Crystal structures of N sub 2 O to 12 GPa by x-ray diffraction

Journal Article · Tue Oct 01 00:00:00 EDT 1991 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.461655· OSTI ID:5170986

Mills, R L; Olinger, B; Cromer, D T; LeSar, R ^[1]

---

1. University of California, Los Alamos National Laboratory, Los Alamos, New Mexico (USA)

The structures and phase transitions of N{sub 2}O were studied by powder x-ray diffraction in a tungsten--carbide anvil device from about 100 to 300 K and 2 to 12 GPa. Two solid phases, {alpha}-N{sub 2}O and {beta}-N{sub 2}O, were observed. The {alpha} pattern is consistent with the known low-pressure low-temperature ordered cubic form, space group Pa3, up to 4.8 GPa where transition to a new {beta} solid occurs. From refinements using photographic x-ray intensities, the {beta}-N{sub 2}O structure was determined to be orthorhombic Cmca. There are four molecules in a unit cell with {ital a}=4.954 A, {ital b}=4.497 A, and {ital c}=6.201 A at 5.81 GPa and 298 K. The molecular axes lie parallel to the {ital bc} plane and are tipped at an angle of 37.2{degree} to the {ital b} axis. Random head-to-tail orientation is probable in both solids. The phase diagram and values of the molar volume for N{sub 2}O are compared with published data for the isoelectronic molecule CO{sub 2}. Recent theoretical calculations correctly predict the {beta}-N{sub 2}O structure.

• OSTI ID: 5170986
• Journal Information: Journal of Chemical Physics; (United States), Vol. 95:7; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
NITROUS OXIDE
CRYSTAL STRUCTURE
LOW TEMPERATURE
MEDIUM TEMPERATURE
ORTHORHOMBIC LATTICES
PHASE DIAGRAMS
VERY HIGH PRESSURE
X-RAY DIFFRACTION
CHALCOGENIDES
COHERENT SCATTERING
CRYSTAL LATTICES
DIAGRAMS
DIFFRACTION
NITROGEN COMPOUNDS
NITROGEN OXIDES
OXIDES
OXYGEN COMPOUNDS
SCATTERING
360602* - Other Materials- Structure & Phase Studies