Electrical treeing in hexagonal ice crystals under applied impulse voltage

Tree-like alumina nanopores generated in a non-steady-state anodization

“…It seems that the non-steady-state pore growth process here is more like the development of a tree or root in nature, which is reminiscent of electrical treeing in insulative materials under voltage aging. [13][14][15][16] Under our experimental conditions, negative charges (from oxygen-containing species, OH 2 and O 22 ) will build up in the oxide layer due to the unbalanced formation and dissolution rates of oxide. The negative charges will accumulate in continuous nonsteady-state anodization conditions.…”

“…The development of pores is more like that of tree or root in nature, which cannot be simply explained by Wood's models. [2][3][4] Due to its similarity to electrical treeing in insulative materials under voltage aging, [13][14][15][16] it is thought that partial discharge (PD) could occur as a result of continuous charge buildup in non-steady-state anodization conditions. In addition, some preliminary results of gold nanotrees indicate that the treelike nanopores provide the materials science community with a new template towards fabrication of various types of tree-like nanostructures (metal, semiconductor, carbon, polymer) because the template approach has no limitation to material types, and it could find applications in plasmonic waveguiding devices, nonlinear optics, and hierarchical materials assembly, etc.…”

Precise control of the filling stages in branched nanopores

“…24 On the other hand, in the non-steady-state anodisation, pore growth resembles the development of a tree or root in nature, being also reminiscent of electrical treeing in insulator materials under applied voltages. 21,26 Monitoring j anod (t) during dendrites formation allows us to better understand the pore formation in the non-steady-state anodisation process. As shown in Fig.…”

“…This anodisation voltage correlates with the applied potential during the second anodisation by a factor of 1/O2, showing that each stem pore is divided into two new pores, as expected, taking into account the equal area model. 24,26 Afterwards, the 2 nd (G2), 3 rd (G3) and 4 th (G4) generations of n-branched (G n ) pores are obtained by further reducing the anodisation voltage down to 8 V [Fig. 3(b)].…”