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The sp2 hybridized carbon allotropes such as fullerenes and graphene are scientifically and technologically significant because of their unique elastic and electronic properties. These properties make them useful in a wide variety of applications. Recently, experimentalists have synthesized sp-sp2 hybridized carbon tubular arrays of two-dimensional carbon films, referred to as graphdiyne. To explore the possible existence of an sp-sp2 hybridized one-dimensional carbon allotrope, we investigate graphdiyne nanotubes' structural and electronic properties using dispersion-corrected density functional theory calculations. Graphdiyne nanotubes display unique porous characteristics and remarkable stability, which may promote them as a novel class of carbon materials.
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This content will become publicly available on March 1, 2026
Advancements in low-density crystalline silicon allotropes
While numerous crystalline Si allotropes have been predicted in recent years and, in several instances, synthesized under high pressure, the exploration of Si phases with a lower density than conventional diamond Si (d-Si) is still in its infancy. Theoretical calculations on the electronic properties of these expanded Si forms suggest that, unlike the most stable d-Si structure, many may possess direct or quasi-direct bandgaps and only exhibit slightly higher formation energies than d-Si. The few that have been synthesized already display exciting optical properties, making them promising candidates for optoelectronic and photovoltaic applications. Their unique open-framework, guest–host structures enable distinctive interactions between Si and interstitial guest/dopant atoms, offering exciting potentials in spintronics, energy storage, and bio/medical technologies. In this Perspective, we provide an introduction and overview of the latest theoretical and experimental advancements in low-density Si allotropes, emphasizing their potential in various electronic and energy-related applications. This work also highlights the critical challenges and future directions for the continued development of these Si allotropes for next-generation technological applications.
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- Award ID(s):
- 2114569
- PAR ID:
- 10631820
- Publisher / Repository:
- AIP Publishing
- Date Published:
- Journal Name:
- Applied Physics Letters
- Volume:
- 126
- Issue:
- 9
- ISSN:
- 0003-6951
- Subject(s) / Keyword(s):
- Silicon allotropes Open frameworks Guest-host structures Electronic and energy applications
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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