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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
The application of zinc (Zn) and cadmium (Cd) isotopes as palaeo-proxies in carbonate sediment is rapidly expanding due to their potential for tracing changes in biological productivity in the modern and past oceans. However, there are limited investigations into the chemical cleaning methods required to produce the most consistent and accurate data for these novel isotope systems. This could impact their use as palaeo-proxies to reconstruct ocean-atmosphere-climate interactions throughout Earth's history. To address this concern and expand the utility of the Zn and Cd stable isotope systems as palaeo-productivity tracers, the performance of two standard chemical cleaning protocols for acquiring robust and reliable Zn and Cd isotope datasets were assessed. These include (i) the Cd-cleaning method that uses a reductive step to selectively leach contaminating secondary iron (Fe)-manganese (Mn) (oxyhydr)oxide coatings from the carbonate surface, and an oxidative step that is used to remove post-depositional organic matter and sulphide precipitates; and (ii) the magnesium/calcium cleaning protocol that includes an oxidative step only, leaving secondary Fesingle bondMn (oxyhydr)oxide coatings largely intact. Well-preserved Holocene-, and Mesozoic-aged carbonate sediments were used to test the reliability of these two chemical cleaning methods. The Holocene samples comprised not only aliquots of bulk sediment, but also individual species of planktic and benthic foraminifera. Our results show that the best practice chemical cleaning method for retrieving consistent and accurate Zn and Cd isotope, and Zn/Ca and Cd/Ca datasets for carbonate sediments, requires both reductive and oxidative cleaning following the Cd-cleaning method. This differs from most methodological approaches applied to date that remove the reductive step from the chemical cleaning protocol and apply an oxidative step only, or no chemical cleaning at all. Inclusion of the reductive step in the chemical cleaning method typically shifts δ 66 Zn by ~0.1‰ lower and δ 114 Cd by 0.3‰ higher in the solid phase, while Zn/Ca and Cd/Ca typically decrease 2-fold. The benthic foraminifera, C. wuellerstorfi, that live in ocean bottom waters where the seawater Zn and Cd isotope composition is homogeneous display evidence of Zn and Cd isotope fractionation between seawater and carbonate on the order of 0.08 ± 0.08‰ (2SE, n = 4) and -0.25 ± 0.13‰ (2SE, n = 4), respectively, in agreement with experimental constraints. Furthermore, evidence of Zn isotope fractionation effects are recorded in a naturally-dissolved carbonate sediment, together with laboratory-controlled carbonate dissolution experiments. Based on these results, we recommend the Cd-cleaning method and the application of Zn and Cd isotope fractionation factors to accurately reconstruct past seawater Zn and Cd isotope compositions from carbonate sediments.
According to a United Nations report, by 2050 nearly six billion people worldwide will suffer from clean water scarcity. This is mostly because of the exponential proliferation of world population, urbanization, industrialization, and water pollution. Heavy metals are common water pollutants that can pose grave public health consequences. Existing water purification systems are lack of materials that have the potential for quick, simultaneous, efficient, and cost-efficient removal of numerous toxic metals from wastewater. Here, in this work, we report the design and synthesis of an economically viable Layered Double Hydroxides - Stannic Sulfide, LDH–[Sn 2 S 6 ] that exhibits a rapid, efficient, selective, and concurrent removal of Cu 2+ , Ag + , Cd 2+ , Pb 2+ , and Hg 2+ from parts per million (ppm) level to below 5 parts per billion (ppb) satisfying World Health Organization’s (WHO) safe drinking water limit. Moreover, LDH–[Sn 2 S 6 ] shows exceptionally high removal efficiencies of the above metals in acidic, neutral, and basic conditions. LDH–[Sn 2 S 6 ] also demonstrates enormous sorption capacities of 378, 978, 332, 579, and 666 mg/g for Cu 2+ , Ag + , Cd 2+ , Pb 2+ , and Hg 2+ , respectively. Remarkably, LDH–[Sn 2 S 6 ] displays extraordinary tolerance to the concentrations of Na + , Ca 2+ , Mg 2+ , Cl - , CO 3 2– , NO 3 – ,and SO 4 2- , and other constituents in tap and river water, it efficiently sequestrates Cu 2+ , Ag + , Cd 2+ , Pb 2+ , and Hg 2+ from ppm to safe drinking water levels in minutes. LDH–[Sn 2 S 6 ] shows pseudo-second-order sorption kinetics suggesting chemisorption adsorption mechanism involving M–S bonding. Altogether, the regeneratable LDH–[Sn 2 S 6 ] becomes an exceptional material that shows ultrahigh removal, unprecedented selectivity, rapid adsorption kinetics, wide pH stability, and a massive adsorption capacity. The integration of these features places LDH–[Sn 2 S 6 ] at the top of all adsorbents known to date and thus could be used for wastewater purifications.
