Elastic constants of polycrystalline Y1Ba2Cu3Ox

1992 ◽  
Vol 7 (11) ◽  
pp. 2905-2907 ◽  
Author(s):  
Hassel Ledbetter
Keyword(s):  
Grain Boundary ◽  
Bulk Modulus ◽  
Debye Temperature ◽  
Oxygen Content ◽  
Elastic Constants ◽  
Model Prediction ◽  
Ionic Crystal ◽  
Poisson Ratio ◽  
Young’S Moduli ◽  
Crystal Model

We measured the elastic constants of polycrystalline Y1Ba2Cu3Ox with eleven oxygen contents varying from 6.2 to 6.9. Reported properties include sound velocities; bulk, shear, Young's moduli; Poisson ratio; Debye temperature. After correction to the void-free state, the measurements fail to show a systematic dependence on oxygen content. Focusing on the bulk modulus, all measurements fall below an ionic-crystal model prediction, by 5–50%. We attribute this macroscopic softness to either microcracks or weak grain-boundary mechanical linkages. For the case x = 6.9, we suggest a set of intrinsic elastic constants.

Elastic constants of inflated lobes of dog lungs

1976 ◽  
Vol 40 (4) ◽  
pp. 508-513 ◽  
Author(s):  
S. J. Lai-Fook ◽  
T. A. Wilson ◽  
R. E. Hyatt ◽  
J. R. Rodarte
Keyword(s):  
Bulk Modulus ◽  
Young’S Modulus ◽  
Elastic Constants ◽  
Young's Modulus ◽  
Poisson Ratio ◽  
Inflation Pressure ◽  
Initial State ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Indentation Tests

The elastic constants of dog lungs were determined at various degrees of inflation. In one set of experiments, the lobes were subjected to deformations that approximated the conditions of uniaxial loading. These data, together with the bulk modulus data obtained from the local slope of the pressure-volume curve, were used to determine the two elastic moduli that are needed to describe small nonuniform deformations about an initial state of uniform inflation. The bulk modulus was approximately 4 times the inflation pressure, and Young's modulus was approximately 1.5 times the inflation pressure. In a second set of experiments, lobes were subjected to indentation tests using cylindric punches 1–3 cm in diameter. The value for Young's modulus obtained from these data was slightly higher, approximately twice the inflation pressure. These experiments indicate that the lung is much more easily deformable in shear than in dilatation and that the Poisson ratio for the lung is high, approximately 0.43.

scholarly journals Pressure Effect on Elastic Constants and Related Properties of Ti3Al Intermetallic Compound: A First-Principles Study

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2015 ◽  
Author(s):  
Xianshi Zeng ◽  
Rufang Peng ◽  
Yanlin Yu ◽  
Zuofu Hu ◽  
Yufeng Wen ◽  
...  
Keyword(s):  
Intermetallic Compound ◽  
Debye Temperature ◽  
Elastic Constants ◽  
First Principles ◽  
Density Functional ◽  
Mechanical Stability ◽  
Theoretical Data ◽  
Young’S Moduli ◽  
Anisotropic Factor ◽  
Isotropic Pressure

Using first-principles calculations based on density functional theory, the elastic constants and some of the related physical quantities, such as the bulk, shear, and Young’s moduli, Poisson’s ratio, anisotropic factor, acoustic velocity, minimum thermal conductivity, and Debye temperature, are reported in this paper for the hexagonal intermetallic compound Ti 3 Al. The obtained results are well consistent with the available experimental and theoretical data. The effect of pressure on all studied parameters was investigated. By the mechanical stability criteria under isotropic pressure, it is predicted that the compound is mechanically unstable at pressures above 71.4 GPa. Its ductility, anisotropy, and Debye temperature are enhanced with pressure.

Temperature Dependences of the Elastic Constants of Precipitation-Hardened Aluminum Alloys 2014 and 2219

1977 ◽  
Vol 99 (2) ◽  
pp. 181-184 ◽  
Author(s):  
D. T. Read ◽  
H. M. Ledbetter
Keyword(s):  
Aluminum Alloys ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
Temperature Dependence ◽  
Elastic Properties ◽  
Elastic Constants ◽  
Ultrasonic Pulse ◽  
Young’S Moduli ◽  
Temperature Dependences ◽  
Sound Velocities

Elastic properties of precipitation-hardened aluminum alloys 2014 and 2219 were studied between 4 and 300 K using ultrasonic pulse techniques. Both the longitudinal and transverse sound velocities were measured. Also reported are the Young’s modulus, shear modulus, bulk modulus, and Poisson’s ratio. For both alloys, the Young’s moduli are about ten percent higher than for unalloyed aluminum, and they increase about ten percent on cooling from 300 to 4 K. All the elastic constants show normal temperature dependence.

