Fig. 3
From: Structure and electrochromism of two-dimensional octahedral molecular sieve h’-WO3
Thermal stability of the new h’-WO3 framework. a XRD patterns and corresponding photographs of h’-H0.07WO3 (before thermal treatment) and h’-WO3 (after heating at 100 °C under air) powders. Note that the h’-WO3 appears blueish as it is shortly exposed to air in order to take the photograph, so that it already starts to reduce again. b TGA and DTA traces under air of the hydrogen bronze. c Powder XRD patterns of the heat-treated bronze as a function of the annealing temperature. Stars indicate peaks of the orthorhombic WO3 structure, lozenges indicate peaks probably due to additional distortions in the structure. The h’-WO3 framework is maintained up to 425 °C where it transforms into orthorhombic WO3 (o-WO3), then into tetragonal WO3 (t-WO3) at 780 °C (b)
