Preparation and characterizations of cadmium sulfide nanoparticles

Cadmium sulfide nanoparticles have been synthesized by chemical precipitation method. The X-ray diffraction patterns conform their hexagonal structure. Raman spectra show first, second and third order longitudinal optical modes, and are slightly shifted to lower wavenumber side as compared to its bulk. Optical absorption spectra of cadmium sulfide nanoparticles show that band edge is slightly shifted toward longer wavelength side (red shift) and this shift is due to the quantum confinement effect. Particle size calculated by absorption data shows quantum confinement effect. Photoluminescence shows a broad emission with peak centered at around 460 nm after excitation with 360 nm. The frequency dependent dielectric constant of cadmium sulfide nanoparticles was also investigated and normal behavior with applied field is seen. The values of real part of dielectric constant and imaginary part of dielectric constant show dispersion at low frequencies and become almost saturated at higher frequencies. The above characterizations support the quantum dot formation of cadmium sulfide by this low cost technique.