Oxidation-induced three-dimensional morphological changes in Ni nanoparticles observed by coherent X-ray diffraction imaging

Abstract

Three-dimensional structures of Ni nanoparticles undergoing significant morphological changes on oxidation were observed non-destructively using coherent X-ray diffraction imaging. The Ni particles were oxidized into Ni1O1 while forming pores of various sizes internally. For each Ni nanoparticle, one large void was identified at a lower corner near the interface with the substrate. The porosity of the internal region of the agglomerated Ni oxide was about 38.4%. Regions of high NiO density were mostly observed at the outer crust of the oxide or at the boundary with the large voids. This research expands our understanding of general catalytic reactions with direct observation of oxidation-induced nanoscale morphological changes.

Thermal Nanostructuring for Rectifying Resistive Switching Behaviors of Cobalt Oxide Neuromorphic Devices

“…Before RTA, we found no such texture on the Co surface, as shown in Figure S1b. According to our understanding, the high temperature and different structural properties of metal and oxide are the main reasons . At 500 °C, the Co layer was thermally expanded and absorbed oxygen molecules into it; the oxide nuclei were then formed and grew, and their grain boundaries were merged, forming a fiber-like nanostructure.…”

“…According to our understanding, the high temperature and different structural properties of metal and oxide are the main reasons. 38 At 500 °C, the Co layer was thermally expanded and absorbed oxygen molecules into it; the oxide nuclei were then formed and grew, and their grain boundaries were merged, forming a fiber-like nanostructure. Importantly, the strong oxide bonds helped to maintain that nanostructure after cooling.…”

Similarity score for screening phase-retrieved maps in X-ray diffraction imaging – characterization in reciprocal space

“…In addition, the background scattering from the membrane was assumed to be incoherent and the interference between the background scattering and the diffraction wave from the specimen was negligible. Therefore, the background subtraction procedure was routinely applied as reported for SR-XDI experiments at BL24XU (Takayama et al, 2018) and BL29XUL (Nishino et al, 2009;Nam et al, 2013;Kobayashi et al, 2018b) at SPring-8 and also for XDI experiments at BL9C at Pohang Light Source II (Ahn et al, 2021).…”

Noise tolerance of a sub-pixel shift method for upsampling diffraction patterns in coherent X-ray diffraction imaging

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