Doping-induced changes in the structural, optical, magnetic and thermal properties of Ni:ZnS nanoparticles prepared by microwave-assisted chemical method

Zn (1- x ) Ni x S nanoparticles with Polyvinylpyrrolidone (PVP) are synthesized for different Ni concentration of x = 0, 0.05, 0.10, 0.15 using microwave heating by chemical route. EDS of all samples confirms presence of Zn, S and Ni without any impurities. XRD and TEM study reveals that pristine and Ni-doped ZnS samples possess cubic (Zinc Blende) structure without secondary phase or impurity phase formation such as NiO or NiS, up to 15% Ni doping. Raman spectra analysis corroborates the results of XRD and TEM, as observed from TO (Transverse Optical) and LO (Longitudinal Optical) phonon modes. UV–Vis absorption spectra show increment in the bandgap with increasing Ni doping concentration. The functional groups associated with the vibration of molecules are investigated by FTIR spectroscopy. We observed quenching in photoluminescence intensity at high Ni concentration in ZnS. Magnetic behavior is studied for the 15% Ni-doped ZnS by SQUID measurements. 520 K is the thermal stability of Ni-doped ZnS nanoparticles in the present case and is studied by TGA/DTG curves.