Ethylenediamine-Mediated Wurtzite Phase Formation in ZnS

The usual high temperature wurtzite
phase of ZnS was successfully
obtained at low temperature (170 °C) in the presence of ethylenediamine
(EN) as the soft template. X-ray diffraction and Raman spectroscopy
analysis confirmed the EN-mediated phase transformation (zinc blende
to wurtzite) of ZnS. X-ray photoelectron spectroscopy (XPS) showed
that all the samples were sulfur deficient. A high temperature X-ray
diffraction (XRD) study showed that ZnS samples, both EN-mediated
and without EN, retained their phases except small changes in the
unit cell dimension. Besides the EN-mediated phase transition, morphology
transformations from nearly spherical shape to nanorods are also observed
by scanning electron microscopy (SEM) and transmission electron microscopy
(TEM). The coupling between EN molecules with ZnS is confirmed by
Fourier transform infrared spectroscopy. A significant reduction in
the phase transition temperature of ZnS has been achieved as compared
to the bulk transition temperature (1020 °C). Mechanisms of phase
transformation have been discussed. The density functional theory
(DFT) supports the rod formation and wurtzite structure in the presence
of nitrogen-terminated ZnS surface.