Photoluminescence, thermoluminescence and Raman studies of CdS nanocrystalline phosphor

This paper reports on the photoluminescence (PL), thermoluminescence (TL) and Raman spectra of cadmium sulphide (CdS) nanoparticles prepared by solid-state reaction. The structures and morphologies of the products were characterized by XRD, HRTEM and EDAX. XRD confirmed the single-phase formation of CdS nanoparticles. TEM micrograph revealed the formation of nearly spherical nanoparticles with a diameter of 3.5 nm. PL emission of CdS:Bi nanoparticles is at 413 nm with a shoulder at 438 nm in addition to CdS peak at 550 nm. This may correspond to transition from (3)P(1) state to (1)S(0) states of Bi(3+). Thermoluminescence and Raman studies have also been carried out on CdS nanophosphor. The Raman spectrum of CdS nanoparticles clearly shows first, second and third order LO Raman peaks when excited using the wavelength of 488 nm. The red shift of the Raman peaks in nanoparticles compared to that of bulk CdS may be attributed to optical phonon confinement. (c) 2009 Elsevier B.V. All rights reserved.