Preparation and magnetoresistance of Ag 2+x Se thin films deposited via Pulsed Laser Deposition

The preparation of Ag 2+x Se thin films with thicknesses between 4 nm and 3000 nm by pulsed laser deposition on single crystalline NaCl and MgO substrates is reported. The films are perfectly dense and show a good lateral uniformity with a small number of defects. The microstructure of the films corresponds to a nanoparquet, being composed of two different phases of silver selenide. One phase is identified as the Naumannite low temperature phase of silver selenide, the structure of the other phase has not been reported in detail before and probably represents a metastable phase. Silver-rich films contain silver precipitates with typical sizes on the nanoscale. Their presence and their size appears to be responsible for the large and linear magnetoresistance effect of silver-rich silver selenide

Evidence-informed policy for tackling adverse climate change effects on health: Linking regional and global assessments of science to catalyse action.

Robin Fears and co-authors discuss evidence-informed regional and global policy responses to health impacts of climate change

a transparent plastic varnish with nanoparticulate magnetic additives

For the purpose of preparing TCCs (= transparent and electrical conducting coatings), metallic and ferromagnetic nano-additives were dispersed into a transparent varnish and the obtained dispersions were coated on transparent plastic substrates. During hardening of the dispersion the magnetic nano- additives were aligned by a magnetic field. The resulting coatings have electrical pathways along lines of nano-additive chains and are highly transparent in the areas between the lines. Therefore, the electrical conductivity is anisotropic, and it depends on the alignment of the nano- additives (i.e. on the distance between the nano-additives within the chains and the length of the lines) as well as on the thickness of an oxide and/or solvent shell around the nano-additives. The transparency depends also on the alignment and here especially on the thickness and the distance between the formed lines. The quality of the alignment in turn, depends on the magnetic properties and on the size of the particles. We used commercial plastic varnishes, which form electrically isolating (≥ 10− 12 S/m) and transparent (about 90% transparency) coatings, and the following magnetic additives: Co-, Fe-, CoPt3, CoPt3@Au- and Fe@Au-nanoparticles as well as CoNi-nanowires. Coatings with Fe@Au-nanoparticles show the best results in terms of the electrical conductivity (10− 5 S/m–10− 6 S/m) at transparencies above 70%. Furthermore, in addition to the magnetic nano-additives, transparent additives (Al2O3-particles) and non-magnetic, but better conducting additives (carbon- nanotubes) were added to the varnish to increase the transparency and the electrical conductivity, respectively

Influence of texture and grain misorientation on the ionic conduction in multilayered solid electrolytes – interface strain effects in competition with blocking grain boundaries

Interface strain and its influence on the ionic transport along hetero-interfaces has gained a lot of attention over the last decade and is controversially discussed. We investigate the relaxation of mismatch induced interfacial strain as a function of the degree of orientation/texture of the columnar crystallites and assess the impact on the oxygen ion conductivity in Er2O3/YSZ multilayer systems. Results from X-ray diffraction clearly show, that the width of the strained hetero-interface region increases with an increasing degree of orientation of the crystallites. The combined impact of film texture and strain at the hetero-interfaces of the film on the ionic conductivity however is not easily deduced from these measurements. The samples with the highest degree of orientation, i.e. with only one azimuthal variant, show strong anisotropic electrical properties. In samples with a lower degree of orientation, i.e. samples with a fiber texture, anisotropic properties cannot be detected, possibly due to a geometrical averaging of the electrical properties. The expected strain induced monotonic increase of the ionic conductivity with decreasing layer thickness and thus increasing interfacial influence could only be detected for samples with a fiber texture and a considerable degree of crystallite misorientation. This leads to the important conclusion that the texture and therefore the nature of the grain boundaries and their network influence the ionic conductivity of the multilayer thin films in the same order of magnitude as the misfit induced interface strain. Thus, the potential design of strain-controlled ionic conductors requires additionally the control of the microstructure in terms of grain orientation

Working principle of an ionic liquid interlayer during pressureless lithium stripping on Li6.25Al0.25La3Zr2O12 (LLZO) garnet-type solid electrolyte

Solid-state-batteries employing lithium metal anodes promise high theoretical energy and power densities. However, morphological instability occurring at the lithium/solid–electrolyte interface when stripping and plating lithium during cell cycling needs to be mitigated. Vacancy diffusion in lithium metal is not sufficiently fast to prevent pore formation at the interface above a certain current density during stripping. Applied pressure of several MPa can prevent pore formation, but this is not conducive to practical application. This work investigates the concept of ionic liquids as “self-adjusting” interlayers to compensate morphological changes of the lithium anode while avoiding the use of external pressure. A clear improvement of the lithium dissolution process is observed as it is possible to continuously strip more than 70 μm lithium (i. e., 15 mAh cm−2 charge) without the need for external pressure during assembly and electrochemical testing of the system. The impedance of the investigated electrodes is analyzed in detail, and contributions of the different interfaces are evaluated. The conclusions are corroborated with morphology studies using cryo-FIB-SEM and chemical analysis using XPS. This improves the understanding of the impedance response and lithium stripping in electrodes employing liquid interlayers, acting as a stepping-stone for future optimization. © 2021 The Authors. Batteries & Supercaps published by Wiley-VCH Gmb