Pressure Induced Properties of UXLa1-XS Compound

2016 ◽  
Vol 28 ◽  
pp. 108-114
Author(s):  
Ashok K. Ahirwar ◽  
Mahendra Aynyas ◽  
Sankar P. Sanyal
Keyword(s):  
Experimental Data ◽  
Phase Transition ◽  
Thermal Properties ◽  
Bulk Modulus ◽  
Debye Temperature ◽  
Elastic Constants ◽  
Volume Change ◽  
Mechanical And Thermal Properties ◽  
Phase Transition Pressure ◽  
Crystal Structural

The crystal structural, mechanical and thermal properties of UXLa1-XS compound with different concentrations (x= 0.00, 0.08 and 0.40) are investigated using modified inter-ionic potential theory (MIPT), which parametrically includes the effect of coulomb screening by the delocalized f-electrons. Our calculated values of phase transition pressure, bulk modulus and volume change are agree well with the theoretical and experimental data. We have also calculated the second order elastic constants and Debye temperature of these three concentrations.

Is Y1Ba2Cu3O7 stiff or soft?

1990 ◽  
Vol 5 (2) ◽  
pp. 241-244 ◽  
Author(s):  
Hassel Ledbetter ◽  
Ming Lei
Keyword(s):  
High Pressure ◽  
Metal Oxide ◽  
Physical Properties ◽  
Bulk Modulus ◽  
Model Calculation ◽  
Ionic Crystal ◽  
Oxide Superconductor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Model

Using several measured and calculated physical properties, we argue that the high-Tc metal-oxide superconductor Y1Ba2Cu3O7 is elastically soft compared with BaTiO3 or SrTiO3. We conclude that the bulk modulus equals approximately 107 GPa, despite several high-pressure x-ray diffraction studies that report values up to approximately 200 GPa. Part of the argument uses an ionic-crystal-model calculation of the bulk modulus.

Molybdenum effect on Fe–Cr–Ni-alloy elastic constants

1988 ◽  
Vol 3 (1) ◽  
pp. 40-44 ◽  
Author(s):  
H. M. Ledbetter ◽  
S. A. Kim
Keyword(s):  
Bulk Modulus ◽  
Elastic Constants ◽  
Poisson Ratio ◽  
Face Centered Cubic ◽  
Electron Theory ◽  
Shear Moduli ◽  
Ni Alloys ◽  
Ni Alloy ◽  
Face Centered ◽  
Mo Content

This study involved the ultrasonic measurement of the polycrystalline elastic constants of six face-centered-cubic Fe–Cr–Ni alloys, nominally Fe–19Cr–12Ni (at. %). In these alloys, Mo content ranged up to 2.4 at. %. Molybdenum lowers the Young and shear moduli, and it raises the Poisson ratio. Against expectation (because it increases volume), Mo raises the bulk modulus. Qualitatively, the results show that Ni raises the bulk modulus and Poisson ratio; but Ni lowers the Young and shear moduli. (Nickel decreases the alloy's atomic volume.) The discussion includes existing models based on 3d-electron theory.

Elastic Constants and Related Properties of Compressed Rocksalt CuX (X =Cl, Br): Ab Initio Study

2018 ◽  
Vol 73 (8) ◽  
pp. 767-773 ◽  
Author(s):  
Nadhira Bioud ◽  
Xiao-Wei Sun ◽  
Nadir Bouarissa ◽  
Salah Daoud
Keyword(s):  
Bulk Modulus ◽  
Debye Temperature ◽  
Elastic Constants ◽  
First Principles ◽  
Pressure Range ◽  
Structural Parameters ◽  
First Principles Calculations ◽  
Ab Initio Study ◽  
Wave Velocities ◽  
Longitudinal Sound Velocity

