Debye model

About: Debye model is a research topic. Over the lifetime, 7462 publications have been published within this topic receiving 133987 citations.

Mechanical properties and electronic structures of Fe-Al intermetallic

Abstract: Using the first-principles calculations, the elastic properties, anisotropy properties, electronic structures, Debye temperature and stability of Fe-Al (Fe 3 Al, FeAl, FeAl 2 , Fe 2 Al 5 and FeAl 3 ) binary compounds were calculated. The formation enthalpy and cohesive energy of these Fe-Al compounds are negative, and show they are thermodynamically stable structures. Fe 2 Al 5 has the lowest formation enthalpy, which shows the Fe 2 Al 5 is the most stable of Fe-Al binary compounds. These Fe-Al compounds display disparate anisotropy due to the calculated different shape of the 3D curved surface of the Young’s modulus and anisotropic index. Fe 3 Al has the biggest bulk modulus with the value 233.2 GPa. FeAl has the biggest Yong’s modulus and shear modulus with the value 296.2 GPa and 119.8 GPa, respectively. The partial density of states, total density of states and electron density distribution maps of the binary Fe-Al binary compounds are analyzed. The bonding characteristics of these Fe-Al binary compounds are mainly combination by covalent bond and metallic bonds. Meanwhile, also exist anti-bond effect. Moreover, the Debye temperatures and sound velocity of these Fe-Al compounds are explored.

FP-LAPW study of the elastic properties of Al2X (X=Sc,Y,La,Lu)

Abstract: From the first principles total energy calculations based on full-potential linear augmented plane wave method (FP-LAPW), the elastic properties of Al 2 X (X=Sc,Y,La,Lu) are reported here. Theoretical values of Young's modulus, shear modulus, Poisson's ratio and Debye temperature are estimated from the computed elastic constants. From the analysis of the ratio of shear to bulk modulus, it is found that these intermetallic compounds are brittle in nature. The calculated results are compared with other reported values.

Electrical, thermal, and elastic properties of the MAX-phase Ti2SC

Abstract: We report on the electronic, thermal, and elastic properties of the layered ternary, Ti2SC. Resistivity, Hall effect, and magnetoresistance were measured as a function of temperature between 2 and 300 K and at fields up to 9 T. The Hall coefficient is negative and roughly temperature independent. The transport results were analyzed within a two-band framework, with electrons as the dominant charge carrier. The room-temperature thermal conductivity (≈60 W/m K) is the highest of any MAX phase measured to date, with a substantial phonon contribution. The specific heat was measured from 2 to 300 K, yielding a Debye temperature of 765 K and in agreement with the Debye temperature of 745 K found from ultrasonic time-of-flight measurements. Young’s, shear, and bulk moduli from the latter measurements were 290, 125, and 145 GPa, respectively. The calculated values of the lattice parameters (a=3.2051 A and c=11.2636 A), and Young’s, shear, and bulk moduli (329, 138, and 179 GPa, respectively), based on the results...

Experimental compressions for sodium, potassium, and rubidium metals to 20 kbar from 4.2 to 300 K

Abstract: Experimental piston-displacement equations of state are given for sodium, potassium, and rubidium to 20 kbar for temperatures from 4 K to just below the melting line in each case. Except for sodium at high pressures, where the low-temperature bcc-hcp martensitic transition appears to cause problems, these data can be represented by a room-temperature pressure-volume reference function and a thermal pressure which is a function of temperature only. In addition, these three solids appear to obey a reduced equation of state at both 4 K and room temperature, for which $\frac{V}{{V}_{0}}$ is a common function of $\frac{P}{{B}_{0}}$. A modification of the second-order Murnaghan equation which is well behaved at large compressions is used to extrapolate these results to 40 kbar for comparison with higher-pressure, room-temperature results. These data are compared with other high-pressure equation-of-state experiments and are extrapolated to $P=0$ to obtain thermal expansions and isothermal bulk moduli, which in turn are compared with results from other measurements. These comparisons and those with theoretical calculations show, on the whole, satisfactory agreement. The elementary form for the temperature-dependent equation of state is in agreement with a previous suggestion that the Gr\"uneisen parameter is temperature independent and is a linear function of the volume for temperatures greater than the Debye temperature. The 295-K Gr\"uneisen parameters for these solids, as deduced from the high-pressure results, are 1.24 for sodium and potassium and 1.26 for rubidium.

First‐principles calculations of structural, elastic and electronic properties of Ni2MnZ (Z = Al, Ga and In) Heusler alloys

Abstract: We have performed ab-initio density-functional theory self-consistent calculations using the full-potential linear muffin-tin orbital method within local spin-density approximation to study the electronic and magnetic properties of Ni2MnZ (Z = Al, Ga and In) in L21 structure. The magnetic phase stability is determined from the total energy calculations for both the nonmagnetic (NM) and magnetic (M) phases. The theoretical calculations clearly indicate that at both ambient and high pressures, the magnetic phase is more stable than the nonmagnetic phase. The elastic constants at equilibrium are also determined. We derived the bulk and shear moduli, Young's modulus, and Poisson's ratio. The Debye temperature of Ni2MnZ was estimated from the average sound velocity. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)