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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Steam-Assisted Ammonolysis of MoO2 as a Synthetic Pathway to Oxygenated δ-MoN

A common route for the synthesis of molybdenum nitrides is through the temperature-programmed reaction of molybdenum oxides with NH3, or ammonolysis. In this work, the role of precursor phase, gas phase chemistry (impact of H2O), and temperature profile on the reaction outcome (700 °C) was examined, which resulted in varying amounts of MoO2, H2MoO5, and the nitride phases—cubic γ (nominally Mo2N) and hexagonal δ (nominally MoN). The phase fraction of the δ phase increased with precursor in the sequence MoO2 > MoO3 > H2MoO5. Steam in the reaction gas also favored the production of δ over γ, but with too much steam, MoO2 was obtained in the product. Synthesis conditions for obtaining nearly phase-pure δ were identified: MoO2 as the precursor, 2% H2O in the gas stream, and a moderate heating rate (3 °C/min). In situ X-ray diffraction provided insights into the reaction pathway. Extensive physico-chemical analysis of the δ phase, including synchrotron X-ray and neutron diffraction, electron microscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, and prompt gamma activation analysis, revealed its stoichiometry to be MoO0.108(8)N0.892(8)H0.012(5), indicating non-trivial oxygen incorporation. The presence of N/O ordering and an impurity phase Mo5N6 were also revealed, detectable only by neutron diffraction. Notably, a computationally predicted MoON phase (doi: 10.1103/PhysRevLett.123.236402), of interest due to its potential to display a metal-insulator transition, did not appear under any reaction condition examined.

Pandey, Shobhit↗
DOE OSTI2020

Materials Data on MoO2 by Materials Project

MoO2 is trigonal omega-like structured and crystallizes in the trigonal R-3m space group. The structure is two-dimensional and consists of three MoO2 sheets oriented in the (0, 0, 1) direction. Mo4+ is bonded to six equivalent O2- atoms to form edge-sharing MoO6 octahedra. All Mo–O bond lengths are 2.10 Å. O2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Mo4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoO2 by Materials Project

MoO2 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one MoO2 sheet oriented in the (0, 0, 1) direction. Mo4+ is bonded to six equivalent O2- atoms to form edge-sharing MoO6 octahedra. There are four shorter (2.07 Å) and two longer (2.15 Å) Mo–O bond lengths. O2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Mo4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(MoO2)4 by Materials Project

K(MoO2)4 crystallizes in the monoclinic P2/c space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 3.08–3.25 Å. In the second K1+ site, K1+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 3.03–3.27 Å. There are four inequivalent Mo+3.75+ sites. In the first Mo+3.75+ site, Mo+3.75+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 50–56°. There are a spread of Mo–O bond distances ranging from 2.12–2.18 Å. In the second Mo+3.75+ site, Mo+3.75+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 46–53°. There are a spread of Mo–O bond distances ranging from 2.03–2.17 Å. In the third Mo+3.75+ site, Mo+3.75+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 46–56°. There are a spread of Mo–O bond distances ranging from 1.99–2.16 Å. In the fourth Mo+3.75+ site, Mo+3.75+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 50–55°. There are a spread of Mo–O bond distances ranging from 1.97–2.16 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to two K1+ and three Mo+3.75+ atoms. In the second O2- site, O2- is bonded in a trigonal planar geometry to three Mo+3.75+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two K1+ and three Mo+3.75+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two K1+ and three Mo+3.75+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Mo+3.75+ atoms. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Mo+3.75+ atoms. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to three Mo+3.75+ atoms. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to two K1+ and three Mo+3.75+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoO2 by Materials Project

MoO2 is Rutile structured and crystallizes in the tetragonal P4_2/mnm space group. The structure is three-dimensional. Mo4+ is bonded to six equivalent O2- atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedral tilt angles are 51°. There are two shorter (2.02 Å) and four longer (2.10 Å) Mo–O bond lengths. O2- is bonded in a distorted trigonal planar geometry to three equivalent Mo4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoO2 by Materials Project

