Structure properties of silica gel doped with CdS prepared by sol-gel technique

CdS/silica xerogel glasses were prepared via silica gels containing mixture solution of 0.2 M (CdCl2 and thiourea) with molar ratio 1:1. Doping the ge ls with this mixture solution and its heat treatment gave transparent yello w silica gel glasses doped with US crystals. X-ray diffraction XRD and tran smission electron microscope TEM make it possible to evaluate the nanoparti cle size of the prepared samples. The nanoparticle size was dependent on th e concentration of the dopant materials and the heating temperature. In the optical transmission spectra, the absorption edge exhibited a blue shift c ompared to that of bulk US and its energy shift was inversely proportional to the square of the radius. Thus the quantum size effect could be found fo r the silica gel containing US prepared by the sol-gel process. The energy band gap shifted to higher energy by decreasing the nanoparticle size.