TY - JOUR
T1 - Control of carrier concentration in Bi-2212
AU - Yamashita, S.
AU - Kasai, T.
AU - Fujii, T.
AU - Watanabe, T.
AU - Matsuda, A.
PY - 2010/12
Y1 - 2010/12
N2 - We realized highly underdoped Bi-2212 crystals by using a Bi substitution into a Sr site (x), together with the excess oxygen (δ) control. The samples with x = 0-0.3 were grown by a traveling solvent floating zone method. For each x, δ was varied using the precision annealing method [1]. Under several assumptions, the effective Bi valence was evaluated to be +2.2, which is much lower than the formal valence +3. This indicates that the Bi substitution accompanies additional uptake in excess oxygen. The x dependent δ-doping level p relation and the observed shrink in the c-axis length are consistent with this assumption. Based on the decomposition phase diagram obtained in this study, Tc of 22 K was realized by careful annealing treatments. The samples showed a superconducting volume fraction of over 50%.
AB - We realized highly underdoped Bi-2212 crystals by using a Bi substitution into a Sr site (x), together with the excess oxygen (δ) control. The samples with x = 0-0.3 were grown by a traveling solvent floating zone method. For each x, δ was varied using the precision annealing method [1]. Under several assumptions, the effective Bi valence was evaluated to be +2.2, which is much lower than the formal valence +3. This indicates that the Bi substitution accompanies additional uptake in excess oxygen. The x dependent δ-doping level p relation and the observed shrink in the c-axis length are consistent with this assumption. Based on the decomposition phase diagram obtained in this study, Tc of 22 K was realized by careful annealing treatments. The samples showed a superconducting volume fraction of over 50%.
KW - Bi-2212
KW - STM
KW - Superconductor
KW - Underdoped
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U2 - 10.1016/j.physc.2009.11.065
DO - 10.1016/j.physc.2009.11.065
M3 - Article
AN - SCOPUS:78649698224
SN - 0921-4534
VL - 470
SP - S170-S172
JO - Physica C: Superconductivity and its applications
JF - Physica C: Superconductivity and its applications
IS - SUPPL.1
ER -