Effects of TiO2 addition on the superconducting properties of Bi-Sr-Ca-Cu-O system (original) (raw)
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Optimization of Bi-2212 high temperature superconductors by potassium substitution
Superconductor Science and Technology, 2015
Polycrystalline bulks of Bi 2 Sr 2 Ca 1−x K x Cu 2.0 O 8+δ (Bi-2212) with x = 0, 0.05, 0.10 and 0.15 were fabricated by the spark plasma sintering technique. The influences of K doping on the microstructures, electronic structures, as well as the related superconducting properties, were systematically investigated. The XRD analyses confirmed that K + ions have successfully substituted into the matrix of Bi-2212, and lead to a systematical change of lattice parameters. Due to the change of thermodynamic properties, bulks with higher density, larger grain size and better texture structures were obtained after doping. Therefore, ac susceptibility measurement revealed the optimization of intergrain connections, which lead to the optimization of both selfand in-field critical current density, J c of this system. The optimization of microstructures also caused the enhancement of surface pinning. Based on the enhancements of both intergrain connections and flux pinning properties, an obvious improvement of critical current density was obtained with the optimal doping content of K = 0.05. Meanwhile, Bi-2212 single filament tapes with K doping content of 0 and 0.05 were also fabricated by the powder-in-tube process. The XRD patterns also proved the successful doping of K ions in the Bi-2212 matrix. The critical current density J c , measured by the transport method under the magnetic field from 0 to 20 T at 4.2 K, proved the effectiveness of K doping on the enhancement of flux pinning properties of Bi-2212.
One and multi-step solid state reaction methods were used to prepare a high temperature superconductor with a nominal composition Bi 2−x Li x Pb 0.3 Sr 2 Ca 2 Cu 3 O 10+δ for (0 ≤ x ≤ 0.5). The effect of preparation conditions and substituting Li on Bi sites had been investigated by the use of X-ray diffraction, resistance measurements and oxygen content to obtain the optimum conditions for formation and stabilization of the 2223-phase. It has been found that intermediate grinding will force to convert and accelerate the formation rate of the 2223-phase. The morphological analyses were carried out by SEM. The results showed that the multi-step technique was appropriate to prepare the composition Bi2−xLixPb0.3Sr2Ca2Cu3O10+δ. X-ray diffraction analysis showed two phases: high-T C phase 2223 and low-T C phase 2212 with orthorhombic structure for all samples. However, the optimum concentration was found for 0.3 which improved the microstructure and had the highest T C value 130 K for the highest value of oxygen content.
Modern Physics Letters B, 2005
0, 0.015, 0.03, 0.06, 0.09 and 0.12. Samples of series Bi 1.6 Pb 0.4 Sr 2 Ca 2 Cu 3-x Zn x O 10-δ with x = 0.0, 0.015, 0.03, 0.06, 0.09 and 0.12 are synthesized by solid-state reaction route. All the samples crystallize in tetragonal structure with majority (> 90%) of Bi-2223 (Bi 2 Sr 2 Ca 2 Cu 3 O 10 ) phase (c-lattice parameter ~ 36 A 0 ). The proportion of Bi-2223 phase decreases slightly with an increase in x. The lattice parameters a and c of main phase (Bi-2223) do not change significantly with increasing x. Superconducting critical transition temperature (T c ) decreases with x as evidenced by both resistivity [ρ(T)] and AC magnetic susceptibility [χ(T)] measurements. Interestingly the decrement of T c is not monotonic and the same saturates at around 96 K for x > 0.06. In fact T c decreases fast (~10K/at%) for x = 0.015 and 0.03 samples and later nearly saturates for higher x values. Present results of Zn doping in Bi-2223 system are compared with Zn doped other HTSC (High temperature superconducting) systems, namely the RE-123 (REBa 2 Cu 3 O 7 ) and La-214 ((La,Sr) 2 CuO 4 ).
Superconductivity in La-doped Bi “2201”
Physica C: Superconductivity, 1993
La 3+ substitution into the Bi 2201 structure, of the "ideal" composition Bi2Sr2CuO6, has been investigated by means of an extensive phase diagram study into the solid solution formation at 885 °C in air. Single phase solid solutions may be represented by the formula Bi2÷~r2_~_yLayCuO6, where y has a maximum value of 0.6. With increasing La content, the crystal symmetry changes from orthorhombic to tetragonal and the incommensurate supercell becomes less pronounced, as indicated by a decrease in intensity of the supercell X-ray powder reflections. Superconducting Tcon~ct values vary systematically with cation contents x, y and oxygen content ~; a maximum Tc of 36.5 K is observed for composition x=-0.05, y= 0.4.
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.
The effect of Al2O3 and MgO addition on the superconducting properties of Bi, Pb-2223
THE 2ND UNIVERSITAS LAMPUNG INTERNATIONAL CONFERENCE ON SCIENCE, TECHNOLOGY, AND ENVIRONMENT (ULICoSTE) 2021
In this study, we investigate the effect of Al2O3 and MgO addition on the critical temperature of the (Bi, Pb)2Sr2Ca2Cu3O10+ (Bi, Pb)-2223 superconductors. The (Bi, Pb)-2223/ Al2O3 and (Bi, Pb)-2223/MgO composite were synthesized using a sol-gel method. BPSCCO with nominal composition was sintered at 840°C for 60 hours Phase investigation and Morphology observation were carried out by using an X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM), respectively. Critical onset temperature (Tc-onset), and critical offset temperature (Tc-offset) used the fourpoint probe technique. SEM image showed that the BPSCCO superconductor's morphological characteristics seem to dominate the microstructure for all samples. The best result was found in the (Bi, Pb)-2223 with addition 1% MgO.
Structural and Superconducting Properties of Bi1.7Pb0.3VxSr2Ca2Cu 2.7Ti0.3O10+δ. System
Superconductivity is a unique and powerful phenomenon of nature. it is a characterized by the disappearance of electrical resistance in various metals, alloys and compounds ). The effects c when they are cooled below a certain temperature (critical temperature, T bulk and δ 10+ O 0.3 Ti 2.7 Cu 2 Ca 2 Sr x V 0.3 Pb 1.7 of vanadium addition on the properties of Bi thin film samples for (0 ≤ x ≤ 0.4) were studied. The XRD analyses for all superconductor samples as bulk and thin films showed an orthorhombic structure with two superconducting phases . The critical temperature for the most films is less than t hat x V 0.3 Pb 1.7 of the bulk samples except for pure film. The surface morphology of bulk Bi and thin films before and after annealing obtained by AFM in 10+δ O 0.3 Ti 2.7 Cu 2 Ca 2 Sr three dimensions views. It was observed that the average roughness was higher at x= 0.2 (179.66nm) with a particle size of 219 nm
Effect of growth conditions on crystal morphology and superconductivity of Bi-2212 oxide
Physica C: Superconductivity, 1996
The effects of growth velocity and the nominal starting composition of the feed rod on the crystal morphology and stability of the solid-liquid interface in Bi-Sr-Ca-Cu-O high-T c superconducting oxides were studied by a floating zone method. The result showed that an indispensable condition for the growth of large single crystals is that the solid-liquid interface maintains a stable planar growth front. The planar solid-liquid interface tends to break down into a cellular growth interface if the velocity is increased above 0.2 mm/h. The largest single crystals of size 20 × 5.5 × 1.5 mm 3, along the a-, band c-axes, respectively, were grown in 6.5 mm diameter rods. The superconducting transition temperature of the as-grown single crystals varies from 84 to 92 K under the different growth velocities and nominal compositions of a feed rod. The homogeneity of the superconducting phase of the crystals also depends on the growth conditions.