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oai:recercat.cat:2445/105822025-12-05T16:47:15Zcom_2072_1057col_2072_478823col_2072_478917

Contribution of low-frequency modes to the specific heat of Cu-Zn-Al shape-memory alloys Lashley, J. C. Drymiotis, F. R. Safarik, D. J. Smith, J. L. Romero, Ricardo Fisher, R. A. Planes Vila, Antoni Mañosa, Lluís Dispersió (Física nuclear) Fonons Aliatges Scattering (Physics) Phonons Alloys We report a comparison of the specific-heat measurements on isoelectronic Cu-Zn-Al shape-memory alloys in the parent cubic phase L21 and in the close-packed martensitic phase 18R. Measurements were made by thermal-relaxation calorimetry over the temperature range 1.9 T 300 K. For the close-packed martensitic phase we find that the specific heat behaves similarly to that of pure copper which is also close packed. However, we observe deviations from Debye behavior for the cubic phase at low temperatures. This deviation is accounted for by the addition of 5% of Einstein localized modes to the Debye modes. Although the microscopic origin remains unknown, it was anticipated that it is related to the well-known softening of the TA2 110 phonon branch. In order to address this hypothesis an analysis of the lattice heat capacity of the cubic phase was compared to the calculated lattice heat capacity of -brass, as determined by integrating over the phonon density of states. A similar comparison was made between the close-packed phase and -brass. 2009-12-28T11:05:57Z 2009-12-28T11:05:57Z 2007 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 0163-1829 https://hdl.handle.net/2445/10582 557077 eng Reproducció digital del document publicat en format paper, proporcionada per http://dx.doi.org/10.1103/PhysRevB.75.064304 Physical Review B, 2007, vol. 75, núm. 6, p. 064304-1-064304-7 http://dx.doi.org/10.1103/PhysRevB.75.064304 (c) The American Physical Society, 2007 info:eu-repo/semantics/openAccess 7 p. application/pdf The American Physical Society Articles publicats en revistes (Física Quàntica i Astrofísica)