Chemical Composition and Microstructure of Magnetically Melt-Textured Bi2Sr2Ca0.8Dy0.2Cu2O8−y

Abstract

Dysprosium-doped Bi-based 2212 materials have been synthesized in the presence of a magnetic field, applied perpendicularly to the lateral face of a cylinder, by a melt-textured growth process. Thick (well oriented) layers of different chemical composition have been observed. A dysprosium-doped 2212 phase (the expected D phase) and a dysprosium-free bismuth-rich and strontium-deficient 2212 phase have been found. It is argued that the latter is a so-called M phase. Other impurity phases have been observed, connected with both 2212-type layers. A novel aspect of this work is the calcium solubility at the strontium site in the 2201 structure, and inversely the strontium solubility at the calcium site in the 8250 structure.

Broadening of the resistive transition in polycrystalline Bi/Pb-2223

“…However, pinning centres can be secondary phases. Therefore some optimization must be found and that is why so many synthesis routes have been attempted [1][2][3][4][5][6][7][8][9][10][11][12][13][14], including rare earth substitution for grain alignment in a magnetic field. Let us recall that the role of Pb is still disputed.…”

Texturing studies on bulk crystals

“…Due to different processing techniques and dopants, apart from CuO and Bi-2201 phases, variety of nonsuperconducting phases like (Ca,Sr) 2 CuO 3 , Bi 2 SrCaO 5 , Bi 2.2 SrO 2.8 and Bi 9 Sr 11 Ca 5 O x were identified in between the superconducting grains [8]. Stassen et al studied the texturing nature of the Dy doped Bi-2212 polycrystalline sample by applying (1.2 T) magnetic induction during the process and it ended up with a multi-phase textured compound [9]. Awana et al reported that the valence state of the Pr and Ce varies between 3 + and 4 + while in the formation of Bi-2212 phase [10].…”

Textured BSCCO superconductors produced by magnetic pulsed compaction and hot pressing

“…Techniques of texturation used so far are based on solidification from a melt in a thermal gradient [1] or in a magnetic field [2][3][4][5][6][7][8][9][10][11]: magnetic melt texturizing (MMT) [2][3][4][5][6][7][8][9], zone melting [10,11], etc. Other techniques use the effect of isostatic or uniaxial pressure applied at low or high temperature [12][13][14][15][16][17][18].…”