ChemInform Abstract: Conversion of Colloidal ZnO—WO₃ Heteroaggregates into Strongly Blue Luminescing ZnWO₄ Xerogels and Films.

Abstract

1998 luminescence, fluorescence luminescence, fluorescence (solids and liquids) D 6540 -016Conversion of Colloidal ZnO-WO 3 Heteroaggregates into Strongly Blue Luminescing ZnWO 4 Xerogels and Films.-ZnO-WO 3 heteroaggregates are prepared from Zn 4 O(OAc) 6 and W(OMe) 6 . In a second step ZnWO 4 xerogels and films are prepared by annealing at 300-500 • C. The ZnWO 4 has a monoclinic Sanmartinite structure determined by powder XRD. The blue emission is activated during the thermal conversion of ZnO-WO 3 sandwich structures into the nanocrystalline ZnWO 4 sanmartinite phase. The electronic correlation diagram before and after the thermal conversion into ZnWO 4 shows the different band gaps for photo-and X-ray-luminescence processes. -(BONANNI, M.; SPANHEL, L.; LERCH, M.; FUEGLEIN, E.; MUELLER, G.; JERMANN, F.; Chem. Mater. 10 (1998) 1, 304-310; Lehrstuhl Silicatchem., Julius-Maximilians-Univ.,

The Thermodynamic Stability, Electronic and Photocatalytic Properties of the ZnWO4(100) Surface as Predicted by Screened Hybrid Density Functional Theory

“…For a better comparison, the band structures, DOS, and PDOS of bulk ZnWO 4 are also calculated. As shown in Figure 7 a, the VBM and CBM lie on the Gamma point, so bulk ZnWO 4 is a direct band gap semiconductor with a 3.77 eV band gap, which is in excellent agreement with previous experimental results 32 , 33 and theoretical results. 13 …”

“…The screening parameter is set to 0.2 Å -1 , and a small mixing parameter α (α = 0.19) for the short-range Hartree–Fock exchange instead used a value of 0.25. Using these parameters (i.e., ω = 0.2 Å –1 and α = 0.19), the calculated band gaps of bulk ZnWO 4 is 3.77 eV, which compared well with the experimental band gap 3.75 eV 32 , 33 and a previous theory. 13 The valence electron configurations of the PAW potentials are treated as 5d 4 6s 2 for W, 3d 10 4s 2 for Zn, and 2s 2 2p 4 for O.…”

Tungstate/titanate composite nanorod as an efficient visible light photo catalyst

“…The synthesis is found to be strongly dependent on pH, temperature and reaction times. Most previous approaches to the preparation of the tungstate families of compounds need high temperature and harsh reaction conditions such as the solid state metathesis reaction at 1000 • C and the sol-gel methods [30] include the block copolymer assisted synthesis of thin one dimensional and two dimensional CdWO 4 [26] and the reverse micelle soft template method for the synthesis of BaWO 4 nanorods [25]. The hydrothermal synthesis of CdWO 4 [31] and ZnWO 4 [32] nanocrystals has been reported.…”

Non-thermal plasma-assisted growth of ZnWO4 hierarchical nanostructures: morphology, structure and photoactivity

“…The lower PL intensity often implies the lower recombination rate of excited electrons/holes and the higher photocatalytic activity of semiconductor materials [19]. It can be clearly seen that untreated and plasma treated ZnWO4 samples display the main emissions band at about 450-480 nm ascribed to band gap transition of ZnWO4 [38]. The treatment of plasma weakens the PL intensity of ZnWO4 nanoparticles.…”