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Metallic glass thin films (MGTFs) are a recently developed class of alloy coatings with potential applications ranging from biomedical devices to electrical components. Their tribological performance in service conditions is dictated by MGTF bulk composition but can be limited by the native oxide surface that inevitably forms upon exposure to atmosphere. Surface oxidation, thickness, and composition of ZrCuNiAl MGTFs were characterized using a combination of X-ray photoelectron microscopy (XPS) and electron probe microanalysis (EPMA). MGTF samples with nominal thicknesses of 50, 500, and 1500 nm were sputtered onto Si and SiN wafer substrates within a high vacuum deposition chamber and their amorphicity was confirmed by X-ray diffraction. XPS depth profiling identified the thin film composition and showed that the surface oxide was dominated by a mixed layer of mostly ZrO2, a little oxidized Al, and some metallic Zr. EPMA X-ray intensities were acquired as a function of beam energy to excite characteristic X-rays from different depths of the MGTFs and reconstructed using open-source thin film analysis software BadgerFilm, to determine the composition and thickness of sample layers. EPMA results constrain the composition to be Zr54Cu29Al10Ni7 within 0.7 at. % variation and total thicknesses to be 49, 470, and 1546 nm. Using the oxide composition identified from XPS depth profiling as an input for BadgerFilm analysis, EPMA results indicate the surface oxidation layer on each of the thin film samples was 6.5 ± 1.1 nm thick and uniform across a 0.25 mm region of the film. 

Abstract The relatively recent entry of field emission electron microprobes into the field of microanalysis provides another tool for the study of small features of interest (e.g., mineral and melt inclusions, ex-solution lamellae, grain boundary phases, high-pressure experimental charges). However, the critical limitation for accurate quantitative analysis of these submicrometer- to micrometer-sized features is the relationship between electron beam potential and electron scattering within the sample. To achieve submicrometer analytical volumes from which X-rays are generated, the beam accelerating voltage must be reduced from 15–20 to ≤10 kV (often 5 to 7 kV) to reduce the electron interaction volume from ~3 to ~0.5 μm in common geological materials. At these low voltages, critical Kα X-ray lines of transition elements such as Fe are no longer generated, so L X-ray lines must be used. However, applying the necessary matrix corrections to these L lines is complicated by bonding and chemical peak shifts for soft X-ray transitions such as those producing the FeLα X-ray line. It is therefore extremely challenging to produce accurate values for Fe concentration with this approach. Two solutions have been suggested, both with limitations. We introduce here a new, simple, and accurate solution to this problem, using the common mineral olivine as an example. We also introduce, for the first time, olivine results from a new analytical device, the Extended Range Soft X-ray Emission Spectrometer. 

Abstract Although calcareous anatomical structures have evolved in diverse animal groups, such structures have been unknown in insects. Here, we report the discovery of high-magnesium calcite [CaMg(CO 3 ) 2 ] armor overlaying the exoskeletons of major workers of the leaf-cutter ant Acromyrmex echinatior . Live-rearing and in vitro synthesis experiments indicate that the biomineral layer accumulates rapidly as ant workers mature, that the layer is continuously distributed, covering nearly the entire integument, and that the ant epicuticle catalyzes biomineral nucleation and growth. In situ nanoindentation demonstrates that the biomineral layer significantly hardens the exoskeleton. Increased survival of ant workers with biomineralized exoskeletons during aggressive encounters with other ants and reduced infection by entomopathogenic fungi demonstrate the protective role of the biomineral layer. The discovery of biogenic high-magnesium calcite in the relatively well-studied leaf-cutting ants suggests that calcareous biominerals enriched in magnesium may be more common in metazoans than previously recognized.