• Title/Summary/Keyword: Na subsitution

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Effect of Na Substitution for the Ca Site in the Bi$_2$Sr$_2$Ca$_{1-x}$Na$_x$Cu$_2$O$_{8+y}$ Superconductors (Bi$_2$Sr$_2$Ca$_{1-x}$Na$_x$Cu$_2$O$_{8+y}$ 산화물 고온초전도체의 Ca 위치에 Na 치환 효과)

  • 이민수;송승용;이종용;송기영;최봉수
    • Journal of the Korean Ceramic Society
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    • v.35 no.10
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    • pp.1007-1013
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    • 1998
  • The samples of Bi2Sr2Ca1-xNaxCu2O8+y with various carrier concentration were synthesized by substituting Na for Ca ion. The superconducting properties hall coefficients and X-ray powder diffraction were measur-ed the sampled. Single phase samples were obtained for 0$\leq$x<0.3 of Bi2Sr2Ca1-xNaxCu2O8+y In the single phase the critical temperature. {{{{ { T}_{c } }} and carrier concentration increase with the increase of Na concentration pass through a maximum and then decreases. In the range of x$\geq$0.7 to the Na doped samples however we observed the metal-semiconductor transition. The c-axis seemed to decrease and a and b-axes increase with increasing Na concentration in the single phase. Decreasing of c-axis while increasing x is due to the smaller size of {{{{ {Na}^{+1 } }} ions to the {{{{ { Ca}^{+2 } }} ions. In the range of x>0.3 however the trend becomes ambiguous due to the inclusion of the 10K phase and impurity phase.

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