Growth of thick single crystals of the high Tc superconductor Bi2Sr2CaCu2O8+x (original) (raw)
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Bulletin of Materials Science, 1991
Single crystals of Bi2Sr2CaCu2Os (2212) have been grown by self-flux technique using stoichiometric and non-stoichiometric melts of excess CuO and Bi20 3. Single-crystal and powder X-ray diffraction studies have been made on the grown crystals to confirm their single crystallinity and structure respectively. Resistivity and susceptibility measurements provide information on the superconducting nature of the crystals. The effects of fluxing agents and starting composition on surface morphology and superconductin~ properties have been discussed.
Morphology of growth of Bi2Sr2CaCu2O8 single crystals
Journal of Low Temperature Physics, 1996
A good correlation of twins on the basal surface of flux-grown Bi2Sr2CaCu20x (BSCCO) single crystals with surface growth steps is ohserved, the b-axis being perpendicular to the steps and, thus, parallel to the growth direction. It is found that mono-twin BSCCO single crystals produced by the travelling solvent floating zone method also grow preferentially along b, i.e. nearly perpendicularly to the boule axis, contrary to the common belief. This new understanding of the morphology of growth explains the nature of major defects in these crystals, which considerably change their measured superconducting properties, in a different way. PACSnumbers: 7~.62.Bf, 7~.25.Gz, 7~.72.Hs. 1529
Growth and superconducting properties of (Bi1 − xPbx)2Sr2CaCu2O8 single crystals
Materials Research Bulletin, 1990
Superconducting single crystals of the compound (Bil_,Pb,)2Sr2CaCu2Os with a critical temperature above 80 K have been synthesized using the method reported by Wang Hong et al. (1). The X-ray diffraction data do not confirm the existence of a new superconducting phase in spite of the similarity of the powder X-ray diffraction patterns to those of Ref. 1. The estimated lattice constants, a = 5.4/~, b = 5.4/~, c = 30.8 /~, and the composition are characteristic of the 80-K phase of the Bi compound family. The electrical and magnetic measurements indicate a high crystal anisotropy.
A new single crystal growth method of (Bi,Pb)2Sr2CaCu2Oz superconductor
Journal of Crystal Growth, 1999
A new method was developed to elaborate (Bi,Pb) Sr CaCu O V (Pb-2212) single crystals. The new process makes use of a progressive increase of the oxygen chemical potential in gaseous phase at a constant temperature 875°C below the incongruent melting temperature (¹"884°C) of the Pb-2212. The composition of this crystal is homogeneous and very close to the stoichiometric composition. Structure characterization of a single crystal was realized by measuring the (0 0 l) X-ray diffraction intensity. The superconducting temperature ¹ "90 K with a sharp transition width (10-90% level) between 5 and 10 K was determined from resistivity and DC susceptibility measurments.
Investigations for the growth of large underdoped Bi2Sr2CaCu2O8+δ single crystals
Journal of Crystal Growth, 2010
In order to study superconducting physical properties by neutron scattering technique, the necessity to obtain large and high quality optimally doped Bi 2 Sr 2 CaCu 2 O 8 + d (Bi-2212) and underdoped Bi-2212 single crystals is prominent. Three routes have been investigated to reach this goal: synthesis under low oxygen pressure by travelling solvent floating zone technique (TSFZ), TSFZ synthesis of yttrium doped Bi 2 Sr 2 Ca 1 À x Y x Cu 2 O 8 + d and TSFZ synthesis under air followed by post-annealing treatments. With decreasing p(O 2) from ambient pressure to 0.1 atm during the TSFZ growth, the superconducting transition temperature, T c , transits from 87 K (slightly overdoped) to 93 K. On yttrium doped growth, a systematic study of Bi 2 Sr 2 Ca 1 À x Y x Cu 2 O 8 + d , where x= 0-0.5, was undertaken to correlate the nominal yttrium composition with the yttrium crystal composition and to control the T c as a function of yttrium composition. 85 K underdoped Bi-2212 crystals with a size up to 220 mm 3 and a 5 K transition width, DT c , were obtained by post-annealing under p(O 2)= 0.1 atm at 450 1C.
