it is seen that the optical nonlinearity is enhanced in core-shell structures when compared with single counterparts. This effective three-photon type absorption at this wavelength, is of potential application in fabricating optical limiting devices.
About the journal
JournalWorld Academy of Science, Engineering and Technology