| dc.description.abstract | The purpose of this research is to develop a low-cost, low environmental impact,
and high yield of ZnS: Mn2 + QDs process. ZnS: Mn2 + QD were successfully prepared
by neutralizing aqueous solution of zinc chloride and sodium sulfide under controlled
the pH value. Using XRD to identify the crystal shows that the product was ZnS
sphalerite (zinc-blend) structure, whose domain size is only 2~3nm calculated from
the power XRD peak width.
ZnS: Mn2 + QD was washed by deionized water, centrifuged out the sediment,
and modified by MPA aqueous. The obtained ZnS: Mn2 +@ MPA QDs can be
dispersed in water. The transparent dispersed solution crystal size also calculated by
on-set of the UV-abs absorption, it shows that crystal size was between 4 ~ 7nm.
TEM observation also showed that the size of a single crystal in 5 ~ 7nm.
We also tried to add different ratio of Zn/S. We found that when sulfur atoms
were excess, it will cause crystal size became larger and reduces the 420nm blue light
radiation. We not only use the MPA as a modifier, but also try to add it as a protective
agent during synthesis process.
Although the pH value of synthesis under the alkaline (pH> 10.8), MPA will
dissociate its thiol groups and enhance its bonding ability. However, we found that
will significantly reduce the crystallization of zinc sulfide. But under acid synthesis,
XRD showed that the larger diffraction intensity. UV-abs also had quite obvious
absorption peak, calculated by on-set of the UV-abs absorption, crystal size was
3.7nm.
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