Direct Mechanochemical Synthesis of Nanocrystalline NiWO₄

Abstract

The possibilities of mechanochemical activation as a successful route for direct synthesis of NiWO4 have been studied. A stoichiometric mixture of NiO and WO3 in a 1:1 molar ratio was subjected to intense mechanical treatment in air using a planetary ball mill for different periods of time. The phase and structural transformations were monitored by X-ray diffraction (XRD), infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS). It was found that 7.5 h of milling of the reagents leads to complete crystallization of single nanostructured phase NiWO4 at room temperature.

Fabrication of CoWO4@NiWO4 nanocomposites with good supercapacitve performances

“…The W 4f 7/2 peak (Fig. 4c) appearing at 36.0 eV indicates +6 oxidation state of W [17]. The O 1s core level spectrum of CoWO 4 @NiWO 4 was also shown in Fig.…”

CoWO4 nanoparticles prepared by two methods displaying different structures and supercapacitive performances

“…In Fig. 2a, the bands at 940 and 815 cm À1 correspond to the stretching modes of the W¼O bond and W-O-W bringing bonds, respectively [27]. The appearance of bands at 870, 675 and 530 cm À1 shows the mechanical activation formation for the new bonds starts [27].…”

Synchrotron-based far-infrared spectroscopy of nickel tungstate

“…The vibrational properties of NiWO 4 in the mid-infrared range 400-2000 cm −1 were studied previously in [21][22][23].…”