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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
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
Li1.0Fe(SO4)2 crystallizes in the monoclinic Pc space group. The structure is three-dimensional. there are four inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Li–O bond distances ranging from 1.90–2.52 Å. In the second Li1+ site, Li1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Li–O bond distances ranging from 1.92–2.41 Å. In the third Li1+ site, Li1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Li–O bond distances ranging from 1.95–2.60 Å. In the fourth Li1+ site, Li1+ is bonded to six O2- atoms to form distorted LiO6 pentagonal pyramids that share corners with four FeO6 octahedra, corners with two SO4 tetrahedra, and edges with two SO4 tetrahedra. The corner-sharing octahedra tilt angles range from 48–59°. There are a spread of Li–O bond distances ranging from 1.99–2.29 Å. There are four inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one LiO6 pentagonal pyramid and corners with six SO4 tetrahedra. There are a spread of Fe–O bond distances ranging from 1.98–2.12 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one LiO6 pentagonal pyramid and corners with six SO4 tetrahedra. There are a spread of Fe–O bond distances ranging from 1.98–2.11 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six SO4 tetrahedra. There are a spread of Fe–O bond distances ranging from 2.03–2.09 Å. In the fourth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent LiO6 pentagonal pyramids and corners with six SO4 tetrahedra. There are a spread of Fe–O bond distances ranging from 2.02–2.08 Å. There are eight inequivalent S6+ sites. In the first S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three FeO6 octahedra and a cornercorner with one LiO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 37–46°. There are a spread of S–O bond distances ranging from 1.47–1.51 Å. In the second S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three FeO6 octahedra and an edgeedge with one LiO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 47–48°. There are a spread of S–O bond distances ranging from 1.44–1.52 Å. In the third S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three FeO6 octahedra. The corner-sharing octahedra tilt angles range from 44–46°. There are a spread of S–O bond distances ranging from 1.45–1.50 Å. In the fourth S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three FeO6 octahedra. The corner-sharing octahedra tilt angles range from 42–49°. There are a spread of S–O bond distances ranging from 1.43–1.53 Å. In the fifth S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three FeO6 octahedra. The corner-sharing octahedra tilt angles range from 39–48°. There are a spread of S–O bond distances ranging from 1.44–1.53 Å. In the sixth S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three FeO6 octahedra and a cornercorner with one LiO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 46–50°. There are a spread of S–O bond distances ranging from 1.45–1.51 Å. In the seventh S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three FeO6 octahedra. The corner-sharing octahedra tilt angles range from 47–48°. There are a spread of S–O bond distances ranging from 1.45–1.52 Å. In the eighth S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three FeO6 octahedra and an edgeedge with one LiO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 38–47°. There are a spread of S–O bond distances ranging from 1.45–1.52 Å. There are thirty-two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Fe3+, and one S6+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Li1+ and one S6+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Fe3+, and one S6+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Fe3+, and one S6+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Fe3+, and one S6+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Fe3+ and one S6+ atom. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to one Fe3+ and one S6+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Li1+ and one S6+ atom. In the ninth O2- site, O2- is bonded in a bent 120 degrees geometry to one Li1+ and one S6+ atom. In the tenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Fe3+ and one S6+ atom. In the eleventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Fe3+ and one S6+ atom. In the twelfth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Fe3+ and one S6+ atom. In the thirteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Fe3+, and one S6+ atom. In the fourteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Fe3+, and one S6+ atom. In the fifteenth O2- site, O2- is bonded in a bent 120 degrees geometry to one Li1+ and one S6+ atom. In the sixteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Fe3+ and one S6+ atom. In the seventeenth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Fe3+, and one S6+ atom. In the eighteenth O2- site, O2- is bonded in a single-bond geometry to one S6+ atom. In the nineteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Fe3+, and one S6+ atom. In the twentieth O2- site, O2- is bonded in a bent 150 degrees geometry to one Fe3+ and one S6+ atom. In the twenty-first O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Fe3+, and one S6+ atom. In the twenty-second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Fe3+, and one S6+ atom. In the twenty-third O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Fe3+, and one S6+ atom. In the twenty-fourth O2- site, O2- is bonded in a 2-coordinate geometry to two Li1+ and one S6+ atom. In the twenty-fifth O2- site, O2- is bonded in a bent 120 degrees geometry to one Li1+ and one S6+ atom. In the twenty-sixth O2- site, O2- is bonded in a bent 150 degrees geometry to one Fe3+ and one S6+ atom. In the twenty-seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Fe3+ and one S6+ atom. In the twenty-eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Fe3+, and one S6+ atom. In the twenty-ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Fe3+, and one S6+ atom. In the thirtieth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Fe3+, and one S6+ atom. In the thirty-first O2- site, O2- is bonded in a distorted trigonal planar geometry to two Li1+ and one S6+ atom. In the thirty-second O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Fe3+, and one S6+ atom.
