Appraising the absolute limits of nanotubes and nanospheres to preserve high-pressure materials

TL;DR

This paper develops a theoretical model to evaluate the maximum pressure nanostructures like nanotubes and nanospheres can withstand to preserve high-pressure materials at ambient conditions, using first-principles calculations.

Contribution

It introduces a new physical model to quantify the pressure-bearing limits of various nanomaterials, guiding the design of nanostructures for high-pressure material preservation.

Findings

Graphene nanotubes/nanospheres have the highest pressure-bearing capacity.

Structure stability correlates with average binding energy per bond and bond density.

Multi-layer nanospheres can contain higher pressures, enabling recovery of high-pressure phases.

Abstract

Matter under high pressure often exhibits attractive properties, which, unfortunately, are typically irretrievable when released to ambient conditions. Intuitively, nanostructure engineering might provide a promising route to contain high-pressure phase of materials because of the exceptional mechanical strength at nanoscale. However, there is no available theoretical model that can analyze this possibility, not to mention to quantitatively evaluate the pressure-bearing capability of nano-cavities. Here, a physical model is proposed to appraise the absolute theoretical limit of various nanotubes/nanospheres to preserve high-pressure materials to ambient conditions. By incorporating with first-principles calculations, we screen and select four types of representative nanomaterials: graphene, hexagonal boron nitride (h-BN), biphenylene, and {\gamma}-graphyne, and perform systematic investigations. The results indicate that nanotube/nanosphere of graphene exhibits the best pressure-bearing capability, followed by h-BN, biphenylene and {\gamma}-graphyne. Our model reveals that the structure with the largest average binding energy per bond and the highest density of bonds will have the highest absolute limit to contain pressure materials, while electron/hole doping and interlayer interactions have minor effects. Our finding suggests that one can utilize nanotube/nanosphere with multiple layers to retrieve compressed material with higher pressures. For example, a single layer graphene sphere can retrieve compressed LaH10 with a volume size of 26 nm3 that corresponding to a pressure of 170 GPa and with a near room temperature superconductor transition of Tc=250 K. Similarly, in order to retrieve the metastable atomic hydrogen or molecular metallic hydrogen at about 250 GPa, it requires only three layers of a nanosphere to contain a volume size of 173 nm^3.