For the most part, enzymes contain one active site wherein they catalyze in a serial manner chemical reactions between substrates both efficiently and rapidly. Imagine if a situation could be created within a chiral porous crystal containing trillions of active sites where substrates can reside in vast numbers before being converted in parallel into products. Here, we report how it is possible to incorporate 1-anthracenecarboxylate (1-AC – ) as a substrate into a γ-cyclodextrin-containing metal–organic framework (CD-MOF-1), where the metals are K + cations, prior to carrying out [4+4] photodimerizations between pairs of substrate molecules, affording selectively one of four possible regioisomers. One of the high-yielding regioisomers exhibits optical activity as a result of the presence of an 8:1 ratio of the two enantiomers following separation by high-performance liquid chromatography. The solid-state superstructure of 1-anthracenecarboxylate potassium salt (1-ACK), which is co-crystallized with γ-cyclodextrin, reveals that pairs of substrate molecules are not only packed inside tunnels between spherical cavities present in CD-MOF-1, but also stabilized—in addition to hydrogen-bonding to the C-2 and C-3 hydroxyl groups on the d-glucopyranosyl residues present in the γ-cyclodextrin tori—by combinations of hydrophobic and electrostatic interactions between the carboxyl groups in 1-AC– and four K + cations on the waistline between the two γ-cyclodextrin tori in the tunnels. Here, these non-covalent bonding interactions result in preferred co-conformations that account for the highly regio- and enantioselective [4+4] cycloaddition during photoirradiation. Theoretical calculations, in conjunction with crystallography, support the regio- and stereochemical outcome of the photodimerization.
CdZn(GaS2)4 crystallizes in the tetragonal P-4 space group. The structure is three-dimensional. Cd2+ is bonded to four equivalent S2- atoms to form CdS4 tetrahedra that share corners with eight GaS4 tetrahedra. All Cd–S bond lengths are 2.53 Å. Zn2+ is bonded to four equivalent S2- atoms to form ZnS4 tetrahedra that share corners with eight GaS4 tetrahedra. All Zn–S bond lengths are 2.39 Å. There are three inequivalent Ga3+ sites. In the first Ga3+ site, Ga3+ is bonded to four equivalent S2- atoms to form GaS4 tetrahedra that share corners with four equivalent CdS4 tetrahedra and corners with four equivalent GaS4 tetrahedra. All Ga–S bond lengths are 2.31 Å. In the second Ga3+ site, Ga3+ is bonded to four equivalent S2- atoms to form GaS4 tetrahedra that share corners with four equivalent ZnS4 tetrahedra and corners with four equivalent GaS4 tetrahedra. All Ga–S bond lengths are 2.32 Å. In the third Ga3+ site, Ga3+ is bonded to four S2- atoms to form GaS4 tetrahedra that share corners with two equivalent CdS4 tetrahedra, corners with two equivalent ZnS4 tetrahedra, and corners with four GaS4 tetrahedra. There are two shorter (2.30 Å) and two longer (2.31 Å) Ga–S bond lengths. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a trigonal non-coplanar geometry to one Zn2+ and two Ga3+ atoms. In the second S2- site, S2- is bonded in a trigonal non-coplanar geometry to one Cd2+ and two Ga3+ atoms.
