Thermodynamics of Mechanical Oscillations in Crystalline Superlattices

Jaćimovski, Stevo; Šetrajčić, Jovan P.; Zorić, Vojkan M.; Tošić, B. S.; Sajfert, Vjekoslav; Ilić, D. I.

doi:10.1142/s0217979207036783

Cited by 4 publications

(3 citation statements)

References 4 publications

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“…On the other hand, it is well known fact that the more inferior electrical conductor material is (under normal conditions), the better superconductor it becomes [1][2][3][11][12][13]. Due to that, the experimental fact can be concluded and justified, that in spatially very confined structures more qualitative superconductive properties have been achieved.…”

Section: Discussionmentioning

confidence: 99%

Phonon Contribution in Thermodynamics οf Nano-Crystalline Films and Wires

et al. 2009

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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.

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Section: Discussionmentioning

confidence: 99%

Phonon Contribution in Thermodynamics οf Nano-Crystalline Films and Wires

et al. 2009

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“…The standard Hamiltonian of phonon subsystem [20][21][22][23] in the nearest neighbors approximation can be written as follows:…”

Section: Micro-theory Of Phonons In Layered Structuresmentioning

confidence: 99%

Phonon contribution to heat capacitance of nanolayered crystalline structures

Šetrajčić

Jaćimovski²,

Sajfert

2015

Mod. Phys. Lett. B

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The paper presents the innovated method of two-time dependent Green's functions applied to the bounded and translational perturbed systems. Film-structures and superlattices were analyzed by employing the phonon spectra for the calculation of relevant thermodynamic characteristics. Free energy and the internal energy of the system were found as well as the temperature behavior of layered structures. Heat capacitances of these nanostructures were compared to bulk ones. It was shown that heat capacitances of nanolayered structures in low-temperature region were higher than the same quantities of the corresponding bulk sample. In the middle and the highest temperature region, temperature behavior was inverse: heat capacitance of layered structures was lower than of the corresponding bulk ones. The consequences were discussed with relation to the (super)conductive properties of nanomaterials.

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“…13 In these structures, the phonon modes are divided into three groups: fluctuations in the inner layer of the coating and general oscillations as a whole. Redistribution of atom displacements between layers leads to attenuations of electron-phonon interaction and to the increase of the mobility of electrons in materials that are coated with other materials 14 .…”

Section: Theoretical Modellingmentioning

confidence: 99%

Review of results of theoretical approaches to phonon engineering of thermodynamic properties for different quantum structures

Jaćimovski¹,

Šetrajčić²

2015

NBP

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Summary: Application of nano-structures requires a knowledge of their fundamental physical (mechanical, electro-magnetic, optical, etc.) characteristics. Thermodynamic properties associated with phonon displacements through the nanosamples are particularly interesting. Independent of the type of lattices, the thermodynamics of their subsystems (electrons, excitons, spin waves, etc.) is determined when the subsystem is in thermodynamic equilibrium with phonons. Phonons are collective mechanical oscillations of molecules or atoms and represent the most important system of excitations. Besides, the acoustical characteristics as well as conductive and superconductive properties etc. could not be realistically explained without phonons. In this paper we will try to observe the difference between the characteristics of different nano-crystalline structures: ultrathin films, composite films, i.e. superlattices, nanorods and quantum dots, we were interested in whether the quantum size effects (quantum confinement), quantum (de)coherence and influence of boundary conditions, strengthen or weaken in nanosamples. Finally, this paper describes how the dimensional confinement of phonons in nanostructures leads to modifications in the electronic, optical, acoustic, superconducting and thermodynamic properties of quantum.1 Associate Professor, stevo.jacimovski@kpa.edu.rs 2 Academician, Full Professor, jovan.setrajcic@df.uns.ac.rs[68] NBP • Žurnal za kriminalistiku i pravo Stevo K. Jacimovski, Jovan P. Setrajcic Thermal properties of nanostructures have recently attracted a lot of attention. The influence of size effects on thermal conductivity is becoming extremely important for device design and reliability. On the basis of the calculated dispersion law and distribution of phonon states in nanoscopic crystals, free energy and entropy will be calculated. Internal energy as well as heat capacitance will also be analyzed.

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Thermodynamics of Mechanical Oscillations in Crystalline Superlattices

Cited by 4 publications

References 4 publications

Phonon Contribution in Thermodynamics οf Nano-Crystalline Films and Wires

Phonon Contribution in Thermodynamics οf Nano-Crystalline Films and Wires

Phonon contribution to heat capacitance of nanolayered crystalline structures

Review of results of theoretical approaches to phonon engineering of thermodynamic properties for different quantum structures

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