Synthesis of a stable sol of Mn2+-doped ZnS nanoparticles by low-temperature heating of sulfide precipitate in ethylene glycol

摘要

A sol of Mn2+-doped ZnS nanoparticles was prepared by heating a ZnS precipitate with Mn2+ ions in ethylene glycol at 348 K for 24 h. The precipitate was prepared by mixing the aqueous solution of Zn(NO₃)₂·6H₂O and Mn(NO₃)₂·6H₂O with an aqueous solution of Na₂S According to the UV–VIS absorption spectra, when the wavelength was more than 400 nm, the optical absorptions of the obtained sols with the molar fraction of Mn2+ ions in the solution (X_Solution: the molar fraction of Mn2+/(Mn2+ + Zn2+) in the aqueous solution) less than 0.02 were less than 0.12 and the obtained sols were clear and transparent for the visible light. The sol of Mn2+-doped ZnS nanoparticles showed PL characteristics when irradiated with an excitation light with a wavelength of 345 nm. Accordingly, a simple process to heat the mixture of the sulfide precipitate and ethylene glycol at 348 K enabled us to obtain a homogeneous transparent sol of Mn2+-doped ZnS nanoparticles with PL characteristics. According to the results of the chemical analysis of the molar fraction of Mn2+ in the obtained precipitate (X_Precipitate) and the nanoparticles in the sols (X_Nano), the X_Nano was less than that the X_Precipitate as compared with the same X_Solution. The Mn2+ ions in the nanoparticles were dissolved in the solvent during the heat treatment since the solubility product of MnS was much larger than that of ZnS. As such, the dissolution-precipitate process played an important role in the formation of the sol.