Superconducting properties of Bi<sub>2-x-y</sub>Pb<sub>x</sub>Sn<sub>y</sub>Sr<sub>2</sub>Ca<sub>2</sub>Cu<sub>3</sub>O<sub>z</sub>
H M Seyoum; J M Habib; L H Bennett; W Wong-Ng; A J Shapiro; L J Swartzendruber; H M Seyoum; Dept. of Phys., Univ. of the District of Columbia, Washington, DC, USA; J M Habib; Dept. of Phys., Univ. of the District of Columbia, Washington, DC, USA; L H Bennett; Dept. of Phys., Univ. of the District of Columbia, Washington, DC, USA; W Wong-Ng; Dept. of Phys., Univ. of the District of Columbia, Washington, DC, USA; A J Shapiro; Dept. of Phys., Univ. of the District of Columbia, Washington, DC, USA; L J Swartzendruber; Dept. of Phys., Univ. of the District of Columbia, Washington, DC, USA
Журнал:
Superconductor Science and Technology
Дата:
1990-12-01
Аннотация:
Two systematically processed series, Bi<sub>1.6</sub>Pb<sub>x</sub>Sn<sub>0.4-x</sub>Sr<sub>2</sub>Ca<sub>2</sub>Cu<sub>3</sub>O<sub>z</sub> and Bi<sub>1.9-x</sub>Pb<sub>x</sub>Sn<sub>0.1</sub>Sr<sub>2</sub>Ca<sub>2</sub>Cu<sub>3</sub>O<sub>z</sub> (where X ranges from 0 to 0.4) have been examined via magnetization measurements X-ray diffraction and scanning electron microprobe. In addition to observing the often reported high T<sub>c</sub> superconducting transition temperatures at 80 K (2212) and 110 K (2223), a range of well resolved transition temperatures have been found, implying the possible existence of new phases. The presence of Sn in these materials appeared to suppress the formation of the low T<sub>c</sub> Raveau 2201 phase. Also observed was an ordered variation in the amount of flux pinning as the Sn and Pb concentrations were changed. The authors suggest that Sn increases flux pinning by forming the compound Sr<sub>3</sub>Sn<sub>2</sub>O<sub>7</sub>.
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