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The Effect of Deposition Parameters on the Mechanical and Transport Properties in Nanostructured Cu/W Multilayer Coatings
Published in Sam Zhang, Jyh-Ming Ting, Wan-Yu Wu, Functional Thin Films Technology, 2021
Alexander M. Korsunsky, León Romano Brandt
Grazing-Incidence Small-Angle X-Ray Scattering (GISAXS) is a surface and interface scattering technique that is ideally suited to detect nanoscale periodic features buried within or present on the surface of samples [33]. Due to the very shallow angle of incidence between beam and sample surface this technique provides large-scale averaged geometric distribution statistics. Temperature-dependent GISAXS patterns during a single heat ramp from 30 °C to 400 °C were acquired in steps of 10 °C at the BM28 beamline at ESRF. An incidence angle slightly above the conventional GISAXS range (0.05° and 0.5°) of 0.66° was chosen, as it revealed additional lateral and vertical roughness correlation information compared to shallower angles at which the GISAXS pattern was averaged to one large feature without distinct layer separation. The sample environment was identical to the one used for the XRR analysis. An X-ray photon energy of 8 keV with a beam size of 100 × 80 μm2 was chosen to achieve the best possible resolution of the GISAXS patterns on the detector. A PILATUS3 300K area detector with a pixel size of 172 × 172 μm2 and a resolution of 487 × 619 pixels split into three detector modules was used. A sample-detector distance of 1.56 m was determined using a AgBh standard calibration sample, followed by analysis in the DAWN software package [34]. GISAXS patterns were simulated and fitted using the BornAgain software package [35, 36].
Recent progress at the interface between nanomaterial chirality and liquid crystals
Published in Liquid Crystals Reviews, 2021
Diana P. N. Gonçalves, Marianne E. Prévôt, Şenay Üstünel, Timothy Ogolla, Ahlam Nemati, Sasan Shadpour, Torsten Hegmann
A related strategy was then also pursued by Mehl and co-workers, where the Au NPs were simultaneously capped with aliphatic, mesogenic as well as axially chiral binaphthyl thiol ligands. This combination contributes to a ‘domino/sergeant-soldier effect’ effect, which is introduced to explain the even higher βmol values achieved for these Au NPs in 5CB. Here, the additional introduction of the mesogenic groups to the surface of the mixed ligand shell Au NPs further enhances the miscibility and compatibility of the Au NPs with the N-LC host matrix best supported by arguments of solute-solvent interactions (Figure 6A)[51]. Furthermore, combinations of aliphatic and chiral mesogenic ligands on Au NP surfaces can lead to chiral (helical) NP superstructures (oblique 2D lattices) as demonstrated using grazing incidence small-angle X-ray scattering (GI-SAXS) as well as synchrotron radiation-based CD experiments (Figure 6B)[52]. Similar design strategies involving cholesterol functionalized arylamine-capped Au NPs have led to the discovery of chiral (helically-twisted) lamellar superstructure [53, 54].
Progress on highly proton-conductive polymer thin films with organized structure and molecularly oriented structure
Published in Science and Technology of Advanced Materials, 2020
Tesfaye and co-workers reported the nanodomain orientation and swelling kinetics by hygrothermal aging in perfluorosulfonic acid thin films of two types [71]. They described that the higher the orientation parallel to the substrate surface becomes, the slower water is transported normal to the surface (Figure 2(g)). Shrivastava and co-workers demonstrated evolution of hydration-dependent microscopic hydrophilic domains and macroscopic expansion of 55 nm-thick Nafion film on a Pt surface (Figure 2(h)) [72]. Cross-correlation among the film macro-expansion from ellipsometry, micro-expansion from grazing incidence small angle X-ray scattering (GISAXS), and the water distribution from neutron reflectometry showed randomly and spatially non-uniform distribution of water domains. Discussion involving proton conductivity as a macroscopic factor and domain size and swelling as microscopic factors revealed that a tortuosity of proton conduction pathways, which has an inverse relation with proton conductivity [73], was found to be inversely proportional to the domain expansion. These reports also support the oriented structure of Nafion thin films.