Manley, M. E. and Fultz, B. and Brown, D. W. and Clausen, B. and Lawson, A. C. and Cooley, J. C. and Hults, W. L. and Hanrahan, R. J., Jr. and Smith, J. L. and Thoma, D. J. (2002) Microstructural strain energy of α-uranium determined by calorimetry and neutron diffractometry. Physical Review B, 66 (2). Art. No. 024117. ISSN 1098-0121 http://resolver.caltech.edu/CaltechAUTHORS:MANprb02b
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The microstructural contribution to the heat capacity of α-uranium was determined by measuring the heat-capacity difference between polycrystalline and single-crystal samples from 77 to 320 K. When cooled to 77 K and then heated to about 280 K, the uranium microstructure released (3±1) J/mol of strain energy. On further heating to 300 K, the microstructure absorbed energy as it began to redevelop microstrains. Anisotropic strain-broadening parameters were extracted from neutron-diffraction measurements on polycrystals. Combining the strain-broadening parameters with anisotropic elastic constants from the literature, the microstructural strain energy is predicted in the two limiting cases of statistically isotropic stress and statistically isotropic strain. The result calculated in the limit of statistically isotropic stress was (3.7±0.5) J/mol K at 77 K and (1±0.5) J/mol at room temperature. In the limit of statistically isotropic strain, the values were (7.8±0.5) J/mol K at 77 K and (4.5±0.5) J/mol at room temperature. In both cases the changes in the microstructural strain energy showed good agreement with the calorimetry.
|Additional Information:||©2002 The American Physical Society. Received 8 January 2002; revised 22 April 2002; published 22 July 2002. M.E.M. is grateful for helpful discussions with T.M. Holden. The Manuel Lujan, Jr. Neutron Scattering Center is funded by the U.S. Department of Energy, Office of Basic Energy Sciences–Materials Science, under Contract No. W-7405-ENG-36 with the University of California. Additional support was provided by the U.S. Department of Energy under Contract No. DE-FG03-96ER45572 and other programs.|
|Subject Keywords:||VIBRATIONAL ENTROPY; POWDER DIFFRACTION; HEAT|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||21 Aug 2007|
|Last Modified:||26 Dec 2012 09:40|
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