Sur l'effet Mössbàuer dans les couches minces

Corciovei, A.; Berinde, A.

doi:10.1051/jphys:0196300240208900

Cited by 19 publications

(7 citation statements)

References 7 publications

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“…CORCIOVEI and C. MOTOC such problems can be found in [2]. We note that the general solution uni .can be written asa sum of expressions (4) for all possible values of f, r and s. Now, so as to obtain some more practical solutions we shall assume that the tensors A~q" are diagonal, which means that the force exerted by the j'th atom from the n'th layer on the jth atom of the nth layer has the same direction as the displacement of the j'th atom.…”

Section: Thermal Vibrations In Thin Filmsmentioning

confidence: 97%

“…We note that in the case q = 1 we obtain the equation Z --a = 0. In [2] ate given the solutions of (8) in the approximation a = 0, from q = 2 to q = 6. Ir is also shown that when a is smaller than 1, ir is sufficient for practieal purposes to introduce a correction a/q to all the values of Z~ which have been obtained in the approximation a = 0.…”

Section: Thermal Vibrations In Thin Filmsmentioning

confidence: 99%

“…Ifthe atom is situated in the layer in contact with the substrate, in A 0 and B 0 will appear also the contribution of the substrate force, which we denote by Ap, respeetively B v for the directions ix and iy, respectively iz. A full discussion is given in [2].…”

Section: Thermal Vibrations In Thin Filmsmentioning

confidence: 99%

“…The position of the ni atom at the time t will be given by* rnj = a(jxi x ~-jyiy -~-niz) + u,j (t), (2) where Unj(t ) is the displacement of the atom with respect to its equilibrium position.…”

Section: Thermal Vibrations In Thin Filmsmentioning

confidence: 99%

“…In a previous paper of CoRcxovEI and BV~RINDE [2], a thermal vibrational model of simple cubic thin films with q monoatomic layers was developed. It has thus become possible to deal with the problem of the specific heat of thin films, and this is the aim of our paper.…”

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The specific heat of thin films

Corciovei

Motoc

1963

Acta Phys. Hung.

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The specifie heat of thin films is studied theoretically. It is based on the preliminary ~tudy of the problem of thermal vibrations in thin films. After obtaining the dispersion relations, the specific heat is calculated by taking into account the contribution of all vibrational modes to the thermal energy of the thin film. Two limiting cases are considered: the hightemperature case, in which the well-known independence of the specific heat of the temperature T is found, and the low-temperature Fase in which for the specific heat of thin films with few monoatomic layers a T 2 dependence is found. Finally the dependence of the specific heat on the thickness is considered and it is shown that for large thickness, which corresponds to the solid body, the well-known T 3 dependence of the specific heat is obtained.As it is known, the theoretical study of the specific heat is based on the calculation of vibrational modes of the solid. In the same manner ir is possible to calculate the specific heat of thin films ir the vibrational spectrum has been ~)btained.In the literature ir is the custom when dealing with thin films to use the results obtained in the study of solid bodies and make insignificant modifications of some eonstants, such as Debye temperature, Curie temperature, etc. This method is not very accurate because the thin film has its characteristic particularities, its specific heat directly depending on the lattice type, the :substrate and especially the number q of monoatomie layers of the film.So as to be able to give a theoretical foundation of the specific heat in thin fflms ir is necessary to study previously the thermal vibrations in these. An important work in this field is MONTaOLL'S paper [1], in which a theoretical study of thermal vibrations in ah ideal bidimensional lattice is given. Unfortunately, in this article only the vibrations within the bidimensional lattice ate studied, without taking into account the vibrations normal to the lattiee, nor the influenee of the substrate.In a previous paper of CoRcxovEI and BV~RINDE [2], a thermal vibrational model of simple cubic thin films with q monoatomic layers was developed. It has thus become possible to deal with the problem of the specific heat of thin films, and this is the aim of our paper. After giving a general expression for the specific heat of a thin film with q layers, so as to obtain more conclusive results, two limiting cases ate treated, i.e. the case of high and that of low temperatures.Acla Phys. Hung. Tora. XI/'. Fase. 4.

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Section: Thermal Vibrations In Thin Filmsmentioning

confidence: 97%

Section: Thermal Vibrations In Thin Filmsmentioning

confidence: 99%

Section: Thermal Vibrations In Thin Filmsmentioning

confidence: 99%

Section: Thermal Vibrations In Thin Filmsmentioning

confidence: 99%

mentioning

confidence: 99%

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