Fabrication of Ca-doped large grain Y-Ba-Cu-O superconductors

Babu, N. Hari; Kambara, Makoto; McCrone, J. E.; Cooper, J. R.; Tallon, J. L.; Cardwell, D. A.

doi:10.1109/77.919823

Cited by 16 publications

(10 citation statements)

References 8 publications

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“…As mentioned earlier, the magnetization measurements (FC-ZFC separation) indicate towards flux pining, which could enhance the critical current density J c of the system. This is possible due to the increment of effective number of charge carriers in the matrix with increasing Ca content and hence increasing the effective current carrying through cross section [22,[20][21][22]. This is facilitated by inducing extra holes at grain boundary regions via controlling oxygen deficiency [20].…”

Section: Resultsmentioning

confidence: 99%

The Role of Ca in Superconducting and Magnetic Properties of Y1−x Ca x Ba2Cu3O7−δ (x=0.0–0.30)

Liyanawaduge

Kumar

et al. 2011

J Supercond Nov Magn

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We report the structural, superconducting, magnetic and granular properties of Y 1-x Ca x Ba 2 Cu 3 O 7-δ; x = 0.0, 0.1, 0.2 and 0.3. Rietveld fitted X-ray diffraction data confirms the single phase formation for all the samples. The orthorhombicity of parent compound (x = 0.0) decreases and becomes closer to the tetragonal structure for higher Ca concentration. The superconducting transition temperature (T c ) decreases with increasing Ca content due to both over-doping and ensuing disorder in the superconducting CuO 2 planes with Ca doping. DC susceptibility measurements reveal reduction of Meissner fraction with Ca doping, suggesting the flux pining effect. The AC susceptibility measurements reveal the enhancement of grain coupling with increasing Ca content in the system. The average grain size is found to increase with Ca doping.The Scanning Electron Microscopy (SEM) observations indicate better grain connectivity in terms of narrow grain boundaries for Ca doped samples. It is concluded that limited Ca doping enhances the superconducting performance of YBa 2 Cu 3 O 7-δ system.

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Section: Resultsmentioning

confidence: 99%

The Role of Ca in Superconducting and Magnetic Properties of Y1−x Ca x Ba2Cu3O7−δ (x=0.0–0.30)

Liyanawaduge

Kumar

et al. 2011

J Supercond Nov Magn

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“…Ever since the effect of calcium overdoping at the grain boundaries in the thin film was found, numerous studies relating to the calcium substitutions for the YBa 2 Cu 3 O z (YBCO or Y123) system have been performed to examine the physical properties of these compounds. In particular, several reports indicate that the value of charge carrier concentration ( p ) raised by calcium doping, which further influences the superconducting transition temperature ( T c ) and the critical current density ( J c ) of the polycrystalline powders, thin films, and melt‐processed bulks …”

Section: Introductionmentioning

confidence: 99%

“…To date, due to the difficulty in growing highly doped REBCO single crystals in centimeters, the top‐seeded melt‐textured growth (TSMTG) is considered to be a promising method to process large doped bulk superconductors. The effect of Ca doping has been investigated in melt‐processed YBCO and GdBCO bulk superconductors . Nevertheless, the growth of highly Ca‐doped REBCO single domain with a large size encountered two main obstacles: (1) the growth rate decreases significantly with the increasing CaCO 3 content; (2) unexpected spontaneous nucleation occurs as the amount of CaCO 3 is more than 1 wt% .…”

Section: Introductionmentioning

confidence: 99%

“…The effect of Ca doping has been investigated in melt‐processed YBCO and GdBCO bulk superconductors . Nevertheless, the growth of highly Ca‐doped REBCO single domain with a large size encountered two main obstacles: (1) the growth rate decreases significantly with the increasing CaCO 3 content; (2) unexpected spontaneous nucleation occurs as the amount of CaCO 3 is more than 1 wt% . Hence, it is necessary to investigate the doping effect on the growth behaviors to achieve the critical doping.…”

Section: Introductionmentioning

confidence: 99%

“…Hence, it is necessary to investigate the doping effect on the growth behaviors to achieve the critical doping. In addition, it was also demonstrated using differential thermal analysis (DTA) that the melting point of Y 1− x Ca x Ba 2 Cu 3 O z calcined powders raised by 10°C as the x value increased from 0 to 0.1 . As a result, high thermal stability seeds for inducing epitaxial growth of Ca‐doped YBCO bulks were correspondingly required, as the maximum processing temperature ( T max ) is supposed to increase with the CaCO 3 addition.…”

Section: Introductionmentioning

confidence: 99%

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Growth of Ca‐Doped Large Grain Gd–Ba–Cu–O Superconductors

Cheng

Kou

et al. 2012

J. Am. Ceram. Soc.

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The effect of calcium doping on growing GdBa 2 Cu 3 O z (GdBCO or Gd123) bulk superconductors using top-seeded melt-textured growth (TSMTG) method in air was studied. NdBCO thin films deposited on MgO substrate were effectively used as cold-seeds because of their superheating natures, which allow them enduring a higher maximum processing temperature (T max ) than that of a conventional TSMTG process. Several heavily Ca-doped GdBCO (up to 3 wt% CaCO 3 ) single domains were obtained without heterogeneous nucleation. Moreover, an interesting phenomenon of negative growth was observed during the cooling-down process of Ca-GdBCO, which prevented the grain from further crystallization. The compositional analysis revealed that the Ca content has a declined tendency from the initial growth region toward the edge. It is deduced that the effective Ca distribution coefficient k > 1, which gives rise to a decreased peritectic temperature (T p ) with the reduction of the Ca content, is the main origin of the negative growth behavior. To overcome this obstacle, a two-stage cooling procedure was developed, i.e., slow cooling followed by fast cooling, to compensate the loss of the growth driving force caused by the decrease of T p . Consequently, a highly doped Ca-GdBCO bulk was grown with a size of 14 mm 2 .

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Enhancement of Cystal Growth in Melt Texturing Ca‐Doped Y‐Ba‐Cu‐O Superconductors

Jongprateep

Doğan

2006

Ceramic Transactions Series

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Fabrication of Ca-doped large grain Y-Ba-Cu-O superconductors

Cited by 16 publications

References 8 publications

The Role of Ca in Superconducting and Magnetic Properties of Y1−x Ca x Ba2Cu3O7−δ (x=0.0–0.30)

The Role of Ca in Superconducting and Magnetic Properties of Y1−x Ca x Ba2Cu3O7−δ (x=0.0–0.30)

Growth of Ca‐Doped Large Grain Gd–Ba–Cu–O Superconductors

Enhancement of Cystal Growth in Melt Texturing Ca‐Doped Y‐Ba‐Cu‐O Superconductors

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