Effects of pore design on mechanical properties of nanoporous silicon

Abstract

Nanoporous silicon has been emerging as a powerful building block for next-generation sensors, catalysts, transistors, and tissue scaffolds. The capability to design novel devices with desired mechanical properties is paramount to their reliability and serviceability. In order to bring further resolution to the highly variable mechanical characteristics of nanoporous silicon, here we perform molecular dynamics simulations to study the effects of ligament thickness, relative density, and pore geometry/orientation on the mechanical properties of nanoporous silicon, thereby determining its Young's modulus, ultimate strength, and toughness as well as the scaling laws versus the features of interior ligaments. Results show that pore shape and pattern dictate stress accumulation inside the designed structure, leading to the corresponding failure signature, such as stretching-dominated, bending-dominated, or stochastic failure signatures, in nanoporous silicon. The nanostructure of the material is also seen to drive or mute size effects such as "smaller is stronger" and "smaller is ductile". This investigation provides useful insight into the behavior of nanoporous silicon and how one might leverage its promising applications.

Molecular Dynamics Simulations of Deformation Mechanisms in the Mechanical Response of Nanoporous Gold

“…In all the aforementioned studies, the surface energy is determined to be the main reason of the size effect in np structures; this has drawn attention to the modification of the scaling law. While pore size and relative density are found to be effective parameters to change the scaling law, recent studies demonstrate the influence of pore shape on the mechanical properties of np silicon [16,17]. Moreover, network connectivity has shown to have important influence on the scaling law of np metal foams [18].…”

3D multiscale analysis of the hierarchical porosity in Coscinodiscus sp. diatoms using a combination of tomographic techniques

“…In the same context, the BET (Brunauer-Emmett-Teller) technique enables the quantification of various parameters of the porous network such as the specific surface area, the pore size distribution and porous volume below 8*10 6 nm 3 . However, the latter technique can be affected by diffusion problems through the small pores (< 0.7 nm), which complicates the analysis of the measured data [19,20]. An alternative solution is the use of other types of gases which are able to probe smaller pores.…”

“…16 Their structure is made of an external siliceous skeleton with a complex and intriguing architecture called the "frustule". 17 From the point of view of the properties of interest, these self-assembled porous biosilica structures benet from peculiar and very interesting properties in terms of photonic response, thermal stability and mechanical strength [18][19][20][21] . Several species of diatoms do exist with unit cells of various shapes and a wide range of pore diameters (from micrometer to nanometer) having typical sizes from that of large bacteria (size in the micrometric range), through intermediate ones which correspond to the size of a virus, to smaller sizes such as for instance those of nitrate molecules (in the nanometric range).…”

Mechanical Integrity Assessment of Two-Side Etched Type Printed Circuit Heat Exchanger with Additional Elliptical Channel

“…The phenomenon where the stress is shown high at the tip has also been observed at the nanoscale. Winter et al [14] conducted a study which shows that the different pore shape and pattern will cause stress accumulation inside the structure and may lead to failure. Vo et al [15] investigated the impact of nanopores and porosity on the mechanical properties of amorphous silica (a-SiO 2 ).…”