ZnSe nanocrystals doped in silica were prepared by using sol-gel process and in situ growth technique. It was found that when n(Zn)∶n(Se)=1∶1 in the sol precursor, the resultant ZnSe nanocrystals were rather instable and after several days the color of the ZnSe nanocrystals-doped SiO 2 glass changed from yellow to red. According to the analysis results of XRD, UV-Vis transmission spectra and XPS, the existence of many zinc vacancies in the ZnSe nanocrystals was considered as the reason of the instability. Based on this reason, the synthesis process was improved by introducing much larger amount of zinc to the precursor sol and this made the stability of the ZnSe nanocrystals improved greatly from several days to more than 6 months.
