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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Y2Ti2O7 by Materials Project

Y2Ti2O7 crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Y3+ is bonded to eight O2- atoms to form distorted YO8 hexagonal bipyramids that share edges with six equivalent YO8 hexagonal bipyramids and edges with six equivalent TiO6 octahedra. There are two shorter (2.21 Å) and six longer (2.50 Å) Y–O bond lengths. Ti4+ is bonded to six equivalent O2- atoms to form TiO6 octahedra that share corners with six equivalent TiO6 octahedra and edges with six equivalent YO8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 48°. All Ti–O bond lengths are 1.97 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Y3+ atoms to form corner-sharing OY4 tetrahedra. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Y3+ and two equivalent Ti4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y2Ti2O7 by Materials Project

Y2Ti2O7 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are eight inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Y–O bond distances ranging from 2.26–2.88 Å. In the second Y3+ site, Y3+ is bonded to eight O2- atoms to form distorted YO8 hexagonal bipyramids that share a cornercorner with one TiO6 octahedra, an edgeedge with one YO8 hexagonal bipyramid, and edges with six TiO6 octahedra. The corner-sharing octahedral tilt angles are 67°. There are a spread of Y–O bond distances ranging from 2.20–2.75 Å. In the third Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 hexagonal pyramids that share corners with four TiO6 octahedra and edges with four TiO6 octahedra. The corner-sharing octahedra tilt angles range from 53–68°. There are a spread of Y–O bond distances ranging from 2.15–2.60 Å. In the fourth Y3+ site, Y3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Y–O bond distances ranging from 2.31–2.65 Å. In the fifth Y3+ site, Y3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are two shorter (2.17 Å) and four longer (2.43 Å) Y–O bond lengths. In the sixth Y3+ site, Y3+ is bonded to eight O2- atoms to form distorted YO8 hexagonal bipyramids that share edges with four YO8 hexagonal bipyramids and edges with six TiO6 octahedra. There are a spread of Y–O bond distances ranging from 2.20–2.52 Å. In the seventh Y3+ site, Y3+ is bonded to eight O2- atoms to form distorted YO8 hexagonal bipyramids that share edges with three YO8 hexagonal bipyramids and edges with six TiO6 octahedra. There are a spread of Y–O bond distances ranging from 2.20–2.55 Å. In the eighth Y3+ site, Y3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Y–O bond distances ranging from 2.23–2.50 Å. There are seven inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share a cornercorner with one YO8 hexagonal bipyramid, corners with four equivalent TiO6 octahedra, and edges with two equivalent YO7 hexagonal pyramids. The corner-sharing octahedra tilt angles range from 45–50°. There are a spread of Ti–O bond distances ranging from 1.88–2.11 Å. In the second Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share a cornercorner with one YO7 hexagonal pyramid, corners with six TiO6 octahedra, an edgeedge with one YO8 hexagonal bipyramid, and an edgeedge with one YO7 hexagonal pyramid. The corner-sharing octahedra tilt angles range from 36–50°. There are a spread of Ti–O bond distances ranging from 1.86–2.13 Å. In the third Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with two equivalent YO7 hexagonal pyramids and corners with four equivalent TiO6 octahedra. The corner-sharing octahedral tilt angles are 48°. There are four shorter (1.98 Å) and two longer (2.06 Å) Ti–O bond lengths. In the fourth Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six TiO6 octahedra and edges with four YO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 47–50°. There are a spread of Ti–O bond distances ranging from 1.95–2.05 Å. In the fifth Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share a cornercorner with one YO7 hexagonal pyramid, corners with five TiO6 octahedra, and edges with two equivalent YO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 42–50°. There are a spread of Ti–O bond distances ranging from 1.92–2.17 Å. In the sixth Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six TiO6 octahedra and edges with four YO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 46–51°. There are a spread of Ti–O bond distances ranging from 1.95–2.03 Å. In the seventh Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six TiO6 octahedra and edges with four equivalent YO8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 48°. There is four shorter (1.96 Å) and two longer (2.00 Å) Ti–O bond length. There are twenty inequivalent O2- sites. In the first O2- site, O2- is bonded to three Y3+ and one Ti4+ atom to form corner-sharing OY3Ti tetrahedra. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two Y3+ and two Ti4+ atoms. In the third O2- site, O2- is bonded to three Y3+ and one Ti4+ atom to form OY3Ti tetrahedra that share corners with three OY3Ti tetrahedra and an edgeedge with one OY4 tetrahedra. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two Y3+ and two Ti4+ atoms. In the fifth O2- site, O2- is bonded to three Y3+ and one Ti4+ atom to form a mixture of edge and corner-sharing OY3Ti tetrahedra. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Y3+ and two equivalent Ti4+ atoms. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Y3+ and two equivalent Ti4+ atoms. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to two Y3+ and two Ti4+ atoms. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to two Y3+ and two Ti4+ atoms. In the tenth O2- site, O2- is bonded to three Y3+ and one Ti4+ atom to form a mixture of distorted edge and corner-sharing OY3Ti tetrahedra. In the eleventh O2- site, O2- is bonded to four Y3+ atoms to form a mixture of edge and corner-sharing OY4 tetrahedra. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to two Y3+ and two Ti4+ atoms. In the thirteenth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Y3+ and two Ti4+ atoms. In the fourteenth O2- site, O2- is bonded in a 4-coordinate geometry to two Y3+ and two Ti4+ atoms. In the fifteenth O2- site, O2- is bonded to four Y3+ atoms to form corner-sharing OY4 tetrahedra. In the sixteenth O2- site, O2- is bonded in a 4-coordinate geometry to two Y3+ and two equivalent Ti4+ atoms. In the seventeenth O2- site, O2- is bonded in a 4-coordinate geometry to two Y3+ and two Ti4+ atoms. In the eighteenth O2- site, O2- is bonded in a 2-coordinate geometry to two Y3+ and two equivalent Ti4+ atoms. In the nineteenth O2- site, O2- is bonded in a 4-coordinate geometry to two Y3+ and two Ti4+ atoms. In the twentieth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Y3+ and two Ti4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y2Ti2O7 by Materials Project

Y2Ti2O7 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Y–O bond distances ranging from 2.16–2.71 Å. In the second Y3+ site, Y3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Y–O bond distances ranging from 2.26–2.63 Å. In the third Y3+ site, Y3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Y–O bond distances ranging from 2.18–2.76 Å. In the fourth Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 pentagonal bipyramids that share a cornercorner with one TiO6 octahedra, a cornercorner with one TiO5 trigonal bipyramid, a cornercorner with one TiO4 trigonal pyramid, an edgeedge with one TiO6 octahedra, and an edgeedge with one YO7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 46°. There are a spread of Y–O bond distances ranging from 2.24–2.72 Å. In the fifth Y3+ site, Y3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Y–O bond distances ranging from 2.20–2.30 Å. In the sixth Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 pentagonal bipyramids that share a cornercorner with one TiO6 octahedra, corners with two equivalent TiO5 trigonal bipyramids, and an edgeedge with one YO7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 15°. There are a spread of Y–O bond distances ranging from 2.14–2.42 Å. In the seventh Y3+ site, Y3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Y–O bond distances ranging from 2.16–2.70 Å. In the eighth Y3+ site, Y3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Y–O bond distances ranging from 2.23–2.54 Å. There are eight inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to four O2- atoms to form TiO4 trigonal pyramids that share a cornercorner with one YO7 pentagonal bipyramid. There are a spread of Ti–O bond distances ranging from 1.85–1.92 Å. In the second Ti4+ site, Ti4+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Ti–O bond distances ranging from 1.83–2.09 Å. In the third Ti4+ site, Ti4+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with two YO7 pentagonal bipyramids, a cornercorner