K16Na9(CdTl6)3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are four inequivalent K sites. In the first K site, K is bonded in a 4-coordinate geometry to six K, four Na, and six Tl atoms. There are a spread of K–K bond distances ranging from 4.06–4.45 Å. There are two shorter (4.10 Å) and two longer (4.13 Å) K–Na bond lengths. There are a spread of K–Tl bond distances ranging from 3.99–4.20 Å. In the second K site, K is bonded in a 4-coordinate geometry to five K, four equivalent Na, two equivalent Cd, and six Tl atoms. There are two shorter (4.11 Å) and three longer (4.19 Å) K–K bond lengths. All K–Na bond lengths are 4.20 Å. Both K–Cd bond lengths are 3.96 Å. There are two shorter (4.10 Å) and four longer (4.20 Å) K–Tl bond lengths. In the third K site, K is bonded in a 3-coordinate geometry to three K and four Tl atoms. There are a spread of K–Tl bond distances ranging from 3.82–4.06 Å. In the fourth K site, K is bonded in a 6-coordinate geometry to three equivalent K and six equivalent Tl atoms. All K–Tl bond lengths are 3.84 Å. There are two inequivalent Na sites. In the first Na site, Na is bonded in a 6-coordinate geometry to four K, one Cd, and five Tl atoms. The Na–Cd bond length is 3.18 Å. There are a spread of Na–Tl bond distances ranging from 3.26–3.46 Å. In the second Na site, Na is bonded in a 12-coordinate geometry to four equivalent K and six Tl atoms. There are four shorter (3.32 Å) and two longer (3.43 Å) Na–Tl bond lengths. Cd is bonded in a 12-coordinate geometry to two equivalent K, two equivalent Na, and six Tl atoms. There are four shorter (3.18 Å) and two longer (3.39 Å) Cd–Tl bond lengths. There are five inequivalent Tl sites. In the first Tl site, Tl is bonded to six K, three equivalent Na, and three equivalent Tl atoms to form a mixture of distorted face and corner-sharing TlK6Na3Tl3 cuboctahedra. All Tl–Tl bond lengths are 3.25 Å. In the second Tl site, Tl is bonded in a 12-coordinate geometry to three equivalent K, three equivalent Na, three equivalent Cd, and three equivalent Tl atoms. All Tl–Tl bond lengths are 3.32 Å. In the third Tl site, Tl is bonded in a 12-coordinate geometry to six K, two equivalent Na, two equivalent Cd, and two Tl atoms. The Tl–Tl bond length is 3.21 Å. In the fourth Tl site, Tl is bonded in a 3-coordinate geometry to three equivalent K, three Na, and two Tl atoms. The Tl–Tl bond length is 3.24 Å. In the fifth Tl site, Tl is bonded to six K, three equivalent Na, and three equivalent Tl atoms to form a mixture of distorted face and corner-sharing TlK6Na3Tl3 cuboctahedra.
Recently, we have succeeded in fabricating diffused junction p(sup +)n(Cd,S) InP solar cells with measured AMO, 25 C open circuit voltage (V(sub OC)) of 887.6 mV, which, to the best of our knowledge, is higher than previously reported V(sub OC) values for any InP homojunction solar cells. The experiment-based projected achievable efficiency of these cells using LEC grown substrates is 21.3 percent. The maximum AMO, 25 C internal losses due to date on bare cells is, however, only 13.2 percent. This is because of large external and internal losses due to non-optimized front grid design, antireflection (AR) coating and emitter thickness. This paper summarizes recent advances in the technology of fabrication of p(sup +)n InP diffused structures and solar cells, resulted from a study undertaken in an effort to increase the cell efficiency. The topics discussed in this paper include advances in: (1) the formation on thin p(sup +) InP:Cd emitter layers, (2) electroplated front contacts, (3) surface passivation and (4) the design of a new native oxide/Al2O3/MgF2 tree layer AR coating using a chemically-grown P-rich passivating oxide as a first layer. Based on the high radiation resistance and the excellent post-irradiation annealing and recovery demonstrated in the early tests done to date, as well as the projected high efficiency and low-cost high-volume fabricability, these cells show a very good potential for space photovoltaic applications.
