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Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations
WNa2W2Rh(SO4)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional and consists of four tungsten molecules and one Na2W2Rh(SO4)2 framework. In the Na2W2Rh(SO4)2 framework, there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Na–O bond distances ranging from 2.27–2.89 Å. In the second Na1+ site, Na1+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Na–O bond distances ranging from 2.31–2.91 Å. There are two inequivalent W5+ sites. In the first W5+ site, W5+ is bonded in a single-bond geometry to one O2- atom. The W–O bond length is 2.20 Å. In the second W5+ site, W5+ is bonded in a single-bond geometry to one O2- atom. The W–O bond length is 2.20 Å. Rh3+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Rh–O bond distances ranging from 2.24–2.70 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of S–O bond distances ranging from 1.48–1.54 Å. In the second S2- site, S2- is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of S–O bond distances ranging from 1.48–1.53 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Na1+, one W5+, and one S2- atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Rh3+ and one S2- atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one W5+, and one S2- atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one S2- atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Na1+, one Rh3+, and one S2- atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to one Rh3+ and one S2- atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Rh3+, and one S2- atom. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Na1+ and one S2- atom.
Abstract. Anthropogenic emissions of aerosols and precursor compounds are known to significantly affect the energy balance of the Earth–atmosphere system, alter the formation of clouds and precipitation, and have a substantial impact on human health and the environment. Global models are an essential tool for examining the impacts of these emissions. In this study, we examine the sensitivity of model results to the assumed height of SO2 injection, seasonality of SO2 and black carbon (BC) particulate emissions, and the assumed fraction of SO2 emissions that is injected into the atmosphere as particulate phase sulfate (SO4) in 11 climate and chemistry models, including both chemical transport models and the atmospheric component of Earth system models. We find large variation in atmospheric lifetime across models for SO2, SO4, and BC, with a particularly large relative variation for SO2, which indicates that fundamental aspects of atmospheric sulfur chemistry remain uncertain. Of the perturbations examined in this study, the assumed height of SO2 injection had the largest overall impacts, particularly on global mean net radiative flux (maximum difference of −0.35 W m−2), SO2 lifetime over Northern Hemisphere land (maximum difference of 0.8 d), surface SO2 concentration (up to 59 % decrease), and surface sulfate concentration (up to 23 % increase). Emitting SO2 at height consistently increased SO2 and SO4 column burdens and shortwave cooling, with varying magnitudes, but had inconsistent effects across models on the sign of the change in implied cloud forcing. The assumed SO4 emission fraction also had a significant impact on net radiative flux and surface sulfate concentration. Because these properties are not standardized across models this is a source of inter-model diversity typically neglected in model intercomparisons. These results imply a need to ensure that anthropogenic emission injection height and SO4 emission fraction are accurately and consistently represented in global models.
UW3(SO5)2(CN3H6)2 crystallizes in the monoclinic C2/c space group. The structure is two-dimensional and consists of eight guanidinium molecules and two UW3(SO5)2 sheets oriented in the (0, 0, 1) direction. In each UW3(SO5)2 sheet, U4+ is bonded to six O2- atoms to form distorted UO6 octahedra that share corners with four equivalent SO4 tetrahedra. There are a spread of U–O bond distances ranging from 1.84–2.54 Å. There are two inequivalent W6+ sites. In the first W6+ site, W6+ is bonded in a linear geometry to two equivalent O2- atoms. Both W–O bond lengths are 2.23 Å. In the second W6+ site, W6+ is bonded in a single-bond geometry to one O2- atom. The W–O bond length is 2.22 Å. S2- is bonded to four O2- atoms to form SO4 tetrahedra that share corners with two equivalent UO6 octahedra. The corner-sharing octahedra tilt angles range from 33–36°. There are a spread of S–O bond distances ranging from 1.48–1.51 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one W6+ and one S2- atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one S2- atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one U4+ and one S2- atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one U4+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one W6+ and one S2- atom.
Rb4WS3O14 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are four inequivalent Rb1+ sites. In the first Rb1+ site, Rb1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Rb–O bond distances ranging from 2.94–3.30 Å. In the second Rb1+ site, Rb1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Rb–O bond distances ranging from 2.86–3.48 Å. In the third Rb1+ site, Rb1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Rb–O bond distances ranging from 2.88–3.33 Å. In the fourth Rb1+ site, Rb1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Rb–O bond distances ranging from 3.00–3.53 Å. W6+ is bonded to six O2- atoms to form distorted WO6 octahedra that share corners with four SO4 tetrahedra. There are a spread of W–O bond distances ranging from 1.76–2.31 Å. There are three inequivalent S6+ sites. In the first S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with two equivalent WO6 octahedra. The corner-sharing octahedra tilt angles range from 43–48°. There are a spread of S–O bond distances ranging from 1.46–1.55 Å. In the second S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share a cornercorner with one WO6 octahedra. The corner-sharing octahedral tilt angles are 42°. There is three shorter (1.47 Å) and one longer (1.60 Å) S–O bond length. In the third S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share a cornercorner with one WO6 octahedra. The corner-sharing octahedral tilt angles are 40°. There are a spread of S–O bond distances ranging from 1.47–1.55 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three Rb1+ and one W6+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two Rb1+ and one W6+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Rb1+, one W6+, and one S6+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Rb1+, one W6+, and one S6+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two Rb1+, one W6+, and one S6+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to two Rb1+, one W6+, and one S6+ atom. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to three Rb1+ and one S6+ atom. In the eighth O2- site, O2- is bonded in a distorted single-bond geometry to three Rb1+ and one S6+ atom. In the ninth O2- site, O2- is bonded in a distorted single-bond geometry to three Rb1+ and one S6+ atom. In the tenth O2- site, O2- is bonded in a distorted single-bond geometry to three Rb1+ and one S6+ atom. In the eleventh O2- site, O2- is bonded in a distorted single-bond geometry to three Rb1+ and one S6+ atom. In the twelfth O2- site, O2- is bonded in a single-bond geometry to three Rb1+ and one S6+ atom. In the thirteenth O2- site, O2- is bonded in a distorted single-bond geometry to three Rb1+ and one S6+ atom. In the fourteenth O2- site, O2- is bonded in a distorted single-bond geometry to three Rb1+ and one S6+ atom.
