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Title: Temperature dependence of the Pd [ital K]-edge extended x-ray-absorption fine structure of PdC[sub [ital x]] ([ital x][similar to]0. 13)

Abstract

Pd [ital K]-edge extended x-ray-absorption fine-structure (EXAFS) and x-ray-absorption near-edge-structure (XANES) measurements were performed on a Pd carbide phase, PdC[sub [ital x]] (with [ital x][similar to]0.13), and metallic Pd powder at temperatures between 40 and 423 K. The data were analyzed by nonlinear least-squares fitting using an [ital ab] [ital initio] theoretical standard. The average lattice expansion of the carbide phase, 2.7[plus minus]0.1% relative to Pd metal, agrees well with previous x-ray- and neutron-diffraction results. The temperature dependence of the Pd-Pd nearest-neighbor mean-squared relative displacement ([sigma][sup 2]) yields a Debye temperature, [Theta][sub [ital D]]=295[plus minus]10 K for Pd powder. There is an additional static-disorder contribution in [sigma][sup 2] of 0.0009[plus minus]0.0002 A[sup 2], relative to bulk Pd metal. The Debye temperature of PdC[sub 0.13] powder is also 295[plus minus]10 K. There is, however, an additional static-disorder contribution to [sigma][sup 2] of 0.0012 A[sup 2], relative to Pd powder, probably the result of local distortion of the Pd lattice by interstitial C. The Pd-C coordination is not directly observed in a Fourier transform of the EXAFS. The location of C in octahedral interstices is evident by its effect, through multiple scattering, on the magnitude of the second Pd-Pd peak in themore » Fourier transform magnitude of the EXAFS data, which is greatly reduced. The Pd [ital K]-edge XANES spectrum of PdC[sub 0.13] is nearly identical to that of Pd metal. There is no significant chemical shift ([le]0.5 eV) of the Pd [ital K] edge of PdC[sub [similar to]0.13].« less

Authors:
 [1]
  1. Hoechst Celanese Research Division, Robert L. Mitchell Technical Center, 86 Morris Avenue, Summit, New Jersey 07901 (United States)
Publication Date:
OSTI Identifier:
6952347
DOE Contract Number:  
FG05-89ER45384; AC02-76CH00016
Resource Type:
Journal Article
Journal Name:
Physical Review, B: Condensed Matter; (United States)
Additional Journal Information:
Journal Volume: 47:9; Journal ID: ISSN 0163-1829
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; PALLADIUM CARBIDES; K ABSORPTION; CHEMICAL COMPOSITION; DEBYE TEMPERATURE; EXPANSION; LATTICE PARAMETERS; TEMPERATURE DEPENDENCE; ABSORPTION; CARBIDES; CARBON COMPOUNDS; PALLADIUM COMPOUNDS; SORPTION; TRANSITION ELEMENT COMPOUNDS; 360602* - Other Materials- Structure & Phase Studies

Citation Formats

McCaulley, J A. Temperature dependence of the Pd [ital K]-edge extended x-ray-absorption fine structure of PdC[sub [ital x]] ([ital x][similar to]0. 13). United States: N. p., 1993. Web. doi:10.1103/PhysRevB.47.4873.
McCaulley, J A. Temperature dependence of the Pd [ital K]-edge extended x-ray-absorption fine structure of PdC[sub [ital x]] ([ital x][similar to]0. 13). United States. https://doi.org/10.1103/PhysRevB.47.4873
McCaulley, J A. Mon . "Temperature dependence of the Pd [ital K]-edge extended x-ray-absorption fine structure of PdC[sub [ital x]] ([ital x][similar to]0. 13)". United States. https://doi.org/10.1103/PhysRevB.47.4873.
@article{osti_6952347,
title = {Temperature dependence of the Pd [ital K]-edge extended x-ray-absorption fine structure of PdC[sub [ital x]] ([ital x][similar to]0. 13)},
author = {McCaulley, J A},
abstractNote = {Pd [ital K]-edge extended x-ray-absorption fine-structure (EXAFS) and x-ray-absorption near-edge-structure (XANES) measurements were performed on a Pd carbide phase, PdC[sub [ital x]] (with [ital x][similar to]0.13), and metallic Pd powder at temperatures between 40 and 423 K. The data were analyzed by nonlinear least-squares fitting using an [ital ab] [ital initio] theoretical standard. The average lattice expansion of the carbide phase, 2.7[plus minus]0.1% relative to Pd metal, agrees well with previous x-ray- and neutron-diffraction results. The temperature dependence of the Pd-Pd nearest-neighbor mean-squared relative displacement ([sigma][sup 2]) yields a Debye temperature, [Theta][sub [ital D]]=295[plus minus]10 K for Pd powder. There is an additional static-disorder contribution in [sigma][sup 2] of 0.0009[plus minus]0.0002 A[sup 2], relative to bulk Pd metal. The Debye temperature of PdC[sub 0.13] powder is also 295[plus minus]10 K. There is, however, an additional static-disorder contribution to [sigma][sup 2] of 0.0012 A[sup 2], relative to Pd powder, probably the result of local distortion of the Pd lattice by interstitial C. The Pd-C coordination is not directly observed in a Fourier transform of the EXAFS. The location of C in octahedral interstices is evident by its effect, through multiple scattering, on the magnitude of the second Pd-Pd peak in the Fourier transform magnitude of the EXAFS data, which is greatly reduced. The Pd [ital K]-edge XANES spectrum of PdC[sub 0.13] is nearly identical to that of Pd metal. There is no significant chemical shift ([le]0.5 eV) of the Pd [ital K] edge of PdC[sub [similar to]0.13].},
doi = {10.1103/PhysRevB.47.4873},
url = {https://www.osti.gov/biblio/6952347}, journal = {Physical Review, B: Condensed Matter; (United States)},
issn = {0163-1829},
number = ,
volume = 47:9,
place = {United States},
year = {1993},
month = {3}
}