Recently, we have succeeded in fabricating diffused junction p(+)n(Cd,S) InP solar cells with measured AMO, 25 C open circuit voltage (V(sub OC)) of 887.6 mV, which, to the best of our knowledge, is higher than previously reported V(sub OC) values for any InP homojunction solar cells. The experiment-based projected achievable efficiency of these cells using LEC grown substrates is 21.3%. The maximum AMO, 25 C efficiency recorded to date on bare cells is, however, only 13.2%. This is because of large external and internal losses due to non-optimized front grid design, antireflection (AR) coating and emitter thickness. This paper summarizes recent advances in the technology of fabrication of p(+)n InP diffused structures and solar cells, resulted from a study undertaken in an effort to increase the cell efficiency. The topics discussed in this paper include advances in: 1) the formation of thin p(+) InP:Cd emitter layers, 2) electroplated front contacts, 3) surface passivation and 4) the design of a new native oxide/AI203/MgF2 three layer AR coating using a chemically-grown P-rich passivating oxide as a first layer. Based on the high radiation resistance and the excellent post-irradiation annealing and recovery demonstrated in the early tests done to date, as well as the projected high efficiency and low-cost high-volume fabricability, these cells show a very good potential for space photovoltaic applications.
Contributions of NASA sponsored programs dealing with electroforming, Ni-Cd-Zn-Ag batteries, refractory alloys, fuel cells, solar cells, and stress corrosion in titanium alloys
V3Cd4TlO12 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. there are three inequivalent V5+ sites. In the first V5+ site, V5+ is bonded to four O2- atoms to form VO4 tetrahedra that share corners with four CdO6 octahedra and corners with two equivalent CdO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 54–61°. There is three shorter (1.75 Å) and one longer (1.77 Å) V–O bond length. In the second V5+ site, V5+ is bonded to four O2- atoms to form VO4 tetrahedra that share corners with four CdO6 octahedra and corners with two equivalent CdO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 41–64°. There are a spread of V–O bond distances ranging from 1.73–1.78 Å. In the third V5+ site, V5+ is bonded to four O2- atoms to form VO4 tetrahedra that share corners with four CdO6 octahedra and corners with two equivalent CdO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 40–64°. There are a spread of V–O bond distances ranging from 1.72–1.81 Å. There are four inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to six O2- atoms to form CdO6 octahedra that share corners with six VO4 tetrahedra, an edgeedge with one CdO6 octahedra, and an edgeedge with one CdO6 pentagonal pyramid. There are a spread of Cd–O bond distances ranging from 2.27–2.32 Å. In the second Cd2+ site, Cd2+ is bonded to six O2- atoms to form CdO6 octahedra that share corners with six VO4 tetrahedra, an edgeedge with one CdO6 octahedra, and an edgeedge with one CdO6 pentagonal pyramid. There are a spread of Cd–O bond distances ranging from 2.24–2.35 Å. In the third Cd2+ site, Cd2+ is bonded to six O2- atoms to form distorted CdO6 pentagonal pyramids that share corners with six VO4 tetrahedra and edges with two CdO6 octahedra. There are a spread of Cd–O bond distances ranging from 2.35–2.41 Å. In the fourth Cd2+ site, Cd2+ is bonded in a 5-coordinate geometry to six O2- atoms. There are a spread of Cd–O bond distances ranging from 2.31–2.93 Å. Tl1+ is bonded in a 4-coordinate geometry to eight O2- atoms. There are a spread of Tl–O bond distances ranging from 2.75–3.28 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one V5+ and three Cd2+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one V5+ and two Cd2+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one V5+ and two Cd2+ atoms. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to one V5+ and three Cd2+ atoms. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one V5+, two Cd2+, and one Tl1+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one V5+, two Cd2+, and one Tl1+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to one V5+, two Cd2+, and one Tl1+ atom. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to one V5+, two Cd2+, and one Tl1+ atom. In the ninth O2- site, O2- is bonded in a 1-coordinate geometry to one V5+ and two Cd2+ atoms. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to one V5+ and two Cd2+ atoms. In the eleventh O2- site, O2- is bonded in a 4-coordinate geometry to one V5+, one Cd2+, and two equivalent Tl1+ atoms. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to one V5+, one Cd2+, and two equivalent Tl1+ atoms.
