High-Resolution Electron Microscopic Studies of CS Structure in Reduced WO₃ Thin Crystals

Abstract

A dimerized quantum Heisenberg or XY antiferromagnetic chain has a gap in the spectrum. We show that a weak incommensurate modulation around a dimerized chain produces a zero-temperature quantum critical point. As the incommensuration wavelength is varied, there is a transition to a modulated gapless state. The critical behaviour is in the universality class of the classical commensurate-incommensurate (Pokrovsky-Talapov) transition. An analogous metal-insulator transition can also take place for an incommensurate chain. §

Defect and Ordered Tungsten Oxides Encapsulated Inside 2H–WX2(X=S and Se) Fullerene-Related Structures

“…All high-resolution images were recorded at or close to optimum Scherzer defocus conditions. Because of the known tendency of a high-energy electron beam to induce defect formation and even crystal growth in tungsten oxides (21,(23)(24), care was taken to minimize the amount of beam irradiation received by each specimen during lattice imaging. This was achieved by keeping the condenser aperture size to an optimal minimum and only exposing the crystals to a partially spread electron beam.…”

“…Previously, average compositions of the encapsulated oxides have been determined, from bulk specimens, by X-ray powder diffraction (XRD) to be MoO , in the case of the encapsulated molybdenum oxides, and either -WO (W O ) or -WO (W O ), depending on the reducing conditions, in the case of the encapsulated tungsten oxides (12). However, as the particle sizes of the encapsulated materials are in the range 7-50 nm (9), the contribution to the growth behavior of the encapsulating 2H-MX materials from defects in the encapsulated oxides could be considerable, especially in view of the fact that tungsten oxides in particular form a wide range of nonstoichiometric compositions between MO and MO (13)(14)(15)(16)(17)(18)(19)(20)(21). This paper therefore describes the first detailed microstructural study with respect to tungsten oxides incorporated inside 2H-WX fullerene-related structures.…”

Structure of WO3 ultrafine particles and their characteristic solid states

“…WO 3 powder changes color drastically via the reduction process. Yellow (WO 3 ) changes to yellowish green (WO 3 that the powder color is due to this CS structure [4], and each color depends on a specific CS structure.…”

Investigations of Nonstoichiometric Tungsten Oxide Nanoparticles

“…In other cases, the +001, 0 CS formed two or more separated domains within the nanowhisker with a clearly observable boundary separating the two phases. Miyano et al (6) (5). The CS planes are represented through the planes of edge sharing WO octahedra.…”