THEORETICAL PREDICTION OF DEBYE TEMPERATURE FOR MANTLE MINERALS AT HIGH TEMPERATURES

2011 ◽  
Vol 25 (12) ◽  
pp. 1593-1600 ◽  
Author(s):  
ANJANI K. PANDEY ◽  
ABHAY P. SRIVASTAVA
Keyword(s):  
Shear Modulus ◽  
Elastic Properties ◽  
Laboratory Data ◽  
Seismic Velocities ◽  
Mantle Minerals ◽  
Seismic Properties ◽  
Debye Temperatures ◽  
Temperature Ranges ◽  
Experimental Values ◽  
Good Agreement

The seismic properties of a material depend on composition, crystal structure, temperature, pressure and in some cases defect concentrations. Most of the earth is made up of crystals. The elastic properties of crystals depend on orientation and frequency. Thus, the interpretation of seismic data or the extrapolation of laboratory data requires knowledge of crystal or mineral physics, elasticity and thermodynamics. In the present work, we calculated the shear modulus, seismic velocities and Debye temperatures at different high temperature ranges. The temperature dependence of elastic properties such as shear modulus, seismic velocities and Debye temperatures has been measured using Hill's averaging method and other thermodynamic methods for five silicate mantle minerals viz. MgAl 2 O 4, Mg 2 SiO 4, Fe 2 SiO 4, Mn 2 SiO 4, and Co 2 SiO 4. The results are found to be in good agreement with experimental values.

scholarly journals ELASTIC PROPERTIES OF TRANSITION METAL DIOXIDES: XO2 (X = Ru, Rh, Os, andIr)

2008 ◽  
Vol 19 (08) ◽  
pp. 1269-1275 ◽  
Author(s):  
YANLING LI ◽  
ZHI ZENG
Keyword(s):  
Density Functional Theory ◽  
Transition Metal ◽  
Shear Modulus ◽  
Elastic Properties ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Debye Temperatures ◽  
Metal Dioxides

The elastic properties of rutile transition metal dioxides XO2 ( X = Ru , Rh , Os , and Ir ) are investigated using first-principles calculations based on density functional theory. Elastic constants, bulk modulus, shear modulus, and Young's modulus as well as Possion ratio are given. OsO 2 and IrO 2 show strong incompressibility. The hardness estimated for these dioxides shows that they are not superhard solids. The obtained Debye temperatures are comparative to those of transition metal dinitrides or diborides.

Measurements of the normal-mode frequencies of magnesium

1972 ◽  
Vol 326 (1566) ◽  
pp. 347-360 ◽  
Keyword(s):  
Normal Mode ◽  
Time Of Flight ◽  
Physical Significance ◽  
Crystal Spectrometer ◽  
Calorimetric Measurements ◽  
Debye Temperatures ◽  
Nearest Neighbours ◽  
Interpolation Technique ◽  
Experimental Values ◽  
Good Agreement

The normal-mode frequencies of magnesium at 290 K have been determined by the inelastic scattering of slow neutrons. The frequencies of about 3500 phonons with wavevectors in the (0001) and (01T0) planes have been measured with a time-of-flight apparatus, and an interpolation technique has been used to deduce the dispersion curves along closely spaced lines in the two planes. Measurements with a triple-axis crystal spectrometer have been used to supplement the time-of-flight data along several symmetry directions. In order to generate the frequencies throughout the entire Brillouin zone a simple force-constant model extending to eight-nearest neighbours has been used. The values of the force constants were obtained from the phonons along five symmetry directions. Although the model has little physical significance, it gives frequencies in good agreement with the experimental values over the two planes for which measurements have been made. The model has been used to calculate the phonon density of states, and hence the Debye temperatures for the specific heat. The latter are in satisfactory agreement with the values deduced from calorimetric measurements.

ELASTIC PROPERTY PREDICTION OF THE STITCHED MULTI-AXIAL WARP KNIT FABRIC COMPOSITES

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4022-4027 ◽  
Author(s):  
HEOUNG-JAE CHUN ◽  
HYUNG-WOO KIM ◽  
JOON-HYUNG BYUN
Keyword(s):  
Composite Materials ◽  
Elastic Properties ◽  
Cross Sections ◽  
Averaging Method ◽  
Geometric Parameters ◽  
Suggested Model ◽  
Fabric Composites ◽  
Out Of Plane ◽  
Experimental Values ◽  
Good Agreement

In order to improve the resistances to delamination, damage tolerance, some in-plane and out-of-plane properties of composite materials, a through-thickness reinforcement must be provided. This through-thickness reinforcement is achieved by stitching multi-axial warp knit (MWK) fabrics used as preforms for the fabrication of composite materials. The MWK fabrics are constructed with layers of insertion fiber bundles in the warp, weft and bias directions. In order to correlate the microstructure of a preform with the elastic properties of stitched MWK composite, the analytical model for stitched MKW composite is developed. The overall geometry and geometric parameters of a representative volume are determined from the photomicrographs of cross sections of the fabricated composite specimens. The various elastic properties of MWK fabric composites are predicted as functions of various geometric parameters using an averaging method. The experimental results are compared with the predicted results in order to validate the suggested model. It is found that the predicted elastic properties are in reasonably good agreement with the experimental values.

