Suchergebnisse

Kinking is a deformation mechanism ubiquitous to layered systems, ranging from the nanometer scale in layered crystalline solids, to the kilometer scale in geological formations. Herein, we demonstrate its origins in the former through multiscale experiments and atomistic simulations. When compressively loaded parallel to their basal planes, layered crystalline solids first buckle elastically, then nucleate atomic-scale, highly stressed ripplocation boundaries - a process driven by redistributing strain from energetically expensive in-plane bonds to cheaper out-of-plane bonds. The consequences are far reaching as the unique mechanical properties of layered crystalline solids are highly dependent upon their ability to deform by kinking. Moreover, the compressive strength of numerous natural and engineered layered systems depends upon the ease of kinking or lack there of. ; Funding Agencies|CoorsTek Graduate Fellowship Program at Colorado School of Mines; ARO [W911NF1910389]; U.S. National Science Foundation through the DMREF program [1729335, 1729350]; NSF through CMMI program [1728041]; Swedish Research CouncilSwedish Research CouncilEuropean Commission [2016-04412]; Knut and Alice Wallenbergs FoundationKnut & Alice Wallenberg Foundation; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]; [KAW 2015.0043]

Rare-earth-based (RE) nanolaminates have attracted attention recently because of their complicated magnetism and their potential as precursors for strongly correlated two-dimensional materials. In this work, we synthesized a class of nanolaminates with a Mo4RE4Al7C3 chemistry, where RE = Ce or Pr. Powder samples of both phases were characterized with respect to structure and composition. Single crystals of Mo4Ce4Al7C3 were used for magnetization measurements. The crystal structure was investigated by means of x-ray diffraction and scanning transmission electron microscopy. Magnetization analysis reveals a ferromagnetic ground state with a Curie temperature of similar to 10.5 K. X-ray absorption near-edge structure provides experimental evidence that Ce is in a mixed-valence state. X-ray magnetic circular dichroism shows that only the Ce atoms with 4f(1) configuration occupying one of the two possible sites are ferromagnetically coupled, with a saturation moment of similar to 1.2 mu(B) per atom. We thus classify Mo4Ce4Al7C3 as a ferromagnetic, mixed-valence compound. ; Funding Agencies|Knut and Alice Wallenberg (KAW) Foundation through a Fellowship [0358, KAW 2015.0043]; Swedish Research council [642-2013-8020]; Flag-ERA JTC; chair of excellence program of the Nanosciences Foundation (Universite Grenoble-Alpes Foundation); Federation Wallonie-Bruxelles through the Action de Recherche Concertee "3D nanoarchitecturing of 2D crystals" [16/21-077]; European Union [696656]; Belgium FNRS (Flag-ERA) [R. 50.01.18.F]; Fonds de la Recherche Scientifique de Belgique (F.R.S. -FNRS) [2.5020.11]; Linkoping Ultra Electron Microscopy Laboratory