Raman spectra of superconducting and impurity phases in Bi-Ca-Sr-Cu-O ceramics

✍ Scribed by M.N. Iliev; V.G. Hadjiev

• Publisher: Elsevier Science
• Year: 1988
• Tongue: English
• Weight: 287 KB
• Volume: 156
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(88)90127-x

✦ Synopsis

Micro-Raman technique in conjunction with electron microanalysis were employed for identification of Raman spectra of superconducting and impurity phases in Bi-Ca-Sr-Cu-O ceramics obtained by three different technologies. Two of the main impurity phases are (Cao.gSro. j )2CUO3 and (Cao.rSro 4)CUl.7503 and their Raman spectra are very similar in the region below 400 cm-~. Another impurity phase is Bi2Ca~Sr3Ox (with slight variations of Bi-Ca-Sr composition) which displays strong Raman scattering at 615-622 cm-~ and a sharp peak at 90 crn-~. The Raman spectrum of the superconducting Bi:Ca~ Sr2Cu20,. phase is characterized by a strong peak at 635 cm-J and a weak feature near 460 cm-~. The Raman spectra from microcystals of Bi-Ca-Sr-Cu-O composition close to 3233, 3223, 2142 and 4123 have common features with the one of Bi2Ca~Sr2Cu2Ox. Some of them, e.g. 2142, exhibit almost continuous scattering below 620 cm-~, which may be caused by strong disorder thus displaying the onephonon density of states.