Synthesis of ZnWO4 nanocrystalline powders, by the polymerized complex method

Nanocrystalline ZnWO4 powders were successfully prepared by the polymerized complex method using zinc nitrate and tungstic acid as starting materials. The polymeric precursors were heat-treated at temperatures from 300 to 600 degreesC for 3 h. The precursors and heat-treated powders were evaluated for crystallization process, thermal decomposition, surface morphology and crystallite size. Crystallization of the ZnWO4 powders was detected at 400 degreesC and entirely completed at a temperature of 600 degreesC. The particles heat-treated at 400 and 500 degreesC showed primarily co-mixed morphology with spherical and silkworm-like forms, while the particles heat-treated at 600 degreesC showed more homogeneous morphology with a narrow size distribution. The average crystalline sizes were 19.92-24.16 nm, showing an ordinary tendency to increase with the temperatures from 400 to 600 degreesC. (C) 2002 Elsevier Science B.V. All rights reserved.