Preferred Orientation Contribution to the Anisotropic Normal State Resistivity in Superconducting Melt-Cast Processed Bi2Sr2CaCu2O8+δ (original) (raw)
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Anisotropy of the superconducting properties of Bi2Sr2CaCu2O8
Solid State Communications, 1988
We report magnetoresistance measurements up to 20 teslas on the superconducting hightemperature compound Bi2Sr2CaCu208. The upper critical field is very anisotropic ; Hc2///I-Ic2± = 20. (HI/for H H c-axis and H.L for H//(a,b) plane). This value is twice larger than in YBa2Cu307, it demonstrates the stronger 2-D character of Bi2Sr2CaCu208.
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.
Enhanced superconducting performance of melt quenched Bi2Sr2CaCu2O8 (Bi-2212) superconductor
Materials Chemistry and Physics, 2013
We scrutinize the enhanced superconducting performance of melt quench Bismuth based Bi 2 Sr 2 CaCu 2 O 8 (Bi-2212) superconductor. The superconducting properties of melt quenched Bi-2212 (Bi2212-MQ) sample are compared with non-melted Bi2212-NM and Bi 1.4 Pb 0.6 Sr 2 Ca 2 Cu 3 O 10 (Bi-2223). Crystal structure and morphology of the samples are studied using X-ray diffraction and Scanning Electron Microscopy (SEM) techniques. The high field (14T) magneto-transport and DC/AC magnetic susceptibility techniques are extensively used to study the superconducting properties of the investigated samples. The superconducting critical temperature (T c) and upper critical field (H c2) as well as thermally activated flux flow (TAFF) activation energy are estimated from the magneto-resistive [R(T)H] measurements. Both DC magnetization and amplitude dependent AC susceptibility measurements are used to determine the field and temperature dependence of critical current density (J c) for studied samples. On the other hand, the frequency dependent AC susceptibility is used for estimating flux creep activation energy. It is found that melt quenching significantly enhances the superconducting properties of granular Bi-2212 superconductor. The results are interpreted in terms of better alignment and inter-connectivity of the grains along with reduction of grain boundaries for Bi2212-MQ sample.
Solid State Communications, 2012
We study the temperature dependence of the resistivity as a function of magnetic field in superconducting transition (T c onset-T c R=0) region for different Bi 2 Sr 2 CaCu 2 O 8+δ superconducting samples being synthesized using sol-gel method. The superconducting transition temperature (T c R=0) of the studied samples is increased from 32 K to 82K by simply increasing the final sintering temperature with an improved grains morphology. On the other hand, broadening of transition is increased substantially with decrease in sintering temperature; this is because T c onset is not affected much with grains morphology. Further broadening of the superconducting transition is seen under magnetic field, which is being explained on the basis of thermally activated flux flow (TAFF) below superconducting transition temperature (T c). TAFF activation energy (U 0) is calculated using the resistive broadening of samples in the presence of magnetic field. Temperature dependence of TAFF activation energy revealed linear temperature dependence for all the samples. Further, magnetic field dependence is found to obey power law for all the samples and the negative exponent is increased with increase in sintering temperature or the improved grains morphology for different Bi-2212 samples. We believe that the sintering temperature and the ensuing role of grain morphology is yet a key issue to be addressed in case of cuprate superconductors.
Compositional range of the Bi2Sr2CaCu2OxHTc-superconductor and its surrounding phases
Physica C: Superconductivity, 1992
The extension of the single-phase field of the two-layer superconductor Bi2Sr2CaCu208 is clarified for 830°C in air. The singlephase field of "2212" is a trigonal bipyramid with a length of 13.7 mol% parallel to the SrO-CaO edge, and an extension of 9 mol% perpendicular to it. The tolerance of the lattice concerning CuO variation is smaller than + 1.2 mol%. The CaO-rich solid solution is deficient in CuO compared to the ideal 22 12 solid solution, Bir (Sr, _$a,)rCurOs, whereas the SrO-rich side has excess CuO. Multiphase equilibria around "2212" as well as the single phase field were derived by combining the XRD and EDX results of 91 samples of different compositions with the previously published results. The intersections of the multiphase equilibria with three different planar sections of the compositional tetrahedron are shown.
Superconductivity up to 110 K in Bi2Sr2Ca2Cu3O10 compounds
Revue de Physique Appliquée, 1989
2014 Nous avons étudié dans le système Bi-Si-Ca-Cu-O le composé responsable de la supraconductivité jusqu'à 110 K, de formule idéale Bi2Sr2Ca2Cu3O10. Les mesures d'aimantation montrent la présence de deux phases dans les échantillons, avec des transitions à 80 K et 110 K. En faisant varier la composition et les traitements thermiques de ces échantillons, nous avons réussi à augmenter la proportion de la phase supraconductrice jusqu'à 110 K. L'effet Meissner atteint 30 % de -3/8 03C0 à 90 K pour les échantillons non dopés et 50 % pour ceux dopés au plomb. La grande réversibilité des courbes d'aimantation en fonction du champ au voisinage de Tc nous a permis d'évaluer le champ critique thermodynamique. Celui-ci conduit à un coefficient de chaleur spécifique électronique similaire à celui des composés YBaCuO. Abstract. 2014 In the Bi-Sr-Ca-Cu-O system, we have studied the compound with the ideal formula Bi2Sr2Ca2Cu3O10, responsible for the superconductivity up to 110 K. The magnetic measurements reveal the presence of two phases in the samples with superconducting transitions up to 80 K and 110 K. By varying the composition and the thermal treatment of those samples, we have succeeded in increasing the amount of the superconducting phase with Tc up to 110 K. The Meissner effect reaches 30 % of -3/8 03C0 at 90 K for the undoped samples and more than 50 % for the samples doped with Pb. Because of the high reversibility of the magnetization versus magnetic field around Tc, we have evaluated the critical thermodynamic field. This one gives an electronic specific heat coefficient similar to the one of YBaCuO compounds. Revue Phys. Appl. 24 (1989) 485-488 MAI 1989, Classification Physics Abstracts 74.70 Introduction.