共查询到20条相似文献,搜索用时 31 毫秒
1.
Russian Physics Journal - The paper presents modeling and simulation of the Gruneisen parameter depending on the volume and temperature using the principal Hugoniot, isentropes and the Gruneisen... 相似文献
2.
The optic mode Gruneisen parameters in silver, caesium and thallium halides are calculated using the Born model for interionic
forces and the Szigeti theory of dielectric constants. The strain derivatives of the electronic and static dielectric constants
are also evaluated and compared with experimental data. The strain derivative of static dielectric constant reveals the inadequacy
of the Born model for the crystals under study. Possible modifications have been suggested to improve the situation. The theoretical
values of the optic mode Gruneisen parameters closely agree with recent experimental data. An appropriate process has been
adopted to evaluate the average values for the Gruneisen parameter. 相似文献
3.
The specific heat of a resole-type phenolic polymer has been determined. A secondary transition is noted at 125° C. The thermodynamic Gruneisen parameter is 1.3 and the lattice Gruneisen parameter is 6.3. Interchain specific heat is about 21% of the total. 相似文献
4.
Panayiotis Antoniou Varotsos 《Physics letters. A》1978,64(4):411-412
By using the Swenson formula, for the pressure derivative of the bulk modulus, and the Slater formulation for the Gruneisen constant a simple useful relation between the vacancy-formation entropy and the Gruneisen constant is derived in the case of metals. This relation also indicates that actually a close correlation between the vacancy-formation enthalpy, the coefficient of the volume expansivity and the corresponding melting point exists. 相似文献
5.
Expressions for the higher order elastic constants are derived using the sublattice displacements to the second degree in
strains. These expressions are used to obtain the higher order elastic constants and their pressure derivatives in gadolinium.
The higher order elastic constants are used to find out the generalized Gruneisen parameters of the elastic waves propagating
in different directions in gadolinium. The Brugger gammas are evaluated and the low temperature limit of the Gruneisen gamma
is obtained. The results are compared with the available reported values. 相似文献
6.
R.R. Reddy K. Rama Gopal K. Narasimhulu L. Siva Sankara Reddy K. Raghavendra Kumar A. Venkatesulu C.V. Krishna Reddy 《Journal of Molecular Liquids》2008,140(1-3):48-53
Thermo-acoustical parameters of liquid mixtures viz., Acetone, Methyl Iodide and Acetone + Methyl Iodide have been evaluated at different temperatures in terms of the coefficient of volume expansion, on the assumption that the Moelwyn–Hughes parameter has been utilized to establish some simple relations between the lattice Gruneisen parameter, Beyer's non-linearity parameter, the Anderson–Gruneisen parameter and the Sharma constant. A relationship among the isobaric, isothermal and isochoric microscopic (lattice) Gruneisen parameters have been studied and analysed in the case of liquid mixtures. The Sharma's parameter S0 remains invariant with the temperature over a wide range of temperatures and retains its characteristics value i.e., 1.11 ± 0.01 as observed in case of liquid systems. The present treatment has the distinct advantage of calculating available volume (Va) and intermolecular free-length (Lf) through Moelwyn–Hughes parameter mainly. Analysis of such type is not found so far in literature. 相似文献
7.
Abstract First-order Raman spectra and lattice parameters of BN and SiC were measured simultaneously up to a pressure of 34 and 45 GPa. The bulk moduli, their pressure derivatives and the volume dependence of Gruneisen parameters of LO and TO phonons were obtained. The average Gruneisen parameter for BN does not change much; on the contrary, the same parameter for SiC decreases under pressure. The definite connection between the crystal stability, the pressure behaviour of the optical phonons and the electron structure of the ionic cores is pointed out. 相似文献
8.
9.
A first-principle procedure is proposed to determine the Gruneisen parameter for a crystal by calculating the external pressure
and the vibration spectrum as functions of the volume of a unit cell. In the gradient approximation of the electron density
functional theory, on the basis of a linear combination of atomic orbitals, the elastic and the thermodynamic Gruneisen parameters
of silver azide, which decrease with volume (with increasing pressure), are calculated with the use of the CRYSTAL09 code.
The equilibrium values of the parameter γ0 for various cold equations of state of crystals and for the thermodynamic models used are, respectively, ~2.3 and 1.6. 相似文献
10.
Russian Physics Journal - The paper determines a Gruneisen function of density and temperature for the alkali metals such as Li, Na, K, Rb, Cs, based on the experimental dependences of the... 相似文献
11.
S. Tolpadi 《Solid State Communications》1975,16(7):937-939
Temperature variation of isobaric and isochoric Gruneisen parameters of aluminium and copper have been calculated by using a lattice dynamical method which includes the effect of dispersion and crystal anharmonicity. 相似文献
12.