MoO2 crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. Mo4+ is bonded to six equivalent O2- atoms to form edge-sharing MoO6 octahedra. There are four shorter (2.07 Å) and two longer (2.13 Å) Mo–O bond lengths. O2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Mo4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoO2 by Materials Project

MoO2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Mo4+ sites. In the first Mo4+ site, Mo4+ is bonded to six O2- atoms to form edge-sharing MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.05–2.17 Å. In the second Mo4+ site, Mo4+ is bonded to six O2- atoms to form edge-sharing MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.05–2.17 Å. In the third Mo4+ site, Mo4+ is bonded to six O2- atoms to form distorted edge-sharing MoO6 octahedra. There are four shorter (2.18 Å) and two longer (2.19 Å) Mo–O bond lengths. In the fourth Mo4+ site, Mo4+ is bonded to six O2- atoms to form edge-sharing MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 1.96–2.07 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Mo4+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Mo4+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Mo4+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Mo4+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Mo4+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to three Mo4+ atoms. In the seventh O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Mo4+ atoms. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to three Mo4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoO2 by Materials Project

MoO2 is Rutile structured and crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Mo4+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MoO6 octahedra. The corner-sharing octahedral tilt angles are 49°. There are a spread of Mo–O bond distances ranging from 2.02–2.11 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to three equivalent Mo4+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to three equivalent Mo4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoO2 by Materials Project

MoO2 is Hydrophilite-like structured and crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. Mo4+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedral tilt angles are 51°. There are a spread of Mo–O bond distances ranging from 2.02–2.12 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to three equivalent Mo4+ atoms. In the second O2- site, O2- is bonded in a trigonal non-coplanar geometry to three equivalent Mo4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zn(MoO2)4 by Materials Project

Zn(MoO2)4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Mo+3.50+ sites. In the first Mo+3.50+ site, Mo+3.50+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 50–53°. There are a spread of Mo–O bond distances ranging from 2.00–2.15 Å. In the second Mo+3.50+ site, Mo+3.50+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 50–53°. There are a spread of Mo–O bond distances ranging from 2.11–2.19 Å. In the third Mo+3.50+ site, Mo+3.50+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 50–52°. There are a spread of Mo–O bond distances ranging from 2.03–2.17 Å. In the fourth Mo+3.50+ site, Mo+3.50+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 50–52°. There are a spread of Mo–O bond distances ranging from 1.98–2.19 Å. Zn2+ is bonded in a bent 120 degrees geometry to two O2- atoms. There are one shorter (2.05 Å) and one longer (2.12 Å) Zn–O bond lengths. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to three Mo+3.50+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to three Mo+3.50+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to three Mo+3.50+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Mo+3.50+ atoms. In the fifth O2- site, O2- is bonded in a trigonal non-coplanar geometry to three Mo+3.50+ atoms. In the sixth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Mo+3.50+ and one Zn2+ atom. In the seventh O2- site, O2- is bonded to three Mo+3.50+ and one Zn2+ atom to form distorted corner-sharing OZnMo3 tetrahedra. In the eighth O2- site, O2- is bonded in a trigonal non-coplanar geometry to three Mo+3.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zn(MoO2)2 by Materials Project

Zn(MoO2)2 is Spinel structured and crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. Mo3+ is bonded to six equivalent O2- atoms to form MoO6 octahedra that share corners with six equivalent ZnO4 tetrahedra and edges with six equivalent MoO6 octahedra. There are four shorter (2.18 Å) and two longer (2.19 Å) Mo–O bond lengths. Zn2+ is bonded to four equivalent O2- atoms to form ZnO4 tetrahedra that share corners with twelve equivalent MoO6 octahedra. The corner-sharing octahedral tilt angles are 57°. All Zn–O bond lengths are 2.05 Å. O2- is bonded in a distorted rectangular see-saw-like geometry to three equivalent Mo3+ and one Zn2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(MoO2)2 by Materials Project

