In situ TEM study of WO3 structural and phase evolution in carbothermal reduction

Understanding the transformation pathways of WO3 during carbothermal reduction (CTR) is crucial for tailoring the properties of tungsten-based nanopowders. In this study, the dynamic structural and phase evolution of WO3 during CTR was investigated using in situ heating transmission electron microscopy. Three distinct pathways were identified: oriented growth into W18O49 followed by reduction to W, direct reduction to W, and vapor-phase nucleation forming β-W and α-W. These pathways exhibit markedly different nucleation and growth mechanisms, critically influencing the final morphology and phase composition of the products.