When a negative heat flux introduced at the specific nanopost structure, it can induce the Chinese character (pronunciation: Ren) formed at the area with lower temperature.

<p>When the dendritic structure extends to the lower-temperature area, solid phase intend to grow in a lower-temperature field and fill up the whole low-temperature area and then form Chinese character comparing to the area without any negative heat flux introduced which can provide an indicator for the development of smart self-organized architecture.</p

Parameters of the mesh.

<p>Parameters of the mesh.</p

Numerical simulation of nanopost-guided self-organization dendritic architectures using phase-field model - Fig 4

<p>Schematics of nanopost arrays (a) Analogy for exposure angle 28 low-density elliptical arrays, the major radius of elliptical is 10 units and minor radius is 5 units, the longitudinal spacing is 40 units and lateral spacing is 19.92 units. (b) Medium-density elliptical arrays, the major radius of elliptical is 5 units and minor radius is 1.5 units, the longitudinal spacing is 20 units and lateral spacing is 9.96 units. (c) High-density elliptical arrays, the major radius of elliptical is 2.5 units and minor radius is 1.25 units, the longitudinal spacing is 10 units and lateral spacing is 4.98 units.</p

The total numbers of circular and elliptical nanoposts employed in the simulation domain in different densities.

<p>The total numbers of circular and elliptical nanoposts employed in the simulation domain in different densities.</p

The ratio of <i>W</i>₀ and nanoposts spacing at <i>W</i>₀ = 0.25 for three different nanoposts.

<p>The ratio of <i>W</i>₀ and nanoposts spacing at <i>W</i>₀ = 0.25 for three different nanoposts.</p

Distribution of dendritic architecture branch angles, that is, the angle between the primary-branch and the secondary-branch.

<p>Histograms of dendritic architecture branching angles on 90 degree circle with (a) no heat flux (b) heat flux = -0.001 and (c) heat flux = -0.01. The distributions still show identical twin peaks. The first peak is around 90°, and the second peak is 36° ± 7° for no heat flux, 40° ± 6° for heat flux = -0,001, and 47° ± 6° for heat flux = -0.01.</p

Phase field and corresponding temperature field of the dendritic structure at interface thickness <i>W</i>₀ = 0.25 on the surface without nanoposts guided.

<p>At t = 0, the center region of the simulation domain is assigned to be solid state (<i>ψ</i> = 1). Due to the temperature difference of solid region and surrounding environment, there is a driving force which gives rise to dendritic architecture self-organization. As long as the temperature achieves the balanced temperature, the dendritic self-organization growth stops.</p

Dendritic structure at different interface thickness.

<p>(a)-(d) represent the dendritic structure self-organization growth at the same simulation conditions and the same growth time for <i>W</i>₀ = 1, <i>W</i>₀ = 0.75, <i>W</i>₀ = 0.5, and <i>W</i>₀ = 0.25, respectively. (e)-(h) are the enlarged views of (a)-(d), respectively, and it is seen that branching ability is getting weaker while the interface thickness <i>W</i>₀ increases.</p

Phase field and corresponding temperature field of the dendritic structure at interface thickness = 0.25 on the surface without nanoposts.

<p>At t = 0, the center region of the simulation domain is assigned to be solid state (<i>ψ</i> = 1). Due to the temperature difference of solid region and surrounding environment, there is a driving force which gives rise to the dendritic architecture self-organization. As long as the temperature achieves the balanced temperature, the dendritic self-organization growth will be stopped.</p

Branch angles of dendritic self-organization architecture on nanosubstrate.

<p>Branch angles of dendritic self-organization architecture on nanosubstrate.</p