On Preparing ZnO:Zn Phosphor

many different methods have been reported in the literature. The mechanism of the formation of interstitial Zn

which is considered to be responsible for the performance of luminescence and n-type semiconductor

has thus been proposed in various respects. Thisstudy has placed emphasis on the sulfide method

in which three different systems in the presence of sulfur oxide

zinc sulfide and free sulfur respectively are examined on the basis of thermodynamic calculations.It is found theoretically and verified experimentally that these following changes cannot occur spontaneously in the range of 600~1300℃:ZnO+SO

2

=Zn+SO

3

2ZnO+ZnS=SZn+SO

2

4ZnO+S

2

(g)=4Zn+2SO

2

while the last reaction shown above may involve a decrease in free energy under the condition given below

and tends to proceed spontaneously to the right side.2ZnO+S

2

+O

2

=2Zn(g)+2SO

2

(or 2ZnS+O

2

=2ZnO+S

2

)It seems clear that trace O

2

but not any sulfide or sulfur

has played an important role in the system.