Synthesis and characterization of NiWO4 crystals

Nickel tungstate (NiWO4) catalyst has been synthesized by reacting ammonium metatungstate and nickel nitrate as a function of temperature from 673 to 1073 K and of 1-h reaction time. It was found that NiWO4 is formed from 823 to 1073 K. The yield of 99% was obtained from 903 K to higher temperatures. The average crystal sizes have been determined by the Scherrer analysis and the surface area was measured by the Brunauer-Emmett-Teller (BET) method. The former increase from 55 to 112 nm, while the second decrease from 16 to 3 m(2) g(-1) in both cases, as the reaction temperature increases from 823 to 1073 K. Elemental composition and morphological structure were studied by energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). The structural characterization has been performed using X-ray diffraction (XRD). (C) 2001 Elsevier Science B.V. All rights reserved.