Ultrasonic attenuation anomalies of n-type superconductor Pr2−xCexCuO4

2016 ◽  
Vol 30 (23) ◽  
pp. 1650314 ◽  
Author(s):  
Tet Vui Chong ◽  
R. Abd-Shukor
Keyword(s):  
Critical Temperature ◽  
Ultrasonic Attenuation ◽  
Magnetic Transition ◽  
Longitudinal Mode ◽  
Shear Mode ◽  
Longitudinal And Shear Waves ◽  
Temperature Dependences ◽  
Overlap Method ◽  
Pulse Echo ◽  
Mode A

Pr[Formula: see text]Ce[Formula: see text]CuO4 ([Formula: see text] = 0 and 0.15) samples were prepared via solid state reaction. Pr2CuO4 sample is insulating while Pr[Formula: see text]Ce[Formula: see text]CuO4 sample exhibited an onset critical temperature, [Formula: see text] of 21 K. The temperature dependences of ultrasonic attenuation in these polycrystalline n-type superconductor Pr[Formula: see text]Ce[Formula: see text]CuO4 ([Formula: see text] = 0 and 0.15) samples have been measured between 80 K and 300 K using longitudinal and shear waves by pulse-echo-overlap method with frequencies between 5 MHz and 10 MHz. For the longitudinal mode, a pronounced attenuation peak around 200 K was observed in Pr2CuO4, but it is not observed in the superconducting material Pr[Formula: see text]Ce[Formula: see text]CuO4. For the shear mode, no pronounced attenuation peaks were observed in the samples. It is suggested that the attenuation peak in the [Formula: see text] = 0 sample at 200 K is due to the weak structural distortion induced by the magnetic transition.

Elastic Property Measurement of High-Tension Bolt Based on Mode Converted Ultrasound

2006 ◽  
Vol 326-328 ◽  
pp. 709-712
Author(s):  
Noh Yu Kim ◽  
Sang Soon Lee
Keyword(s):  
Mode Conversion ◽  
Longitudinal Mode ◽  
Shear Mode ◽  
Ultrasonic Technique ◽  
Wave Velocities ◽  
Shear Wave Velocities ◽  
High Tension ◽  
Longitudinal And Shear Waves ◽  
Property Measurement ◽  
Mechanical Modulus

Elastic properties of high tension bolt are evaluated non-destructively by measuring acoustic longitudinal and shear wave velocities using mode-converted ultrasound. Mode-converted longitudinal and shear waves along bolt are captured to calculate acoustic wave velocities and determine elastic constants such as Young’s modulus and Bulk modulus based on acoustoelasticity. Ray analysis to select a specific mode conversion from longitudinal mode to shear mode is carried out and discussed with experimental results. From experiment results of maximum 5% of measurement error, it is shown that the proposed mode-converted ultrasonic technique is very effective and sensitive enough to characterize mechanical modulus of high-tension bolts quantitatively.

ACOUSTIC STUDY ON POLYCRYSTALLINE Pr2-xCexCuO4(x=0 AND 0.15)

2004 ◽  
Vol 18 (07n08) ◽  
pp. 301-308 ◽  
Author(s):  
TET VUI CHONG ◽  
R. ABD-SHUKOR
Keyword(s):  
Magnetic Transition ◽  
Acoustic Properties ◽  
Structural Distortion ◽  
Shear Mode ◽  
Coupling Constant ◽  
Phonon Coupling ◽  
Acoustic Study ◽  
Electron Phonon Coupling ◽  
Overlap Method ◽  
Lattice Softening

The acoustic properties of Pr 2-x Ce x CuO 4(x=0 and 0.15) samples are measured using the pulsed-echo-overlap method between 5–10 MHz. An elastic anomaly signifying a lattice softening tendency towards lower temperatures is observed in the x=0 sample between 220–250 K for longitudinal velocities but not observed in the shear mode, nor the x=0.15 sample (both longitudinal and shear mode). The electron-phonon coupling constant is calculated. It is suggested that the softening tendency in the x=0 sample between 220–250 K is due to the weak structural distortion induced in the magnetic transition.

ACOUSTIC PROPERTIES OF MgB2 SUPERCONDUCTOR UNDER PRESSURE

2002 ◽  
Vol 16 (30) ◽  
pp. 4587-4592 ◽  
Author(s):  
FENG-YING LI ◽  
RU-JU WANG ◽  
RI-CHENG YU ◽  
ZHEN-XING LIU ◽  
CHANG-QING JIN
Keyword(s):  
Specific Heat ◽  
Sound Velocity ◽  
Debye Temperature ◽  
Pressure Dependence ◽  
Pressure Coefficient ◽  
Acoustic Properties ◽  
Electron Phonon Coupling ◽  
Longitudinal And Shear Waves ◽  
Overlap Method ◽  
Pulse Echo

