Single-crystal growth and characterization of REBa2Cu4O8 and Y1−xCaxBa2Cu4O8

Hijar, C. A.; Stern, Christine; Poeppelmeier, Kenneth R.; Rogacki, K.; Chen, Z.; Dąbrowski, B.

doi:10.1016/0921-4534(95)00462-9

Cited by 11 publications

(9 citation statements)

References 19 publications

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“…The refinement was done allowing the Ca 2+ to replace both Y 3+ and Ba 2+ . The refinement has shown that the Ca ion substitutes only Y ions as in other similar compounds (Nagao et al, 2003;Hijar et al, 1995); the obtained molar ratio Y/Ca is 0.93/0.07. At this stage a close inspection has been performed on the anisotropic displacement parameters; O2 and O4 ions have abnormally ORTEP plot of the unit cell of crystal (1), (Y 0.93 ,Ca 0.07 )Ba 2 Cu 3 O 6.85 (displacement parameters at 50% probability).…”

Section: Single-crystal X-ray Diffractionmentioning

confidence: 82%

“…Actually, the influence of Ca doping in Y-123 has been widely studied from the point of view of its crystal structure both for polycrystalline material and for single crystals not grown with the whisker technique (Bö ttger et al, 1997;Chen et al, 2000;Stoyanova-Ivanova et al, 2006;Hijar et al, 1995). In principle, Ca should preferably substitute Y since the ionic radius of Ca 2+ (r = 1.12 Å ) is much closer to that of Y 3+ (r = 1.019 Å ) than to that of Ba 2+ (r = 1.42 Å ), and indeed X-ray structure refinements of single crystals have shown that at low Ca concentrations (< 11%) Y 3+ ions are substituted, while at higher concentrations Ca 2+ also replaces Ba 2+ (Bö ttger et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

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X-ray crystal structures of Al-doped (Y,Ca)Ba₂Cu₃O_7−ywhiskers

Bertolotti

Calore

Gervasio

et al. 2014

Acta Crystallogr Sect B

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Al(+3)-doped (Y,Ca)Ba2Cu3O(7-y) (YBCO) whiskers have been synthesized using a solid-state reaction technique. These materials are promising candidates for solid-state THz applications based on sequences of Josephson Junctions (IJJs). Alumina addition was systematically varied and the effect of aluminium incorporation on the structure has been investigated using single-crystal X-ray diffraction. Aluminium only replaces Cu atoms in the O-Cu-O-Cu chains and a gradual transition from orthorhombic to tetragonal space group occurs, thus increasing the Al content. A gradual modification of the coordination sphere of the copper site has also been observed. The Ca(2+) ion substitutes mainly the Y(3+) ion and also, to a small extent, the Ba(2+) ion.

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Section: Single-crystal X-ray Diffractionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

X-ray crystal structures of Al-doped (Y,Ca)Ba₂Cu₃O_7−ywhiskers

Bertolotti

Calore

Gervasio

et al. 2014

Acta Crystallogr Sect B

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“…The best crystals have been made for starting compositions with a metals ratio Y:Ba:Cu from 1:8:20 to 1:10:25, i.e. with large excess of Ba and Cu [3,5]. Mixtures of polycrystalline Y123, BaCuO 2 and CuO were used to obtain a desired composition.…”

Section: Crystal Growthmentioning

confidence: 99%

Single-crystal growth and properties of substituted

Dąbrowski

1998

Supercond. Sci. Technol.