Ca(MoO2)2 is Spinel-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are six inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to four O2- atoms to form CaO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine MoO6 octahedra. The corner-sharing octahedra tilt angles range from 54–64°. There are a spread of Ca–O bond distances ranging from 2.19–2.27 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six MoO4 tetrahedra, edges with two CaO6 octahedra, and edges with four MoO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.30–2.39 Å. In the third Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four MoO4 tetrahedra, an edgeedge with one CaO6 octahedra, and edges with five MoO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.26–2.42 Å. In the fourth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six MoO4 tetrahedra, edges with two CaO6 octahedra, and edges with four MoO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.30–2.40 Å. In the fifth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six MoO4 tetrahedra, edges with two CaO6 octahedra, and edges with four MoO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.32–2.39 Å. In the sixth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five MoO4 tetrahedra, an edgeedge with one CaO6 octahedra, and edges with five MoO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.25–2.48 Å. There are twelve inequivalent Mo3+ sites. In the first Mo3+ site, Mo3+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four MoO4 tetrahedra, edges with three CaO6 octahedra, and edges with three MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.13–2.28 Å. In the second Mo3+ site, Mo3+ is bonded to four O2- atoms to form MoO4 tetrahedra that share corners with six CaO6 octahedra and corners with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 43–66°. There are a spread of Mo–O bond distances ranging from 1.99–2.21 Å. In the third Mo3+ site, Mo3+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with three equivalent CaO4 tetrahedra, corners with three equivalent MoO4 tetrahedra, edges with two CaO6 octahedra, and edges with four MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.08–2.28 Å. In the fourth Mo3+ site, Mo3+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four MoO4 tetrahedra, edges with three CaO6 octahedra, and edges with three MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.13–2.28 Å. In the fifth Mo3+ site, Mo3+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with six MoO4 tetrahedra, edges with two equivalent MoO6 octahedra, and edges with four CaO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.16–2.26 Å. In the sixth Mo3+ site, Mo3+ is bonded to four O2- atoms to form MoO4 tetrahedra that share corners with six CaO6 octahedra and corners with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 44–77°. There are a spread of Mo–O bond distances ranging from 2.09–2.25 Å. In the seventh Mo3+ site, Mo3+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with six MoO4 tetrahedra, edges with two equivalent MoO6 octahedra, and edges with four CaO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.15–2.24 Å. In the eighth Mo3+ site, Mo3+ is bonded to six O2- atoms to form MoO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five MoO4 tetrahedra, edges with three CaO6 octahedra, and edges with three MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.10–2.36 Å. In the ninth Mo3+ site, Mo3+ is bonded to four O2- atoms to form MoO4 tetrahedra that share corners with six CaO6 octahedra and corners with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 44–71°. There are a spread of Mo–O bond distances ranging from 2.08–2.20 Å. In the tenth Mo3+ site, Mo3+ is bonded to six O2- atoms to form MoO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five MoO4 tetrahedra, edges with three CaO6 octahedra, and edges with three MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.13–2.32 Å. In the eleventh Mo3+ site, Mo3+ is bonded to four O2- atoms to form MoO4 tetrahedra that share corners with six CaO6 octahedra and corners with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 46–76°. There are a spread of Mo–O bond distances ranging from 2.07–2.26 Å. In the twelfth Mo3+ site, Mo3+ is bonded to four O2- atoms to form MoO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine MoO6 octahedra. The corner-sharing octahedra tilt angles range from 48–62°. There are a spread of Mo–O bond distances ranging from 1.98–2.04 Å. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Ca2+ and two Mo3+ atoms. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Mo3+ atoms. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Ca2+ and two Mo3+ atoms. In the fourth O2- site, O2- is bonded to one Ca2+ and three Mo3+ atoms to form distorted corner-sharing OCaMo3 trigonal pyramids. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Mo3+ atoms. In the sixth O2- site, O2- is bonded to one Ca2+ and three Mo3+ atoms to form corner-sharing OCaMo3 trigonal pyramids. In the seventh O2- site, O2- is bonded in a trigonal pyramidal geometry to one Ca2+ and three Mo3+ atoms. In the eighth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Mo3+ atoms. In the ninth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Mo3+ atoms. In the tenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Mo3+ atoms. In the eleventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Mo3+ atoms. In the twelfth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Mo3+ atoms. In the thirteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Mo3+ atoms. In the fourteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Mo3+ atoms. In the fifteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Mo3+ atoms. In the sixteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Mo3+ atoms. In the seventeenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Mo3+ atoms. In the eighteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Mo3+ atoms. In the nineteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Mo3+ atoms. In the twentieth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Mo3+ atoms. In the twenty-first O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Mo3+ atoms. In the twenty-second O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Mo3+ atoms. In the twenty-third O2- site, O2- is bonded in a trigonal pyramidal geometry to one Ca2+ and three Mo3+ atoms. In the twenty-fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Mo3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li11(MoO2)12 by Materials Project

