By combining molecular dynamics (MD) simulations with 29 Si and 27 Al magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy, we present a comprehensive structural report on rare-earth (RE) aluminosilicate (AS) glasses of the RE 2 O 3 −Al 2 O 3 −SiO 2 (RE = Y, Lu) systems, where the latter is studied for the first time. The structural variations stemming from changes in the glass composition within each RE systemas well as the effects of the increased cation field-strength (CFS) of Lu 3+ relative to Y 3+ are explored and correlated to measured physical properties, such as density, molar volume, glass transition temperature, and Vickers hardness (H V ). 29 Si NMR reveals a pronounced network ordering for an increase in either the RE or Al content of the glass. Al mainly assumes tetrahedral coordination, but significant AlO 5 and AlO 6 populations are present in all structures, with elevated amounts in the Lu-bearing glasses compared to their Y analogues. The MD-derived oxygen speciation comprises up to 3% of free O 2− ions, as well as non-negligible amounts (4−19%) of O [3] coordinations ("oxygen triclusters"). While the SiO 4 groups mainly accommodate the nonbridging oxygen ions, a significant fraction thereof is located at the AlO 4 tetrahedra, in contrast to the scenario of analogous alkali-and alkaline-earth metal-based AS glasses. The average coordination numbers (CNs) of Al and RE progressively increase for decreasing Si content of the glass, with the average CN of the RE 3+ ions depending linearly on both the amount of Si and the fraction of AlO 5 groups in the structure. The Vickers hardness correlates strongly with the average CN of Al, in turn dictated by the CFS and content of the RE 3+ ions. This is to our knowledge the first structural rationalization of the well-known compositional dependence of H V in RE bearing AS glasses.

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Sodium-ion batteries based on Prussian blue analogues (PBAs) are ideal for large-scale energy storage applications due to the ability to meet the huge volumes and low costs required. For Na 2−x Fe[Fe(CN) 6 ] 1−y •zH 2 O, realizing its commercial potential means fine control of the concentration of sodium, Fe(CN) 6 vacancies, and water content. To date, there is a huge variation in the literature of composition leading to variable electrochemical performance. In this work, we break down the synthesis of PBAs into three steps for controlling the sodium, vacancy, and water content via an inexpensive, scalable synthesis method. We produce rhombohedral Prussian white Na 1.88( 5) Fe[Fe-(CN) 6 ]•0.18(9)H 2 O with an initial capacity of 158 mAh/g retaining 90% capacity after 50 cycles. Subsequent characterization revealed that the increased polarization on the 3 V plateau is coincident with a phase transition and reduced utilization of the high-spin Fe(III)/Fe(II) redox couple. This reveals a clear target for subsequent improvements of the material to boost longterm cycling stability. These results will be of great interest for the myriad of applications of PBAs, such as catalysis, magnetism, electrochromics, and gas sorption.

The structures of 15 La-Al-Si-O glasses, whose compositions span 11-28 mol% La(2)O(3), 11-30 mol% Al(2)O(3), and 45-78 mol% SiO(2), are explored over both short and intermediate length-scales by using a combination of solid-state (27)Al magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations. MAS NMR reveals Al speciations dominated by AlO(4) groups, with minor but significant fractions of AlO(5) (5-10%) and AlO(6) (≲3%) polyhedra present in all La(2)O(3)-Al(2)O(3)-SiO(2) glasses; the amounts of Al([5]) and Al([6]) coordinations increase for decreasing molar fraction of Si. The MD simulations reproduce this compositional trend, with the fractional populations of AlO(p) groups (p = 4, 5, 6) according well with the experimental results. The modeled La speciations mainly involve LaO(6) and LaO(7) polyhedra, giving a range of average La(3+) coordination numbers between 6.0 and 6.6; the latter increases slightly for decreasing Si content of the sample. Besides the expected bridging and non-bridging O species, minor contributions of oxygen triclusters (≤9%) and free O(2-) ions (≤4%) are observed in all MD data. The glass structures exhibit a pronounced Al/Si disorder; the MD simulations reveal essentially random SiO(4)-SiO(4), SiO(4)-AlO(p) and AlO(p)-AlO(q) (p, q = 4, 5, 6) associations, including significant amounts of AlO(4)-AlO(4) contacts, regardless of the n(Al)/n(Si) molar ratio of the glass. The strong violation of Al([4])-Al([4]) avoidance is verified by 2D (27)Al NMR experimentation that correlates double-quantum and single-quantum coherences, here applied for the first time to aluminosilicate glasses, and evidencing AlO(p)-AlO(q) connectivities dominated by AlO(4)-AlO(4) and AlO(4)-AlO(5) pairs. The potential bearings from distinct fictive temperatures of the experimental and modeled glass structures are discussed.

In two-dimensional chromatography, the orthogonality of separation is important for achieving high peak capacity. In this paper, a number of different metrics are compared as measures of orthogonality. Six peptide elution data sets acquired on different stationary phases are plotted against reversed phase retention data and examined as two-dimensional chromatographic pairs. The data, including six in silico prepared data pairs, are utilized to challenge and compare selected orthogonality metrics. The metrics include correlation coefficients, mutual information, box-counting dimensionality, and surface fractional coverage with different hulls. Although correlation coefficients were found to be less suited for the intended purpose, other methods can provide a suitable measure of orthogonality. The presented results are discussed in terms of method utility, simplicity, and applicability for statistically small sets of chromatographic data. Two of the methods, box counting dimensionality and fractional coverage, were found to be mathematically related.