| Autor: |
D. A. Baiko, A. A. Kozhberov |
| Rok vydání: |
2014 |
| Předmět: |
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| Zdroj: |
Contributions to Plasma Physics. 54:859-867 |
| ISSN: |
0863-1042 |
| Popis: |
Vibration modes and thermodynamic properties of a body-centered cubic (bcc) Coulomb crystal with a small admixture of substitutional isotopic impurities are studied analytically applying the perturbation theory of disordered crystal spectra and the Lifshitz-Krein trace formula. We calculate the density of phonon states of the perfect bcc Coulomb crystal and use it to compute the heat capacity of the crystal with impurities in a wide range of temperatures. It is shown that the ratio of an impurity contribution to the crystal heat capacity over the perfect crystal specific heat tends to a constant in the low-temperature quantum regime and decays as T–2 in the classic regime of high temperatures. It is also shown that even a small concentration of heavy impurities amplifies significantly the total crystal heat capacity. The results are compared with those obtained using the more conventional linear mixing theory. It is demonstrated that both methods give similar results at all tempera-tures when the impurity mass is not too different from that of the base ions but a strong discrepancy is observed at low and intermediate temperatures when impurities are noticeably lighter or heavier. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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