Structure and properties of BSCCO-whiskers grown from amorphous precursors with foreign dopants

doi:10.1016/0921-4534(96)00334-6

Physica C: Superconductivity

Volume 266, Issues 1–2, 20 July 1996, Pages 115-126

https://doi.org/10.1016/0921-4534(96)00334-6 Get rights and content

Abstract

The process of BSCCO whisker growth from varying Bi₂Sr₂Ca₃Cu₅Al_xM_yO_z(M = Li, Mg,Pb, Y, Zr, V, Nb, Mo) compositions of amorphous precursor have been investigated. The Al₂O₃ZrO₂ double oxide favours the whisker growth even if the glass precursor contains a crystalline portion. The whiskers grown from a 2235 plate and from 2235AlZr plate had a similar cation composition, but in the second case the Sr and Cu content in the crystal tends to be lower. The Al and Zr additives are distributed uniformly inside the plates with foreign framework fabrication. The variation of whisker structure parameters and superconducting properties have been investigated. The tunnelling characteristics for break junctions of whiskers are discussed and a model of BSCCO whisker growth is presented.

References (17)

I. Matsubara et al.
Physica C
(1992)
T. Kasuga et al.
J. Crystal Growth
(1994)
I. Matsubara et al.
J. Crystal Growth
(1994)
T.E. Oskina et al.
Physica C
(1994)
I. Matsubara et al.
J. Crystal Growth
(1991)
P.B. Mozhaev et al.
Physica C
(1994)
H. Komatsu et al.
Physica C
(1991)
Ya.G. Ponomarev et al.
Physica C
(1995)

There are more references available in the full text version of this article.

Cited by (24)

