Abstract: ZnO nanoparticles were synthesized by the mechanochemical processing. XRD patterns indicate all products are
single ZnO phase while ZnSO₄/NaOH(mol ratio)is in the range from 1/2.1 to 1/3.0, and ZnO yield will obtain the maximum when ZnSO₄/NaOH(mol ratio) is 1/2.5. TEM micrographs show the particle size of ZnO is about 40～80nm.
The heat released by the solid-solid reaction of ZnSO_4 and NaOH makes the product of Zn(OH)₂ tramsform directly to ZnO particles. The optical
absorptivity of ultraviolet (200～400nm) for nanometer ZnO is much better than that of normal ZnO powders.

Key words: mechanochemical reaction, ZnO nanoparticle, optical absorptivity