MnCd4O5 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Mn2+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with six CdO6 octahedra, edges with two equivalent MnO6 octahedra, and edges with ten CdO6 octahedra. The corner-sharing octahedra tilt angles range from 1–4°. There are a spread of Mn–O bond distances ranging from 2.29–2.31 Å. There are five inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to six O2- atoms to form CdO6 octahedra that share corners with six CdO6 octahedra, edges with four equivalent MnO6 octahedra, and edges with eight CdO6 octahedra. The corner-sharing octahedra tilt angles range from 3–7°. All Cd–O bond lengths are 2.37 Å. In the second Cd2+ site, Cd2+ is bonded to six O2- atoms to form CdO6 octahedra that share corners with three equivalent MnO6 octahedra, corners with three CdO6 octahedra, edges with three equivalent MnO6 octahedra, and edges with nine CdO6 octahedra. The corner-sharing octahedra tilt angles range from 1–7°. There are a spread of Cd–O bond distances ranging from 2.37–2.43 Å. In the third Cd2+ site, Cd2+ is bonded to six O2- atoms to form CdO6 octahedra that share corners with two equivalent CdO6 octahedra, corners with four equivalent MnO6 octahedra, edges with two equivalent MnO6 octahedra, and edges with ten CdO6 octahedra. The corner-sharing octahedra tilt angles range from 1–4°. There are two shorter (2.36 Å) and four longer (2.44 Å) Cd–O bond lengths. In the fourth Cd2+ site, Cd2+ is bonded to six O2- atoms to form CdO6 octahedra that share a cornercorner with one MnO6 octahedra, corners with five CdO6 octahedra, edges with two equivalent MnO6 octahedra, and edges with ten CdO6 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are a spread of Cd–O bond distances ranging from 2.35–2.44 Å. In the fifth Cd2+ site, Cd2+ is bonded to six O2- atoms to form CdO6 octahedra that share corners with six CdO6 octahedra, edges with two equivalent MnO6 octahedra, and edges with ten CdO6 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are a spread of Cd–O bond distances ranging from 2.36–2.40 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to one Mn2+ and five Cd2+ atoms to form OMnCd5 octahedra that share corners with six OCd6 octahedra and edges with twelve OMnCd5 octahedra. The corner-sharing octahedra tilt angles range from 0–5°. In the second O2- site, O2- is bonded to two equivalent Mn2+ and four Cd2+ atoms to form a mixture of edge and corner-sharing OMn2Cd4 octahedra. The corner-sharing octahedra tilt angles range from 0–5°. In the third O2- site, O2- is bonded to two equivalent Mn2+ and four Cd2+ atoms to form OMn2Cd4 octahedra that share corners with six OCd6 octahedra and edges with twelve OMnCd5 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. In the fourth O2- site, O2- is bonded to six Cd2+ atoms to form a mixture of edge and corner-sharing OCd6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the fifth O2- site, O2- is bonded to one Mn2+ and five Cd2+ atoms to form OMnCd5 octahedra that share corners with six OCd6 octahedra and edges with twelve OMnCd5 octahedra. The corner-sharing octahedra tilt angles range from 1–3°.
K2CdN12 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eight N+0.33- atoms. There are a spread of K–N bond distances ranging from 2.85–3.37 Å. Cd2+ is bonded to six N+0.33- atoms to form edge-sharing CdN6 octahedra. There are two shorter (2.35 Å) and four longer (2.44 Å) Cd–N bond lengths. There are six inequivalent N+0.33- sites. In the first N+0.33- site, N+0.33- is bonded in a 4-coordinate geometry to one K1+, two equivalent Cd2+, and one N+0.33- atom. The N–N bond length is 1.20 Å. In the second N+0.33- site, N+0.33- is bonded in a linear geometry to two N+0.33- atoms. The N–N bond length is 1.17 Å. In the third N+0.33- site, N+0.33- is bonded in a 3-coordinate geometry to two equivalent K1+ and one N+0.33- atom. In the fourth N+0.33- site, N+0.33- is bonded in a 4-coordinate geometry to two equivalent K1+, one Cd2+, and one N+0.33- atom. The N–N bond length is 1.20 Å. In the fifth N+0.33- site, N+0.33- is bonded in a linear geometry to two N+0.33- atoms. The N–N bond length is 1.18 Å. In the sixth N+0.33- site, N+0.33- is bonded in a 4-coordinate geometry to three equivalent K1+ and one N+0.33- atom.