Al doping influence on crystal growth, structure and superconducting properties of Y(Ca)Ba<inf>2</inf>Cu<inf>3</inf>O<inf>7-y</inf> whiskers
2013, Journal of Alloys and Compounds
Citation Excerpt :
One of the main concerns about YBCO whiskers employment for these kinds of investigation is their synthesis in useful quantities, with respect to the BSCCO counterpart. As a matter of fact, much information is given in the literature about BSCCO whiskers and what is favoring or allowing their growth [11]. In this case, alumina addition as a precursor dopant has been found to drastically enhance the formation of such whiskers [12–15].
We synthesized Al doped Y(Ca)Ba₂Cu₃O₇₋_y (YBCO) whiskers via the solid state reaction method. Al doping was systematically varied in the nominal cationic stoichiometry of YBa₂Cu₃CaTe_0.5Al_xO₇₋_y, with 0 ⩽ x ⩽ 0.5. The amount of the grown whiskers increases for nominal Al addition up to x = 0.05, decreasing for larger concentrations. The concentration of Al incorporated in the crystals (x′) is always higher with respect to the starting stoichiometry and shows a gradient along its length, with a higher amount at the tip regions. The single crystal diffraction analyses show an increasing tetragonal character with increasing x′, with a transition from the orthorhombic to the tetragonal system for x′ = 0.13, which is in agreement with the worsening of electrical transport properties and disappearing of superconductivity for x′ = 0.19.
Crystallization of glass-ceramic Bi<inf>3</inf>Sr<inf>2</inf>Ca <inf>2</inf>Cu<inf>3</inf>O<inf>y</inf> superconducting system
2013, Journal of Crystal Growth
Citation Excerpt :
In order to achieve good superconducting properties, the crystallization mechanism and so kinetics must be carefully determined. Some models for the crystallization mechanism in the HTc materials have been developed by some research groups, such as vapor–liquid–solid (VLS) mechanism [6–8], vapor-phase-deposition on a screw dislocation mechanism [9], growth via ‘melt transport under a temperature gradient’ (MTTG) mechanism [10,11], ‘Microcrucible’ self supporting mechanism [12,13], generalized growth mechanism (GGM) [14], solid-state growth [15], growth induced by the inner stress from the substrates [16], self-flux growth mechanisms [17,18], seeded growth [19,20], models depending based on the ‘catalytic’ impurity [6]. However, there is no consensus among the models.
In this study, the nucleation and the crystallization of the material with nominal composition of Bi₃Sr₂Ca₂Cu₃O_δ have been investigated, depending on the heat treatment conditions. It was found that 4 and 8-fold branched nuclei on the samples occurred with increasing the heat treatment temperature. Finally, crystallization occurred with further increase of the temperature. The needle-like crystals (whiskers) perpendicular to the sample surface was formed above 800 °C, which consisted of the Bi-2212 phase. The results clearly showed that the anisotropy of surface tension is the most important parameter in determining the shape of the nucleus.
Thermodynamic growth model of single crystal Bi-2212 whisker
2012, Physica C: Superconductivity and its Applications
Citation Excerpt :
The Melt Transport under Temperature Gradient model is based on the fast transport of ions in the matrix. The driving force is the temperature gradient in the sample [15–17]. The Microcrucible model was suggested by Matsubara et al. [18].
In this study the growth mechanism of superconducting Bi-2212 whiskers is investigated from a thermodynamic point of view. The evolution of the free energy of the growth region in the main matrix is evaluated by estimating that of its surface energy. It is shown that the local free energy change for partial melting is the same as that of the whole structure of the sample. It is pointed out that the formation of whiskers requires a higher energy than that of plate like grains.
The single crystal superconducting Bi-2212 whiskers fabrication and their thermal transport properties
2010, Journal of Alloys and Compounds
In this study, we have fabricated the superconducting single crystal whiskers using glass–ceramic BiSrCaCuO material. The crystallization kinetic studies (crystallization activation energy, E_a, and the Avrami parameter, n,) were carried out using DTA data. The oxygen diffusion energy was calculated using TG data. XRD and SEM analysis of the whiskers showed Bi-2212 phase formation and the c-axis orientation. The in-plane resistivity, ρ_ab, and the out-of-plane resistivity, ρ_c, properties of the whiskers were investigated. The thermoelectric power, S(T), value between 10 and 300 K is found to be positive, indicating that charge carriers in the whiskers are holes. We analyzed the thermoelectric power as a function of temperature with “Two band model with linear T-term” Linear temperature dependence in the thermal conductivity down to T_c and then a sharp rise just below T_c were obtained.
Application of elevated magnetic fields during growth of BiSrCaCuO superconducting whiskers and studies of growth defects for better understanding of the growth mechanism
2004, Journal of Crystal Growth
Citation Excerpt :
The role of the atmosphere (cation and oxygen) can be active, i.e. cations in the vapor state are supplied to the growth site of the whiskers generating a chemical gradient or of passive type, i.e. cation vapor environment ensures local equilibrium with liquid phase and prevention of cation evaporation and escape from the growth site. For the first case of active role, the driving force would be super-saturation of the liquid due to the continuous arrival of cation vapors at the growth site and for the situation of the passive role, the driving force of the self-growth of whiskers should be thermal gradients [21,22] or capillarity forces of the liquid [18] generating the necessary chemical gradient. On the other hand, analysis of the profile of the kinetics curves of growth are closer to the VLS model [7].
Superconducting whiskers of Bi-2212 have been grown by an airtight crucible method in elevated magnetic fields, up to 10 T. Growth behavior with and without application of a magnetic field, as well as the SEM detailed study of the growth defects of the whiskers allow to emphasize some aspects of the growth mechanism. The conclusion is that whiskers are growing mainly through continuous crystallization at the base-end and from the so-called ‘micro-crucible’ formed by the glassy or powdered substrates. The supply of cations by a vapor transfer is very probable, but is taking place to the micro-crucible reaction site rather than to the droplet, as in the classic vapor–liquid–solid (VLS) growth mechanism. Therefore, whiskers grow by a modified VLS–microcrucible mechanism (MVLS–MC). Application of magnetic fields during growth has proven to be a powerful tool to investigate and influence some processes. Observation of stoichiometric Bi(Pb)-2212, CuO and Ca₂CuO₃ whiskers is also reported.
Effect of atmospheres on characterization of Bi-based superconducting whiskers
2003, Physica C: Superconductivity and its Applications
We prepared Bi₂Sr₂Ca_n−1Cu_nO_y (Bi-based) whiskers by an Al₂O₃-seeded glassy quenched platelet (ASGQP) method. As a result, the O₂ gas flow rates during the whisker growth did not affect the growth rates and the critical temperatures (T_c) of the whiskers, whereas affected the critical current density (J_c). The whisker with maximum J_c was grown at the O₂ gas flow rate of 120 ml/min, and its value was about 2 × 10⁵ A/cm² at 44 K, 0 T. The optimum O₂ gas flow rate for high J_c Bi-based whiskers in the ASGQP method was about 120 ml/min.

View all citing articles on Scopus

¹: Permanent address: Department of Physics, Bergische Universität Wuppertal, Gauss-Str. 20, D-42097 Wuppertal, Germany.

View full text

Structure and properties of BSCCO-whiskers grown from amorphous precursors with foreign dopants

Abstract

Physica C

J. Crystal Growth

J. Crystal Growth

Physica C

J. Crystal Growth

Physica C

Physica C

Physica C