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Raman microprobe studies of Bi2Sr2CaCu2O8 Extrinsic and intrinsic effects

1991; Elsevier BV; Volume: 176; Issue: 1-3 Linguagem: Inglês

10.1016/0921-4534(91)90701-y

1873-2143

Alison Crossley, P.R. Graves, S. Myhra,

Advanced Condensed Matter Physics

Abstract Freshly cleaved single crystal Bi 2 Sr 2 CaCu 2 O 8 specimens were analysed by Raman microscopy. The spectra exhibited only one peak at 538 cm −1 . However, surfaces which were degraded by exposure to the laboratory atmosphere exhibited Raman peaks at 280–295, around 320, 450–465, around 485 and 610–625 cm −1 . The surfaces were also exposed to saturated steam, which in the early stages of degradation tended to promote the bands at 290, 450 and 620 cm −1 . Further degradation tended to make the surfaces inactive, but in the final stages of degradation SrCO 3 modes were positively identified. The degradation process was also monitored by EMPA analyses, which agreed with the Raman data. The combined results suggest that previously reported results may have an ambiguous origin, unless these have been obtained on clean and undegraded surface.