Re-refinement of the structure of the planar hexagonal phase of ZnO nanocrystals

Fuente: arXiv
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Auteurs principaux: Li, Musen, Zhang, Lingyao, Ren, Wei, Reimers, Jeffrey R.
Format: Preprint
Publié: 2025
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author Li, Musen
Zhang, Lingyao
Ren, Wei
Reimers, Jeffrey R.
author_facet Li, Musen
Zhang, Lingyao
Ren, Wei
Reimers, Jeffrey R.
contents The planar hexagonal phase of ZnO, known as h-ZnO, g-ZnO, α-ZnO, the Bk structure, the 5-5 phase, the α-BN phase, etc., has P63/mmc symmetry and is implicated in ferroelectric switching mechanisms for wurtzite-ZnO. It is well-known in thin films on substrates and to be stabilized by external pressure, but critical is its possible existence in high-purity nanocrystals under ambient conditions. Indeed, a crystal structure has been reported, but this work remains controversial as first-principles calculations predict very different structural properties. Herein, the original experimental data is re-refined, through phase-shift determination and Morlet wavelet transformation, that molecular dynamics simulations associate with a P63/mmc structure with lattice parameters at room temperature of a = 3.45{\pm}0.02 Å and c = 4.46{\pm}0.02 Å. These values are 0.35 Å and 0.80 Å, respectively, larger than those previously reported and in good agreement with computational predictions. This confirms that ZnO nanocrystals can form a metastable planar hexagonal phase. It provides key information pertaining to polarization switching in ZnO, its derivatives, and general wurtzite-structured materials.
format Preprint
id arxiv_https___arxiv_org_abs_2511_09912
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Re-refinement of the structure of the planar hexagonal phase of ZnO nanocrystals
Li, Musen
Zhang, Lingyao
Ren, Wei
Reimers, Jeffrey R.
Materials Science
The planar hexagonal phase of ZnO, known as h-ZnO, g-ZnO, α-ZnO, the Bk structure, the 5-5 phase, the α-BN phase, etc., has P63/mmc symmetry and is implicated in ferroelectric switching mechanisms for wurtzite-ZnO. It is well-known in thin films on substrates and to be stabilized by external pressure, but critical is its possible existence in high-purity nanocrystals under ambient conditions. Indeed, a crystal structure has been reported, but this work remains controversial as first-principles calculations predict very different structural properties. Herein, the original experimental data is re-refined, through phase-shift determination and Morlet wavelet transformation, that molecular dynamics simulations associate with a P63/mmc structure with lattice parameters at room temperature of a = 3.45{\pm}0.02 Å and c = 4.46{\pm}0.02 Å. These values are 0.35 Å and 0.80 Å, respectively, larger than those previously reported and in good agreement with computational predictions. This confirms that ZnO nanocrystals can form a metastable planar hexagonal phase. It provides key information pertaining to polarization switching in ZnO, its derivatives, and general wurtzite-structured materials.
title Re-refinement of the structure of the planar hexagonal phase of ZnO nanocrystals
topic Materials Science
url https://arxiv.org/abs/2511.09912