with one TiO5 trigonal bipyramid, and an edgeedge with one YO7 pentagonal bipyramid. There are a spread of Ti–O bond distances ranging from 1.80–2.33 Å. In the fourth Ti4+ site, Ti4+ is bonded in a 4-coordinate geometry to five O2- atoms. There are a spread of Ti–O bond distances ranging from 1.80–2.60 Å. In the fifth Ti4+ site, Ti4+ is bonded to five O2- atoms to form distorted corner-sharing TiO5 trigonal bipyramids. There are a spread of Ti–O bond distances ranging from 1.88–1.94 Å. In the sixth Ti4+ site, Ti4+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Ti–O bond distances ranging from 1.73–2.42 Å. In the seventh Ti4+ site, Ti4+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ti–O bond distances ranging from 1.80–2.48 Å. In the eighth Ti4+ site, Ti4+ is bonded to five O2- atoms to form distorted TiO5 trigonal bipyramids that share a cornercorner with one TiO6 octahedra, corners with three YO7 pentagonal bipyramids, and a cornercorner with one TiO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 46°. There are a spread of Ti–O bond distances ranging from 1.77–2.10 Å. There are twenty-eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two Y3+ and one Ti4+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two Y3+ and one Ti4+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Y3+ and one Ti4+ atom. In the fourth O2- site, O2- is bonded to three Y3+ and one Ti4+ atom to form OY3Ti tetrahedra that share corners with three OY2Ti2 tetrahedra and corners with two equivalent OY3Ti trigonal pyramids. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to one Y3+ and three Ti4+ atoms. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Y3+ and one Ti4+ atom. In the seventh O2- site, O2- is bonded to two Y3+ and two Ti4+ atoms to form distorted corner-sharing OY2Ti2 tetrahedra. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Y3+ and one Ti4+ atom. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to two Y3+ and two Ti4+ atoms. In the tenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Y3+ and two Ti4+ atoms. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to two Y3+ and one Ti4+ atom. In the twelfth O2- site, O2- is bonded to three Y3+ and one Ti4+ atom to form a mixture of distorted edge and corner-sharing OY3Ti tetrahedra. In the thirteenth O2- site, O2- is bonded to three Y3+ and one Ti4+ atom to form a mixture of distorted edge and corner-sharing OY3Ti trigonal pyramids. In the fourteenth O2- site, O2- is bonded in a 1-coordinate geometry to two Y3+ and one Ti4+ atom. In the fifteenth O2- site, O2- is bonded in a 4-coordinate geometry to two Y3+ and two Ti4+ atoms. In the sixteenth O2- site, O2- is bonded in a 3-coordinate geometry to two Y3+ and one Ti4+ atom. In the seventeenth O2- site, O2- is bonded in a 1-coordinate geometry to two Y3+ and two Ti4+ atoms. In the eighteenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Y3+ and one Ti4+ atom. In the nineteenth O2- site, O2- is bonded in a trigonal non-coplanar geometry to two Y3+ and one Ti4+ atom. In the twentieth O2- site, O2- is bonded in a 4-coordinate geometry to two Y3+ and two Ti4+ atoms. In the twenty-first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Y3+ and two Ti4+ atoms. In the twenty-second O2- site, O2- is bonded in a 1-coordinate geometry to two Y3+ and two Ti4+ atoms. In the twenty-third O2- site, O2- is bonded in a 1-coordinate geometry to two Y3+ and one Ti4+ atom. In the twenty-fourth O2- site, O2- is bonded in a 2-coordinate geometry to two Y3+ and two Ti4+ atoms. In the twenty-fifth O2- site, O2- is bonded in a 4-coordinate geometry to two Y3+ and two Ti4+ atoms. In the twenty-sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Y3+ and two Ti4+ atoms. In the twenty-seventh O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Y3+ and one Ti4+ atom. In the twenty-eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Y3+ and one Ti4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y2Ti2O7 by Materials Project

