Crystal engineering of ZnS by cationic and anionic surfactant-cum-solvent

High temperature (1020 °C) wurtzite phase of ZnS is highly valuable multifunctional wide-band gap semiconductors. However it is difficult to stabilized wurtzite phase at room temperature. In the present study, the high temperature phase is successfully stabilized at low temperature (120 °C) in presence of cationic surfactant-cum-solvent like ethanolamine (ENA) and Oleylamine (OLA). While, the use of anionic surfactant likes ethylenediamine tetra acetic acid (EDTA) could not induce cubic to wurtzite phase transformation in ZnS. X-ray diffraction study confirms the cationic surfactant-mediated phase transformation of ZnS. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images shows nanoscale dimensions of as synthesized ZnS. The coupling between surfactant molecules with ZnS is confirmed by Fourier Transform Infrared spectroscopy. A significant reduction in the phase transition temperature of ZnS from 1020 to 120 °C is achieved as compared to the bulk transition temperature (1020 °C). The role of cationic and anionic surfactants-cum-solvent on mechanisms of phase transformations of ZnS is discussed. (paper)