"Ultrasmall" ZrO₂ Nanoparticles: Disentangling Core and Surface Contributions to Structural and Electronic Properties...

Area of Science:

• Materials Science
• Computational Chemistry
• Nanotechnology

Background:

• Zirconia nanoparticles (NPs) are crucial in various applications.
• Understanding their structure-property relationships is essential.
• Computational methods offer insights into nanoscale phenomena.

Purpose of the Study:

• To investigate the structure, stability, and electronic properties of zirconia NPs.
• To explore the impact of size and surface passivation on NP characteristics.
• To develop a reliable method for generating and analyzing zirconia NP models.

Main Methods:

• First-principles molecular dynamics (FPMD) and density functional theory (DFT) at PBE and PBE0 levels.
• MD thermal annealing cycles with water molecules for NP model generation.
• Analysis of structural features, bond lengths, and electronic properties.

Main Results:

• Passivation rate significantly affects NP structure; saturated passivation yields optimal structures.
• Zr-O bond length variation serves as a descriptor for core-shell differentiation in NPs >= 1.3 nm.
• Core atoms resemble cubic zirconia, while surface atoms mimic the monoclinic phase in larger NPs.
• Quantum confinement effects are moderate, and band gap evolution deviates from theoretical predictions.

Conclusions:

• Saturated passivation is key for stable zirconia NP structures.
• A core-shell model is applicable for NPs down to 1.3 nm.
• Surface passivation and core structure influence electronic properties, but not as predicted by simple models.