We show that this technique is also applicable to the growth of high-index single-crystal nickel foils, and we explore the possibility of using our high-index copper foils as substrates for the epitaxial growth of two-dimensional materials. Our high-index foils can be used as seeds for the growth of other Cu foils along either the in-plane or the out-of-plane direction. Instead, facet selection is dictated randomly by the facet of the largest grain (irrespective of its surface energy), which consumes smaller grains and eliminates grain boundaries. The creation of oxide surface layers on our foils means that surface energy minimization is not a key determinant of facet selection for growth, as is usually the case. A mild pre-oxidation of polycrystalline copper foils, followed by annealing in a reducing atmosphere, leads to the growth of high-index copper facets that cover almost the entire foil and have the potential of growing to lengths of several metres. Here we report a seeded growth technique for building a library of single-crystal copper foils with sizes of about 30 × 20 square centimetres and more than 30 kinds of facet. However, the controlled preparation of single-crystal foils with high-index facets is challenging, because they are neither thermodynamically 6, 7 nor kinetically 3 favourable compared to low-index facets 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18. In comparison, high-index facets are in principle infinite and could afford richer surface structures and properties. For a given metal, there are only three sets of low-index facets (). The production of large single-crystal metal foils with various facet indices has long been a pursuit in materials science owing to their potential applications in crystal epitaxy, catalysis, electronics and thermal engineering 1, 2, 3, 4, 5. Nature volume 581, pages 406–410 ( 2020) Cite this article The resulting structural changes of the material during guest and pressure induced external stimuli are evidenced by the new coupled XRD adsorption equipment.Seeded growth of large single-crystal copper foils with high-index facets This powder pattern resembles that of the as-synthesized MOF material containing solvent molecules in the pore system. Similar diffraction patterns were observed for all C 4-hydrocarbons, except 1-butene, where the second step at higher relative pressure ( p/ p 0 > 0.55) is accompanied by an additional phase transition. The differences in the pressure-depending powder diffraction patterns indicate phase transitions as a result of adsorption. Moreover, in situ XRD measurements at different relative hydrocarbon pressures were performed at 298 K for the C 4-isomers. At low loadings the isosteric heat is in a narrow region between 41 and 49 kJ mol −1. The isosteric heat of adsorption was calculated from the experimental isotherms for all C 4-isomers. This result is in good agreement with the value of 0.59 cm 3 g −1 calculated based on single crystal structure data. As a consequence, only 1-butene can fully open the framework resulting in a pore volume of 0.54 cm 3 g −1. From all investigated gases only the isotherms of 1-butene present a second step at a relative pressure above p/ p 0 = 0.55. Gate opening pressures in their endemic characteristic depend on the used hydrocarbon gases. The isotherms show a stepwise pore filling which is typical for structurally flexible materials with broad adsorption–desorption hysteresis loops. Pure component sorption isotherms of n-butane, isobutane, 1-butene and isobutene on the metal–organic framework (MOF) 3 ∞ at various temperatures between 283 K and 343 K and pressures up to 300 kPa are presented.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |