Synthesis Of ZnS Quantum Dots Research Articles

Microstructure characterization of mechanically synthesized ZnS quantum dots

ZnS quantum dots (QDs) with cubic phase have been prepared by mechanical alloying the stoichiometric mixture of Zn and S powders at room temperature in a planetary ball mill under Ar. Initially, an amorphouslike thin wurtzite (hexagonal) shell is formed on major zinc-blende (cubic) core after 3.5 h of milling and, in the course of milling up to 20 h, strain free single phase (cubic) QDs are formed with ∼4.5 nm in size. These ball-milled QDs contain different kinds of stacking faults and the Rietveld analysis of x-ray powder diffraction data reveals their concentration in milled samples. Though the high resolution transmission electron microscope (HRTEM) images could not detect the presence of the wurtzite phase but confirm the presence of cubic phase, core-shell structure, and different kinds of stacking faults in ball-milled samples. The particle size of QDs and their distributions obtained from Rietveld analysis agree well with the observations of HRTEM images.

Luminescence Study of ZnS Quantum Dots Prepared by Chemical Method

We report synthesis of ZnS quantum dots by chemical method at room temperature. In this technique, ZnS quantum dots are produced by simple chemical reactions where zeolite, acts as matrix, plays the key role in controlling particle growth during synthesis. Quantum dots exhibit luminescence properties such as Zn2+ related emission, efficient low voltage electroluminescence, and super linear voltage-brightness EL characteristics. This study demonstrates the technological importance of semiconductor nanosystems prepared by low cost chemical route.

Identification of mass fractal in chemically synthesized ZnS quantum dots

Zinc sulphide quantum dots chemically capped with thioglycerol having two different sizes have been synthesized. The particles have a disordered sphalerite structure and are slightly contracted by 1% against the bulk. Small angle X-ray scattering investigations reveal that powders of these nanocrystallites are mass fractals that aggregate via a reaction-limited process to form irregular but rather dense networks with a fractal dimensionality of Df = 2.7 and 2.1, respectively.