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摘要
Samples of Nd1.85-xCe0.15CaxCuOy are characterized by thermoelectric power and variable-temperature x-ray diffraction. For the superconducting sample Nd1.85Ce0.15CuOy, S is positive in the whole measuring temperature range and weakly dependent on temperature; for the Ca-doped samples, Nd1.85-xCe0.15CaxCuOy, S shows a negative and strong dependence on temperature at low temperature for large x. It is striking that Ca doping leads to a sharp peak at about 200 K for either the superconducting samples Nd1.85-xCe0.15CaxCuOy or the nonsuperconducting samples Nd2-xCaxCuOy. The strength of the peak increases with increasing x. Low-temperature x-ray diffraction shows that the lattice parameters decrease with decreasing temperature and an anomaly is observed at the corresponding temperature.
- 出版日期1997-2-17
- 单位中国科学院; 中国科学技术大学
