X-ray and Electron Diffraction Study of a Precipitation Phase in Nd_<1.85>Ce_<0.15>CuO_<4+y> Single Crystal(Condensed Matter : Electronic Structure, Electrical, Magnetic and Optical Properties)

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X-ray diffraction measurements have been performed to investigate a crystal structure of a precipitation phase in oxygen-reduced Nd_<1.85>Ce_<0.15>CuO_<4+y>(NCCO). A detailed structure analysis of the precipitation phase as well as the parent NCCO phase revealed that the precipitation phase is a cubic (Nd, Ce)_2O_3, which is distorted tetragonally by the surrounding NCCO phase. The averaged grain size of the precipitation phase exceeds 200Å parallel to the CuO_2 plane of the parent NCCO, while the size along layered direction is short-ranged (〜30Å). The grain thickness along layered direction is strongly correlated with the homogeneity of superconducting state. The volume fraction of the (Nd, Ce)_2O_3 phase is about 2%. We also performed electron diffraction as well as microscopy experiment, which confirms that the (Nd, Ce)_2O_3 phase segregate from the parent NCCO phase and exists as an epitaxial layer along the c-axis.
社団法人日本物理学会の論文
2005-08-15