Elastic properties of superconducting and non-superconducting DyBaSrCu3O7−δ (original) (raw)
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Superconducting and elastic properties of (Dy1−xPrx)BaSrCu3O7−δ
Current Applied Physics, 2003
Pr-substituted (Dy 1Àx Pr x)BaSrCu 3 O 7Àd (x ¼ 0:0, 0.1, 0.2, 0.4 and 0.7) has been investigated for its superconducting and elastic properties. Structural transition from orthorhombic to tetragonal symmetry is observed at x ¼ 0:1. Temperaturedependent sound velocity was measured using the pulse-echo overlap method. Elastic anomalies in the form of lattice stiffening with decreasing temperature were observed above 200 K. These anomalies were attributed to oxygen vacancy orderings in the Cu(1)O plane and also depended on the configurational state of oxygen orderings which is strongly influenced by Prdoping.
Ultrasonic velocity anomalies in superconducting sinter-forgedYBa2Cu3O7−δ
Physical Review B, 1989
The velocity of ultrasound was measured on sinter-forged polycrystalline YBa2Cu307-& samples with a superconducting transition temperature of 91 K. The forging process results in crystallites which are preferentially aligned with their c axis aligned parallel to the forging axis as confirmed from optical and x-ray measurements. Sound-velocity measurements show that the material is elastically anisotropic. The temperature dependence
Anisotropy of Elastic and Relaxation Properties of the Superconducting 123-YBCO Single Crystal
Le Journal de Physique IV, 1996
Acoustic properties of the YBazCu306.7 sjngle rystal are studied in the temperature range 5-300 K. The wave vector of the longitudinal and torsional/Standing waves in the frequency range 50-90 kHz was diwcted along and normal to the c-axis. It is showm that the acoustic anomalies observed in the single crystal qualitatively are the same that those found earper in t h k l 2 3-~~~0 ceramics but depend strongly on the mutual orientation of the wave vector and the c-&xis. It is1established that the significant temperature hysteresis and "softening" of the dynamic elastic moduli at thermocycling are observed only in the case when the sound waves have a displacement component along the c-axis. Moreover, in this case the sound absorption peak near 230 K is more pronounced. The locations ofjsound absorption peaks are not sensitive to the oscillation mode and sample orientation. The results obtaiqed are qualitatively consistent with the model of bistable behaviour of the sublattice formed by apical oxygkn .atoms.
Third-order elastic constants of the high temperature superconductor Bi2Sr2CaCu2O8
Journal of Physics and Chemistry of …, 1999
The complete set of non-vanishing third-order elastic moduli of high temperature superconductor Bi 2 Sr 2 CaCu 2 O 8 (Bi-2:2:1:2) is obtained theoretically. The interactions of nine nearest neighbours of each atom in the unit cell of Bi-2:2:1:2 are taken into account, while estimating the strain energy density. Here the finite strain elasticity theory is used to obtain the strain energy density of the Bi-2:2:1:2 system. The energy density f is compared with the strain dependent lattice energy from the continuum model approximation. The second-order parameter of the potential function f is fixed by making use of easily and more accurately measurable principal axis C ij . The third-order potential parameter is estimated by assuming a Mie-Grüneisen type interatomic potential. The interlattice displacements as well as the second-order elastic constants are evaluated along with the 12 third-order elastic constants of Bi 2 Sr 2 CaCu 2 O 8 . The second-order elastic constants are in good agreement with the reported experimental data. In the case of third-order elastic moduli no such experimental data are available for comparison. All the 12 third-order elastic constants are negative; and the absolute magnitude of third-order elastic constants are generally one order higher than second-order elastic constants as generally expected of crystalline solids. The third-order elastic moduli of different modes show anisotropy. ᭧
Reentrant Softening in Copper-Oxide Superconductors
MRS Proceedings, 1987
ABSTRACTOn the basis of our reentrant-softening model, sound-velocity results in La1.85Sr0.15CuO4 and YBa2Cu3O7−x are shown to be neither dissimilar nor inconsistent with thermodynamic requirements. In both materials, as temperature decreases, the lattice softens just above Tc. Below Tc, this softening is offset by increased stiffness associated with the developing superconducting phase. This model agrees with results from other physical-property measurements, and it predicts that elastic stiffness is higher in the normal state than in the superconducting state.
Physica C: Superconductivity, 2005
In this work we present the study of the elastic properties of polycrystalline samples of superconducting YBa 2 Cu 3 O 7-δ prepared by the sol-gel method. The quality of all samples was checked by x-ray diffraction and scanning electronic microscopy while their physical properties were verified by transport and magnetic measurements. The elastic study was performed using the standard pulse-echo technique through measuring the phase velocity and the attenuation of ultrasonic waves (in the range of a few MHz) as a function of temperature. We have focused this study on the low temperatures interval (T < 200K). The obtained results show a strong hysteretic behavior in the ultrasonic attenuation (in addition to usually observed hysteretic behavior for the velocity) which strongly supports the existence of a martensiticlike phase above the superconducting critical temperature T C. We argue that this peculiar behavior can be attributed to the granularity present in the samples.