Y2Ti2O7 crystallizes in the monoclinic P2 space group. The structure is three-dimensional. there are six inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Y–O bond distances ranging from 2.20–2.48 Å. In the second Y3+ site, Y3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Y–O bond distances ranging from 2.21–2.44 Å. In the third Y3+ site, Y3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Y–O bond distances ranging from 2.26–2.47 Å. In the fourth Y3+ site, Y3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Y–O bond distances ranging from 2.17–2.72 Å. In the fifth Y3+ site, Y3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Y–O bond distances ranging from 2.15–2.37 Å. In the sixth Y3+ site, Y3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Y–O bond distances ranging from 2.37–2.72 Å. There are six inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There is two shorter (1.79 Å) and two longer (1.96 Å) Ti–O bond length. In the second Ti4+ site, Ti4+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ti–O bond distances ranging from 1.81–2.45 Å. In the third Ti4+ site, Ti4+ is bonded in a tetrahedral geometry to four O2- atoms. There is one shorter (1.82 Å) and three longer (1.83 Å) Ti–O bond length. In the fourth Ti4+ site, Ti4+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ti–O bond distances ranging from 1.83–2.24 Å. In the fifth Ti4+ site, Ti4+ is bonded to six O2- atoms to form corner-sharing TiO6 octahedra. There are a spread of Ti–O bond distances ranging from 1.83–2.17 Å. In the sixth Ti4+ site, Ti4+ is bonded to four O2- atoms to form distorted corner-sharing TiO4 trigonal pyramids. The corner-sharing octahedral tilt angles are 32°. There is two shorter (1.83 Å) and two longer (1.86 Å) Ti–O bond length. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded to two Y3+ and two Ti4+ atoms to form distorted OY2Ti2 tetrahedra that share corners with three OY2Ti2 tetrahedra and edges with two OY3Ti tetrahedra. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two Y3+ and one Ti4+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two Y3+ and one Ti4+ atom. In the fourth O2- site, O2- is bonded to three Y3+ and one Ti4+ atom to form distorted OY3Ti tetrahedra that share corners with three OY3Ti tetrahedra and an edgeedge with one OY2Ti2 tetrahedra. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to two Y3+ and one Ti4+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two Y3+ and one Ti4+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Y3+ and two Ti4+ atoms. In the eighth O2- site, O2- is bonded to two Y3+ and two Ti4+ atoms to form a mixture of distorted corner and edge-sharing OY2Ti2 tetrahedra. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to one Y3+ and two Ti4+ atoms. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to two Y3+ and one Ti4+ atom. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to two Y3+ and one Ti4+ atom. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to two Y3+ and one Ti4+ atom. In the thirteenth O2- site, O2- is bonded in a 4-coordinate geometry to two Y3+ and two Ti4+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Y3+ and two Ti4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Synthesis of Nano-Oxide Precipitates by Implantation of Ti, Y and O Ions in Fe-10%Cr: Towards an Understanding of Precipitation in Oxide Dispersion-Strengthened (ODS) Steels

The properties of oxide dispersion-strengthened steels are highly dependent on the nature and size distribution of their constituting nano-oxide precipitates. A fine control of the processes of synthesis would enable the optimization of pertinent properties for use in various energy systems. This control, however, requires knowledge of the precise mechanisms of nucleation and growth of the nanoprecipitates, which are still a matter of debate. In the present study, nano-oxide precipitates were produced via the implantation of Y, Ti, and O ions in two different sequential orders in an Fe-10%Cr matrix that was subsequently thermally annealed. The results show that the oxides that precipitate are not necessarily favoured thermodynamically, but rather result from complex kinetics aspects related to the interaction between the implanted elements and induced defects. When Y is implanted first, the formation of nanoprecipitates with characteristics similar to those in conventionally produced ODS steels, especially with a core/shell structure, is evidenced. In contrast, when implantation starts with Ti, the precipitation of yttria during subsequent high-temperature annealing is totally suppressed, and corundum Cr 2 O 3 precipitates instead. Moreover, the systematic involvement of {110} matrix planes in orientation relationships with the precipitates, independently of the precipitate nature, suggests matrix restriction effects on the early stages of precipitation.

36 MATERIALS SCIENCE↗