Intikhab A. Ansari 《Physica C: Superconductivity and its Applications》2010,470(11-12):508-510
Here, we report the efficient and feasible analytical method for the generalized Bloch–Gruneisen law in association with Debye temperature and various temperatures range in terms of incomplete gamma function. In addition, our results are in agreement with previous reports as shown in this letter. Bloch–Gruneisen function describes the contribution of electron–phonon interaction to the results of temperature dependence behavior of resistivity for integer and noninteger values of index m. In conclusion, the algorithm is constructed in Fortran 90 language for replicate the variation of temperature dependence of resistivity for pristine MgB2 sample. Moreover, the comparison of numerical results with the proposed method reveals the validity and precision of the method. 相似文献
13.
The objective of this Letter is to provide an efficient and reliable analytical procedure for the generalized Bloch–Gruneisen function with the Debye temperatures for the wide temperature range using the binomial expansion theorems. As will be seen, the present formulation yields compact closed-form expressions which enable the ready calculation of Bloch–Gruneisen function for integer and noninteger values of parameter m. The proposed procedure guarantees the reliable application of the contribution of electron–photon interaction to the electrical resistivity of metals. Finally, the algorithm is used to simulate the variation of the resistivity and thermal conductivity against temperature sintered polycrystalline MgB2. Furthermore, the comparison of the method with numerical calculations demonstrates the applicability and accuracy of the method. 相似文献
14.
《Infrared physics》1992,33(6):581-582
In the present paper we have calculated the phonon dispersion curves and dielectric constants, their volume derivatives and the Gruneisen parameters of the mixed alkali halide NaCl0.5Br0.5, using the extended three body force shell model. The results of dielectric constants, their volume derivatives and Gruneisen parameters are found to agree reasonably well with the experimental values, which establishes the validity of the three body charge transfer parameter. With this concept the phonon dispersion curves are obtained in all the three symmetry directions (q,o,o), (q,q,o) and (q,q,q), which will be of interest for experimental workers, since no experimental values have so far been obtained for phonon frequencies. 相似文献
15.
Harrison's overlap repulsive potential has been used for evaluating cohesive energies, bulk modulus and its pressure derivatives, Gruneisen parameter, and the volume derivatives of Gruneisen parameter for cuprous halides, silver halides and thallous halides. This potential has replaced the old and widely used Born-Mayer potential in ionic crystals. The Harrison repulsive potential has been represented by a quantum mechanical analytical potential form derived from the tight binding theory. The parameters involved in this potential form have been determined in terms of valence state energies of outermost d-electrons of Cu+, Ag+ and Tl+ ions. The results calculated in the present study have been found in good agreement with experimental data and better than those predicted from the Born potential model.On leave fromDepartment of Physics, G. B. Pant University, Pant Nagar, U. P., India. 相似文献
16.
The generalised Gruneisen parameters γ′ = ?? log ω/??′ and γ″ = ?? log ω/??″ have been calculated for various normal mode frequencies using the force model for Zirconium obtained on Keating's approach. There is a general agreement between the normalised frequency distribution curve of Zirconium obtained on the present model and that of Bezdek et al. The temperature dependence of the effective Gruneisen functions and has been calculated using the procedure of Blackman. The high temperature limits of , and are in good agreement with those obtained by Goldak et al. from an analysis of the thermal expansion data of Zirconium. 相似文献
17.
Intikhab A. Ansari 《Physica C: Superconductivity and its Applications》2010,470(22):2078
Here, I present the reply to the comments from Mamedov regarding numerical solution of Bloch–Gruneisen function to determine the contribution of electron–phonon interaction in polycrystalline superconductor. Reply to the comments from Mamedov is discussed one by one. 相似文献
18.
本文对纤锌矿结构GaN外延层薄膜的热膨胀行为进行了研究,结合热膨胀系数的物理意义与变温Raman散射时声子频移的变化规律,研究了热膨胀系数与变温Raman散射之间的关系.结果表明:通过测量Raman声子E_2(high),A_1(TO)和E_1(TO)频移与温度之间的线性关系,结合相应声子Gruneisen参数的涵义,可对纤锌矿结构GaN外延层薄膜在一定温度范围内的热膨胀系数进行测量.本文提供了一种表征纤锌矿结构GaN外延层薄膜热膨胀行为的有效方法,为进一步研究III族氮化物外延层薄膜在生长过程中热膨胀系数的匹配、降低外延层薄膜中的位错密度并提高发光二极管的发光效率提供了理论依据. 相似文献
19.
20.
The well known Szigeti relations for the dielectric theory of ionic crystals have been critically examined by investigating the volume dependence of dielectric behaviour of alkali halides. It has been predicted that the strain derivative of effective ionic charge parameter should be nearly equal to zero. Values of transverse optic mode Gruneisen parameter for NaCl structure alkali halides have been estimated. 相似文献