This paper reports the preparation of nano-TiO2 (about 10 nm) powder b
y the method of precipitation. In detail, some preparation conditions
were investigated in order to find out how co control the grain size a
nd reduce the agglomeration of powders. Also, the reflex spectra of na
no-scale powders with different grain size were studied. It was found
that the wave length and width of reflex spectra are connected with th
e grain size of nano-TiO2 powders.