Remarkable impact of Ni2+ ion on the structural, optical, and magnetic properties of hexagonal wurtzite ZnS nanopowders

Abstract

Ni-substituted zinc sulfide Zn1−xNixS (x = 0.0–0.8) nanopowders have been purposefully assembled using hydrothermal strategy based on inexpensive chloride salts and thiourea as sulfur sources. By X-ray diffraction, a hexagonal wurtzite structure with preferential orientation along the (0 0 8) plane was recognized at hydrothermal temperature 150 °C for period 24 h with nickel ion content. However, binary ZnS/Ni3S4 nanocomposites were identified by enhancing the nickel molar ratio up to 0.2–0.3 (20–30%). Whereas, ternary ZnS/Ni3S4/NiS nanocomposites were accomplished by increasing Ni ion molar ratio in the range from 0.4 to 0.8. The microstructure of the Ni replaced ZnS particles from 0.0 to 0.6 exhibited microspheres like structure and with increasing the Ni2+ ion concentration, the microspheres converted to three-dimensional layers. The optical band-gap energy was slightly reduced from 3.39 to 3.32 eV with increasing the Ni ion addition from 0.1 to 0.3. Otherwise, two band-gap energies were existed to be 3.16–1.60 and 2.95–1.45 eV at Ni2+ ion substitution 0.60 and 0.80 molar ratios, respectively. Photoluminescence spectra measurements indicated that pure and Ni ion-substituted ZnS (0.1 and 0.2 molar ratios) were manifested three emission bands in the ranges of strong UV emission peak 350–375 nm with the weakest blue UV emission band 375–387 nm and the broadband visible emission at 400–600 nm. Eventually, weak ferromagnetic behavior was evidenced for different Ni2+-substituted ZnS. The saturation magnetization was found to be maximum value of Ms of 0.33 emu/g as the result of improving the crystallization of cubic polydymite Ni3S4 structure at nickel ratio of 0.3.