Optical Properties of ZnS:Co+Cr Nanocrystals Synthesized by a Low Temperature Hydrothermal Process

doi:10.15541/jim20140034

Abstract

Abstract:

Water-soluble ZnS:Co+Cr nanocrystals (NCs) were synthesized by a low temperature hydrothermal process using 3-mercaptopropionic acid (MPA) as capping agent. X-ray diffraction, laser particle size analyzer, transmission electron microscope (TEM), UV-Vis spectrophotometer, fluorescence spectrophotometer, XPS were used to characterized crystalline structure, morphology, particle size and optical properties of the samples. It is found that the ZnS:Co+Cr NCs are monodisperse and show zinc blende structure with an average particle size of about 9.3 nm. The absorption edge of ZnS:Co+Cr NCs is observed at 320 nm from the UV-Vis absorption spectra, furthermore the characteristic absorption peak at 728 nm of Co²⁺is observed. The photoluminescence characteristics indicate that ZnS:Co+Cr NCs shows the maximum PL intensity value under the condition: Cr-doping concentration of 0.75at% and the hydrothermal reaction temperature of 160℃. As confirmed by X-ray photoelectron spectroscope(XPS) , the Cr²⁺ dopants are partialiy oxidized into Cr³⁺.

Key words: hydrothermal synthesis, ZnS:Co+Cr NCs, crystalline structure, optical properties

CLC Number:

O614

WANG Xiao-Xiao, YANG Lin, LIU Hong, CHEN Qiang, XIAO Ding-Quan, ZHU Jian-Guo. Optical Properties of ZnS:Co+Cr Nanocrystals Synthesized by a Low Temperature Hydrothermal Process[J]. Journal of Inorganic Materials, 2014, 29(10): 1049-1054.

Figures/Tables 7

Fig. 1 Particle size distribution (a) and TEM image (b) of ZnS:Co+Cr (0.5at%) nanocrystals

Fig. 2 XRD patterns of ZnS:Co+Cr nanoparticles doped with different concentrations of Cr

Fig. 3 Absorption spectra of ZnS:Co+Cr nanoparticles doped with different concentrations of Cr in UV-Vis region (a) and visible light region (b)

Fig. 4 Plots of (αhν) vs (hν) of ZnS:Co+Cr (0.75at%) nanoc-rystals

Fig. 5 PL spectra of ZnS:Co+Cr nanocrystals doped with different concentrations of Cr

Fig. 6 PL spectra of ZnS:Co+Cr (0.75%) nanocrystals synthesized at different temperatures

Fig. 7 X-ray photoelectron spectra of ZnS:Co+Cr (1at%) nanocrystals

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