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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Li2IrO3 by Materials Project

Li2IrO3 is Caswellsilverite-like structured and crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are eleven inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with six LiO6 octahedra, edges with six LiO6 octahedra, and edges with six IrO6 octahedra. The corner-sharing octahedra tilt angles range from 4–5°. There are two shorter (2.12 Å) and four longer (2.13 Å) Li–O bond lengths. In the second Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with two LiO6 octahedra, corners with four IrO6 octahedra, edges with four IrO6 octahedra, and edges with eight LiO6 octahedra. The corner-sharing octahedra tilt angles range from 3–5°. There are a spread of Li–O bond distances ranging from 2.11–2.22 Å. In the third Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with two LiO6 octahedra, corners with four IrO6 octahedra, edges with four IrO6 octahedra, and edges with eight LiO6 octahedra. The corner-sharing octahedra tilt angles range from 4–6°. There are a spread of Li–O bond distances ranging from 2.12–2.21 Å. In the fourth Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with two LiO6 octahedra, corners with four IrO6 octahedra, edges with four IrO6 octahedra, and edges with eight LiO6 octahedra. The corner-sharing octahedra tilt angles range from 4–6°. There are a spread of Li–O bond distances ranging from 2.12–2.22 Å. In the fifth Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with six LiO6 octahedra, edges with six LiO6 octahedra, and edges with six IrO6 octahedra. The corner-sharing octahedra tilt angles range from 4–5°. There are two shorter (2.12 Å) and four longer (2.13 Å) Li–O bond lengths. In the sixth Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with two LiO6 octahedra, corners with four IrO6 octahedra, edges with four IrO6 octahedra, and edges with eight LiO6 octahedra. The corner-sharing octahedra tilt angles range from 4–5°. There are four shorter (2.15 Å) and two longer (2.17 Å) Li–O bond lengths. In the seventh Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with two LiO6 octahedra, corners with four IrO6 octahedra, edges with four IrO6 octahedra, and edges with eight LiO6 octahedra. The corner-sharing octahedra tilt angles range from 3–5°. There are a spread of Li–O bond distances ranging from 2.10–2.19 Å. In the eighth Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with two LiO6 octahedra, corners with four IrO6 octahedra, edges with four IrO6 octahedra, and edges with eight LiO6 octahedra. The corner-sharing octahedra tilt angles range from 4–5°. There are a spread of Li–O bond distances ranging from 2.15–2.17 Å. In the ninth Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with six LiO6 octahedra, edges with six LiO6 octahedra, and edges with six equivalent IrO6 octahedra. The corner-sharing octahedra tilt angles range from 4–5°. There are two shorter (2.12 Å) and four longer (2.13 Å) Li–O bond lengths. In the tenth Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with two equivalent LiO6 octahedra, corners with four equivalent IrO6 octahedra, edges with four equivalent IrO6 octahedra, and edges with eight LiO6 octahedra. The corner-sharing octahedra tilt angles range from 4–5°. There are four shorter (2.15 Å) and two longer (2.17 Å) Li–O bond lengths. In the eleventh Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with two equivalent LiO6 octahedra, corners with four equivalent IrO6 octahedra, edges with four equivalent IrO6 octahedra, and edges with eight LiO6 octahedra. The corner-sharing octahedra tilt angles range from 3–5°. There are two shorter (2.10 Å) and four longer (2.18 Å) Li–O bond lengths. There are five inequivalent Ir4+ sites. In the first Ir4+ site, Ir4+ is bonded to six O2- atoms to form IrO6 octahedra that share corners with six LiO6 octahedra, edges with three equivalent IrO6 octahedra, and edges with nine LiO6 octahedra. The corner-sharing octahedra tilt angles range from 3–6°. There are a spread of Ir–O bond distances ranging from 2.04–2.06 Å. In the second Ir4+ site, Ir4+ is bonded to six O2- atoms to form IrO6 octahedra that share corners with six LiO6 octahedra, edges with three equivalent IrO6 octahedra, and edges with nine LiO6 octahedra. The corner-sharing octahedra tilt angles range from 4–5°. All Ir–O bond lengths are 2.05 Å. In the third Ir4+ site, Ir4+ is bonded to six O2- atoms to form IrO6 octahedra that share corners with six LiO6 octahedra, edges with three equivalent IrO6 octahedra, and edges with nine LiO6 octahedra. The corner-sharing octahedra tilt angles range from 3–5°. There are a spread of Ir–O bond distances ranging from 2.04–2.06 Å. In the fourth Ir4+ site, Ir4+ is bonded to six O2- atoms to form IrO6 octahedra that share corners with six LiO6 octahedra, edges with three equivalent IrO6 octahedra, and edges with nine LiO6 octahedra. The corner-sharing octahedra tilt angles range from 3–6°. There are five shorter (2.05 Å) and one longer (2.06 Å) Ir–O bond lengths. In the fifth Ir4+ site, Ir4+ is bonded to six O2- atoms to form IrO6 octahedra that share corners with six LiO6 octahedra, edges with three equivalent IrO6 octahedra, and edges with nine LiO6 octahedra. The corner-sharing octahedra tilt angles range from 3–5°. All Ir–O bond lengths are 2.05 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded to four Li1+ and two Ir4+ atoms to form a mixture of edge and corner-sharing OLi4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. In the second O2- site, O2- is bonded to four Li1+ and two Ir4+ atoms to form a mixture of edge and corner-sharing OLi4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. In the third O2- site, O2- is bonded to four Li1+ and two Ir4+ atoms to form a mixture of edge and corner-sharing OLi4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. In the fourth O2- site, O2- is bonded to four Li1+ and two Ir4+ atoms to form a mixture of edge and corner-sharing OLi4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. In the fifth O2- site, O2- is bonded to four Li1+ and two Ir4+ atoms to form a mixture of edge and corner-sharing OLi4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. In the sixth O2- site, O2- is bonded to four Li1+ and two Ir4+ atoms to form a mixture of edge and corner-sharing OLi4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. In the seventh O2- site, O2- is bonded to four Li1+ and two Ir4+ atoms to form a mixture of edge and corner-sharing OLi4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. In the eighth O2- site, O2- is bonded to four Li1+ and two Ir4+ atoms to form a mixture of edge and corner-sharing OLi4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 0–5°. In the ninth O2- site, O2- is bonded to four Li1+ and two Ir4+ atoms to form a mixture of edge and corner-sharing OLi4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 0–5°. In the tenth O2- site, O2- is bonded to four Li1+ and two equivalent Ir4+ atoms to form a mixture of edge and corner-sharing OLi4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 0–5°. In the eleventh O2- site, O2- is bonded to four Li1+ and two equivalent Ir4+ atoms to form a mixture of edge and corner-sharing OLi4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 0–5°. In the twelfth O2- site, O2- is bonded to four Li1+ and two equivalent Ir4+ atoms to form a mixture of edge and corner-sharing OLi4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. In the thirteenth O2- site, O2- is bonded to four Li1+ and two equivalent Ir4+ atoms to form a mixture of edge and corner-sharing OLi4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. In the fourteenth O2- site, O2- is bonded to four Li1+ and two equivalent Ir4+ atoms to form a mixture of edge and corner-sharing OLi4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 0–5°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li2IrO3 by Materials Project

