Journal of Crystal Growth, Vol.518, 89-94, 2019
Formation and morphology evolution of icosahedral and decahedral silver crystallites from vapor deposition in view of symmetry misfit
Five-fold symmetry is prohibited in crystals following the crystallographic restriction theorem, but tiny particles of materials such as some noble metals formed via vapor condensation are often found in icosahedral or decahedral habits since nucleation occurs around a local center, and the point groups I-h and D-5h are close to the spherical symmetry. This inconsistency then has to be resolved by the growing particles. Here we report the growth of decahedral (D-5h symmetry) and icosahedral (I-h symmetry) twinned silver particles from vapor phase, and identification of morphology evolution pathways on the way growing from roughly 0.1 mu m up to 15 mu m as a consequence of competition between intrinsic strain mainly out of symmetry misfit and extrinsic surface energy of different facets. The possible detailed mechanism for the individual morphology evolution pathways is discussed. Our results may help clarify the growth mechanism of five-fold twinned crystallites and improve the morphology control of such noble metal particles for targeted applications.
Keywords:Crystallographic restriction theorem;Decahedral and icosahedral twin crystals;Morphology evolution pathways;Physical vapor deposition