MECHANICAL AND THERMAL PROPERTIES OF PRASEODYMIUM MONOPNICTIDES: AN ULTRASONIC STUDY

2013 ◽  
Vol 27 (22) ◽  
pp. 1350116 ◽  
Author(s):  
VYOMA BHALLA ◽  
RAJ KUMAR ◽  
CHINMAYEE TRIPATHY ◽  
DEVRAJ SINGH
Keyword(s):  
Elastic Constants ◽  
Room Temperature ◽  
Ultrasonic Attenuation ◽  
Poisson Ratio ◽  
Higher Order ◽  
Coupling Constants ◽  
Nonlinearity Parameter ◽  
Mechanical And Thermal Properties ◽  
Temperature Range ◽  
G Ratio

We have computed ultrasonic attenuation, acoustic coupling constants and ultrasonic velocities of praseodymium monopnictides PrX ( X : N , P , As , Sb and Bi ) along the 〈100〉, 〈110〉, 〈111〉 in the temperature range 100–500 K using higher order elastic constants. The higher order elastic constants are evaluated using Coulomb and Born–Mayer potential with two basic parameters viz. nearest-neighbor distance and hardness parameter in the temperature range of 0–500 K. Several other mechanical and thermal parameters like bulk modulus, shear modulus, Young's modulus, Poisson ratio, anisotropic ratio, tetragonal moduli, Breazeale's nonlinearity parameter and Debye temperature are also calculated. In the present study, the fracture/toughness (B/G) ratio is less than 1.75 which implies that PrX compounds are brittle in nature at room temperature. The chosen material fulfilled Born criterion of mechanical stability. We also found the deviation of Cauchy's relation at higher temperatures. PrN is most stable material as it has highest valued higher order elastic constants as well as the ultrasonic velocity. Further, the lattice thermal conductivity using modified approach of Slack and Berman is determined at room temperature. The ultrasonic attenuation due to phonon–phonon interaction and thermoelastic relaxation mechanisms have been computed using modified Mason's approach. The results with other well-known physical properties are useful for industrial applications.

Pressure dependent ultrasonic properties of hcp hafnium metal

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ramanshu P. Singh ◽  
Shakti Yadav ◽  
Giridhar Mishra ◽  
Devraj Singh
Keyword(s):  
Elastic Constants ◽  
Pressure Range ◽  
Room Temperature ◽  
Ultrasonic Attenuation ◽  
Coupling Constants ◽  
Ultrasonic Properties ◽  
Acoustic Coupling ◽  
Third Order Elastic Constants ◽  
The Stability ◽  
The Given

Abstract The elastic and ultrasonic properties have been evaluated at room temperature between the pressure 0.6 and 10.4 GPa for hexagonal closed packed (hcp) hafnium (Hf) metal. The Lennard-Jones potential model has been used to compute the second and third order elastic constants for Hf. The elastic constants have been utilized to calculate the mechanical constants such as Young’s modulus, bulk modulus, shear modulus, Poisson’s ratio, and Zener anisotropy factor for finding the stability and durability of hcp hafnium metal within the chosen pressure range. The second order elastic constants were also used to compute the ultrasonic velocities along unique axis at different angles for the given pressure range. Further thermophysical properties such as specific heat per unit volume and energy density have been estimated at different pressures. Additionally, ultrasonic Grüneisen parameters and acoustic coupling constants have been found out at room temperature. Finally, the ultrasonic attenuation due to phonon–phonon interaction and thermoelastic mechanisms has been investigated for the chosen hafnium metal. The obtained results have been discussed in correlation with available findings for similar types of hcp metals.

Mechanical and thermophysical properties of actinide monocarbides

2018 ◽  
Vol 32 (21) ◽  
pp. 1850248 ◽  
Author(s):  
Devraj Singh ◽  
Amit Kumar ◽  
Vyoma Bhalla ◽  
Ram Krishna Thakur
Keyword(s):  
Thermophysical Properties ◽  
Room Temperature ◽  
Nearest Neighbor ◽  
Ultrasonic Attenuation ◽  
Thermal Relaxation ◽  
Nonlinearity Parameter ◽  
Micro Hardness ◽  
Temperature Dependent ◽  
Third Order ◽  
Pressure Derivative

This paper describes the mechanical and thermophysical properties of actinide monocarbides AnCs (An=Np and Cm) as a function of temperature and crystallographic direction. The temperature-dependent second- and third-order elastic constant (SOECs and TOECs) have been computed first using Coulomb and Born–Mayer potential up to second nearest neighbor. SOECs have been applied to find out mechanical constant such as bulk modulus, shear modulus, tetragonal modulus, Poisson’s ratio and Zener anisotropy for the prediction of futuristic performance of the NpC and CmC. We also found the value of G/B [Formula: see text] 0.59 for the chosen materials, which indicates that NpC and CmC have brittle nature. The computed elastic constants are further applied directly to indirectly find out the ultrasonic velocity, Grüneisen parameters, pressure derivative, Debye temperature, micro-hardness, Breazeale’s nonlinearity parameter, thermal relaxation time and thermal conductivity. These evaluated parameters were finally used to compute ultrasonic attenuation of the NpC and CmC along [Formula: see text], [Formula: see text] and [Formula: see text] directions at room temperature. The behavior of the obtained results of this investigation has been compared with similar type of materials.

