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TiCr crystallizes in the orthorhombic Cmmm space group. The structure is two-dimensional and consists of two TiCr sheets oriented in the (0, 1, 0) direction. Ti is bonded in a 4-coordinate geometry to four equivalent Cr atoms. All Ti–Cr bond lengths are 2.54 Å. Cr is bonded in a 4-coordinate geometry to four equivalent Ti atoms.
TiCr(PO4)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are three inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Ti–O bond distances ranging from 1.91–2.10 Å. In the second Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Ti–O bond distances ranging from 1.91–2.11 Å. In the third Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Ti–O bond distances ranging from 1.89–2.12 Å. There are three inequivalent Cr2+ sites. In the first Cr2+ site, Cr2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Cr–O bond distances ranging from 2.18–2.34 Å. In the second Cr2+ site, Cr2+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Cr–O bond distances ranging from 1.94–2.08 Å. In the third Cr2+ site, Cr2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Cr–O bond distances ranging from 2.20–2.34 Å. There are six inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CrO6 octahedra and corners with three TiO6 octahedra. The corner-sharing octahedra tilt angles range from 24–47°. There are a spread of P–O bond distances ranging from 1.51–1.56 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CrO6 octahedra and corners with three TiO6 octahedra. The corner-sharing octahedra tilt angles range from 25–45°. There are a spread of P–O bond distances ranging from 1.51–1.56 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CrO6 octahedra and corners with three TiO6 octahedra. The corner-sharing octahedra tilt angles range from 26–49°. There are a spread of P–O bond distances ranging from 1.51–1.57 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CrO6 octahedra and corners with three TiO6 octahedra. The corner-sharing octahedra tilt angles range from 25–48°. There are a spread of P–O bond distances ranging from 1.54–1.57 Å. In the fifth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CrO6 octahedra and corners with three TiO6 octahedra. The corner-sharing octahedra tilt angles range from 24–46°. There is three shorter (1.54 Å) and one longer (1.56 Å) P–O bond length. In the sixth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CrO6 octahedra and corners with three TiO6 octahedra. The corner-sharing octahedra tilt angles range from 24–46°. There is two shorter (1.54 Å) and two longer (1.55 Å) P–O bond length. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti4+ and one P5+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti4+ and one P5+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti4+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Ti4+, one Cr2+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr2+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Ti4+, one Cr2+, and one P5+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Ti4+, one Cr2+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Ti4+, one Cr2+, and one P5+ atom. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti4+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ti4+, one Cr2+, and one P5+ atom. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to two Cr2+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti4+ and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr2+ and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ti4+, one Cr2+, and one P5+ atom. In the fifteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ti4+, one Cr2+, and one P5+ atom. In the sixteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr2+ and one P5+ atom. In the seventeenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ti4+, one Cr2+, and one P5+ atom. In the eighteenth O2- site, O2- is bonded in a 3-coordinate geometry to two Cr2+ and one P5+ atom. In the nineteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ti4+, one Cr2+, and one P5+ atom. In the twentieth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti4+ and one P5+ atom. In the twenty-first O2- site, O2- is bonded in a 3-coordinate geometry to two Cr2+ and one P5+ atom. In the twenty-second O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti4+ and one P5+ atom. In the twenty-third O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti4+ and one P5+ atom. In the twenty-fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti4+ and one P5+ atom.
TiCrIr2B2 crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are two inequivalent Ti sites. In the first Ti site, Ti is bonded in a 2-coordinate geometry to eight Ir and four B atoms. There are four shorter (2.71 Å) and four longer (2.83 Å) Ti–Ir bond lengths. There are two shorter (2.39 Å) and two longer (2.59 Å) Ti–B bond lengths. In the second Ti site, Ti is bonded in a 2-coordinate geometry to eight Ir and four B atoms. There are four shorter (2.71 Å) and four longer (2.83 Å) Ti–Ir bond lengths. There are two shorter (2.39 Å) and two longer (2.60 Å) Ti–B bond lengths. There are two inequivalent Cr sites. In the first Cr site, Cr is bonded in a 10-coordinate geometry to four Ir and six B atoms. There are two shorter (2.71 Å) and two longer (2.72 Å) Cr–Ir bond lengths. There are a spread of Cr–B bond distances ranging from 2.16–2.28 Å. In the second Cr site, Cr is bonded in a 10-coordinate geometry to four equivalent Ir and six B atoms. All Cr–Ir bond lengths are 2.71 Å. There are two shorter (2.16 Å) and four longer (2.27 Å) Cr–B bond lengths. There are three inequivalent Ir sites. In the first Ir site, Ir is bonded in a 9-coordinate geometry to four Ti, two equivalent Cr, and three B atoms. There are two shorter (2.24 Å) and one longer (2.30 Å) Ir–B bond lengths. In the second Ir site, Ir is bonded in a 9-coordinate geometry to four equivalent Ti, two equivalent Cr, and three B atoms. There are two shorter (2.24 Å) and one longer (2.30 Å) Ir–B bond lengths. In the third Ir site, Ir is bonded in a 9-coordinate geometry to four Ti, two equivalent Cr, and three B atoms. There are two shorter (2.24 Å) and one longer (2.30 Å) Ir–B bond lengths. There are four inequivalent B sites. In the first B site, B is bonded in a 9-coordinate geometry to six Cr and three B atoms. All B–B bond lengths are 1.74 Å. In the second B site, B is bonded in a 9-coordinate geometry to two equivalent Ti, four equivalent Cr, two equivalent Ir, and one B atom. In the third B site, B is bonded in a 9-coordinate geometry to two equivalent Ti, four Cr, two Ir, and one B atom. In the fourth B site, B is bonded in a 9-coordinate geometry to three Ti and six Ir atoms.