Li11(MoO2)12 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are seven inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with six MoO6 octahedra, edges with five LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 2–12°. There are a spread of Li–O bond distances ranging from 2.19–2.40 Å. In the second Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with six MoO6 octahedra, edges with six LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 3–9°. There are a spread of Li–O bond distances ranging from 2.22–2.31 Å. In the third Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with six MoO6 octahedra, edges with six LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 2–10°. There are a spread of Li–O bond distances ranging from 2.22–2.28 Å. In the fourth Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with six MoO6 octahedra, edges with five LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 3–11°. There are a spread of Li–O bond distances ranging from 2.11–2.47 Å. In the fifth Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with six MoO6 octahedra, edges with five LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 1–12°. There are a spread of Li–O bond distances ranging from 2.14–2.49 Å. In the sixth Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with six MoO6 octahedra, edges with six LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 5–6°. There are a spread of Li–O bond distances ranging from 2.22–2.35 Å. In the seventh Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with six MoO6 octahedra, edges with six LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 3–5°. There are a spread of Li–O bond distances ranging from 2.16–2.34 Å. There are six inequivalent Mo+3.08+ sites. In the first Mo+3.08+ site, Mo+3.08+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with five LiO6 octahedra, edges with six LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 3–6°. There are a spread of Mo–O bond distances ranging from 2.12–2.22 Å. In the second Mo+3.08+ site, Mo+3.08+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with five LiO6 octahedra, edges with five LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 5–12°. There are a spread of Mo–O bond distances ranging from 2.14–2.21 Å. In the third Mo+3.08+ site, Mo+3.08+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with five LiO6 octahedra, edges with six LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 2–11°. There are a spread of Mo–O bond distances ranging from 2.13–2.21 Å. In the fourth Mo+3.08+ site, Mo+3.08+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with six LiO6 octahedra, edges with five LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 3–12°. There are a spread of Mo–O bond distances ranging from 2.17–2.21 Å. In the fifth Mo+3.08+ site, Mo+3.08+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with six LiO6 octahedra, edges with five LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 5–11°. There are a spread of Mo–O bond distances ranging from 2.17–2.23 Å. In the sixth Mo+3.08+ site, Mo+3.08+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with six LiO6 octahedra, edges with six LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 1–6°. There are a spread of Mo–O bond distances ranging from 2.12–2.17 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded to two Li1+ and three Mo+3.08+ atoms to form OLi2Mo3 square pyramids that share corners with four OLi3Mo3 octahedra, corners with five OLi2Mo3 square pyramids, and edges with eight OLi3Mo3 octahedra. The corner-sharing octahedra tilt angles range from 2–10°. In the second O2- site, O2- is bonded to three Li1+ and three Mo+3.08+ atoms to form