Influence of Hydrogen Incorporation and Oxygen Removal on Superconducting YBa2Cu3O7-δ

1996 ◽  
Vol 453 ◽  
Author(s):  
T. Hirata
Keyword(s):  
Transition Temperature ◽  
Lattice Parameter ◽  
Oxygen Removal ◽  
Charge Carrier Concentration ◽  
Oxygen Nonstoichiometry ◽  
The Other ◽  
Superconducting Transition ◽  
Significant Suppression ◽  
Hydrogen Incorporation ◽  
Antiferromagnetic Ordering

AbstractThe influence of hydrogen incorporation and oxygen removal on superconducting YBa2Cu3O7-δ is discussed in comparison with their respective effects. Both hydrogen incorporation and oxygen removal induce the orthorhombic (O)-to-tetragonal (T) transition and antiferromagnetic ordering as well. However, there exist no consistent changes in the c-axis for the O-to-T transition and the superconducting transition temperature Tc upon hydrogen incorporation in YBa2Cu3O7-δ on the other hand, the c-axis certainly increases in the corresponding transition driven by oxygen nonstoichiometry and Tc decreases with increasing δ in YBa2Cu3O7-δ. Plots of Tc vs. the lattice parameter c reveal no significant suppression in Tc upon hydrogenation than oxygen removal. It is concluded that the Cu-O bond distances or the Cu-Cu plane spacings along the c-axis change somewhat differently in two cases; it is believed that the charge-carrier concentration is reduced less significantly upon hydrogenation than oxygen removal in YBa2Cu3O7-δ, giving rise to the aforementioned finding.

Crystallographic studies on single crystals of doped and undoped Bi-Sr-Ca-Cu-O superconductors

1990 ◽  
Vol 48 (4) ◽  
pp. 78-79
Author(s):  
Brigitte H. Krause ◽  
Y. C. Chang ◽  
P. Z. Jiang ◽  
D. J. Lam
Keyword(s):  
Transition Temperature ◽  
Single Crystals ◽  
Layer Structure ◽  
The Other ◽  
Superconducting Transition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Layer Sequence ◽  
Tetragonal Unit Cell ◽  
Chemical Disorder

Diffraction data on single crystals of low Tc phase of Bi-Sr-Ca-Cu-O superconductor indicated a well developed layer structure, but with structural and chemical disorder within the layers. The lattice constant c and the layer sequence for the pseudo-tetragonal unit cell were determined from x-ray diffraction measurements of the 006 reflections. They were found to be 30.84(2) Å for the undoped compound and the same 30.84(2) Å for the lead doped crystals indicating the low superconducting transition temperature (Tc = 80 K) phase. The c-dimension for single crystals doped with both antimony and lead was 29.02(5) Å. Polycrystalline samples of that compound on the other hand formed the high temperature (Tc = 107 K) modification with c = 36.9(6) Å, determined from electron diffraction. A mixture of phases with different stacking of layers was indicated by splitting of diffraction spots. The direction of c was also less well defined in the lead-antimony doped single crystals than in the other two compounds.

Melt Spinning and Phase Transformations of V2CrA11-xBx and Ti3Nb6Mo3Si4 Alloys

1983 ◽  
Vol 21 ◽  
Author(s):  
B.S. Smith ◽  
R.A. Smith ◽  
M T. Clapp
Keyword(s):  
Crystal Structure ◽  
Transition Temperature ◽  
Phase Transformations ◽  
Superconducting Transition Temperature ◽  
Melt Spinning ◽  
Vickers Microhardness ◽  
Lattice Parameter ◽  
Rapid Quenching ◽  
Superconducting Transition

ABSTRACTMelt spinning was used to rapidly quench V2CrA11-xBx and Ti3Nb6Mo3Si4 alloys. Melt spinning had very little effect on the crystal structure of the V2CrA11-xBx alloys. However, a new (NbTiMo)3 Si A–15 phase was found by rapid quenching of the Ti3Nb6Mo3Si4 alloys; the lattice parameter was 5.08 Å. Melt spinning increased the Vickers microhardness values of the V2CrA11-xBx alloys from 500 to 750, and of the Ti3Nb6Mo3Si4 alloys from 1000 to as high as 1675. Melt spinning increased the superconducting transition temperature of the Ti3Nb6Mo3Si4 alloys from 1.9 to 3.4K.

scholarly journals FAR-INFRARED MEASUREMENTS OF OXYGEN-DOPED POLYCRYSTALLINE La2CuO4.0315 SUPERCONDUCTOR UNDER SLOW-COOLED AND FAST-COOLED CONDITIONS

2011 ◽  
Vol 25 (05) ◽  
pp. 315-324 ◽  
Author(s):  
Y. H. KIM ◽  
H. H. HSIEH ◽  
Z. WU ◽  
P. H. HOR
Keyword(s):  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Far Infrared ◽  
The Other ◽  
Pure Oxygen ◽  
Two Dimensional ◽  
Superconducting Transition ◽  
Charge Dynamics ◽  
Infrared Measurements ◽  
Ir And Raman

We have studied the far-infrared (far-IR) charge dynamics of an equilibrated pure oxygen doped La 2 CuO 4.0315 under slow-cooled and fast-cooled conditions. The superconducting transition temperature (Tc) for the slow-cooled and that for the fast-cooled processes were respectively found to be close to the two intrinsic Tc. One at 30 K and the other at 15 K. Direct comparison with our previous results and other far-IR and Raman studies on single crystalline La 2-x Sr x CuO 4, we conclude that the topology of the pristine electronic phases that are responsible for the two intrinsic Tc is holes arranged into two-dimensional (2D) square lattices.

scholarly journals Enhancing Superconductivity of the Nonmagnetic Quasiskutterudites by Atomic Disorder

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5830
Author(s):  
Andrzej Ślebarski ◽  
Maciej M. Maśka
Keyword(s):  
High Temperature ◽  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
High Temperature Superconductors ◽  
Superconducting Phase ◽  
Length Scale ◽  
Superconducting Transition ◽  
Atomic Disorder ◽  
Strong Inhomogeneity ◽  
Related Compounds

We investigated the effect of enhancement of superconducting transition temperature Tc by nonmagnetic atom disorder in the series of filled skutterudite-related compounds (La3M4Sn13, Ca3Rh4Sn13, Y5Rh6Sn18, Lu5Rh6Sn18; M= Co, Ru, Rh), where the atomic disorder is generated by various defects or doping. We have shown that the disorder on the coherence length scale ξ in these nonmagnetic quasiskutterudite superconductors additionally generates a non-homogeneous, high-temperature superconducting phase with Tc⋆>Tc (dilute disorder scenario), while the strong fluctuations of stoichiometry due to increasing doping can rapidly increase the superconducting transition temperature of the sample even to the value of Tc⋆∼2Tc (dense disorder leading to strong inhomogeneity). This phenomenon seems to be characteristic of high-temperature superconductors and superconducting heavy fermions, and recently have received renewed attention. We experimentally documented the stronger lattice stiffening of the inhomogeneous superconducting phase Tc⋆ in respect to the bulk Tc one and proposed a model that explains the Tc⋆>Tc behavior in the series of nonmagnetic skutterudite-related compounds.

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