First-Principles Calculations of the Mechanical and Elastic Properties of 2Hc- and 2Ha-WS2/CrS2 Under Pressure

2016 ◽  
Vol 71 (6) ◽  
pp. 517-524 ◽  
Author(s):  
Hua-Long Jiang ◽  
Song-Hao Jia ◽  
Da-Wei Zhou ◽  
Chun-Ying Pu ◽  
Fei-Wu Zhang ◽  
...  
Keyword(s):  
Shear Modulus ◽  
Elastic Properties ◽  
First Principles ◽  
Elastic Moduli ◽  
Mechanical Stability ◽  
First Principles Calculations ◽  
Stability Criteria ◽  
Poisson Coefficient ◽  
Debye Temperatures ◽  
Two Phases

AbstractBy utilizing the first-principles method, the pressure-induced effects on phase transition, mechanical stability, and elastic properties of WS2/CrS2 are investigated in the pressure range from 0 to 80 GPa. Transitions from 2Hc to 2Ha for WS2 and CrS2 are found to occur at 17.5 and 25 GPa, respectively. It is found that both 2Ha and 2Hc phases of WS2 and CrS2 meet the mechanical stability criteria up to 80 GPa, suggesting that those structures are mechanically stable. The bulk and shear modulus anisotropy of the two phases of WS2 and CrS2 decrease rapidly under pressure and, finally, trend to isotropy. With increasing pressure, the elastic moduli (Y, B, and G), sound velocities (vs, vp, vm), and Debye temperatures (Θ) of 2Ha and 2Hc of WS2 and CrS2 increase monotonously. Moreover, the Debye temperature (Θ) of 2Hc phase is higher than that of 2Ha phase for both WS2 and CrS2. The bulk, shear, and Young’s modulus, Poisson coefficient, and brittle/ductile behaviour are estimated. The percentages of anisotropy in compressibility and shear and the ratio of bulk to shear modulus (B/G) are also studied.

Predictions of Elastic Properties of Multi-Axial Warp Knitted Fabric Composites

2004 ◽  
Vol 261-263 ◽  
pp. 1499-1504 ◽  
Author(s):  
Heoung Jae Chun ◽  
K.S. Ryu ◽  
Joon Hyung Byun
Keyword(s):  
Elastic Properties ◽  
Averaging Method ◽  
Three Dimensional ◽  
Design Parameters ◽  
Fabric Composite ◽  
Fabric Composites ◽  
Out Of Plane ◽  
Experimental Values ◽  
Warp Knitted Fabric ◽  
Good Agreement

An analytical model was proposed to predict the elastic properties of multi-axial warp knitted (MWK) fabric composites for three-dimensional structures. The characteristics of MWK fabric composites are the assemblage of multilayers of rovings in the warp, weft and bias directions for in-plane reinforcement and out-of-plane stitches by knitting rovings to provide through-the- thickness reinforcement. For analysis, a representative volume of the MWK fabric composite was identified. The geometric limitations, effects of stitch fibers and design parameters of MWK composites are considered in the model. Then, the elastic properties of MWK fabric composites are predicted by using an averaging method. The experiments are also conducted on the MWK fabric composites to compare the predicted results with the experimental results for the verification of suggested model. The predicted elastic properties are in reasonably good agreement with the experimental values. Finally the effects of design parameters of the MWK fabric composites are discussed.

First Principles Study of Electronic and Elastic Properties of AlY

2014 ◽  
Vol 1047 ◽  
pp. 45-50
Author(s):  
Mani Shugani ◽  
Mahendra Aynyas ◽  
S.P. Sanyal
Keyword(s):  
Elastic Properties ◽  
Elastic Constants ◽  
Ground State ◽  
Full Potential ◽  
Augmented Plane Wave ◽  
Plane Wave Method ◽  
Lattice Constants ◽  
Ground State Properties ◽  
Experimental Values ◽  
Good Agreement

We have used full potential linear augmented plane wave method within thegeneralized gradient approximation to investigate the structural, electronic and elastic properties of the AlY. The ground state properties are determined for the AlY. The calculated ground state properties such as lattice constants, bulk modulus and elastic constants agree well with the experimental values. From band structure curves it is found that AlY is metallic in nature. The elastic constants are in good agreement with previous theoretical and experimental results.

