Synthesis and characterization of WO3 polymorphs: monoclinic, orthorhombic and hexagonal structures

Review on Recent Progress in the Development of Tungsten Oxide Based Electrodes for Electrochemical Energy Storage

“…Moreover, various crystal structures of WO 3 depend on the temperature. As the temperature changes, WO 6 octahedra undergo displacement of the central W atoms, which exhibit different polymorphic forms for different temperature ranges, including tetragonal (α‐WO 3 , >740 °C), orthorhombic (β‐WO 3 , 330–740 °C), monoclinic I (γ‐WO 3 , 17–330 °C), triclinic (δ‐WO 3 , −43–17 °C), and monoclinic II ( ϵ ‐WO 3 , >−43 °C) . Some of these crystal structures are shown in Figure b–g.…”

“…As the temperature changes, WO 6 octahedrau ndergo displacemento ft he centralWatoms,w hich exhibit different polymorphic forms for different temperature ranges, including tetragonal( a-WO 3 , > 740 8C), orthorhombic( b-WO 3 ,3 30-740 8C), monoclinic I( g-WO 3 ,1 7-330 8C), triclinic (d-WO 3 , À43-17 8C), and monoclinic II (e-WO 3 , > À43 8C). [38] Some of thesec rystal structures are shown in Figure 1b-g. The tilting angle of WO 6 octahedra is the most important parameterf or this phase transformation, whereas the interatomic distances and anglesa re nearly unchanged.…”

Synthesis of Fe8V10W16O85 by a solution method

“…We can't exclude, however, content of hexagonal ammonium tungsten bronze (NH 4 ) 0.33-x WO 3-y (HATB, PDF 00-058-0151) in this sample because there is no sharp division of diffraction reflections between h-WO 3 and HATB [10,13,14]. Powder diffraction pattern of WP sample heated at 600°C comprised only diffraction reflections characteristic for monoclinic WO 3 [10][11][12]14]. Formation of m-WO 3 as an end product of decomposition of WP corroborates our earlier statement that WP contains 89.7 mass% of WO 3 .…”

“…Diffraction pattern recorded after heating at 190°C (curve b) differs considerably from this one of WP (curve a) and any single diffraction pattern of ammonium tungstate(VI) included in PDF-4 2014 database. On the other hand, X-ray phase analysis has revealed that diffraction pattern of WP sample after heating at 375°C comprises a set of diffraction reflections which can be attributed to hexagonal WO 3 (h-WO 3 , PDF 04-007-2322) and monoclinic WO 3 (m-WO 3 , PDF 00-043-1035) [10][11][12]. We can't exclude, however, content of hexagonal ammonium tungsten bronze (NH 4 ) 0.33-x WO 3-y (HATB, PDF 00-058-0151) in this sample because there is no sharp division of diffraction reflections between h-WO 3 and HATB [10,13,14].…”

Enhancing cycling stability of tungsten oxide supercapacitor electrodesviaa boron cluster-based molecular cross-linking approach

“…2b). 32-Please do not adjust margins Please do not adjust margins 34 The broad peaks in the PXRD pattern can be attributed to the small crystal size of WO3 (< 10 nm) in material 1. The surface morphology and elemental composition of material 1 were obtained using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS).…”