In order to predict what biomarkers could be used on Mars, several biomarkers, or key signatures, of extinct life on earth are identified. Some of these biomarkers which may be applicable to Mars include reduced carbon and nitrogen compounds, CO3(2-), SO4(2-), NO3(-), Mg, Mn, Fe, and the isotopic ratios of C, N, and S. It is suggested that a fully equipped Mars rover might be able to perform analyses to measure most of these biomarkers while on the Martian surface.
Theories for the origin of life require the availability of reduced nitrogen. In the non-reducing atmosphere suggested by geochemical evidence, production in the atmosphere and survival of NH3 against photochemical destruction are problematic. Electric discharges and impact shocks would produce NO rather than HCN or NH3. Conversion of NO to nitrous and nitric acid (by way of HNO) and precipitation in acid rain would provide a source of fixed nitrogen to the early ocean. One solution to the NH3 problem may have been the reduction of nitrite/nitrate in the ocean with aqueous ferrous iron, Fe(2+): 6Fe(+2) + 7 H2O + NO2(-) yields 3Fe2O3 + 11 H(+) + NH3. We have measured the kinetics of this reaction as a function of temperature, pH, and concentrations of salts, Fe(+2), and NO2(-). Cations (Na(+), Mg(2+), K(+)) and anions (Cl(-), Br(-), SO4(2-)) increase the rate by factors of 4 to 8. Although a competing pathway yields N2, the efficiency of the conversion of nitrite to ammonia ranges from 25% to 85%. Nitrate reduction was not consistently reproducible; however, when it was observed, its rate was slower by at least 8X than that of nitrite reduction. If the prebiotic atmosphere contained 0.2 to 10 atmospheres CO2 as suggested by Walker (1985), the Fe(+2) concentration and the rate would have been limited by siderite (FeCO3) solubility.
Tobacco plants (Nicotiana tabacum L. cv NC82) were supplied with (NH4)2SO4 or NH4Cl at root-zone pH of 6.0 and 4.5 in hydroponic culture for 28 days. Dry matter accumulation, total N and C content, and leaf area and number were not affected by the NH4+ source or root-zone pH. Plants supplied with NH4Cl accumulated up to 1.2 mM Cl g DW-1, but accumulated 37% less inorganic H2PO4- and 47% less SO4(2-) than plants supplied with (NH4)2SO4. The large Cl- accumulation resulted in NH4Cl- supplied plants having a 31% higher inorganic anion (NO3-, H2, PO4-, SO4(2-), and Cl-) charge. This higher inorganic anion charge in the NH4Cl-supplied plants was balanced by a similar increase in K+ charge. Plants supplied with NH4Cl accumulated greater concentrations of Cl- in leaves (up to 5.1% of DW) than plants supplied with (NH4)2SO4 (less than -% DW). Despite the high Cl- concentration of leaves in NH4Cl supplied plants, these plants showed no symptoms of Cl- toxicity. This demonstrates that toxicity symptoms are not due solely to an interaction between high Cl- concentration in tissue and NH4+ nutrition. The increase in root-zone acidity to pH 4.5 from 6.0 did not induce toxicity symptoms.