(K2Cd3H6(SO5)4)2(H2)3H2O2 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of eight hydrogen molecules; four water molecules; and one K2Cd3H6(SO5)4 sheet oriented in the (0, 0, 1) direction. In the K2Cd3H6(SO5)4 sheet, there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of K–O bond distances ranging from 2.81–3.10 Å. In the second K1+ site, K1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of K–O bond distances ranging from 2.83–3.16 Å. There are three inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to six O2- atoms to form CdO6 octahedra that share corners with four SO4 tetrahedra. There are a spread of Cd–O bond distances ranging from 2.31–2.41 Å. In the second Cd2+ site, Cd2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Cd–O bond distances ranging from 2.23–2.85 Å. In the third Cd2+ site, Cd2+ is bonded in a 4-coordinate geometry to one H1+ and four O2- atoms. The Cd–H bond length is 2.39 Å. There are a spread of Cd–O bond distances ranging from 2.22–2.30 Å. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 1.03 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the sixth H1+ site, H1+ is bonded in a distorted single-bond geometry to one Cd2+ atom. There are four inequivalent S6+ sites. In the first S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share a cornercorner with one CdO6 octahedra. The corner-sharing octahedral tilt angles are 44°. There are a spread of S–O bond distances ranging from 1.48–1.51 Å. In the second S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with two equivalent CdO6 octahedra. The corner-sharing octahedra tilt angles range from 54–55°. There are a spread of S–O bond distances ranging from 1.48–1.51 Å. In the third S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share a cornercorner with one CdO6 octahedra. The corner-sharing octahedral tilt angles are 56°. There are a spread of S–O bond distances ranging from 1.45–1.57 Å. In the fourth S6+ site, S6+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of S–O bond distances ranging from 1.47–1.52 Å. There are twenty inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, one Cd2+, and one S6+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+, one Cd2+, and one S6+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to two K1+ and one S6+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to two Cd2+ and one H1+ atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to one K1+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a distorted water-like geometry to one Cd2+ and two H1+ atoms. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one K1+ and one Cd2+ atom. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, one Cd2+, and one S6+ atom. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Cd2+, and one S6+ atom. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to one Cd2+ and one S6+ atom. In the eleventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cd2+ and one S6+ atom. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to two K1+, one Cd2+, and one S6+ atom. In the thirteenth O2- site, O2- is bonded in a single-bond geometry to one Cd2+ and one S6+ atom. In the fourteenth O2- site, O2- is bonded in a distorted single-bond geometry to three K1+ and one S6+ atom. In the fifteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cd2+ and one S6+ atom. In the sixteenth O2- site, O2- is bonded in a single-bond geometry to one S6+ atom. In the seventeenth O2- site, O2- is bonded in a distorted water-like geometry to one H1+ and one S6+ atom. In the eighteenth O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, one Cd2+, and one S6+ atom. In the nineteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cd2+ and one S6+ atom. In the twentieth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cd2+ and one S6+ atom.
