Growth of YBa2Cu3O7-x crystals in thoria crucibles: twinning and optical effects

Gagnon, R.; Oussena, M.; Aubin, M.

doi:10.1016/0022-0248(92)90562-w

Cited by 28 publications

(4 citation statements)

References 35 publications

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“…Three detwinned YBa 2 Cu 3 O 7−δ single crystals from the same batch have been studied. They were grown by a conventional self-flux method using yttria-stabilized zirconia crucibles [9], starting with powders of Y 2 O 3 (99.9999%), BaCO 3 (99.999%) and CuO (99.9999%), mixed in a molar ratio Y:Ba:Cu of 1:18:45. This procedure has been shown to give crystals of excellent purity [6,8,10,11].…”

Section: Methodsmentioning

confidence: 99%

Effect of oxygen stoichiometry on the out-of-plane anisotropy of YBa₂Cu₃O_7-deltasingle crystals near optimal doping

Kokkaliaris

Deligiannis

Oussena

et al. 1999

Supercond. Sci. Technol.

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We have performed magnetic measurements on pure detwinned YBa2Cu3O7- single crystals in order to investigate the influence of variations in the oxygen stoichiometry on the out-of-plane anisotropy ck in the region close to optimal doping (6.90 < 7- < 6.98). The anisotropy is estimated using the anisotropic London model from the period of the commensurability oscillations of the hysteretic magnetization as observed for fields applied parallel to the a-b-planes. For a variation in the oxygen deficiency by as much as 300%, we find that ck decreases but only slightly (less than 12%) with decreasing oxygen deficiency. The possibility of a temperature-dependent ck is also discussed.

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Section: Methodsmentioning

confidence: 99%

Effect of oxygen stoichiometry on the out-of-plane anisotropy of YBa₂Cu₃O_7-deltasingle crystals near optimal doping

Kokkaliaris

Deligiannis

Oussena

et al. 1999

Supercond. Sci. Technol.

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“…The flux method of growing Y123 single crystals has been widely reported [4][5][6][7][8][9]. Using this method, the crystal nucleation in the melt cannot be controlled.…”

Section: Introductionmentioning

confidence: 99%

“…Due to the low Y solubility and the difficulty of increasing supersaturation, the growth rate R c of the flux method is quite slow; it was found to be 0.004 mm h −1 [6]. By stirring the melt, the thickness of the diffusion layer was reduced and the crystal growth rate could be increased [7,8]. Moreover, by introducing a pin into the middle of the melt, a crystal growth rate of up to 0.016 mm h could be reached [6].…”

Section: Introductionmentioning

confidence: 99%

Large REBCO single crystals: growth processes and superconducting properties

Yao¹,

Shiohara²

1997

Supercond. Sci. Technol.

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A low solubility of yttrium in the Ba - Cu - O melt and a steep liquidus slope near the peritectic temperature lead to a very slow growth rate of (YBCO or Y123) single crystals and this creates a problem in growth of large single crystals. To solve this problem, increasing the growth rate and extending the growth time are significant. Using the crystal pulling method, we have developed several processes and succeeded in growing large Y123 and (NdBCO) single crystals with an edge size over 25 mm in the a - b plane and up to 20 mm in the c-axis direction. In this article, three methods of increasing growth rate are reviewed. They are (i) employing high oxygen partial pressure, (ii) choosing RE (rare earth) elements with higher solubilities in the Ba - Cu - O solution, and (iii) growing REBCO crystals including several RE elements. Using these methods the growth rate was effectively enhanced from two to five times that of Y123. The critical temperature of 92.7 K was achieved from a Y123 single crystal grown under 1 atm oxygen partial pressure, indicating that is insensitive to the oxygen pressure of the growth atmosphere in the YBCO system. A high of about 95 K for NdBCO superconductors with a sharp transition was obtained by controlling the ratio of Ba to Cu (Ba/Cu) in the liquid, suggesting that the Ba/Cu ratio in the liquid composition has a significant importance in controlling . By partial substitution of Sm at the Y sites up to 30%, (Y(Sm)BCO) crystals show a of and do not display depression.

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“…We report results acquired on a detwinned YBa 2 Cu 3 O 7Ϫ␦ single crystal ͑DT3͒ with dimensions 1.29ϫ1.25 ϫ0.08 mm 3 , grown by a conventional self-flux method using yttria-stabilized zirconia crucibles. 9 The sample was initially annealed at 500°C for 6 d in a 1 bar O 2 atmosphere resulting 10 in 7Ϫ␦ϭ6.934. Detwinning was achieved by applying a uniaxial pressure of ϳ50 MPa at 550°C in air for 15 min.…”

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Negative dynamic creep in the peak-effect regime in type-II superconductors

et al. 2000

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We report the observation of a negative dynamic creep rate, i.e., increasing irreversibility in the magnetic hysteresis loop for decreasing sweep rate of the magnetic field, in both YBa 2 Cu 3 O 7Ϫ␦ and 2H-NbSe 2 single crystals. This phenomenon is found to appear on the increasing branch of the peak effect that corresponds to a state which is intermediate between the dislocation-free Bragg glass and a highly disordered vortex phase. The origin of this anomalous creep is shown to be connected to a negative differential resistance resulting from the N-like shape of the current-voltage characteristics.

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Growth of YBa2Cu3O7-x crystals in thoria crucibles: twinning and optical effects

Cited by 28 publications

References 35 publications

Effect of oxygen stoichiometry on the out-of-plane anisotropy of YBa₂Cu₃O_7-deltasingle crystals near optimal doping

Effect of oxygen stoichiometry on the out-of-plane anisotropy of YBa₂Cu₃O_7-deltasingle crystals near optimal doping

Large REBCO single crystals: growth processes and superconducting properties

Negative dynamic creep in the peak-effect regime in type-II superconductors

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Growth of YBa2Cu3O7-x crystals in thoria crucibles: twinning and optical effects

Cited by 28 publications

References 35 publications

Effect of oxygen stoichiometry on the out-of-plane anisotropy of YBa2Cu3O7-deltasingle crystals near optimal doping

Effect of oxygen stoichiometry on the out-of-plane anisotropy of YBa2Cu3O7-deltasingle crystals near optimal doping

Large REBCO single crystals: growth processes and superconducting properties

Negative dynamic creep in the peak-effect regime in type-II superconductors

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Product

Resources

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Effect of oxygen stoichiometry on the out-of-plane anisotropy of YBa₂Cu₃O_7-deltasingle crystals near optimal doping

Effect of oxygen stoichiometry on the out-of-plane anisotropy of YBa₂Cu₃O_7-deltasingle crystals near optimal doping