Superconductivity of Bi-2201 (n=1) as influenced by the substitution of Pb and/or rare-earths (R=La, Nd and Pr)

Bi 2 (Sr, Ln) 2 CuO z (Ln = Nd, Sm) single crystals were successfully grown by a self-flux method from stoichiometric and (Bi, Cu)-rich melts. Thermal analysis and thermogravimetry were used to determine stability and the melting sequence of Bi 2 (Sr, Ln) 2 CuO z phases in air. As-grown crystals of the ideal Bi 2 (Sr, Ln) 2 CuO z phase, of dimensions 1 × 0.5 × 0.03 mm 3 , exhibit superconducting behaviour with critical temperature T c = 21 K for the Bi 1.9 Sr 1.6 Nd 0.6 CuO z crystal and T c = 14 K for the Bi 1.8 Sr 1.6 Sm 0.6 CuO z crystal. The compositions of these crystals were homogeneous and close to the stoichiometric composition. We report on the growth of Bi 2 Sr 2−x Sm x CuO z single crystals of large dimensions 9 × 3 × 0.03 mm 3 using Bi 2 Sr 1.5 Sm 0.5 CuO z as precursor and Bi 2 CuO 4 as flux.

Section: Xrdsupporting

confidence: 93%

Bi₂(Sr, Ln)₂CuO_z(Ln = Nd, Sm) phases: stability, crystal growth and superconducting properties

Faqir¹,

Kikuchi²,

Syono³

et al. 2000

“…Partial substitution of Sr by large atomic radius rare-earth elements such as La or Nd expands the superconducting range and also increases T c to 24-35 K [2,3]. When added La, the BiSrLaCuO system easily becomes superconducting, and the optimum substitution of La for Sr was shown to be 0.4 [4,5]. We have reported the synthesis of epitaxial Bi 2 Sr 2−x La x CuO 6+δ (BSLCO) films on (001) LaAlO 3 (LAO) and (001) SrTiO 3 (STO) substrates by in situ RF-magnetron sputtering [6].…”

Section: Introductionmentioning

confidence: 99%

Anisotropic resistivity in epitaxial films grown on tilted (001) substrate

Qin¹,

Zhang²,

Li³

1998

Epitaxial Bi 2 Sr 2−x La x CuO 6+δ thin films were successfully deposited on tilted (001) SrTiO 3 substrates by in situ RF-magnetron sputtering. Good alignment of the film b-axis with the incommensurate modulation along [110] of SrTiO 3 and the film c-axis tilted 6 • toward [111] from the surface normal were confirmed by XRD, AFM and XTEM. From the in-plane resistivity measurements, the in-plane and out-of-plane resistivities ρ a and ρ c were deduced.

“…Because the critical temperature is increased and the phase purity of Bi-2201 phase is improved by replacing Sr by La, some investigations on Bi 2 Sr 2−x R x CuO 6+y system have been carried out [1][2][3][4][5][6][7][8][9][10]. In this paper, the effects of composition, synthesis condition, oxygen content and F doping on superconductivity were investigated systematically.…”

Section: Introductionmentioning

confidence: 99%

The effects of composition, synthesis conditions, oxygen content and F doping on superconductivity and structure for R-substituted Bi-2201

Lan

Jia

et al. 1996

The effects of composition, synthesis conditions, oxygen content and F doping on superconductivity and structure for the R-substituted Bi-2201 compound was investigated by means of XRD and measurements of superconductivity. For the Bi 1.95 Sr 2.05−x R x CuO 6+y compound (R = La, Pr, Nd and Sm), the optimum value of x for T c is x = 0.4. When x = 0.4, the optimum sintering temperature is 840 • C for R = La, Pr and Nd, 820-830 • C for R = Sm. T c decreases with decreasing the ionic radius of R. For Bi 1.95 Sr 1.65 La 0.4 CuO 6+y , the optimum range of oxygen content is y = 0.28-0.33 and the superconductivity is improved by quenching. For F-doped Bi-2201, T c decreases with increasing F content.