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Single crystals of have been grown from a BaO-CuO flux under 600 bar of at . , BeO, and MgO materials were used for crucibles, resulting in , 76, 74 and 55 K, respectively. Good quality of crystals grown in crucibles was confirmed by single-crystal x-ray diffraction, magnetic and transport measurements. Angle-resolved photoemission showed the presence of the `extended' Van Hove singularity close to along the direction. Optical conductivity, resistivity and thermopower measurements along the a, b and c directions indicate a change in the character of the transport along the c direction at . First Zn- and Ni-substituted crystals with sharp superconducting transitions at for Zn and for Ni have been grown to study the effect of magnetic and nonmagnetic impurities located in the plane. Ratios of the starting flux compositions to the compositions substituted in crystals are close to 3.5 and 1 for Zn and Ni, respectively. Optical conductivity shows that the low-energy electronic states are at the verge of localization. The irreversibility line and critical currents were studied for pure and substituted crystals showing that intrinsic flux pinning is not significantly modified by Zn substitution on the planes.

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“…To date, the influence of Ca-doping in Y-123 has been widely studied from the point of view of its crystal structure, both for polycrystalline material and for single crystals not grown with the whisker technique (Bö ttger et al, 1997;Chen et al, 2000;Hijar et al, 1995). In principle, Ca should preferably substitute Y since the ionic radius of Ca 2+ (r = 1.12 Å ) is much closer to that of Y 3+ (r = 1.019 Å ) than to that of Ba 2+ (r = 1.42 Å ), and X-ray structure refinements of single crystals have shown that at low Ca concentrations (< 11%) Y 3+ ions are actually substituted while, at higher concentrations Ca 2+ also replaces Ba 2+ (Bö ttger et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

Effect of Al and Ca co-doping, in the presence of Te, in superconducting YBCO whiskers growth

Pascale

Truccato

Operti

et al. 2016

Acta Crystallogr Sect B

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High-T superconducting cuprates (HTSC) such as YBaCuO (YBCO) are promising candidates for solid-state THz applications based on stacks of intrinsic Josephson junctions (IJJs) with atomic thickness. In view of future exploitation of IJJs, high-quality superconducting YBCO tape-like single crystals (whiskers) have been synthesized from Ca-Al-doped precursors in the presence of Te. The main aim of this paper is to determine the importance of the simultaneous use of Al, Te and Ca in promoting YBCO whiskers growth with good superconducting properties (T = 79-84 K). Further, single-crystal X-ray diffraction (SC-XRD) refinements of tetragonal YBCO whiskers (P4/mmm) are reported to fill the literature lack of YBCO structure investigations. All the as-grown whiskers have also been investigated by means of X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Our results demonstrate that the interplay of Ca, Te and Al elements is clearly necessary in order to obtain superconducting YBCO whiskers. The data obtained from SC-XRD analyses confirm the highly crystalline nature of the whiskers grown. Ca and Al enter the structure by replacing the Y and the octahedral coordinated Cu1 site, respectively, as in other similar orthorhombic compounds, while Te does not enter the structure of whiskers but its presence in the precursor is essential to the growth of the crystals.

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Single-crystal growth and characterization of REBa2Cu4O8 and Y1−xCaxBa2Cu4O8

Cited by 11 publications

References 19 publications

X-ray crystal structures of Al-doped (Y,Ca)Ba₂Cu₃O_7−ywhiskers

X-ray crystal structures of Al-doped (Y,Ca)Ba₂Cu₃O_7−ywhiskers

Single-crystal growth and properties of substituted

Effect of Al and Ca co-doping, in the presence of Te, in superconducting YBCO whiskers growth

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Single-crystal growth and characterization of REBa2Cu4O8 and Y1−xCaxBa2Cu4O8

Cited by 11 publications

References 19 publications

X-ray crystal structures of Al-doped (Y,Ca)Ba2Cu3O7−ywhiskers

X-ray crystal structures of Al-doped (Y,Ca)Ba2Cu3O7−ywhiskers

Single-crystal growth and properties of substituted

Effect of Al and Ca co-doping, in the presence of Te, in superconducting YBCO whiskers growth

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X-ray crystal structures of Al-doped (Y,Ca)Ba₂Cu₃O_7−ywhiskers

X-ray crystal structures of Al-doped (Y,Ca)Ba₂Cu₃O_7−ywhiskers