II-VI semiconductor nanoparticles have recently attracted a lot of attention due to the possibility of their application in various devices. In the present study, chemical method has been used in synthesis of CdS nanoparticles and thiophenol was used as capping agent. X-ray diffraction studies of both samples were done. The dc conductivity of CdS increases at a lower rate or is approximately constant upto 500K and thereafter the conductivity increases at a rapid rate. Beyond T c it is seen that the portion of the σ dc versus 1000/T is almost a straight line showing an Arrehenious behaviour. The dielectric constant of nanoparticles of CdS is found to be larger than the corresponding values of CdS crystals. It is clearly observed that at lower wavelengths nanocrystalline samples show a blue-shift. The three peaks of sample (S2), A, Band C can be ascribed to the transition from Cd-O complex donor formed by adsorbed oxygen to the valance band, Cdexcess acceptor and the surface states, respectively.

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When mechanically excited, initially the ML intensity increases, attains a maximum value and then decreases with time. The total M L intensity I r initially increases with the impact velocity V o of piston and attains a saturation value for higher values of V o and follows o and 1/ are constants. The ML intensity is the relation /.r=l°exp(-V/V o) where I T maximum for 20% CdS contents in the (Zn, Cd)S phosphors due to increase in hardness which may in turn increase the fracture stress and subsequently the piezoelectric field strength. The wavelength corresponding to the peak of both the ML and PL spectra shift towards longer wavelength with increasing CdS contents. Some models are discussed and it is concluded that the impulsive deformation of these phosphors may be due to piezoelectrification of newly created surfaces. The similarity of M L spectra with EL and PL spectra suggests that although the excitation processes are different, emission process is governed by the states of similar nature.

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