Effects of substituting calcium for yttrium on the properties of YBa2Cu3O7- delta.
Effects of substituting calcium for yttrium on the properties of YBa2Cu3O7- delta.
复制标题
钙替代钇对YBa2Cu3O7-δ性能的影响。
DOI：
10.1103/physrevb.47.6054
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Knizhnik
中科院分区：
文献类型：
--
作者：
Fisher;Genossar;Kuper;Patlagan;Reisner;Knizhnik
我们报告了单相烧结材料的室温晶格参数、温度高达 300 K 的电阻率 (\ensuremath{\rho}) 以及高达 400 K 的绝对热电势的测量结果。 ${\mathrm{Y}}_{1\mathrm{\ensuremath{-}}\mathit{y}}$${\mathrm{Ca}}_{\mathit{y}}$${\mathrm{Ba}} _{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$,对于 y=0\char21{}0.3 和 \ensuremath{\delta} 的值范围。对于纯${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$，我们证实了之前的报告，即存在最优\ensuremath{\delta}，其中${\mathit{T}}_{\mathit{c}}$ 最大（${\mathit{T}}_{\mathit{c}\mathit{m}}$），并且热电势在此浓度附近改变符号。在 y=0.1 的样本中观察到类似的行为，尽管 ${\mathit{T}}_{\mathit{c}\mathit{m}}$ 较低。对于 y=0.2 和 0.3，${\mathit{T}}_{\mathit{c}}$(\ensuremath{\delta}) 的最大值趋于平稳。 Ca掺杂对负热电势的增强幅度远小于预期。这可能是由于 Ca 引入的大部分额外电荷被屏蔽，主要是通过同时引入氧空位。
We report measurements of the room-temperature lattice parameters, of the resistivity (\ensuremath{\rho}) for temperatures up to 300 K, and of the absolute thermoelectric power up to 400 K, of single-phase sintered ${\mathrm{Y}}_{1\mathrm{\ensuremath{-}}\mathit{y}}$${\mathrm{Ca}}_{\mathit{y}}$${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$, for y=0\char21{}0.3 and for a range of values of \ensuremath{\delta}. For pure ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ we confirm earlier reports that an optimal \ensuremath{\delta} exists, for which ${\mathit{T}}_{\mathit{c}}$ is maximal (${\mathit{T}}_{\mathit{c}\mathit{m}}$), and that the thermoelectric power changes sign in the vicinity of this concentration. Similar behavior, though with a lower ${\mathit{T}}_{\mathit{c}\mathit{m}}$ is observed in samples with y=0.1. For y=0.2 and 0.3, the maximum of ${\mathit{T}}_{\mathit{c}}$(\ensuremath{\delta}) flattens off into a plateau. The enhancement of the magnitude of the negative thermoelectric power by Ca doping is much less than expected. This is probably due to the fact that most of the extra charge introduced by the Ca is screened, mainly by the cointroduction of oxygen vacancies.