Na super ion conductor (NaSICON), Na 1+n Zr 2 Si n P 3-n O 12 is considered one of the most promising solid electrolytes; however, the underlying mechanism governing ion transport is still not fully understood. Here, the existence of a previously unreported Na5 site in monoclinic Na 3 Zr 2 Si 2 PO 12 is unveiled. It is revealed that Na + -ions tend to migrate in a correlated mechanism, as suggested by a much lower energy barrier compared to the single-ion migration barrier. Furthermore, computational work uncovers the origin of the improved conductivity in the NaSICON structure, that is, the enhanced correlated migration induced by increasing the Na + -ion concentration. Systematic impedance studies on doped NaSICON materials bolster this finding. Significant improvements in both the bulk and total ion conductivity (e.g., σ bulk = 4.0 mS cm −1 , σ total = 2.4 mS cm −1 at 25 °C) are achieved by increasing the Na content from 3.0 to 3.30-3.55 mol formula unit −1 . These improvements stem from the enhanced correlated migration invoked by the increased Coulombic repulsions when more Na + -ions populate the structure rather than solely from the increased mobile ion carrier concentration. The studies also verify a strategy to enhance ion conductivity, namely, pushing the cations into high energy sites to therefore lower the energy barrier for cation migration.

Atomically thin 2D materials span the common components of electronic circuits as metals, semiconductors, and insulators, and can manifest correlated phases such as superconductivity, charge density waves, and magnetism. An ongoing challenge in the field is to incorporate these 2D materials into multilayer heterostructures with robust electrical contacts while preventing disorder and degradation. In particular, preserving and studying air-sensitive 2D materials has presented a significant challenge since they readily oxidize under atmospheric conditions. We report a new technique for contacting 2D materials, in which metal via contacts are integrated into flakes of insulating hexagonal boron nitride, and then placed onto the desired conducting 2D layer, avoiding direct lithographic patterning onto the 2D conductor. The metal contacts are planar with the bottom surface of the boron nitride and form robust contacts to multiple 2D materials. These structures protect air-sensitive 2D materials for months with no degradation in performance. This via contact technique will provide the capability to produce "atomic printed circuit boards" that can form the basis of more complex multilayer heterostructures.

H diffusion constants have been determined from steady-state fluxes through Pd-Ag alloy membranes. The upstream side is maintained at a nearly constant pup (and consequently at a nearly constant rup=H/(Pd(1-x)Agx)) atom ratio, whereas the downstream side is at pH2 approximately 0 (rdown=0) (423-523 K). It is shown that the permeability is a maximum for atom fraction Ag, XAg=0.23 (423-523 K) at both pup=20.3 and 50.6 kPa. DH has been determined for some Pd-Ag alloys as a function of r in the dilute region, and it decreases with r even at small H contents for alloys with XAg<0.35. The concentration dependence of DH(cH) has been determined for the Pd0.77Ag0.23 alloy over a large concentration range. The effect of nonideality on DH(r) and ED(r) has been systematically determined as a function of XAg, where XAg is the atom fraction of Ag in the H-free alloy. (dDH/dr) increases with XAg up to XAg=0.35 and then changes from negative to positive at approximately 0.35. The activation energies for diffusion, ED(r), have been determined as a function of H content in the dilute range for several Pd-Ag alloy membranes, and the conversion to concentration-independent E*D values has been carried out in several different ways.

In this research, the thermodynamics of H2 solution and hydride formation in a series of disordered Pd-Ag alloys has been determined using both reaction calorimetry and equilibrium PH2-composition-T data. Trends of DeltaHH and DeltaSH with both H and Ag concentration have been determined. For the Pd0.76Ag0.24 alloy, which does not form a hydride phase, DeltaHH and DeltaSH both exhibit minima with H/(Pd0.76Ag0.24) followed by a linear increase of the former. A linear increase of DeltaHH is found for all of the alloys in the high H content region beyond the two-phase region or, if, there is no two-phase region, in the high H content region. DeltaHH degrees at infinite dilution of H decreases with atom fraction Ag, XAg, up to about 0.40 and then increases. Enthalpies for hydride formation/decomposition, 1/2H2(g) + dilute <--> hydride, have been determined calorimetrically for alloys which form two phases (303 K). The enthalpies for hydride formation become more exothermic with XAg while the corresponding entropy magnitudes are nearly constant, 46 +/- 2 J/K mol H.

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Xe129 MRI has high potential to uniquely identify multiple changes in lung physiology in COPD using a single breath-hold acquisition.

The genesis of the Zhaxikang Sb-Pb-Zn-Ag deposit remains controversial. Three different geological environments have been proposed to model mineralization: a hot spring, a magmatic-hydrothermal fluid, and a sedimentary exhalative (SEDEX) overprinted by a hot spring. Here, we present the electron probe microanalysis (EPMA) and Fe-Zn isotopic data (microsampled) of four samples from the first pulse of mineralization that show annular textures to constrain ore genesis. The Zn/Cd ratios from the EPMA data of sphalerite range from 296 to 399 and overlap the range of exhalative systems. The δ56Fe values of Mn-Fe carbonate and δ66Zn values of sphalerite gradually decrease from early to late stages in three samples. A combination of the EPMA and isotopic data shows the Fe-Zn contents also have different correlations with δ66Zn values in sphalerite from these samples. Rayleigh distillation models this isotope and concentration data with the cause of fractionation related to vapour-liquid partitioning and mineral precipitation. In order to verify this Rayleigh distillation model, we combine our Fe-Zn isotopic data with those from previous studies to establish 12 Fe-Zn isotopic fractionation models. These fractionation models indicate the δ56Fei and δ66Zni values (initial Fe-Zn isotopic compositions) of the ore-forming system are in the range of -0.5‰​​ ~−1‰ and -0.28‰​ ~0‰, respectively. To conclude, the EPMA data, Fe-Zn isotopic characteristics, and fractionation models support the SEDEX model for the first pulse of mineralization.