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DOE OSTI2026

TiV_BCC_SolidSolution_128atoms_VASP6

We performed density functional theory (DFT) calculations for body-centered-cubic (BCC) structures with 128 lattices sites of solid solution binary alloys titanium-vanadium (Ti-V). The electronic structures of alloys have been calculated using Vienna Ab initio Simulation Package (VASP). Within this package the DFT approach is used to reduce many-body Schrodinger equation to set of single particle Kohn-Sham (KS) equations. The generalized electronic exchange-correlation functional is described by generalized gradient approximation with the Perdew-Burke-Ernzerhof parametrization. The electron-ion interactions is described by pseudopotentials developed within the plane-wave basis projector augmented-wave (PAW) approach. These pseudopotentials are available at the VASP portal (http://cms.mpi.univie.ac.at/vasp/). Our calculations have been run with the pseudopotentials treating s and p semi-core states as valence in case for the elements Ti and V. The electronic densities and potentials are expanded over plane-waves with energy cutoff of 350 eV. 2x2x2 k-mesh and normal precision were used. The alloys were modeled by supercell containing 128 randomly distributed atoms. At initial step the atoms occupy perfect bcc lattice cites. This initial structure was optimized until energy changes less than 1e-6 eV, while forces acting on atoms don't exceed 1e-2 eV/angstrom. The electron-ion interaction is described by PAW pseudopotentials. The calculations have been collected by sampling chemical compositions across the entire compositional range. The chemical compositions have been sampled by progressively changing the number of atoms per constituent by 4. For each chemical composition of binaries and ternaries, the first-principle calculations have been run for 100 randomized arrangements of the constituents on the BCC lattice sites. We collected data for a total of 3,100 randomized atomic structures over 31 chemical compositions. The calculations have been collected on Air Force HPC11 cluster using the VASP 6.5.1. Additional methodology and file structure information is available in the dataset README.txt file.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on TiV(PO4)2 by Materials Project

TiV(PO4)2 crystallizes in the trigonal R3 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 is three shorter (1.90 Å) and three longer (2.04 Å) Ti–O bond length. In the second Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six PO4 tetrahedra and a faceface with one VO6 octahedra. There are three shorter (1.92 Å) and three longer (2.08 Å) Ti–O bond lengths. In the third Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six PO4 tetrahedra. There is three shorter (1.90 Å) and three longer (2.09 Å) Ti–O bond length. There are three inequivalent V2+ sites. In the first V2+ site, V2+ is bonded to six O2- atoms to form distorted VO6 octahedra that share corners with six PO4 tetrahedra, a faceface with one TiO6 octahedra, and a faceface with one VO6 octahedra. There are three shorter (2.20 Å) and three longer (2.22 Å) V–O bond lengths. In the second V2+ site, V2+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra and a faceface with one VO6 octahedra. There are three shorter (2.01 Å) and three longer (2.11 Å) V–O bond lengths. In the third V2+ site, V2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are three shorter (2.23 Å) and three longer (2.24 Å) V–O bond lengths. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra and corners with three TiO6 octahedra. The corner-sharing octahedra tilt angles range from 25–49°. There are a spread of P–O bond distances ranging from 1.50–1.57 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra and corners with three TiO6 octahedra. The corner-sharing octahedra tilt angles range from 24–49°. There are a spread of P–O bond distances ranging from 1.53–1.56 Å. There are eight 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 3-coordinate geometry to one Ti4+, one V2+, and one P5+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one V2+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Ti4+, one V2+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti4+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two V2+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Ti4+, one V2+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ti4+ and one P5+ atom.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on TiV by Materials Project

TiV crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. Ti is bonded in a 8-coordinate geometry to four equivalent Ti and four equivalent V atoms. All Ti–Ti bond lengths are 2.70 Å. All Ti–V bond lengths are 2.71 Å. V is bonded in a 8-coordinate geometry to four equivalent Ti and four equivalent V atoms. All V–V bond lengths are 2.70 Å.

36 MATERIALS SCIENCE↗

DOE OSTI2021

A Polymer-Assisted Spinodal Decomposition Strategy toward Interconnected Porous Sodium Super Ionic Conductor-Structured Polyanion-Type Materials and Their Application as a High-Power Sodium-Ion Battery Cathode

A general polymer-assisted spinodal decomposition strategy is used to prepare hierarchically porous sodium super ionic conductor (NASICON)-structured polyanion-type materials (e.g., Na 3 V 2 (PO 4 ) 3 , Li 3 V 2 (PO 4 ) 3 , K 3 V 2 (PO 4 ) 3 , Na 4 MnV(PO 4 ) 3 , and Na 2 TiV(PO 4 ) 3 ) in a tetrahydrofuran/ethanol/H 2 O synthesis system. Depending on the boiling point of solvents, the selective evaporation of the solvents induces both macrophase separation via spinodal decomposition and mesophase separation via self-assembly of inorganic precursors and amphiphilic block copolymers, leading to the formation of hierarchically porous structures. We find that the resulting hierarchically porous Na 3 V 2 (PO 4 ) 3 possessing large specific surface area (≈77 m 2 g -1 ) and pore volume (≈0.272 cm 3 g -1 ) shows a high specific capacity of 117.6 mAh g -1 at 0.1 C achieving the theoretical value and a long cycling life with 77% capacity retention over 1000 cycles at 5 C. This method presented here can open a facile avenue to synthesize other hierarchically porous polyanion-type materials.

36 MATERIALS SCIENCE↗