Details

Autor(en) / Beteiligte

• Kang, Sung Bum
• Huang, Guanglong
• Singhal, Gaurav
• Xie, Dajie
• Hsieh, Daniel H.
• Lee, Youngmun
• Kulkarni, Ashish A.
• Smith, John W.
• Chen, Qian
• Thornton, Katsuyo
• Sinha, Sanjiv
• Braun, Paul V.

Titel

Highly Ordered Eutectic Mesostructures via Template‐Directed Solidification within Thermally Engineered Templates

Ist Teil von

• Advanced materials (Weinheim), 2024-04, Vol.36 (15), p.e2308720-n/a

Ort / Verlag

Germany: Wiley Subscription Services, Inc

Erscheinungsjahr

2024

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Template‐directed self‐assembly of solidifying eutectics results in emergence of unique microstructures due to diffusion constraints and thermal gradients imposed by the template. Here, the importance of selecting the template material based on its conductivity to control heat transfer between the template and the solidifying eutectic, and thus the thermal gradients near the solidification front, is demonstrated. Simulations elucidate the relationship between the thermal properties of the eutectic and template and the resultant microstructure. The overarching finding is that templates with low thermal conductivities are generally advantageous for forming highly organized microstructures. When electrochemically porosified silicon pillars (thermal conductivity < 0.3 Wm−1K−1) are used as the template into which an AgCl‐KCl eutectic is solidified, 99% of the unit cells in the solidified structure exhibit the same pattern. In contrast, when higher thermal conductivity crystalline silicon pillars (≈100 Wm−1K−1) are utilized, the expected pattern is only present in 50% of the unit cells. The thermally engineered template results in mesostructures with tunable optical properties and reflectances nearly identical to the simulated reflectances of perfect structures, indicating highly ordered patterns are formed over large areas. This work highlights the importance of controlling heat flows in template‐directed self‐assembly of eutectics. Template thermal engineering greatly enhances long‐range order of mesostructures formed by template‐directed self‐assembly. Employing porous Si rods as a template (thermal conductivity ≈0.28 Wm‐1K‐1, thermal diffusivity ≈0.89 mm2/s) nearly perfect periodic microstructures with optical properties matching simulations result. In distinct contrast, when the thermal diffusivity of the template is much greater, only disordered structures are formed.