Experimental and Thermodynamic Study of Nonstoichiometry in 〈YBa2Cu3O7‐x〉

Lindemer, T.B.; Hunley, John F.; Gates, J.E.; Sutton, A. L.; Brynestad, J.; Hubbard, Camden R.; Gallagher, P. K.

doi:10.1111/j.1151-2916.1989.tb05978.x

Cited by 253 publications

(54 citation statements)

References 36 publications

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“…If the crystal is further annealed at this temperature, the maximum in the reversible magnetisation, which was initially been re-established at a value of around 3.3 T, shifts to lower field values of about 1.5 T for an annealing time of 160 hours, whilst the amplitude of the maximum increases indicating a increase in the critical current. Note that, according to [5], the overall oxygen content of the sample has the same value of 6.92 for the three treatments and that the transition temperatures are not changed.…”

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confidence: 99%

“…However, the oxygenation of YBa 2 Cu 3 O 7−δ is performed in this way only due to the simplicity of the procedure. According to the phase diagram of Lindemer et al [5] which gives the equilibrium oxygen concentrations as a function of oxygen partial pressure and temperature, the same oxygen content can be obtained as well by annealing at higher temperatures in higher pressure oxygen atmospheres.…”

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confidence: 99%

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Experimental evidence for fast cluster formation of chain oxygen vacancies in YBa2Cu3O7−δ as the origin of the fishtail anomaly

Erb

Manuel

Dhallé

et al. 1999

Solid State Communications

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We report on three different and complementary measurements, namely magnetisation measurements positron annihilation spectroscopy and NMR measurements, which give evidence that the formation of oxygen vacancy clusters is on the origin of the fishtail anomaly in YBa 2 Cu 3 O 7−δ . While in the case of YBa 2 Cu 3 O 7.0 the anomaly is intrinsically absent, it can be suppressed in the optimally doped state where vacancies are present. We therefore conclude that the single vacancies or point defects can not be responsible for this anomaly but that clusters of oxygen vacancies are on its origin.

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confidence: 99%

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confidence: 99%

Experimental evidence for fast cluster formation of chain oxygen vacancies in YBa2Cu3O7−δ as the origin of the fishtail anomaly

Erb

Manuel

Dhallé

et al. 1999

Solid State Communications

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“…Oxygenation of the sample took place in a tube furnace at 400 8C while a constant pressure of 13.9 MPa was applied for 120 hours in a¯owing-oxygen gas environment. The sample was then reduced to an oxygen content of about 6.6, in accordance with the techniques developed during an extensive experimental study 17 on the nonstoichiometry in YBa 2 Cu 3 O 7-x (an oxygen content of 6.6 indicates that x in this formula is 0.4). An equation was developed in this study relating the oxygen content and T c to the partial oxygen pressure and temperature.…”

Section: Sample Preparationmentioning

confidence: 99%

One-dimensional nature of the magnetic fluctuations in YBa2Cu 3O6.6

Mook

Dai

Doğan

et al. 2000

Nature

226

173

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There is increasing evidence that inhomogeneous distributions of charge and spinÐso-called`striped phases'Ðplay an important role in determining the properties of the high-temperature superconductors. For example, recent neutron-scattering measurements on the YBa 2 Cu 3 O 7-x family of materials show both spin and charge¯uctuations that are consistent with the stripedphase picture. But the¯uctuations associated with a striped phase are expected to be one-dimensional, whereas the magnetic uctuations observed to date appear to display two-dimensional symmetry. We show here that this apparent two-dimensionality results from measurements on twinned crystals, and that similar measurements on substantially detwinned crystals of YBa 2 Cu 3 O 6.6 reveal the one-dimensional character of the magnetic¯uctuations, thus greatly strengthening the striped-phase interpretation. Moreover, our results also suggest that superconductivity originates in charge stripes that extend along the b crystal axis, where the super¯uid density is found to be substantially larger than for the a direction.Striped phases are inhomogeneous distributions of charge and spin that have been suggested to account for many of the unusual properties of the high-T c copper oxide superconductors 1±7 (T c is the superconducting transition temperature). In the simplest picture, the charge and spin can be thought of as being con®ned to separate linear regions in the crystal and thus resembling stripes. We expect static striped phases for the YBa 2 Cu 3 O 7-x materials not to coexist with superconductivity, except perhaps for materials with low oxygen contents and low values of T c . However, neutronscattering measurements have shown results for¯uctuations of both spin 8,9 and charge 10 that support the existence of a dynamic striped phase in YBa 2 Cu 3 O 7-x materials that have high T c values. Nevertheless, a dif®culty for the dynamic striped-phase picture is that, for both YBa 2 Cu 3 O 7-x (refs 8, 9) and La 2-x Sr x CuO 4 (refs 11, 12) copper oxide superconductors, the magnetic¯uctuations stemming from the spins have displayed a four-fold pattern at incommensurate points around the magnetic (1/2, 1/2) reciprocal lattice position, as shown in Fig. 1A. The interpretation of these measurements has been unclear, with both striped phases 1±7 and nested Fermi surfaces 13±15 being possible explanations. Because the striped phase is expected to propagate along a single direction, only a single set of satellites around the antiferromagnetic position should be observed. Tranquada 7,16 has suggested that the four-fold symmetry might arise from stripes that alternate in direction as the planes are stacked along the c axis.The problem in interpreting the four-fold pattern stems from the fact that the crystals used in the neutron experiments are twinned, so that along a given a or b direction, domains with lattice spacing a or b exist in equal proportion. This makes it impossible to distinguish whether satellites originate from the a* or b* direction in the reciprocal ...

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“…The oxygen content was then calculated from the weight change by adopting as the reference value the equilibrium oxygen content y = 6.993 at 350°C in 1 atm oxygen [17]. This analysis has a precision ± 0.001 limited by precision of the scale, ±0.01 mg.…”

Section: Preparationmentioning

confidence: 99%

Preparation and characterization of homogeneous YBCO single crystals with doping level near the SC-AFM boundary

Liang

Bonn

Hardy

et al. 2002

Physica C: Superconductivity

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High-purity and homogeneous YBa 2 Cu 3 O y single crystals with carrier doping level near the AFM-SC boundary have been obtained in the oxygen content range between y = 6.340 and 6.370. The crystals are ortho-II phase at room temperature and undergo the orthorhombic to tetragonal transition at about 140°C. They show sharp superconducting transitions, with T c between 4 and 20 K. T c changes by 0.8 K when the oxygen content y is changed by 0.001, and is also sensitive to annealing conditions near room temperature, due to the dependence of doping on oxygen ordering correlation lengths. Crystals with oxygen content y lower than 6.345 are non-superconducting.

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Experimental and Thermodynamic Study of Nonstoichiometry in 〈YBa₂Cu₃O_7‐x〉

Cited by 253 publications

References 36 publications

Experimental evidence for fast cluster formation of chain oxygen vacancies in YBa2Cu3O7−δ as the origin of the fishtail anomaly

Experimental evidence for fast cluster formation of chain oxygen vacancies in YBa2Cu3O7−δ as the origin of the fishtail anomaly

One-dimensional nature of the magnetic fluctuations in YBa2Cu 3O6.6

Preparation and characterization of homogeneous YBCO single crystals with doping level near the SC-AFM boundary

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