Vibrational Dynamics of Pd-Ni-P Bulk Metallic Glasses

In the present paper, Phonon modes and elastic constant of three different concentrations of PdxNi1-xP (Pd64Ni16P20, Pd40Ni40P20 and Pd16Ni64P20) bulk metallic glass are calculated using (1) Hubbard-Beeby (HB) and (2) Takeno-Goda (TG) approach along with our well established local model potential. The Hartree (H), Farid et al (F) and Sarkar et al (S) local field correlation functions (LFCF) are employed to examine the effect of the screening function on the collective dynamics of Pd-Ni-P bulk metallic glasses. Results are also reported for phonon dispersion curve, propagation elastic wave and elastic properties viz: bulk modulus BT, modulus of rigidity G, Poisson’s ratio ξ, Young’s modulus Y, Debye temperature ƟD. However, the calculated elastic constants results agree well with other theoretical and available experimental data.

Computational investigations of MnNiCuSb alloy for structural, elasto-mechanical and vibrational properties

The MnNiCuSb Quaternary Heusler Alloy (QHA) in Y-type I stable structure (cubic) is studied for structural, elastic, mechanical and vibrational properties by using Density Functional Theory (DFT). Three independent elastic constants [Formula: see text], [Formula: see text] and [Formula: see text] for this cubic system are computed with Generalized Gradient Approximation (GGA) functional. The mechanical parameters like Young’s modulus, Shear and Bulk modulus, Pugh’s ratio, Poisson’s ratio, anisotropic factor, Cauchy pressure are then calculated by using these cubic elastic parameters. In addition, phonon dispersion curve and phonon density of states (PDOS) are computed with norm-conserving Martins–Troullier pseudo-potential in Perturbed Density Functional Theory. The phonon dispersion curve provides reststrahlen band 0.727 THz [Formula: see text] for which material behaves as 100%. This value corresponds to Far Infra-Red (FIR) spectral region so this alloy can be used for manufacturing FIR-devices.

Structural, elastic, electronic and thermodynamic properties of ZrB2 under high-pressure: First-principle study

The structure of ZrB2 under high-pressure was predicted by Particle Swarm Optimization method (CALYPSO). We investigated the structure stability, phonon dispersion curve, elasticity, electronic structure and thermodynamic properties of ZrB2 under high-pressure and high-temperature via first-principles calculations. It maintained the hexagonal structure when the pressure lowers below 600 GPa at 0 K, which is confirmed by the calculated phonon dispersion curve. Studies indicate that the elastic modulus and Poisson’s ratio increase monotonically with pressure, as supported by some theoretical and experimental evidences. Calculated anisotropic factors demonstrate that compression and shear isotropy of ZrB2 weakens as the pressure increases. Using the quasi-harmonic approximation Debye model, the Debye temperature, sound velocity, expansion coefficient, thermal capacity under the high-temperature and pressure were also predicted.

Vibrational and Elastic Properties of Bulk Metallic Glass: Application to Pd64Fe16P20

Different elastic properties of Pd-based Pd64Fe16P20 have been computed using two different forms of pseudopotential. Both the forms differ within the core region suggesting different degrees of orthogonalization and its r-dependence, while outside the core both preserves the Columbic nature. The only parameter, the core radius, separates these regions, and it is calculated using the realistic assumption based on the nearest neighbor distance. Further, five different forms of the local field correlated functions, namely, Hartree (H), Taylor (T), Ichimaru and Utsumi (IU), Farid et al. (F) and Sarkar et al. (S) are examined for better understanding regarding the screening effect on different elastic constants for Pd64Fe16P20 bulk metallic glass. The calculated results for the various elastic moduli, Poisson's ratio, sound velocity and phonon dispersion curve are all found to be in general agreement with the available experimental data. This confirms the applicability of the model pseudopotential to bulk metallic systems.

Resonant inelastic X-ray scattering spectrometer with 25 meV resolution at the CuK-edge

An unparalleled resolution is reported with an inelastic X-ray scattering instrument at the CuK-edge. Based on a segmented concave analyzer, featuring single-crystal quartz (SiO2) pixels, the spectrometer delivers a resolution near 25 meV (FWHM) at 8981 eV. Besides the quartz analyzer, the performance of the spectrometer relies on a four-bounce Si(553) high-resolution monochromator and focusing Kirkpatrick–Baez optics. The measured resolution agrees with the ray-tracing simulation of an ideal spectrometer. The performance of the spectrometer is demonstrated by reproducing the phonon dispersion curve of a beryllium single-crystal.

Phonon Anomalies in Zirconium Nitride (ZrN)

The phonon dispersion curve is determined by model (BSM) for the crystals transition metal mono-nitride, Zirconium Nitride ZrN and compared with the experimental phonons, which forms perhaps the best test for this purpose. The eight numbers of parameters of the model are determined by using the some set of input data. The results and degrees of agreement obtained in each case show clearly the superiority of the “charge-transfer mechanism” for representing the deformations of electron shells used in the BSM. The phonon dispersion curve and phonon density of state ZrN have been measured in high-symmetry directions Δ, Σ and Λ by breathing shell model (BSM). Anomalies in the dispersion of the acoustic branches and optical branches have been detected which are well described by experimental results.

On the Debye-Waller Factor and Debye Temperature of Dendrite-Shaped PbTe

In this study, the phonon dispersion curve of dendrite-shaped lead telluride (PbTe), a nano structured material is obtained by shell model and the thermal parameters are calculated and compared with experimental results.

Calculation of Phonon Dispersion for 3d Transition Metals Cr and Fe by Modified Analytic Embedded Atom Method

The modified analytical embedded atom method is applied to calculate the phonon dispersion of body-centered cubic 3d transition metals Cr and Fe along five symmetry directions [q 0 0], [1 q q], [q q q], [q q 0] and [1/2 1/2 q]. Our results of phonon dispersion curves are in good agreement with the available experimental data. For the two transition metals Cr and Fe, along the same direction, a similar phonon dispersion curve is obtained in spite of the phonon frequency decreases for Cr and Fe due to the atom mass increases. There are no experimental results for comparison along the directions [1 q q] and [1/2 1/2 q], further experimental measurement are needed.