Hydrogen in high-Tc superconductors

Hirata, T.

doi:10.1002/pssa.2211560202

Cited by 30 publications

(14 citation statements)

References 60 publications

(16 reference statements)

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“…The main goal of most of these early investigations [2], [3] was to modify the electronic properties of the oxide by the electrons of intercalated hydrogen atoms. More recently, hydrogen incorporation during the deposition of Y123 epitaxial films has been used to tune specific characteristics for different applications [4]- [6].…”

Section: Introductionmentioning

confidence: 99%

X-Ray Diffraction Anomalies and Random Intercalation in H-Loaded Y-Ba-Cu-O Films

Ariosa¹,

Tsaneva

Barber

2005

IEEE Trans. Appl. Supercond.

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A model has been developed to account for the structural peculiarities observed by X-ray diffraction of hydrogen-loaded Y123 films deposited in an O 2 Ar + H 2 O atmosphere. The model considers the random inter-growth of two very similar structures with slightly different -axis or, equivalently, the random intercalation of a small spacer in the Y123 matrix causing displacement disorder along the -axis direction. It quantitatively reproduces both the nonmonotonous deviations of Bragg-peaks and their progressive weakening and broadening for higher diffraction orders. The model offers the possibility to evaluate both the fraction of secondary phase and its -axis lattice parameter. In the example given, we have been able to identify 28% of intercalated hydrogen bronze H 0 66 [Y123] with 4% elongated -axis. A simplified procedure for the diagnosis and characterization of random intercalates is extracted from the model. Similar structures observed in other perovskite-based layered oxides are discussed within this framework.

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Section: Introductionmentioning

confidence: 99%

X-Ray Diffraction Anomalies and Random Intercalation in H-Loaded Y-Ba-Cu-O Films

Ariosa¹,

Tsaneva

Barber

2005

IEEE Trans. Appl. Supercond.

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“…Theoretically, the interaction of the 123 structure with water can proceed by three mechanisms: 1) hydrolytic decomposition with the formation of simpler compounds; 2) hydration leading to the incorporation of water into the structure in the form of OHgroups to vacant oxygen positions and formation of new hydroxyl ions due to the attachment of a proton to oxygen; and 3) incorporation of water into the structure in the form of OHgroups and protons, as a result of which the transition of the 123 phase to an oxide-hydroxide of the psedo-124 type takes place [22,23]. Apparently, it is the incorporation of protons into the structure that initiates the splitting of Cu-O chains, which is the reason of this structural transformation.…”

Section: Resultsmentioning

confidence: 99%

Mechanisms of interaction of YBa2Cu3O y with water vapor at low-temperature annealing

Бобылев

Zyuzeva

2016

Phys. Solid State

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The interaction of YBa 2 Cu 3 O y (123) with water vapor at temperatures T ≤ 150° has been studied. It has been shown that, with an increase in temperature, the mechanism of its interaction with water changes. Near room temperature, the main process is hydrolytic decomposition. At T ~ 100°C, the absorption of water is significantly reduced, because the role of hydrolysis becomes less important and water penetrates the structure weakly and is incorporated into oxygen vacancies mainly in the form of OH --groups, which leads to the transition of YBa 2 Cu 3 O y from the tetragonal to orthorhombic phase. With an increase in temperature to 150°C, the absorption of water increases again. In this case, the main mechanism is the penetration of water to the 123 structure, which leads to splitting of Cu-O chains and a phase transition from the 123 to pseudo-124 structure. The role of different mechanisms of interaction with water essentially depends on the oxygen content in the 123 structure. At a low oxygen index (y = 6.3), the role of hydrolysis is more important, and, at y ≥ 6.5, the incorporation of water into the structure prevails. It has been revealed that, at T = 150°C, after absorption of water, YBa 2 Cu 3 O 6.96 becomes a proton conductor.

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“…A number of investigations using di erent methods suggest positions for hydrogen between O(4), O(1) and Cu(1) (Hirata 1996), that is in the copper chain horizon. Independent of the question of location a high mobility of the hydrogen ions has been observed (Baikov and Nikitin 1996).…”

Section: Discussionmentioning

confidence: 98%

“…It has been reported that the intercalation of lower concentrations of hydrogen (less than 0.3 H per formula unit) into YBa 2 Cu 3 O 7 results in the topotactic formation of a solid solution (Reilly et al 1987) (for a review see Hirata (1996)). Intercalation of larger amounts of hydrogen or of water leads to a hydrated compound H x YBa 2 Cu 3 O 8 YBa 2 Cu 3 O 8 x OH x x 2 via structural phase transitions.…”

Section: §1 Introductionmentioning

confidence: 99%

Hydrogen and water intercalation into YBa2Cu3O7-delta: structural properties of H2YBa2Cu3O8-delta

Günther

1999

Philosophical Magazine A

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Structural properties of hydrogen-and water-intercalated superconductors YBa 2 Cu 3 O 7 are discussed on the basis of new high-resolution electron microscopy, electron di raction, X-ray di raction, extended X-ray absorption ® ne structure (EXAFS) and Raman measurements. The multistep intercalation reaction proceeding at temperatures below 200 ë C leads to signi® cant changes in the crystal structure via shear transformation resulting in a highly crystalline end phase. A new structure model was proposed for H 2 YBa 2 Cu 3 O 8 which includes Cu± O single chains as in YBa 2 Cu 3 O 7 . This result di ers in principle from all models proposed before. §1. Introduction Investigations on the chemical reaction of water or reducing agents with superconducting materials like YBa 2 Cu 3 O 7 are of fundamental interest in terms of corrosion processes (for a review see Barkatt et al. (1993)), electronic± protonic conductivity (Baikov and Nikitin 1996) and the understanding of reaction mechanisms of low-temperature solid-state transformations. It has been reported that the intercalation of lower concentrations of hydrogen (less than 0.3 H per formula unit) into YBa 2 Cu 3 O 7 results in the topotactic formation of a solid solution (Reilly et al.

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Hydrogen in high-Tc superconductors

Cited by 30 publications

References 60 publications

X-Ray Diffraction Anomalies and Random Intercalation in H-Loaded Y-Ba-Cu-O Films

X-Ray Diffraction Anomalies and Random Intercalation in H-Loaded Y-Ba-Cu-O Films

Mechanisms of interaction of YBa2Cu3O y with water vapor at low-temperature annealing

Hydrogen and water intercalation into YBa2Cu3O7-delta: structural properties of H2YBa2Cu3O8-delta

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