Nanopowder containing ZnO nanowhiskers and nanoparticles was synthesized by the oxidation of Zn vapor, at temperatures from 1050 to 1450 degreesC in a flow of Ar and O-2 gas mixture. The morphology and structure of the nanowhiskers were dependent on the synthesis parameters such as evaporation temperature and the gas pressure. The nanowhiskers formed had a tetrapod shape with needle-like feet that become shorter and fatter on increasing temperature under a certain pressure range. The amount of Zn phase inside the nanowhiskers increased with increasing temperature. The Zn phase melted at temperature of 420 degreesC, which was confirmed by differential scanning calorimetry (DSC). The nanopowders showed strong sintering activity after they were pressed. The far infrared light was intensely absorbed by the ZnO tetrapod nanowhiskers. (C) 2004 Elsevier Ltd. All rights reserved.