Crystal Research and Technology, 2004
Large and high‐quality single crystals of both Pb‐free and Pb‐doped high temperature superconducting compounds (Bi1‐xPbx)2Sr2Ca2Cu3O10‐y (x = 0 and 0.3) were grown by means of a newly developed “Vapour‐Assisted Travelling Floating Zone” technique (VA‐TSFZ). This modified zone‐melting technique was realised in an image furnace and allowed for the first time to grow Pb‐doped crystals by compensating for the Pb losses occurring at high temperature. Crystals up to 3×2×0.1 mm3 were successfully grown. Post‐annealing under high pressure of O2 (up to 10 MPa at T = 500°C) was undertaken to enhance Tc and improve the homogeneity of the crystals. Structural characterisation was performed by single‐crystal X‐ray diffraction (XRD) and the structure of the 3‐layer Bi‐based superconducting compound was refined for the first time. Structure refinement showed an incommensurate superlattice in the Pb‐free crystals. The space group is orthorhombic, A2aa, with cell parameters a = 27.105(4) Å, b = 5.41...
Investigations for the growth of large underdoped Bi2Sr2CaCu2O8+ [delta] single crystals
Journal of Crystal …, 2010
In order to study superconducting physical properties by neutron scattering technique, the necessity to obtain large and high quality optimally doped Bi 2 Sr 2 CaCu 2 O 8 + d (Bi-2212) and underdoped Bi-2212 single crystals is prominent. Three routes have been investigated to reach this goal: synthesis under low oxygen pressure by travelling solvent floating zone technique (TSFZ), TSFZ synthesis of yttrium doped Bi 2 Sr 2 Ca 1 À x Y x Cu 2 O 8 + d and TSFZ synthesis under air followed by post-annealing treatments. With decreasing p(O 2) from ambient pressure to 0.1 atm during the TSFZ growth, the superconducting transition temperature, T c , transits from 87 K (slightly overdoped) to 93 K. On yttrium doped growth, a systematic study of Bi 2 Sr 2 Ca 1 À x Y x Cu 2 O 8 + d , where x= 0-0.5, was undertaken to correlate the nominal yttrium composition with the yttrium crystal composition and to control the T c as a function of yttrium composition. 85 K underdoped Bi-2212 crystals with a size up to 220 mm 3 and a 5 K transition width, DT c , were obtained by post-annealing under p(O 2)= 0.1 atm at 450 1C.
Nucleation and growth of superconducting phase in Bi2Sr2Ca2.2Cu3OX
Physica C: Superconductivity, 2003
The nucleation and growth of a superconducting phase were investigated using ball milled Bi 2 Sr 2 Ca 2:2 Cu 3 O X precursor powders. As the heat-treatment time increased, more Bi 2 Sr 2 Ca 1 Cu 2 O X (Bi-2212) changed to Bi 2 Sr 2 Ca 2 Cu 3 O X (Bi-2223) and the major second phase was changed from (Sr,Ca) 14 Cu 24 O X (14:24) to (Sr,Ca) 2 Cu 1 O X . Following the formation of the Bi-2212 phase near the 14:24 phase, the Bi-2223 phase nucleated preferentially at the interface between the Bi-2212 and 14:24 phases in the relatively short time of 20 h. The preferential nucleation of Bi-2223 was explained by its structural similarity and low interfacial energy with both the Bi-free and Bi-2212 phases. The texturing mechanism of Bi-2223 was discussed on the basis of its nucleation behavior.
Current Applied Physics, 2008
Single crystals of (Bi 1Àx Pb x ) 2 Sr 2 Ca 2 Cu 3 O 10+d (x = 0 and 0.16) (sizes up to 3 · 2 · 0.1 mm 3 ) have been grown by means of a newly developed ''vapour-assisted travelling solvent floating zone'' technique (VA-TSFZ). Post-annealing under high pressure of O 2 (up to 10 MPa at T = 500°C) was applied to enhance T c (up to 111 K) and improve the homogeneity of the crystals (DT c 6 1 K). The structure of both Pb-free and Pb-doped Bi-2223 was refined for the first time from single crystal X-ray diffraction (XRD) data. The unit cell of the average structure is pseudo-tetragonal with a = 5.4210 , b = 5.4133(6) and c = 37.010(7) Å , and a = 5.395(1), b = 5.413(1) and c = 37.042(11) Å , for the Pb-free and the Pb-doped phase, respectively. An incommensurate modulation in the direction of one of the short cell vectors has been defined (q $ 0.21 a * ), however, the structure can be conveniently described in a supercell with a fivefold volume (a = 27.105(4) Å ). With respect to the ''non-modulated'' structure, one additional oxygen atom for ten initial O was found to be inserted into the BiO layers. The superconducting anisotropy of Bi-2223 was found to be $50, from measurements of the lower critical field. The anisotropy of Bi-2223 is significantly reduced compared to that of Bi-2212, and this accounts for the enhanced irreversibility fields in Bi-2223. Furthermore, Bi-2223 has a higher critical current density, and a reduced magnetic relaxation rate compared to Bi-2212, which are both signatures of more effective pinning in Bi-2223 due to its reduced anisotropy.