Ultrasonic wave propagation in rare-earth monochalcogenides

Open Physics ◽  
2009 ◽  
Vol 7 (1) ◽  
Author(s):  
Devraj Singh ◽  
Dharmendra Pandey ◽  
Pramod Yadawa
Keyword(s):  
Elastic Constants ◽  
Ultrasonic Attenuation ◽  
Mixed Valence ◽  
Thermal Relaxation ◽  
Coupling Constants ◽  
Physical Parameters ◽  
Acoustic Coupling ◽  
Third Order Elastic Constants ◽  
Ultrasonic Parameters ◽  
Physical And Chemical

AbstractThe ultrasonic attenuation in thulium monochalcogenides TmX (X=S, Se and Te) has been studied theoretically with a modified Mason’s approach in the temperature and range 100 K to 300 K along 〈100〉, 〈110〉 〈111〉 crystallographic directions. The thulium monochalcogenides have attracted a lot of interest due to their complex physical and chemical characteristics. TmS, TmSe and TmTe are trivalent metal, mixed valence state, and divalent semiconductor, respectively. Coulomb and Born-Mayer potential is applied to evaluate the second- and third-order elastic constants. These elastic constants are used to compute ultrasonic parameters such as ultrasonic velocities, thermal relaxation time, and acoustic coupling constants that, in turn, are used to evaluate ultrasonic attenuation. A comparison of calculated ultrasonic parameters with available theoretical/experimental physical parameters gives information about classification of these materials.

ELASTIC PROPERTIES AND DEBYE CHARACTERISTIC TEMPERATURE OF PARTIALLY MELTED YBa2Cu3O7−x SUPERCONDUCTOR

1988 ◽  
Vol 02 (09) ◽  
pp. 1111-1117 ◽  
Author(s):  
D.F. LEE ◽  
K. SALAMA
Keyword(s):  
Debye Temperature ◽  
Elastic Properties ◽  
Elastic Constants ◽  
Tetragonal Phase ◽  
Room Temperature ◽  
Characteristic Temperature ◽  
Shear Moduli ◽  
Debye Characteristic Temperature ◽  
Temperature Range ◽  
Free Material

The quasi-isotropic elastic constants are measured in a 85% dense partially melted YBa 2 Cu 3 C 7−x superconductor in the temperature range 80–300 K. The room temperature values of the longitudinal and shear moduli of the void-free material are found to be 168 and 59 GPa respectively, and no decrease in these constants is observed during the transition from normal to superconducting states. The Debye temperature is found to be 426 K which is comparable to that of the tetragonal phase polycrystalline BaTiO 3 (429 K).

scholarly journals Ultrasonic attenuation in Niobium Oxide(NbO) due to phonon-phonon interaction

2016 ◽  
Vol 4 (1) ◽  
Author(s):  
Arvind Kumar Tiwari
Keyword(s):  
Elastic Properties ◽  
Elastic Constants ◽  
Niobium Oxide ◽  
Ultrasonic Attenuation ◽  
Phonon Interaction ◽  
Third Order ◽  
Temperature Range ◽  
Third Order Elastic Constants ◽  
Elastic Mechanism ◽  
Elastic Loss

Ultrasonic attenuation due to phonon-phonon interaction and thermo elastic mechanism have been evaluated in NbO along (110) direction in the temperature range 100-500K. The second and third order elastic constants are also evaluated for the evaluation of ultrasonic attenuation and other associated parameters. The ultrasonic attenuation due to phonon-phonon interaction is predominant over thermo elastic loss in this material. The results are discussed in correlation with thermo elastic properties of NbO.

scholarly journals Elastic, Mechanical and Thermophysical properties of Single-Phase Quaternary ScTiZrHf High-Entropy Alloy

2021 ◽  
Vol 22 (4) ◽  
pp. 687-696
Author(s):  
Sachin Rai ◽  
Navin Chaurasiya ◽  
Pramod K. Yadawa
Keyword(s):  
Mechanical Properties ◽  
Elastic Constants ◽  
Room Temperature ◽  
Single Phase ◽  
Mechanical Characterization ◽  
Ultrasonic Attenuation ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Different Temperatures ◽  
Ultrasonic Parameters

