Phonon Contribution in Thermodynamicsi οf Nano-Crystalline Films and Wires

J.P. Šetrajčića,f, D.Lj. Mirjanićb, S.M. Vučenovićb, D.I. Ilićc, B. Markoskic, S.K. Jaćimovskid, V.D. Sajferte and V.M. Zorića a Department of Physics, Faculty of Sciences, University of Novi Sad, Trg D. Obradovića 4, 21000 Novi Sad, Vojvodina, Serbia b Faculty of Medicine, University of Banja Luka, Republic of Srpska, BIH c Faculty of Technical Sciences, University of Novi Sad, Vojvodina, Serbia d Police Academy, Belgrade, Serbia e Technical Faculty "M. Pupin", University of Novi Sad, Vojvodina, Serbia f Academy of Sciences and Arts, Banja Luka, Republic of Srpska, BIH

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Spectra of possible phonon states, as well as thermodynamic characteristics of nanocrystals (ultrathin film and quantum wire) of simple cubic crystalline structure are analyzed in this paper, using the method of two-time dependent Green functions. From energy spectra and internal energy of the system the thermal capacitance of these structures in low temperature region is found. The temperature behavior of specific heat is compared to that of corresponding bulk structure. It is shown that at extremely low temperatures thermal capacitance of quantum wire is considerably lower than the thermal capacitance of film as well as the bulk sample. Consequences of this fact are discussed in detail and its influence to thermodynamic properties of materials is estimated.

DOI: 10.12693/APhysPolA.115.778 PACS numbers: 63.20.-e, 65.40.Ba, 67.25.dp, 68.60.-p, 68.65.La