Phonon Raman spectra of the modulation-free Bi1. 2Pb 0. eSr 2Ca 1-y, Cu 2O. (0.2 ⪳y⪳0.8) have been investigated both in polycrystalline and single crystal forms. Polarized Raman spectroscopic measurements of single crystals made it possible to clarify some controversies on the Raman mode assignments for Bi2Sr2CaCu 2O8+d(Bi2212), most notably in high-frequency three prominent oxygen modes observed at 290, 460 and 630cm-1, which we assigned to AgOB1+B1gOCu, AgOBiand AgOapox, respectively. The energies of the three oxygen modes show drastic change with a decrease of the hole concentration: (1)AgOB1+ B 1gOCu. mode is shifted towards higher frequencies, (2)AgOBimode hardly varies for y< 0.6, while softens for y=0.6, and AgOapox. P. mode is shifted towards lower frequencies. The observed changes in these oxygen modes are similar to those observed for the modulated Bi 2Sr 2Ca 1-yYyT Cu2OZ. We propose that the Y/Ca substitution both in the modulated and modulation-free Bi2212 systems induced a hole filling on the CuO 2 plane, which can explain the behaviour of the oxygen modes observed in their Raman spectra.
|ジャーナル||Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy|
|出版ステータス||Published - 1994|
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