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Title: A high-temperature neutron diffraction study of Nb 2AlC and TiNbAlC

Abstract

In this paper, we report on the crystal structures of Nb 2AlC and TiNbAlC actual composition (Ti 0.45,Nb 0.55) 2AlC compounds determined from Rietveld analysis of neutron diffraction patterns in the 300-1173 K temperature range. The average linear thermal expansion coefficients of a Nb 2AlC sample in the a and c directions are, respectively, 7.9(5)x10 -6 K -1 and 7.7(5)x10 -6 K -1 on one neutron diffractometer and 7.3(3)x10 -6 K -1 and 7.0(2)x10 -6 K -1 on a second diffractometer. The respective values for the (Ti 0.45,Nb 0.55) 2AlC composition - only tested on one diffractometer - are 8.5(3)x10 -6 K -1 and 7.5(5)x10 -6 K -1. These values are relatively low compared to other MAX phases. Like other MAX phases, however, the atomic displacement parameters show that the Al atoms vibrate with higher amplitudes than the Ti and C atoms, and 1 more along the basal planes than normal to them. In addition, when the predictions of the atomic displacement parameters obtained from density functional theory are compared to the experimental results, good quantitative agreement is found for the Al atoms. In case of the Nb and C atoms, the agreement was more qualitative.

Authors:
 [1];  [1];  [2];  [3];  [1];  [1]
  1. Drexel Univ., Philadelphia, PA (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1286845
Alternate Identifier(s):
OSTI ID: 1352749; OSTI ID: 1401597
Grant/Contract Number:  
AC05-00OR22725; DE‐AC52‐06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of the American Ceramic Society (Online)
Additional Journal Information:
Journal Name: Journal of the American Ceramic Society (Online); Journal Volume: 98; Journal Issue: 3; Journal ID: ISSN 1551-2916
Publisher:
American Ceramic Society
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; neutron diffraction; high temperature

Citation Formats

Bentzel, Grady W., Lane, Nina J., Vogel, Sven C., An, Ke, Barsoum, Michel W., and Caspi, El'ad N.. A high-temperature neutron diffraction study of Nb2AlC and TiNbAlC. United States: N. p., 2014. Web. doi:10.1111/jace.13366.
Bentzel, Grady W., Lane, Nina J., Vogel, Sven C., An, Ke, Barsoum, Michel W., & Caspi, El'ad N.. A high-temperature neutron diffraction study of Nb2AlC and TiNbAlC. United States. doi:10.1111/jace.13366.
Bentzel, Grady W., Lane, Nina J., Vogel, Sven C., An, Ke, Barsoum, Michel W., and Caspi, El'ad N.. Tue . "A high-temperature neutron diffraction study of Nb2AlC and TiNbAlC". United States. doi:10.1111/jace.13366. https://www.osti.gov/servlets/purl/1286845.
@article{osti_1286845,
title = {A high-temperature neutron diffraction study of Nb2AlC and TiNbAlC},
author = {Bentzel, Grady W. and Lane, Nina J. and Vogel, Sven C. and An, Ke and Barsoum, Michel W. and Caspi, El'ad N.},
abstractNote = {In this paper, we report on the crystal structures of Nb2AlC and TiNbAlC actual composition (Ti0.45,Nb0.55)2AlC compounds determined from Rietveld analysis of neutron diffraction patterns in the 300-1173 K temperature range. The average linear thermal expansion coefficients of a Nb2AlC sample in the a and c directions are, respectively, 7.9(5)x10-6 K-1 and 7.7(5)x10-6 K-1 on one neutron diffractometer and 7.3(3)x10-6 K-1 and 7.0(2)x10-6 K-1 on a second diffractometer. The respective values for the (Ti0.45,Nb0.55)2AlC composition - only tested on one diffractometer - are 8.5(3)x10-6 K-1 and 7.5(5)x10-6 K-1. These values are relatively low compared to other MAX phases. Like other MAX phases, however, the atomic displacement parameters show that the Al atoms vibrate with higher amplitudes than the Ti and C atoms, and 1 more along the basal planes than normal to them. In addition, when the predictions of the atomic displacement parameters obtained from density functional theory are compared to the experimental results, good quantitative agreement is found for the Al atoms. In case of the Nb and C atoms, the agreement was more qualitative.},
doi = {10.1111/jace.13366},
journal = {Journal of the American Ceramic Society (Online)},
number = 3,
volume = 98,
place = {United States},
year = {Tue Dec 16 00:00:00 EST 2014},
month = {Tue Dec 16 00:00:00 EST 2014}
}

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