Consequent to the interaction potential model, the high-order elastic constants at high entropy alloys in single-phase quaternary ScTiZrHf have been calculated at different temperatures. Elastic constants of second order (SOECs) helps to determine other ultrasonic parameters. With the help of SOECs other elastic moduli, bulk modulus, shear modulus, Young’s modulus, Pugh’s ratio, elastic stiffness constants and Poisson’s ratio are estimated at room temperature for elastic and mechanical characterization. The other ultrasonic parameters are calculated at room temperature for elastic and mechanical characterization. The temperature variation of ultrasonic velocities along the crystal's z-axis is evaluated using SOECs. The temperature variation of the  average debye velocity and the thermal relaxation time (τ) are also estimated along this orientation axis. The ultrasonic properties correlated with elastic, thermal and mechanical properties which is temperature dependent is also discussed. The ultrasonic attenuation due to phonon – phonon (p-p) interactions is also calculated at different temperatures. In the study of ultrasonic attenuation such as a function of temperature, thermal conductivity appears to be main contributor and p- p interactions are the responsible reason of attenuation and found that the mechanical properties of the high entropy alloy ScTiZrHf are superior at room temperature.

A NUCLEAR MAGNETIC RESONANCE STUDY OF COLEMANITE

1960 ◽  
Vol 38 (4) ◽  
pp. 515-546 ◽  
Author(s):  
F. Holuj ◽  
H. E. Petch
Keyword(s):  
Phase Transition ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Electric Field ◽  
Room Temperature ◽  
Point Group ◽  
Coupling Constants ◽  
Temperature Range ◽  
Group 2 ◽  
Nuclear Magnetic

A single crystal of colemanite, CaB3O4(OH)3∙H2O, which is known to be ferroelectric at temperatures below about −2 °C, has been investigated by means of nuclear magnetic resonance (n.m.r.) techniques. The B11 resonances are split because the nuclear Zeeman levels are perturbed by the interactions between the nuclear electric quadrupole moments and the electric field gradients existing at the boron sites. The splittings have been examined in detail at room temperature and at −40 °C. The results have been analyzed and the quadrupole coupling constants, the asymmetry parameters, and the orientations of the principal axes of the electric field gradient tensors existing at the boron sites at room temperature and −40 °C are reported. Selected B11 resonance lines have been examined over the temperature range 40 °C to −120 °C with particular emphasis on the region about 0 °C where a phase transition occurs. The complex proton signal was also studied over the same temperature range. Abrupt broadening of this signal occurred at the phase transition. These studies revealed that the crystal may transform from its centrosymmetrical room-temperature (point group 2/m) form either to a metastable monoclinic form with point group 2 or to a triclinic form with point group 1. It is not clear whether two transitions, separated by only about 3 °C, are involved or whether there is only one transition with two alternative arrangements, differing only slightly in activation energy, available to the structure. The transition or transitions are of the second-order displacive type. Where possible, the results have been interpreted in terms of the crystal structure.

scholarly journals Computations of Ultrasonic Parameters in Alloys

2011 ◽  
Vol 2011 ◽  
pp. 1-7
Author(s):  
Pramod Kumar Yadawa
Keyword(s):  
Sound Velocity ◽  
Elastic Constants ◽  
Room Temperature ◽  
Ultrasonic Attenuation ◽  
Physical Parameters ◽  
Third Order ◽  
Ultrasonic Properties ◽  
Third Order Elastic Constants ◽  
Ultrasonic Parameters

The ultrasonic properties like ultrasonic attenuation, sound velocity in the hexagonal alloys have been studied along unique axis at room temperature. The second- and third-order elastic constants (SOEC & TOEC) have been calculated for these alloys using Lennard-Jones potential. The velocities and have minima and maxima, respectively, at 45° with unique axis of the crystal, while increases with the angle from unique axis. The inconsistent behaviour of angle-dependent velocities is associated to the action of second-order elastic constants. Debye average sound velocities of these alloys are increasing with the angle and has maximum at 55° with unique axis at room temperature. Hence, when a sound wave travels at 55° with unique axis of these alloys, then the average sound velocity is found to be maximum. The mechanical and ultrasonic properties of these alloys will be better than pure Zr and Sn due to their high SOEC and ultrasonic velocity and low ultrasonic attenuation. The comparison of calculated ultrasonic parameters with available theoretical/experimental physical parameters gives information about classification of these alloys.