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
Hybridization events complicate the accurate reconstruction of phylogenies, as they lead to patterns of genetic heritability that are unexpected under traditional, bifurcating models of species trees. This phenomenon has led to the development of methods to infer these varied hybridization events, both methods that reconstruct networks directly, as well as summary methods that predict individual hybridization events from a subset of taxa. However, a lack of empirical comparisons between methods – especially those pertaining to large networks with varied hybridization scenarios – hinders their practical use. Here, we provide a comprehensive review of popular summary methods: TICR, MSCquartets, HyDe, Patterson’s D-Statistic (ABBA-BABA), D3, and Dp. TICR and MSCquartets are based on quartet concordance factors gathered from gene tree topologies and HyDe, Patterson’s D-Statistic, D3, and Dp use site pattern frequencies to identify hybridization events between sets of three taxa. We then use simulated data to address questions of method accuracy and ideal use scenarios by testing methods against complex networks which depict gene flow events that differ in depth (timing), quantity (single vs. multiple, overlapping hybridizations), and rate of gene flow (γ). We find that deeper or multiple hybridization events may introduce noise and weaken the signal of hybridization, leading to higher relative false negative rates across all methods. Despite some forms of hybridization eluding quartet-based detection methods, MSCquartets displays high precision in most scenarios. While HyDe results in high false negative rates when tested on hybridizations involving extinct or unsampled ghost lineages, HyDe is the only method able to identify the direction of hybridization, distinguishing the source parental lineages from recipient hybrid lineages. Lastly, we test the methods on a dataset of ultraconserved elements from the bee subfamily Nomiinae, finding possible hybridization events between clades which correspond to regions of poor support in the species tree estimated in a previous study.
Concentrating solar power plants can achieve low cost and efficient renewable electricity production if equipped with adequate thermal energy storage systems. Metal hydride based thermal energy storage systems are appealing candidates due to their demonstrated potential for very high volumetric energy densities, high exergetic efficiencies, and low costs. The feasibility and performance of a thermal energy storage system based on NaMgH 2 F hydride paired with TiCr 1.6 Mn 0.2 is examined, discussing its integration with a solar-driven ultra-supercritical steam power plant. The simulated storage system is based on a laboratory-scale experimental apparatus. It is analyzed using a detailed transport model accounting for the thermochemical hydrogen absorption and desorption reactions, including kinetics expressions adequate for the current metal hydride system. The results show that the proposed metal hydride pair can suitably be integrated with a high temperature steam power plant. The thermal energy storage system achieves output energy densities of 226 kWh/m 3 , 9 times the DOE SunShot target, with moderate temperature and pressure swings. Also, simulations indicate that there is significant scope for performance improvement via heat-transfer enhancement strategies.
Novel wide band gaps and magnetism in ordered titanium–vanadium, titanium–chromium, and titanium–manganese carbide and nitride based MXenes are predicted using density functional theory. Based on the recent synthesis of Ti centred double transition metal MXenes, we study MXenes with a central Ti layer and different surface early 3d metals, and various terminations, TiM 2 X 2 T (M = V, Cr, Mn; X = C, N; T = H, F, O, OH). While previously studied MXenes are strongly metallic, we predict surface metal and termination dependent metal–insulator transitions in the Cr–N and Mn–N series. A uniquely wide band gap over 1 eV is predicted for TiMn 2 N 2 F 2 using the HSE06 density functional while the unterminated TiMn 2 N 2 remains metallic. The entire TiCr 2 C 2 T series is predicted to be semiconducting. Distinct from the more common Ti–C MXenes, not all combinations of metals and terminations are predicted to be stable. Within the examined sets of materials, anti-ferromagnetic orders are generally most favorable. In conclusion, the new MXenes further extend the range of properties accessible in this family of two-dimensional nanomaterials.
The structural stability and electronic properties of TiMgCr{sub 2} laves phase have been calculated and compared. It is found that Mg prefer to substitutes titanium than chromium. The values of entalpies of formation show that Ti{sub 1-x}Mg{sub x}Cr{sub 2} may exist for only one concentration x=0.125 and the more favorable alloy is Ti{sub 0.875}Mg{sub 0.125}Cr{sub 2}. For TiCr{sub 2}, the optimized structural parameters were in good agreement with experimental values, while for TiMgCr{sub 2}, there is not experimental data. The electronic densities of states (DOS) are given and the nature of bonds are also discussed.