Fully coordinated silica nanoclusters: (SiO2)N molecular rings

Area of Science:

• Materials Science
• Computational Chemistry
• Solid State Chemistry

Background:

• Silica (SiO2) is a fundamental material with diverse applications.
• Understanding the structure-property relationships of finite silica clusters is crucial for materials design.
• Existing models often focus on linear or branched silica structures.

Purpose of the Study:

• To propose and investigate a new finite silica structure based on edge-sharing SiO2 units arranged in a ring.
• To determine the energetic stability of these proposed silica rings compared to linear chains.
• To explore the potential applications of these silica rings as models for extended silica systems and precursors for novel silica polymorphs.

Main Methods:

• High-level density-functional calculations were employed to model (SiO2)N clusters, with N ranging from 4 to 14.
• Energetic stability of ring structures was compared against corresponding linear chain structures.
• Vibrational frequency modes of the proposed silica rings were calculated and compared with experimental infrared spectroscopy data.

Main Results:

• A new finite silica structure, featuring edge-sharing SiO2 units in a ring formation, was computationally proposed.
• Density-functional calculations revealed that these silica rings are energetically more stable than linear chains for N > 11.
• Calculated frequency modes of the silica rings showed excellent agreement with experimentally observed infrared bands on dehydrated silica surfaces.

Conclusions:

• The proposed finite silica rings represent a stable structural motif.
• These rings can serve as valuable models for understanding strained extended silica systems.
• Synthesized silica rings could be precursors for novel tubular or porous bulk silica materials.