Ultrasonic Investigations on Polonides of Ba, Ca, and Pb

2017 ◽  
Vol 72 (11) ◽  
pp. 977-983 ◽  
Author(s):  
Devraj Singh ◽  
Vyoma Bhalla ◽  
Jyoti Bala ◽  
Shikha Wadhwa
Keyword(s):  
Room Temperature ◽  
Ultrasonic Attenuation ◽  
Thermal Relaxation ◽  
Theoretical Data ◽  
Coupling Constants ◽  
Temperature Dependent ◽  
Phonon Interaction ◽  
Third Order ◽  
Acoustic Coupling ◽  
Third Order Elastic Constants

AbstractThe temperature-dependent mechanical and ultrasonic properties of barium, calcium, and lead polonides (BaPo, CaPo, and PbPo) were investigated in the temperature range 100–300 K. The second- and third-order elastic constants (SOECs and TOECs) were computed using Coulomb and Born-Mayer potential and these in turn have been used to estimate other secondary elastic properties such as strength, anisotropy, microhardness, etc. The theoretical approach followed the prediction that BaPo, CaPo, and PbPo are brittle in nature. PbPo is found to be the hardest amongst the chosen compounds. Further the SOECs and TOECs are applied to determine ultrasonic velocities, Debye temperature, and acoustic coupling constants along <100>, <110>, and <111> orientations at room temperature. Additionally thermal conductivity has been computed using Morelli and Slack’s approach along different crystallographic directions at room temperature. Finally ultrasonic attenuation due to phonon–phonon interaction and thermoelastic relaxation mechanisms has been computed for BaPo, CaPo, and PbPo. The behaviour of these compounds is similar to that of semi-metals with thermal relaxation time of the order 10−11 s. The present computation study is reasonably in agreement with the available theoretical data for the similar type of materials.

NUCLEAR MAGNETIC RESONANCE STUDY OF FERROELECTRIC LITHIUM HYDRAZINIUM SULPHATE, Li(N2H5)SO4

1963 ◽  
Vol 41 (10) ◽  
pp. 1629-1650 ◽  
Author(s):  
J. D. Cuthbert ◽  
H. E. Petch
Keyword(s):  
Nuclear Magnetic Resonance ◽  
High Temperature ◽  
Magnetic Resonance ◽  
Room Temperature ◽  
Coupling Constants ◽  
Proton Resonance ◽  
Second Moment ◽  
Temperature Range ◽  
A Value ◽  
Nuclear Magnetic

The proton and Li7 nuclear magnetic resonance signals have been investigated in powdered samples and single crystals of lithium hydrazinium sulphate, Li(N2H5)SO4, which is known to be ferroelectric from −15 °C to above 80 °C.The quadrupolar splitting of the Li7 resonance, which was examined over the temperature range from −70 °C to +205 °C, undergoes rapid but continuous change between 80 °C and 160 °C indicating a crystal phase transition from a low to a high temperature polymorph. This transition is of the second-order type and completely reversible. The Li7 spectrum was examined in detail in the low and high temperature polymorphs at room temperature and +205 °C, respectively. The results have been analyzed and the quadrupole coupling constants, the asymmetry parameters, and the orientations of the principal axes of the electric field gradient tensors at the Li7 sites are reported.The second moment of the proton resonance in powdered Li(N2H5)SO4 at −183 °C was found to have a value of 39 ± 2 gauss2 which is consistent with the N2H5+ group existing as the hydrazinium ion NH2—NH3+ in an effectively rigid state. In the region of −130 °C, the second moment decreased rapidly to a little more than a third of its value at the temperature of liquid air. This effect is interpreted as resulting from the onset of rotation of the —NH3+ group about the N—N axis. As the crystal temperature was increased from −70 °C, the second moment remained virtually constant at 16.5 ± 0.5 gauss2 over a wide temperature range, began to decrease at +50 °C, paused slightly at a value of 8.8 ± 0.5 gauss2 at 150 °C, and again decreased rapidly to 0.74 ± 0.14 gauss2 at 210 °C. Our interpretation of the rapid decrease of the second moment between 50 °C and 150 °C is that it is caused by the onset of rotation of the —NH2 group about the N—N axis, which triggers the transition observed in the Li7 study. The very low value of the second moment at high temperatures indicates that the protons become highly mobile, probably diffusing by transfer from one hydrazinium ion to another along the c axis.The fine structure of the proton resonance obtained with a single crystal at room temperature was studied at selected crystal orientations. From these measurements, the H—H distances were inferred to be 1.67 ± 0.01 Å in the —NH3+ group and 1.64 ± 0.02 Å in the —NH3+ group. Assuming tetrahedral bond angles, this implies N—H distances of 1.03 ± 0.01 Å and 1.01 ± 0.01 Å in the —NH2 and —NH3+ groups, respectively.A possible mechanism for the ferroelectric behavior of lithium hydrazinium sulphate is suggested.

Sign in / Sign up

Export Citation Format

Share Document