AbstractFirst-principles calculations are performed to study the structural and elastic properties, sound velocities, and Debye temperature of rocksalt-structured copper monochloride (CuCl) and copper monobromide (CuBr). The structural parameters, elastic constants, longitudinal, transverse, and average elastic wave velocities, and the Debye temperature in the pressure range 10–20 GPa are successfully predicted and analysed. The variation of the elastic constants and bulk modulus as a function of pressure is found to be non-linear for CuCl and almost linear for CuBr. Based on the obtained values of the elastic constants, the bulk modulus, the isotropic shear modulus, Young’s modulus, Poisson’s ratio, and Pugh’s ratio of the aggregate materials are also investigated. The analysis of Poisson’s and Pugh’s ratios shows that these materials become ductile for pressures in the range 10–20 GPa. The evolution of the longitudinal sound velocity under pressure indicates the hardening of the corresponding phonons in both materials.

Elastic constants and Debye temperature of Y1Ba2Cu3Ox: effect of oxygen content

1993 ◽  
Vol 16 (4) ◽  
pp. 165-168 ◽  
Author(s):  
Lin Sihan ◽  
Lei Ming ◽  
Hassel Ledbetter
Keyword(s):  
Debye Temperature ◽  
Oxygen Content ◽  
Elastic Constants ◽  
Effect Of Oxygen

scholarly journals Generalization of intrinsic ductile-to-brittle criteria by Pugh and Pettifor for materials with a cubic crystal structure

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
O. N. Senkov ◽  
D. B. Miracle
Keyword(s):  
Crystal Structure ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
Single Crystal ◽  
Elastic Constants ◽  
Mechanical Analysis ◽  
Quantum Mechanical ◽  
Modulus Ratio ◽  
Cubic Crystal ◽  
The Difference

AbstractTwo classical criteria, by Pugh and Pettifor, have been widely used by metallurgists to predict whether a material will be brittle or ductile. A phenomenological correlation by Pugh between metal brittleness and its shear modulus to bulk modulus ratio was established more than 60 years ago. Nearly four decades later Pettifor conducted a quantum mechanical analysis of bond hybridization in a series of intermetallics and derived a separate ductility criterion based on the difference between two single-crystal elastic constants, C12–C44. In this paper, we discover the link between these two criteria and show that they are identical for materials with cubic crystal structures.

Study of thermo-elastic and lattice dynamics properties of half-Heusler compounds XMgAl (X = Li, Na) by computational investigations

2019 ◽  
Vol 33 (08) ◽  
pp. 1950093 ◽  
Author(s):  
A. Afaq ◽  
Abu Bakar ◽  
M. Rizwan ◽  
M. Aftab Fareed ◽  
H. Bushra Munir ◽  
...  
Keyword(s):  
Debye Temperature ◽  
Elastic Constants ◽  
Density Functional ◽  
Phonon Dispersion ◽  
Dynamic Properties ◽  
Mechanical Parameters ◽  
Heusler Compounds ◽  
Generalized Gradient ◽  
Text Type ◽  
Quantum Espresso

In this study, thermo-elastic and lattice dynamic properties of XMgAl (X = Li, Na) half-Heusler compounds are investigated using density functional theory implemented in WIEN2k and Quantum ESPRESSO codes. Generalized gradient approximation (GGA) as an exchange correlation function has been used in Kohn–Sham equations. Firstly, the structure of these Heusler compounds is optimized and then these optimized parameters are used to find three elastic constants [Formula: see text], [Formula: see text] and [Formula: see text] for [Formula: see text] type structures. Three elastic constants are then used to determine different elastic moduli like bulk modulus, shear modulus, Young’s modulus and other mechanical parameters like Pugh’s ratio, Poisson’s ratio, anisotropic ratio, sound velocities, Debye temperature and melting temperature. On behalf of these mechanical parameters, the brittle/ductile nature and isotropic/anisotropic behavior of the materials has been studied. Different regions of vibrational modes in the materials are also discussed on behalf of Debye temperature calculations. The vibrational properties of the half-Heusler compounds are computed using Martins–Troullier pseudo potentials implemented in Quantum ESPRESSO. The phonon dispersion curves and phonon density of states in first Brillion zone are obtained and discussed. Reststrahlen band of LiMgAl is found greater than NaMgAl.

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