Structure and dynamics of terephthalic acid from 2 to 300 K. I. High-resolution neutron diffraction evidence for a temperature-dependent order-disorder transition: a comparison of reactor and pulsed neutron source powder techniques

Journal Article · Wed Jan 01 04:00:00 EST 1986 · J. Solid State Chem.; (United States)

DOI:https://doi.org/10.1016/0022-4596(86)90012-5· OSTI ID:5953522

Fischer, P; Zolliker, P; Meier, B H; Ernst, R R; Hewat, A W; Jorgensen, J D; Rotella, F J

The structure of deuterated ..cap alpha..-terephthalic acid C/sub 6/D/sub 4/(COOD)/sub 2/ is triclinic (low-temperature lattice constants: a = 7.70 A, b = 6.34 A, c = 3.66 A, ..cap alpha.. = 92.98/sup 0/, ..beta.. = 107.88/sup 0/, ..gamma.. = 94.60/sup 0/, space group P/sup 1/). It has been refined to R/sub I/ approx. 7% from high-resolution reactor neutron powder data (D1A/ILL, Grenoble) at 2, 82, and 300 K. It has also been refined from high-resolution time-of-flight pulsed neutron source data (SEPD/IPNS, Argonne) at 15 and 80 K to R/sub I/ approx. 6%. Concerning the acid hydrogen and the carbon-oxygen double bond the structure is almost fully disordered at 300 K. At low temperature there is a gradual transition to an ordered arrangement of almost linear O-D ... O (angle = 178/sup 0/) acid hydrogen bonds (O-D = 1.01 A, D ... O = 1.62 A; order parameter approx. 1 below approx. 80 K). Both time-of-flight and constant wavelength data reveal a sample-contributed peak broadening which results either from strain or a small departure from the assumed structure. This systematic error in the data degrades the reliability of both the constant wavelength and time-of-flight refinements such that standard deviations of structural parameters do not overlap to the expected degree. 27 references, 5 figures, 3 tables.

• Research Organization: ETH Zuerich, Wurenlingen, Switzerland
• OSTI ID: 5953522
• Journal Information: J. Solid State Chem.; (United States), Journal Name: J. Solid State Chem.; (United States) Vol. 61:1; ISSN JSSCB
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
BOND ANGLE
BOND LENGTHS
CARBOXYLIC ACIDS
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DATA
DEUTERIUM COMPOUNDS
DICARBOXYLIC ACIDS
DIFFRACTION
DIMENSIONS
EXPERIMENTAL DATA
HYDROGEN COMPOUNDS
INFORMATION
LATTICE PARAMETERS
LENGTH
LOW TEMPERATURE
MEDIUM TEMPERATURE
NEUTRON DIFFRACTION
NEUTRON SOURCES
NEUTRON SPECTRA
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
PARTICLE SOURCES
POWDERS
RADIATION SOURCES
SCATTERING
SPECTRA
STEADY-STATE CONDITIONS
TEREPHTHALIC ACID
TIME-OF-FLIGHT METHOD
TRICLINIC LATTICES
ULTRALOW TEMPERATURE
VERY LOW TEMPERATURE