Raman-active phonons in Bi2Sr2−xLaxCaCu2Oy: effect of the oxygen content induced by La doping

Polycrystalline samples of Bi2Sr2-xLaxCaCu2Oy and pure Bi2212 with different oxygen content have been prepared and studied by Raman spectroscopy. No frequency change of O(Bi)A(g) mode is observed. The O(Sr)A(g) mode exhibits remarkable downward frequency shift. The analysis indicates that the content of excess oxygen inserted into the Bi2O2 layer is the important factor causing frequency shift of the O(Sr)A(g) mode. (C) 1999 Elsevier Science B.V. All rights reserved.