Cs2Cd3(B4O7)4 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Cs1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Cs–O bond distances ranging from 3.02–3.49 Å. There are two inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to six O2- atoms to form distorted CdO6 octahedra that share corners with eight BO4 tetrahedra. There are a spread of Cd–O bond distances ranging from 2.25–2.42 Å. In the second Cd2+ site, Cd2+ is bonded to six O2- atoms to form distorted CdO6 octahedra that share corners with eight BO4 tetrahedra. There are a spread of Cd–O bond distances ranging from 2.32–2.40 Å. There are eight inequivalent B3+ sites. In the first B3+ site, B3+ is bonded to four O2- atoms to form BO4 tetrahedra that share corners with three CdO6 octahedra and a cornercorner with one BO4 tetrahedra. The corner-sharing octahedra tilt angles range from 62–71°. There are a spread of B–O bond distances ranging from 1.47–1.50 Å. In the second B3+ site, B3+ is bonded to four O2- atoms to form BO4 tetrahedra that share corners with three CdO6 octahedra and a cornercorner with one BO4 tetrahedra. The corner-sharing octahedra tilt angles range from 55–67°. There are a spread of B–O bond distances ranging from 1.47–1.50 Å. In the third B3+ site, B3+ is bonded to four O2- atoms to form BO4 tetrahedra that share corners with three CdO6 octahedra and corners with two BO4 tetrahedra. The corner-sharing octahedra tilt angles range from 60–68°. There are a spread of B–O bond distances ranging from 1.48–1.51 Å. In the fourth B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.38 Å) and one longer (1.39 Å) B–O bond length. In the fifth B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.37 Å) and two longer (1.38 Å) B–O bond length. In the sixth B3+ site, B3+ is bonded to four O2- atoms to form BO4 tetrahedra that share corners with three CdO6 octahedra and corners with two BO4 tetrahedra. The corner-sharing octahedra tilt angles range from 62–67°. There are a spread of B–O bond distances ranging from 1.46–1.53 Å. In the seventh B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.36–1.39 Å. In the eighth B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.36–1.38 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to one Cs1+ and two B3+ atoms. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Cs1+ and two B3+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Cd2+ and two B3+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Cd2+ and two B3+ atoms. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Cd2+ and two B3+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Cd2+ and two B3+ atoms. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cd2+ and two B3+ atoms. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to one Cd2+ and two B3+ atoms. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Cd2+ and two B3+ atoms. In the tenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cs1+ and two B3+ atoms. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to one Cd2+ and two B3+ atoms. In the twelfth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cs1+ and two B3+ atoms. In the thirteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Cd2+ and two B3+ atoms. In the fourteenth O2- site, O2- is bonded in a bent 120 degrees geometry to one Cs1+ and two B3+ atoms.
Rb2Cd3(B4O7)4 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Rb1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Rb–O bond distances ranging from 2.93–3.53 Å. There are two inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to six O2- atoms to form distorted CdO6 octahedra that share corners with eight BO4 tetrahedra. There are a spread of Cd–O bond distances ranging from 2.32–2.41 Å. In the second Cd2+ site, Cd2+ is bonded to six O2- atoms to form distorted CdO6 octahedra that share corners with eight BO4 tetrahedra. There are a spread of Cd–O bond distances ranging from 2.26–2.40 Å. There are eight inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.37 Å) and two longer (1.38 Å) B–O bond length. In the second B3+ site, B3+ is bonded to four O2- atoms to form BO4 tetrahedra that share corners with three CdO6 octahedra and corners with two BO4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–68°. There are a spread of B–O bond distances ranging from 1.48–1.51 Å. In the third B3+ site, B3+ is bonded to four O2- atoms to form BO4 tetrahedra that share corners with three CdO6 octahedra and a cornercorner with one BO4 tetrahedra. The corner-sharing octahedra tilt angles range from 54–68°. There are a spread of B–O bond distances ranging from 1.47–1.50 Å. In the fourth B3+ site, B3+ is bonded to four O2- atoms to form BO4 tetrahedra that share corners with three CdO6 octahedra and corners with two BO4 tetrahedra. The corner-sharing octahedra tilt angles range from 63–67°. There are a spread of B–O bond distances ranging from 1.46–1.53 Å. In the fifth B3+ site, B3+ is bonded to four O2- atoms to form BO4 tetrahedra that share corners with three CdO6 octahedra and a cornercorner with one BO4 tetrahedra. The corner-sharing octahedra tilt angles range from 61–71°. There are a spread of B–O bond distances ranging from 1.47–1.50 Å. In the sixth B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.38 Å) and one longer (1.39 Å) B–O bond length. In the seventh B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.36–1.40 Å. In the eighth B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.36–1.39 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent Rb1+ and two B3+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Cd2+ and two B3+ atoms. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Rb1+ and two B3+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Cd2+ and two B3+ atoms. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Cd2+ and two B3+ atoms. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cd2+ and two B3+ atoms. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Cd2+ and two B3+ atoms. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Cd2+ and two B3+ atoms. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Cd2+ and two B3+ atoms. In the tenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cd2+ and two B3+ atoms. In the eleventh O2- site, O2- is bonded in a bent 120 degrees geometry to one Rb1+ and two B3+ atoms. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to one Cd2+ and two B3+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Rb1+ and two B3+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Rb1+ and two B3+ atoms.
