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Raman scattering of Nd 0.9 Ca 0.1 Ba 2 Cu 3 O 7−δ with different oxygen contents
Author(s) -
Zhao Yun,
Xing Tang Ding,
Zuo Jian,
Xu Cunyi
Publication year - 2001
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.657
Subject(s) - raman spectroscopy , oxygen , analytical chemistry (journal) , impurity , raman scattering , chemistry , seebeck coefficient , superconductivity , copper , stoichiometry , materials science , condensed matter physics , thermal conductivity , physics , organic chemistry , optics , composite material , chromatography
A series of Nd 0.9 Ca 0.1 Ba 2 Cu 3 O 7−δ samples with different oxygen contents were fabricated by the solid‐state reaction method and thermally treated under different conditions. The superconducting transition temperatures T c were measured to be above liquid nitrogen temperature. The measurements of the thermopower S showed a monotonic decrease with increasing oxygen content. The Raman peak of the apical oxygen O(4) stretching vibration shifts to higher wavenumber, which also shows a monotonic increase in oxygen content. Two modes at 224 and 597 cm −1 are assigned to the disorder‐induced stretching vibrations of copper and oxygen atoms, respectively. They arise from symmetry breaking from short‐chain fragments and are not due to impurity phases. Copyright © 2001 John Wiley & Sons, Ltd.