Synthesis of tungsten silicide nanophases and nanorods via electrical explosion of tungsten wire in solid-state silicon matrices

초록

The synthesis of tungsten silicides (W-Si) under extreme conditions yields valuable insights into their thermodynamic behavior, diffusion dynamics, and nanostructure formation. Using the electrical explosion of a wire (EEW) technique, high-temperature reactions between pure tungsten and silicon matrices are initiated. This process produces two distinct product types within silicon nanoparticle (NP) and microparticle (MP) matrices: nanocrystalline phases (20-90 nm) and one-dimensional (1D) nanostructures. The formation of nanocrystalline phases is matrix size-dependent, with reactivity governed by the interplay between thermodynamic stability and silicon diffusion. In the 1D nanostructures, chestnut-burr-like aggregates of nanorods are formed in the Si NP matrix, while nail-like nanorods grow perpendicularly in the Si MP matrix, driven by vapor-liquid-solid (VLS) growth and surface stress-induced nanowhisker growth, respectively. In contrast, the Si wafer matrix does not exhibit NP or 1D structures; instead, infiltration reactions produce dendritic surface structures. Additionally, six new tetragonal W-Si compositions are identified, expanding the high-temperature phase boundaries and enriching the W-Si phase diagram. These findings offer new insights into high-temperature nucleation, nanodroplet condensation, and the fundamental mechanisms underlying W-Si reactions, opening avenues for advanced material design and applications.

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