Ageing and temperature-dependent behaviour of CdS nanoparticles

Abstract

Nanoparticles of inorganinc semiconductors in the form of coloids have attracted researchers due to their interesting optical properties. We report the process of the controlled coalescence of the nanoparticles in a colloid with time and also with temperature. Cadmium sulfide (CdS) nanoparticles were prepared in ethylene glycol (EG). The size of the particles was estimated by X-ray diffraction and transmission electron microscopy and matched with the optical absorption data. The particles in the EG matrix were subjected to controlled annealing and the shift in the absorption edge towards its bulk value (similar to 2.4 eV) was monitored. The change in the band gap value has been used to calculate the increasing particle radii using the effective-mass model. A similar effect is also reported with ageing of these particulates. (C) 2009 WILEY-VCH Verlag GmBH & co. KGaA, Weinheim