2025/11/13 by Li, Musen, Zhang, Lingyao, Ren, Wei +1
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci)
paper · doi:10.48550/arxiv.2511.09912
The planar hexagonal phase of ZnO, known as h-ZnO, g-ZnO, alpha-ZnO, the Bk structure, the 5-5 phase, the alpha-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, to be pressure stabilized, etc., 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, using more sophisticated techniques, to yield lattice parameters of a = 3.45+/-0.02 Å and c = 4.46+/-0.02 Å that 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 can form a metastable planar hexagonal phase. It provides key information pertaining to polarization switching in ZnO, its derivatives, and general wurtzite-structured materials.