Sonochemical synthesis of neodymium doped zinc sulfide nanoparticles

Zinc sulfide (ZnS) nanoparticles have attracted particular attention for properties such as a wide band gap, high UV absorption potential, and high exciting binding energy [1]. Doping with lanthanide metals is a practical way to increase the catalytic activity of ZnS by preventing fast recombination of the electron–hole (e--h+) pairs [2]. In the current research, a simple sonochemical method was used to preparing neodymium doped zinc sulfide nanoparticles (Nd-doped ZnS). Doped ZnS particles were synthesized by a probe sonicator (60 W–20 kHz, BANDELIN, SONOPULS HD 3200). First, an aqueous solution of Na2S (100 mL, 0.5 M) was placed in a three-neck round-bottom flask under ultrasonic irradiation and N2 gas. After 30 min, an aqueous solution of Zn(CH3COO)2.2H2O (100 mL, 0.5 M) with appropriate molar ratio of Nd was slowly added to the previous solution, and the obtained mixture was sonicated for 1 h. The white precipitates were collected by centrifugation (Hettich, EBA 20), treated thoroughly with ethanol and deionized water, and finally dried at ambient temperature (25°C). The prepared samples were characterized for structural, and morphological properties by X-ray diffraction (XRD, X’Pert Pro, Panalytical) and field emission scanning electron microscopy (FE-SEM, SIGMA, Zeiss). The XRD pattern of the Nd-doped ZnS included the characteristic peaks of ZnS without any diffraction peaks from neodymium or other impurities. The intensity of peaks was reduced in the doped sample, which can be explained by the expansion of the ZnS lattice through doping by neodymium due to the larger ionic radius of Nd3+ (0.983 Å) in comparison with Zn2+ (0.74 Å). The FE-SEM image of Nd-doped ZnS showed the formation of uniformity and miscibility of nanoparticles with high density spherical shape particles.