Rb2Cd5As4 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Rb1+ is bonded in a 4-coordinate geometry to four As3- atoms. There are two shorter (3.63 Å) and two longer (3.78 Å) Rb–As bond lengths. There are three inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to four As3- atoms to form a mixture of edge and corner-sharing CdAs4 tetrahedra. There are a spread of Cd–As bond distances ranging from 2.69–2.90 Å. In the second Cd2+ site, Cd2+ is bonded to four As3- atoms to form a mixture of edge and corner-sharing CdAs4 tetrahedra. There are a spread of Cd–As bond distances ranging from 2.69–2.92 Å. In the third Cd2+ site, Cd2+ is bonded in a 4-coordinate geometry to four As3- atoms. There are two shorter (2.79 Å) and two longer (2.84 Å) Cd–As bond lengths. There are two inequivalent As3- sites. In the first As3- site, As3- is bonded in a 7-coordinate geometry to two equivalent Rb1+ and five Cd2+ atoms. In the second As3- site, As3- is bonded in a 5-coordinate geometry to two equivalent Rb1+ and five Cd2+ atoms.
We present results from a Chandra observation of the core region of the nearby X-ray bright galaxy cluster AWM 7. There are blob-like substructures, which are seen in the energy band 2-10 keV, within 10 kpc (20") of the cD galaxy NGC 1129, and the brightest sub-peak has a spatial extent more than 4 kpc. We also notice that the central soft X-ray peak is offset from the optical center by 1.3 kpc. These structures have no correlated features in optical, infrared, or radio band. Energy spectrum of the hard sub-peak indicates a temperature higher than 3 keV with a metallicity less than 0.3 solar, or a power-law spectrum with photon index approximately 1.2. A hardness ratio map and a narrow Fe-K band image jointly indicate two Fe-rich blobs symmetrically located around the cD galaxy, with the direction perpendicular to the sub-peak direction. In larger scales (r less than 60 kpc), the temperature gradually drops from 4 keV to 2 keV toward the cluster center and the metal abundance rises steeply to a peak of 1.5 solar at r approximately equal to 7 kpc. These results indicate that a dynamical process is going on in the central region of AWM 7, which probably creates heated gas blobs and drives metal injection.
Dynamic nuclear polarization (DNP) solid-state NMR (SSNMR) spectroscopy was used to obtain detailed surface structures of zinc blende CdSe nanocrystals (NCs) with plate or spheroidal morphologies which are capped by carboxylic acid ligands. 1D 113 Cd and 77 Se cross-polarization magic angle spinning (CPMAS) NMR spectra revealed distinct signals from Cd and Se atoms on the surface of the NCs, and those residing in bulk-like environments, below the surface. 113 Cd cross-polarization magic-angle-turning (CP-MAT) experiments identified CdSe 3 O, CdSe 2 O 2 , and CdSeO 3 Cd coordination environments on the surface of the NCs, where the oxygen atoms are presumably from coordinated carboxylate ligands. The sensitivity gain from DNP enabled natural isotopic abundance 2D homonuclear 113 Cd– 113 Cd and 77 Se– 77 Se and heteronuclear 113 Cd– 77 Se scalar correlation solid-state NMR experiments which revealed the connectivity of the Cd and Se atoms. Importantly, 77 Se{ 113 Cd} scalar heteronuclear multiple quantum coherence ( J -HMQC) experiments were used to selectively measure one-bond 77 Se– 113 Cd scalar coupling constants ( 1 J ( 77 Se, 113 Cd)). With knowledge of 1 J ( 77 Se, 113 Cd), heteronuclear 77 Se{ 113 Cd} spin echo ( J -resolved) NMR experiments were used to determine the number of Cd atoms bonded to Se atoms and vice versa. Furthermore, the J -resolved experiments directly confirmed that major Cd and Se surface species have CdSe 2 O 2 and SeCd 4 stoichiometries, respectively. Considering the crystal structure of zinc blende CdSe and the similarity of the solid-state NMR data for the platelets and spheroids, we conclude that the surface of the spheroidal CdSe NCs is primarily composed of {100} facets. The methods outlined here will generally be applicable to obtain detailed surface structures of various main group semiconductor nanoparticles.