Elastic Properties of High-Symmetry Sb₄O₆ Cage-Molecular Crystal

Abstract

The cubic-phase antimony trioxide (α-Sb2O3) is a room-temperature stable molecular crystal, composed of cage-like tetraantimony hexoxide (Sb4O6) molecules. Despite its versatile functionality, the van der Waals (vdW) bond-dominated nanomechanics is still unclear. Here, the bending plate-like linear behaviors of high-quality α-Sb2O3 nanoflakes were observed using the nanoindentation method. It is found that the cage-molecular crystal owns a very low in-plane Young’s modulus of 14.9 ± 0.8 GPa and a remarkable maximum tensile strain of 6.0–8.8%, corresponding to a rupture strength of 0.89–1.31 GPa. Elucidated by the atomistic simulations, the compliant elastic modulus and the unexpectedly strong rupture strain are associated with the high-symmetry vdW bonding structure. The vdW nanomechanics is of fundamental and technological relevance to nanoelectronics.

Emerging Two-Dimensional Inorganic Molecular Crystals: The Concept and Beyond

“…How the molecules move, how the 2D IMCs can crack under mechanical load, and how the vdW grain boundaries affect its mechanical behaviors are all open questions, and some unexpected behaviors may emerge in this respect. We note that a relevant work on mechanical properties of 2D IMC flakes has recently appeared, and we expect more systematic research works will be carried out regarding its intrinsic peculiarity in crystal structure. Obviously, the hybrid inorganic molecular crystals composed of different molecules also deserve the above-mentioned research attention.…”

Giant Tunability of Charge Transport in 2D Inorganic Molecular Crystals by Pressure Engineering

“…b–e) Pressure dependence of Raman peak positions of the α‐Sb 2 O 3 flake. Insets are schematic diagrams of the corresponding vibration modes [11, 14b] . f) Pressure dependence of the A g mode (255 cm −1 ) peak position in α‐Sb 2 O 3 flakes with different thicknesses.…”

Recent Advances in Growth, Properties and Applications of 2D Inorganic Molecular Crystals†

“…At present, five 2DIMCs have been successfully prepared and a summary of these 2DIMCs is presented in Table 1. In this section, we will classify them into three categories, including cage‐like molecular crystals (P 4 Se 3 , [ 1 ] Sb 2 O 3 , [ 4,7‐11,13‐15 ] P 4 S 3 [ 12 ] ), HgI 2, [ 6 ] bimolecular crystals SbI 3 ·(S 8 ) 3 , [ 2‐3 ] and describe the structure (shown in Figure 2) and properties of each separately.…”

“…[ 14 ] For instance, Sb 4 O 6 cage‐like molecules have a quite small in‐plane Young's modulus of 14.9 ± 0.8 GPa, and their maximum tensile strain can reach 6.0%—8.8%, corresponding to a breaking strength of 0.89—1.31 GPa. [ 14 ]…”

“…[ 6‐8 ] The existing problem is that strong intermolecular interactions caused by π‐π stacking in 2D organic crystals have been extensively studied, [ 9‐12 ] however, there are few studies on strong intermolecular interactions in 2DIMCs. [ 13‐14 ] Therefore, the lack of understanding of the strong intermolecular interactions in 2DIMCs has greatly hindered its development in expanding new members, developing new properties and exploring new applications. In addition, as a novel two‐dimensional material, there are many challenges for large area and high quality controlled fabrication of 2DIMCs.…”