The pressure dependence of sound velocity of longitudinal and shear waves were measured up to 0.5 GPa using a pulse echo overlap method on polycrystalline single-phase MgB 2 superconductor which was high pressure synthesized and with a T c of 39 K. The pressure dependence of Debye temperature and specific heat were calculated based on sound velocity data. The results indicate that Debye temperature increases with the applied pressures while specific heat decreases. The Grüneisen constant was calculated as well. From the sound velocities, the pressure coefficient of the averaged phonon frequency was obtained, which is consistent with the value estimated by Vogt et al. This indicates that the importance of phonon hardening in the variation of T c under pressure. Upon changing the Debye temperature, unit cell volume and transition temperature with the pressure, volume dependence of electron-phonon coupling constant are also calculated.

scholarly journals Thermophysical Properties of 1-Butanol at High Pressures

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5046
Author(s):  
Marzena Dzida
Keyword(s):  
Speed Of Sound ◽  
Thermophysical Properties ◽  
High Pressures ◽  
Fuel Additive ◽  
Temperature Range ◽  
Isobaric Thermal Expansion ◽  
Isentropic And Isothermal Compressibilities ◽  
Overlap Method ◽  
Pulse Echo ◽  
Better Than

1-Butanol can be considered as a good fuel additive, which can be used at high pressures. Therefore, the knowledge of high-pressure thermophysical properties is crucial for this application. In this paper, new experimental data on the speed of sound in 1-butanol in the temperature range from 293 to 318 K and at pressures up to 101 MPa are reported. The speed of sound at a frequency of 2 MHz was measured at atmospheric and high pressures using two measuring sets operating on the principle of the pulse–echo–overlap method. The measurement uncertainties were estimated to be better than ±0.5 m·s−1 and ± 1 m·s−1 at atmospheric and high pressures, respectively. Additionally, the density was measured under atmospheric pressure in the temperature range from 293 to 318 K using a vibrating tube densimeter Anton Paar DMA 5000. Using the experimental results, the density and isobaric and isochoric heat capacities, isentropic and isothermal compressibilities, isobaric thermal expansion, and internal pressure were calculated at temperatures from 293 to 318 K and at pressures up to 100 MPa.

Three-dimensional stability analysis for a salt-finger convecting layer

2018 ◽  
Vol 841 ◽  
pp. 636-653
Author(s):  
Ting-Yueh Chang ◽  
Falin Chen ◽  
Min-Hsing Chang
Keyword(s):  
Stability Analysis ◽  
Three Dimensional ◽  
Longitudinal Mode ◽  
Transverse Mode ◽  
Solute Diffusion ◽  
Two Dimensional ◽  
Grashof Number ◽  
Significant Difference ◽  
The Stability ◽  
Mode A

A three-dimensional linear stability analysis is carried out for a convecting layer in which both the temperature and solute distributions are linear in the horizontal direction. The three-dimensional results show that, for $Le=3$ and 100, the most unstable mode occurs invariably as the longitudinal mode, a vortex roll with its axis perpendicular to the longitudinal plane, suggesting that the two-dimensional results are sufficient to illustrate the stability characteristics of the convecting layer. Two-dimensional results show that the stability boundaries of the transverse mode (a vortex roll with its axis perpendicular to the transverse plane) and the longitudinal modes are virtually overlapped in the regime dominated by thermal diffusion and the regime dominated by solute diffusion, while these two modes hold a significant difference in the regime the salt-finger instability prevails. More precisely, the instability area in terms of thermal Grashof number $Gr$ and solute Grashof number $Gs$ is larger for the longitudinal mode than the transverse mode, implying that, under any circumstance, the longitudinal mode is always more unstable than the transverse mode.

Ultrasonic Investigation of the Ni40Ti50Cu10 Alloy

2006 ◽  
Vol 115 ◽  
pp. 63-66
Author(s):  
U. Straube ◽  
Giovanni Mazzolai ◽  
A. Biscarini ◽  
B. Coluzzi ◽  
Fabio M. Mazzolai ◽  
...  
Keyword(s):  
Phase Transition ◽  
Ultrasonic Attenuation ◽  
Shear Stiffness ◽  
Elastic Stiffness ◽  
Elastic Behavior ◽  
Strong Increase ◽  
Propagation Mode ◽  
Stiffness Coefficients ◽  
The One ◽  
Overlap Method

The ultrasound pulse echo overlap method has been used to determine the elastic stiffness coefficients and the corresponding ultrasonic attenuation for a single crystal of the Ni40Ti50Cu10 alloy as a function of temperature. The elastic stiffness coefficients exhibit anomalies near the martensitic phase transition. In the shear stiffness coefficient, corresponding to C44 propagation mode in austenite, a large jump occurs from 36 GPa, above the transition, down to 15 GPa, below the transition. This jump is accompanied by a strong increase in the ultrasonic attenuation. The stiffness coefficients corresponding to C11 and C' = (C11 – C12)/2 modes in austenite show an anomaly at the phase transition, however, these are small effects compared to the one associated with C44 mode. The elastic behavior of this crystal has been characterised down to a temperature of 100 K.

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