Pyrite oxidation plays a critical role in the relationship between weathering and climate, and its impact on the global carbon cycle has previously been constrained through inversion models utilizing observations of river sulfate ($SO^{2–}_{4}$) and its 34 S/ 32 S isotope ratio (δ 34 S SO4 ). However, measurements from some rivers have suggested that SSO4 can be substantially impacted by processes such as microbial sulfate reduction and/or sulfur assimilation and cycling, rather than simply reflecting a weighted mixture of lithologic sulfur sources. To study the prevalence and controls on $SO^{2–}_{4}$ transformations, in this study we measured dissolved major element concentrations and δ 34 S SO4 in river water samples from throughout western Iceland. Our analyses focused on samples from a small catchment hosting the Efri Haukadalsá river, a system with relatively uniform and isotopically constrained basaltic bedrock. We also measured sediment δ 34 S and sulfur speciation using sulfur K-edge X-ray absorption spectroscopy on sediment and vegetation samples from this catchment. Values of dissolved δ 34 S SO4 in the Efri Haukadalsá ranged from 2.5‰ to 23.7‰ and had a linear relationship with Cl – /$SO^{2–}_{4}$ ratios, indicating that $SO^{2–}_{4}$ predominantly derived from basalt weathering and meteoric precipitation. The lower δ 34 S SO4 values were found in fluvial valleys with V-shaped cross sections, while higher values of δ 34 S SO4 occurred in U-shaped, glacially eroded valleys with thick alluvial fills blanketing the valley floor. Spectroscopic observations identified organic sulfur phases in suspended river sediment, floodplain deposits, and vegetation. Mass balance calculations quantified the organic sulfur flux as less than 10% of $SO^{2–}_{4}$ export, and sediment δ 34 S values were comparable to river δ 34 S SO4 . We interpreted these isotopic and chemical patterns as reflecting differences in the availability of unweathered bedrock across the Efri Haukadalsá catchment, with V-shaped valleys having greater access to fresh sulfide-bearing minerals than alluviated U-shaped valleys; this interpretation is in contrast to one in which the elevated δ 34 S SO4 values reflect fractionation during sulfur transformations along alluvial reaches. These results validated the application of river inversion models for constraining weathering fluxes and affirmed that pyrite oxidation globally, even in the presence of river sulfur cycling, modulates the abundance of atmospheric carbon dioxide.
In this study, a novel, to the best of our knowledge, method of wet chemical etching of sapphire workpieces (such as optics, wafers, windows, and cones), called the sapphire advanced mitigation process (or sapphire AMP), has been developed that exposes sub-surface mechanical damage created during the optical fabrication process and significantly enhances the surface laser damage resistance (> 2×) and mechanical strength (up to ~ 2.6×). Sapphire AMP involves first treating the workpiece with a mixture of sulfuric and phosphoric acid ([H 2 SO 4 ]:[H 3 PO 4 ]= 1 : 3) at 220°C, followed with phosphoric acid at 160°C, then with sodium hydroxide base (NaOH) and surfactant at 40°C, and finally with a high-pressure deionized water spray rinse. Sapphire AMP has been demonstrated on both A- and C-plane sapphire workpieces. The mechanism of this etch process involves the reaction of the sapphire (Al 2 O 3 ) surface with sulfuric acid (H 2 SO 4 ) forming aluminum sulfate [Al2(SO4)3], which has low solubility. The high phosphoric acid content in the first and second steps of sapphire AMP results in the efficient conversion of Al 2 (SO 4 ) 3 to aluminum phosphate (AlPO 4 ), which is very soluble, greatly reducing reaction product redeposition on the workpiece surface. Sapphire AMP is shown to expose sub-surface mechanical damage on the sapphire surface created during the grinding and polishing processes, whose etched morphology has either isotropic or anisotropic evolution depending on the nature of the initial surface damage. Sapphire AMP was also designed to remove the key known surface, laser absorbing precursors (namely, foreign chemical impurities, the fracture surface layer of preexisting sub-surface damage, and reaction product or foreign species redeposition or precipitation). Static and sliding indention induced surface microfractures on sapphire are shown after sapphire AMP to have a significant decrease in the fast photoluminescence intensity (a known metric for measuring the degree of laser damaging absorbing precursors). In addition, the onset of laser damage (at 351 nm 3 ns) on sapphire AMP treated workpieces was shown to increase in fluence from ~ 4 to >9.5J/cm 2 . Finally, biaxial ball-on-ring mechanical tests on sapphire disks showed an increase in the failure stress from 340 MPa (with pre-existing 28 µm flaws) to ~ 900MPa after sapphire AMP, which is attributed to the blunting of the surface microfractures.