Search NASA⌕ Search

SEARCH · Search NASA

Results for “La2Ti2O7”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

3 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on La2Ti2O7 by Materials Project

La2Ti2O7 crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. La3+ is bonded to eight O2- atoms to form distorted LaO8 hexagonal bipyramids that share edges with six equivalent LaO8 hexagonal bipyramids and edges with six equivalent TiO6 octahedra. There are two shorter (2.27 Å) and six longer (2.62 Å) La–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 LaO8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 45°. All Ti–O bond lengths are 2.01 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent La3+ atoms to form corner-sharing OLa4 tetrahedra. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent La3+ and two equivalent Ti4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La2Ti2O7 by Materials Project

La2Ti2O7 crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. there are two inequivalent La3+ sites. In the first La3+ site, La3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of La–O bond distances ranging from 2.42–2.95 Å. In the second La3+ site, La3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of La–O bond distances ranging from 2.41–2.63 Å. There are two inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to six O2- atoms to form distorted corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles are 22°. There are a spread of Ti–O bond distances ranging from 1.80–2.36 Å. 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 1.78–2.40 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded to three equivalent La3+ and one Ti4+ atom to form distorted corner-sharing OLa3Ti tetrahedra. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent La3+ and two Ti4+ atoms. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two La3+ and two equivalent Ti4+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent La3+ and two equivalent Ti4+ atoms. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent La3+ and two equivalent Ti4+ atoms. In the sixth O2- site, O2- is bonded to two equivalent La3+ and two Ti4+ atoms to form distorted corner-sharing OLa2Ti2 tetrahedra. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent La3+ and one Ti4+ atom.

36 MATERIALS SCIENCE↗
NASA NTRS2003

Temperature Dependent Electrical and Micromechanical Properties of Lanthanum Titanate with Additions of Yttria

Lanthanum titanate (La2Ti2O7) a layered distorted perovskite (1) with space group Pna2(sub 1) has been shown to have potential as a high temperature piezoelectric (2). However this highly refractory oxide compound must be consolidated at relatively high temperatures approximately 1400 C. Commercial La2Ti207 powders were mechanically alloyed with additions of Y2O3 to lower the consolidation temperature by 300 C and to provide post processing mechanical stability. Temperature dependent electrical, elastic and anelastic behavior were selected as nondestructive means of evaluating the effects of yttria on the properties of this ferroceramic material.

Goldsby, Jon C.↗