OLi3Mo3 octahedra that share corners with four OLi3Mo3 octahedra, corners with two OLi2Mo3 square pyramids, edges with ten OLi3Mo3 octahedra, and edges with two equivalent OLi2Mo3 square pyramids. The corner-sharing octahedra tilt angles range from 0–3°. In the third O2- site, O2- is bonded to three Li1+ and three Mo+3.08+ atoms to form OLi3Mo3 octahedra that share corners with four OLi3Mo3 octahedra, corners with two OLi2Mo3 square pyramids, edges with ten OLi3Mo3 octahedra, and edges with two OLi2Mo3 square pyramids. The corner-sharing octahedra tilt angles range from 0–4°. In the fourth O2- site, O2- is bonded to three Li1+ and three Mo+3.08+ atoms to form OLi3Mo3 octahedra that share corners with four OLi3Mo3 octahedra, corners with two OLi2Mo3 square pyramids, edges with ten OLi3Mo3 octahedra, and edges with two OLi2Mo3 square pyramids. The corner-sharing octahedra tilt angles range from 0–4°. In the fifth O2- site, O2- is bonded to three Li1+ and three Mo+3.08+ atoms to form OLi3Mo3 octahedra that share corners with four OLi3Mo3 octahedra, corners with two OLi2Mo3 square pyramids, edges with eleven OLi3Mo3 octahedra, and an edgeedge with one OLi2Mo3 square pyramid. The corner-sharing octahedra tilt angles range from 0–4°. In the sixth O2- site, O2- is bonded to two Li1+ and three Mo+3.08+ atoms to form OLi2Mo3 square pyramids that share corners with four OLi3Mo3 octahedra, corners with five OLi2Mo3 square pyramids, edges with seven OLi3Mo3 octahedra, and an edgeedge with one OLi2Mo3 square pyramid. The corner-sharing octahedra tilt angles range from 3–7°. In the seventh O2- site, O2- is bonded to three Li1+ and three Mo+3.08+ atoms to form OLi3Mo3 octahedra that share corners with five OLi3Mo3 octahedra, a cornercorner with one OLi2Mo3 square pyramid, edges with eight OLi3Mo3 octahedra, and edges with four OLi2Mo3 square pyramids. The corner-sharing octahedra tilt angles range from 0–8°. In the eighth O2- site, O2- is bonded to three Li1+ and three Mo+3.08+ atoms to form OLi3Mo3 octahedra that share corners with five OLi3Mo3 octahedra, a cornercorner with one OLi2Mo3 square pyramid, edges with eight OLi3Mo3 octahedra, and edges with four OLi2Mo3 square pyramids. The corner-sharing octahedra tilt angles range from 0–10°. In the ninth O2- site, O2- is bonded to three Li1+ and three Mo+3.08+ atoms to form OLi3Mo3 octahedra that share corners with five OLi3Mo3 octahedra, a cornercorner with one OLi2Mo3 square pyramid, edges with nine OLi3Mo3 octahedra, and edges with three OLi2Mo3 square pyramids. The corner-sharing octahedra tilt angles range from 0–10°. In the tenth O2- site, O2- is bonded to three Li1+ and three Mo+3.08+ atoms to form OLi3Mo3 octahedra that share corners with five OLi3Mo3 octahedra, a cornercorner with one OLi2Mo3 square pyramid, edges with eleven OLi3Mo3 octahedra, and an edgeedge with one OLi2Mo3 square pyramid. The corner-sharing octahedra tilt angles range from 0–3°. In the eleventh O2- site, O2- is bonded to three Li1+ and three Mo+3.08+ atoms to form OLi3Mo3 octahedra that share corners with five OLi3Mo3 octahedra, a cornercorner with one OLi2Mo3 square pyramid, edges with eight OLi3Mo3 octahedra, and edges with four OLi2Mo3 square pyramids. The corner-sharing octahedra tilt angles range from 0–3°. In the twelfth O2- site, O2- is bonded to two Li1+ and three Mo+3.08+ atoms to form OLi2Mo3 square pyramids that share corners with five OLi3Mo3 octahedra, corners with four OLi2Mo3 square pyramids, and edges with eight OLi3Mo3 octahedra. The corner-sharing octahedra tilt angles range from 3–8°.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Selective CW Laser Synthesis of MoS2 and Mixture of MoS2 and MoO2 from (NH4)2MoS4 Film