Li2IrO3 is Caswellsilverite-like structured and crystallizes in the orthorhombic Fddd space group. The structure is three-dimensional. there are two inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with two equivalent LiO6 octahedra, corners with four equivalent IrO6 octahedra, edges with four equivalent IrO6 octahedra, and edges with eight LiO6 octahedra. The corner-sharing octahedra tilt angles range from 3–5°. There are two shorter (2.13 Å) and four longer (2.15 Å) Li–O bond lengths. In the second Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with two equivalent IrO6 octahedra, corners with four LiO6 octahedra, edges with five equivalent IrO6 octahedra, and edges with seven LiO6 octahedra. The corner-sharing octahedra tilt angles range from 3–5°. There are two shorter (2.10 Å) and four longer (2.14 Å) Li–O bond lengths. Ir4+ is bonded to six O2- atoms to form IrO6 octahedra that share corners with six LiO6 octahedra, edges with three equivalent IrO6 octahedra, and edges with nine LiO6 octahedra. The corner-sharing octahedra tilt angles range from 3–5°. There are two shorter (2.05 Å) and four longer (2.06 Å) Ir–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four Li1+ and two equivalent Ir4+ atoms to form a mixture of edge and corner-sharing OLi4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 1–4°. In the second O2- site, O2- is bonded to four Li1+ and two equivalent Ir4+ atoms to form a mixture of edge and corner-sharing OLi4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 0–4°.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Interpretation of Ir L-edge isotropic x-ray absorption spectra across the pressure-induced dimerization transition in hyper-honeycomb beta-Li2IrO3

The extended nature of atomic 5d orbitals, together with a relatively short ~ 3 °A Ir-Ir distance across edge-shared octahedra in honeycomb iridate lattices, leads to a tendency to disrupt the local, spin-orbit entangled jeff = 1 2 moments of Ir4+ ions in favor of dimerization and formation of molecular orbitals, especially upon lattice compression. The sensitivity of Ir L-edge spectroscopy to both spin-orbit entanglement in jeff states and quenching of orbital degrees of freedom in dimerized states, results in a peculiar evolution of x-ray absorption spectra across dimerization transitions including energy shifts in opposite direction for L3 and L2 leading absorption edges, and substantial changes in their isotropic branching ratio. We present a theoretical description of the evolution of 5d electronic states, and related x-ray absorption spectra, in going from the single ion to the dimerized limit. The calculations reproduce the experimental results for hyper-honeycomb β-Li2IrO3[1, 2] and shed light into the weakening of the coupling between spin and orbital degrees of freedom as the strength of dimerization increases. The results provide a basis for interpretation of L-edge xray absorption spectra in 5d systems where competition between formation of local jeff states and molecular orbitals is at play.

van Veenendaal, Michel↗