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Abstract Using Pair Distribution Function (PDF) analysis of in situ total scattering data, we investigate the formation of tungsten and niobium oxides in a simple solvothermal synthesis. We use Pearson Correlation Coefficient (PCC) analysis of the time resolved PDFs to both map the structural changes taking place throughout the synthesis and identify structural models for precursor and product through PCC‐based structure mining. Our analysis first shows that ultra‐small tungsten and niobium oxide nanoparticles form instantaneously upon heating, with sizes between 1.5 and 2 nm. We show that the main structural motifs in the nanoparticles can be described with structures containing pentagonal columns, which is characteristic for many bulk tungsten and niobium oxides. We furthermore elucidate the structure of the precursor complex as clusters of octahedra with O‐ and Cl‐ligands. The PCC based methodology automates the structure characterization and proves useful for analysis of large datasets of for example, time resolved X‐ray scattering studies. The PCC is implemented in ‘PDF in the cloud’, a web platform for PDF analysis.
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Abstract Electronic properties of silicon, the most important semiconductor material, are controlled through doping. The range of achievable properties can be extended by hyperdoping, i.e., doping to concentrations beyond the nominal equilibrium solubility of the dopant. Here, hyperdoping is achieved in a laser pyrolysis reactor capable of providing nonequilibrium conditions, where doping is governed by kinetics rather than thermodynamics. High resolution scanning transmission electron microscopy (TEM) with energy‐dispersive X‐ray spectroscopy shows that the boron atom distribution in the hyperdoped nanoparticles is relatively uniform. The hyperdoped nanoparticles demonstrate tunable localized surface plasmon resonance (LSPR) and are stable in air for periods of at least one year. The hyperdoped nanoparticles are also stable upon annealing at temperatures up to 600 °C. Furthermore, boron hyperdoping does not change the diamond cubic crystal structure of silicon, as demonstrated in detail by high flux synchrotron X‐ray diffraction and pair distribution function (PDF) analysis, supported by high‐resolution TEM analysis.
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Abstract The synthesis of low‐dimensional transition metal nitride (TMN) nanomaterials is developing rapidly, as their fundamental properties, such as high electrical conductivity, lead to many important applications. However, TMN nanostructures synthesized by traditional strategies do not allow for maximum conductivity and accessibility of active sites simultaneously, which is a crucial factor for many applications in plasmonics, energy storage, sensing, and so on. Unique interconnected two‐dimensional (2D) arrays of few‐nanometer TMN nanocrystals not only having electronic conductivity in‐plane, but also allowing transport of ions and electrolyte through the porous nanosheets, which are obtained by topochemical synthesis on the surface of a salt template, are reported. As a demonstration of their application in a lithium–sulfur battery, it is shown that 2D arrays of several nitrides can achieve a high initial capacity of >1000 mAh g−1at 0.2 C and only about 13% degradation over 1000 cycles at 1 C under a high areal sulfur loading (>5 mg cm−2).
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Abstract Ultrathin and 2D magnetic materials have attracted a great deal of attention recently due to their potential applications in spintronics. Only a handful of stable ultrathin magnetic materials have been reported, but their high‐yield synthesis remains a challenge. Transition metal (e.g., manganese) nitrides are attractive candidates for spintronics due to their predicted high magnetic transition temperatures. Here, a lattice matching synthesis of ultrathin Mn3N2is employed. Taking advantage of the lattice match between a KCl salt template and Mn3N2, this method yields the first ultrathin magnetic metal nitride via a solution‐based route. Mn3N2flakes show intrinsic magnetic behavior even at 300 K, enabling potential room‐temperature applications. This synthesis procedure offers an approach to the discovery of other ultrathin or 2D metal nitrides.