Very recently, the synthesis of 2D MoS2 and WS2 through pulsed laser-directed thermolysis can achieve wafer-scale and large-area structures, in ambient conditions. In this paper, we report the synthesis of MoS2 and MoS2 oxides from (NH4)2MoS4 film using a visible continuous-wave (CW) laser at 532 nm, instead of the infrared pulsed laser for the laser-directed thermolysis. The (NH4)2MoS4 film is prepared by dissolving its crystal powder in DI water, sonicating the solution, and dip-coating onto a glass slide. We observed a laser intensity threshold for the laser synthesis of MoS2, however, it occurred in a narrow laser intensity range. Above that range, a mixture of MoS2 and MoO2 is formed, which can be used for a memristor device, as demonstrated by other research groups. We did not observe a mixture of MoS2 and MoO3 in the laser thermolysis of (NH4)2MoS4. The laser synthesis of MoS2 in a line pattern is also achieved through laser scanning. Due to of the ease of CW beam steering and the fine control of laser intensities, this study can lead toward the CW laser-directed thermolysis of (NH4)2MoS4 film for the fast, non-vacuum, patternable, and wafer-scale synthesis of 2D MoS2.

(NH4)2MoS4↗
DOE OSTI2021

High work function MoO2 back contacts for improved solar cell performance

Improved high work function back contacts for solar cells are provided. In one aspect, a method of forming a solar cell includes: forming a completed solar cell having a substrate coated with an electrically conductive material, an absorber disposed on the electrically conductive material, a buffer layer disposed on the absorber, a transparent front contact disposed on the buffer layer, and a metal grid disposed on the transparent front contact; removing the substrate and the electrically conductive material using exfoliation, exposing a backside surface of the solar cell; depositing a high work function material onto the back side surface of the solar cell; and depositing a back contact onto the high work function material. A solar cell formed by the present techniques is also provided. Yield of the exfoliated device can be improved by removing bubbles from adhesive used for exfoliation and/or forming contact pads to access the metal grid.

Antunez, Priscilla D.↗
DOE OSTI2020

Materials Data on Mo2P2O11 by Materials Project

(MoO2)2P2O7 crystallizes in the monoclinic Pm space group. The structure is two-dimensional and consists of one (MoO2)2P2O7 sheet oriented in the (0, 0, 1) direction. there are two inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with two equivalent MoO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedral tilt angles are 13°. There are a spread of Mo–O bond distances ranging from 1.70–2.15 Å. In the second Mo6+ site, Mo6+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mo–O bond distances ranging from 1.70–2.40 Å. There are two 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 MoO6 octahedra. The corner-sharing octahedral tilt angles are 16°. There are a spread of P–O bond distances ranging from 1.50–1.59 Å. In the second P5+ site, P5+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.46 Å) and two longer (1.48 Å) P–O bond length. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two equivalent Mo6+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Mo6+ atoms. In the third O2- site, O2- is bonded in a single-bond geometry to one Mo6+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one Mo6+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Mo6+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to one Mo6+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to one Mo6+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to one Mo6+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a single-bond geometry to one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2022

A study of in situ reduction of MoO 3 to MoO 2 by X-ray Photoelectron Spectroscopy

Results from X-ray Photoelectron Spectroscopy (XPS) of molybdenum oxide samples are presented to elucidate how Mo (VI) oxide evolves to Mo (IV) oxide upon heating of a MoO 3 sample. XPS data analysis techniques based on manipulation of spectra treated as vectors are shown and allow insights into intermediate phases of Mo oxide which suggest how the original oxide changes under the influence of heat but also supports an interpretation of as-received tetravalent Mo powders as multivalent materials. In particular, several new spectral components were observed and assigned to the Magnéli phase as well as MoO 3 domains that have been modified by the presence of X-rays or temperature. Finally, these assignments comprise a new method of data processing where sample modification is used to inform XPS data interpretation and differ from previous work where the linear relationship of the binding energy of molybdenum oxides has been used.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