Diffraction studies of the thermal properties of nanocrystalline Pd and Cr

Conference · Tue Sep 01 00:00:00 EDT 1992

OSTI ID:6859233

Eastman, J A; Thompson, L J ^[1]; Fitzsimmons, M R; Lawson, A C; Robinson, R A ^[2]

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1. Argonne National Lab., IL (United States)
2. Los Alamos National Lab., NM (United States)

Quantitative X-ray and neutron diffraction measurements were made on nanocrystalline and coarse-grained samples of Pd and Cr. For both materials, Debye-Waller parameter comparisons over a temperature range of approximately 20-300 K indicate that the nanocrystalline materials have increased static displacements of atoms from their equilibrium sites compared to coarse-grained material. No grain-size-correlated differences in thermal vibrational amplitude, lattice parameter, or thermal expansion coefficients were observed in either material. In contrast to earlier results on nanocrystalline Pd, significantly more non-peak intensity is observed from a nanocrystalline Cr sample than from a coarse-grained Cr sample. Impurities may account for the increased background intensity from nanocrystalline Cr. These results indicate that there is no significant grain boundary excess volume in nanocrystalline Pd, and therefore the reduced density typically observed in nanocrystalline Pd samples must be due to porosity.

• Research Organization: Argonne National Lab., IL (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: W-31109-ENG-38; W-7405-ENG-36
• OSTI ID: 6859233
• Report Number(s): ANL/MSD/CP-77539; CONF-920947-2; ON: DE93002911
• Resource Relation: Conference: Conference on nanostructured materials, Cancun (Mexico), 21-25 Sep 1992
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHROMIUM
THERMODYNAMIC PROPERTIES
PALLADIUM
DEBYE-WALLER FACTOR
GRAIN BOUNDARIES
GRAIN SIZE
LATTICE PARAMETERS
NEUTRON DIFFRACTION
POROSITY
THERMAL EXPANSION
X-RAY DIFFRACTION
COHERENT SCATTERING
CRYSTAL STRUCTURE
DIFFRACTION
ELEMENTS
EXPANSION
METALS
MICROSTRUCTURE
PHYSICAL PROPERTIES
PLATINUM METALS
SCATTERING
SIZE
TRANSITION ELEMENTS
360104* - Metals & Alloys- Physical Properties
360102 - Metals & Alloys- Structure & Phase Studies