TEM characterization of twinned nanocrystalline palladium freestanding thin films deformed using lab-on-chip technique

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Peculiar interaction of guests with porous γ-Mg(BH4)2

We investigated an interaction of porous γ-Mg(BH4)2 with small gas molecules, using neutron powder diffraction to accurately localize the guests at low temperatures and synchrotron X-ray powder diffraction to collect data along the adsorption isobars. The latter allows to study structural changes with pressure and temperature variation, giving insight into guest-host and guest-guest interactions, as well as to extract relevant thermodynamic parameters. I will discuss the guest-host and guest-guest interactions, size effects, the role of hydridic hydrogen in physisorption, reactivity between the guest and the host. The specific examples of guests and the related phenomena to be covered are: • hydrogen vs nitrogen - difference of sizes yields different localization and adsorption capacities; high hydrogen adsorption density • adsorption properties in the C2 series (ethane, ethylene and acetylene) and their relation to the size and acidity of the hydrocarbons • methane & ethane - size effects, interaction with the host, high adsorption enthalpies • CO2 - interaction with the host and high reactivity of the framework • noble gases - competition of guest-guest and guest-host interactions • ammonia borane - nanoconfinement of chemical hydride in complex hydride

High throughput GW

High-thoughput calculations at the DFT level already require sophisticated scripts for job generation, execution, error handling and date processing. At the level of many-body perturbation theory the demands become even more stringent. Basically a 'one parameter set fits all' approach does not work anymore and individual converged parameter-sets and computational settings need to be determined. We present the approaches developed to tackle this problem for GW calculations with the Pymatgen/Abipy framework. We discuss our approach of automatic convergence testing, dynamical test grid extension and data analysis. As a first application we calculate the quasiparticle spectrum of 100+ solids. This ensemble size allows for the statistically relevant extraction of correlations between converged input parameters and observables from the KS spectrum

On-Chip Graphene Tensile Testing

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Direct Transcription of Two-Dimensional Colloidal Crystal Arrays into Large-Area Three-Dimensional Silicon Photonic Crystals.

Amongst the photonic crystals architectures, the 3D design remains the most challenging to fabricate. This originates from the stringent requirements on the constituent materials and the quality of processing. Structuring dielectric materials at the 100-nm scale and with 3D periodicity is not straightforward and several methods have been proposed to address this bottleneck. In this talk, we will discuss a large area 3D structuring strategy for advanced photonic materials by adding the third dimension to 2D etch masks. Surface structuring by nanosphere lithography (NSL) is merged with a novel silicon etching method to fabricate ordered 3D architectures. The SPRIE method, Sequential Passivation Reactive Ion Etching, is a one-step processing protocol relying on sequential passivation and reactive ion etching reactions using C4F8 and SF6 plasma chemistries. Instead of generating smooth and straight etch profiles we have adapted the procedure in such a way that it produces regular size variations in the etch profile. The diffusion of fresh reactants and etch product species inside the etched channels is found to play an important role affecting the structural uniformity of the designed structures and the etch rate drift is corrected by adjusting the reaction times. High quality photonic crystals are thus obtained by adding the third dimension to the 2D colloidal crystal assemblies through SPRIE. Careful adjustments of both mask design and lateral etch extent balance allow the implementation of even more complex functionalities including photonic crystal slabs and precise defect engineering. We demonstrate 3D photonic crystal lattices exhibiting optical stop-bands in the infrared spectral region proving the potential of SPRIE for fast, simple and large-scale fabrication of photonic structures. Numerical modeling based on a structural characterization of the fabricated structures correctly predicts the optical response of the obtained photonic structures [1]. The SPRIE protocol is presently investigated for the realization of tapered structures with axial diameter modulation designed to enhance the light absorption in silicon solar cells or in conductive polymer Schottky junction solar cells [2]. [1] A. Vlad et al., Advanced Functional Materials 2013, 23, 1164; [2] A. Vlad et al., in preparation