Systematic calculations of energy levels and transitions rates in Mo XXVIII

2020 ◽  
Vol 75 (8) ◽  
pp. 739-747
Author(s):  
Feng Hu ◽  
Yan Sun ◽  
Maofei Mei
Keyword(s):  
Energy Levels ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Data Sets ◽  
Electron Systems ◽  
Excitation Energies ◽  
Experimental Values ◽  
Qed Effects ◽  
Hyperfine Structures ◽  
Good Agreement

AbstractComplete and consistent atomic data, including excitation energies, lifetimes, wavelengths, hyperfine structures, Landé gJ-factors and E1, E2, M1, and M2 line strengths, oscillator strengths, transitions rates are reported for the low-lying 41 levels of Mo XXVIII, belonging to the n = 3 states (1s22s22p6)3s23p3, 3s3p4, and 3s23p23d. High-accuracy calculations have been performed as benchmarks in the request for accurate treatments of relativity, electron correlation, and quantum electrodynamic (QED) effects in multi-valence-electron systems. Comparisons are made between the present two data sets, as well as with the experimental results and the experimentally compiled energy values of the National Institute for Standards and Technology wherever available. The calculated values including core-valence correction are found to be in a good agreement with other theoretical and experimental values. The present results are accurate enough for identification and deblending of emission lines involving the n = 3 levels, and are also useful for modeling and diagnosing plasmas.

scholarly journals DFT calculation and assignment of vibrational spectra of aryl and alkyl chlorophosphates

2014 ◽  
Vol 12 (2) ◽  
pp. 153-163
Author(s):  
Viktor Anishchenko ◽  
Vladimir Rybachenko ◽  
Konstantin Chotiy ◽  
Andrey Redko
Keyword(s):  
Vibrational Spectra ◽  
Basis Sets ◽  
Heavy Atoms ◽  
Wide Range ◽  
Complete Assignment ◽  
Key Factor ◽  
Polarization Functions ◽  
Experimental Values ◽  
Semi Empirical ◽  
Good Agreement

AbstractDFT calculations of vibrational spectra of chlorophosphates using wide range of basis sets and hybrid functionals were performed. Good agreement between calculated and experimental vibrational spectra was reached by the combination of non-empirical functional PBE0 with both middle and large basis sets. The frequencies of the stretching vibrations of the phosphate group calculated using semi-empirical functional B3LYP for all basis sets deviate significantly from the experimental values. The number of polarization functions on heavy atoms was shown to be a key factor for the calculation of vibrational frequencies of organophosphates. The importance of consideration of all the stable rotamers for a complete assignment of fundamental modes was shown.

scholarly journals Constraints on the composition and temperature of LLSVPs from seismic properties of lower mantle minerals

2021 ◽  
Vol 554 ◽  
pp. 116685
Author(s):  
Kenny Vilella ◽  
Thomas Bodin ◽  
Charles-Edouard Boukaré ◽  
Frédéric Deschamps ◽  
James Badro ◽  
...  
Keyword(s):  
Lower Mantle ◽  
Mantle Minerals ◽  
Seismic Properties

scholarly journals Structural elastic and thermal properties of SrxCd1−x O mixed compounds — a theoretical approach

2014 ◽  
Vol 32 (3) ◽  
pp. 350-357
Author(s):  
Purvee Bhardwaj
Keyword(s):  
Phase Transition ◽  
Vibrational Energy ◽  
Zero Point ◽  
Study Phase ◽  
Energy Effect ◽  
Phase Transition Pressure ◽  
Vegard’S Law ◽  
Extended Interaction ◽  
Experimental Values ◽  
Good Agreement

AbstractIn the present paper, the structural and mechanical properties of alkaline earth oxides mixed compound SrxCd1−x O (0 ≤ x ≤ 1) under high pressure have been reported. An extended interaction potential (EIP) model, including the zero point vibrational energy effect, has been developed for this study. Phase transition pressures are associated with a sudden collapse in volume. Phase transition pressure and associated volume collapses [ΔV (Pt)/V(0)] calculated from this approach are in good agreement with the experimental values for the parent compounds (x = 0 and x = 1). The results for the mixed crystal counterparts are also in fair agreement with experimental data generated from the application of Vegard’s law to the data for the parent compounds.

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