Study Of Solid Materials Research Articles

Multi-phase quantitative compositional mapping by LA-ICP-MS: Analytical approach and data reduction protocol implemented in XMapTools

Mapping of trace element signatures is an expanding tool in geoscience and material sciences, which allows the study of solid materials, and processes that may not be captured by major elements. Developments in laser-ablation inductively-coupled-plasma mass-spectrometry (LA-ICP-MS) capabilities in the last decade now provide the necessary spatial resolution for in situ element mapping. The acquisition of two-dimensional, fully quantitative and geologically meaningful data with LA-ICP-MS is still a challenging task, and a particular obstacle is the calibration of inhomogeneous phases, such as chemically zoned minerals. This work presents a novel approach to data reduction and image generation for multi-element mapping employing LA-ICP- quadrupole MS (LA-ICP-QMS), implemented in the free and open-source software XMapTools. Three geological applications are presented to illustrate the benefits of the procedures. Garnet from an eclogitic sample (Lato Hills, Togo) and plagioclase, K-feldspar, biotite from a migmatite sample (El Oro Complex, Ecuador) were mapped multiple times at different spatial resolutions to test the calibration quality and chemical detection capabilities. Rutile in a metapelite sample (Val Malenco, Italian Alps) was mapped, and Zr-in-rutile thermometry shows a temperature range of 510 to 550 °C within a single grain. The accuracy of the LA-ICP-MS method was verified by comparison with zoned major and minor element maps (garnet, plagioclase) and Ti-in-biotite geothermometry maps obtained by electron probe microanalysis (EPMA). A spatial resolution of up to 5 μm is achieved with LA-ICP-QMS, which is similar to the resolution reported for LA-ICP time-of-flight mass spectrometry (LA-ICP-TOFMS), albeit at significantly lower acquisition speed. Maps with lower spatial resolution offer better chemical detection power as demonstrated by lower per-pixel limit of detection (LOD) map calculation. Moreover, such maps are also recorded faster. The pixel allocation strategy and the instrumental conditions also have a direct impact on map quality. We recommend that maps are interpolated to square pixels, where a pixel consists of multiple sweeps to gain an improved detection power. Benchmarks using an emulated LA-ICP-MS mapping show that the spot size, together with scan direction, can lead to a shift in composition depending on the feature size of chemical patterns. This is verified by mapping a thin 10 μm annulus in garnet visible in REE and such compositional shifts can have a significant impact on e.g., diffusion modelling. The new software solution provides a multi-standard and variable composition calibration of LA-ICP-MS maps with single pixel LOD filtering at 95% confidence, allowing the user to quantify inhomogeneous materials of major and trace elements simultaneously with improved accuracy.

Solid State Ionics - the key to the discovery, introduction and domination of lithium batteries for portable energy storage

2017 is the 50th anniversary of the discovery of fast ion transport in β-alumina. This discovery led to a revolution in the study of solid materials that might exhibit ionic motion as fast as that found in liquids. The need for materials with both fast ionic and electronic conductivity and a wide stoichiometry range to measure the ionic conductivity of beta alumina led to the intercalation concept for rechargeable alkali metal batteries. These discoveries and the resulting development of the lithium battery are described.

Robust NMR Approaches for the Determination of Homonuclear Dipole–Dipole Coupling Constants in Studies of Solid Materials and Biomolecules

This review addresses the NMR spectroscopy study of molecular structure and dynamics by way of homonuclear dipole-dipole couplings by relying on their orientation and direct distance dependence. The study of homonuclear couplings as opposed to heteronuclear couplings poses specific challenges. On the one hand, two like spins cannot be independently manipulated easily, which means that simple shift-refocusing concepts by using hard π pulses cannot be used to cope with potentially large chemical-shift dispersions at the high fields used today. On the other hand, the noncommutativity of the different pair Hamiltonians in a multispin system leads to complications associated with the isolation of specific pair couplings while minimizing the influence of the other spins. In particular, the so-called dipolar-truncation effect challenges the observation of weak couplings of interest in the presence of stronger ones. Recent advances in determining homonuclear dipole-dipole coupling constants are reviewed, stressing the use of double-quantum spectroscopy approaches and their similarity to the popular heteronuclear rotational-echo double-resonance experiment. Particular emphasis is put on corrections for the influence of transverse relaxation effects on the measured data, and the handling of distribution effects as well as potential dynamic heterogeneities in complex substances.

Applications of the SHRIMP I ion microprobe to the understanding of processes and timing of diamond formation

The ion microprobe is a highly versatile analytical instrument capable of a wide variety of in situ isotopic and trace element studies of solid materials, with a spatial resolution of 15 to 25 mm, consuming only 2 to 5 ng of sample per determination. In a study combining uranium-lead isotope dating, rare earth element fingerprinting, and sulfur plus lead isotope tracing, it has been possible to address critical questions concerning the timing of, sources of materials for, and processes involved in diamond formation in African kimberlites. The zircon uranium-lead data indicate that kimberlites may host two generations of minerals: one crystallizing at the time of kimberlite emplacement and the other significantly older, perhaps relict from a previous kimberlite magma-generating event. Rare earth element analyses of the same zircons suggest that the two generations of zircons are different from each other and both are quite distinct from crustal zircons. Since zircon is not a common phase in the mantle, it may be that some mantle metasomatic event is required to form these minerals and may actually trigger kimberlite generation. The sulfur isotope data from sulfide inclusions in diamonds suggest that two different reservoirs are being sampled during diamond growth: one with essentially pristine mantle characteristics and another with variability more reminiscent of a low-temperature or more oxidizing, possibly crustal, environment. Paragenetic data, based on nickel contents of the sulfides, indicate that it is the eclogitic diamonds which record the crustal signatures. Lead isotope variability parallels that found in sulfur, with perdiotitic sulfides having apparently normal mantle lead and eclogitic sulfides having much more radiogenic lead which in some cases requires very high U/Pb ratio growth environments, more consistent with a crustal source. The data from this study and others, including the carbon isotope heterogeneity of eclogitic diamonds, can be reconciled with a single model in which introduction of crustal material into the mantle triggers both generation of the kimberlite and diamond growth. This makes plate tectonics of paramount importance in locating economic reserves of diamonds.