On BSCCO Superconductor-Related Bi2Sr2MnO6+x and BiPbSr2MnO6: X-Ray Absorption Spectroscopy and Diffraction Study

✍ Scribed by M. Catti; G. Dalba; P. Fornasini; M. Mölgg

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 279 KB
• Volume: 112
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1994.1322

✦ Synopsis

(\mathrm{Bi}{2} \mathrm{Sr}{2} \mathrm{MnO}{6+x}) and (\mathrm{BiPbSr}{2} \mathrm{MnO}{6}), isotypic with the (2201 \mathrm{BSCCO}) superconductor, were investigated by X-ray powder diffraction and (X)-ray absorption spectroscopy (synchrotron radiation). The unit-cell constants are (a=21.796(3), b=5.4268(7), c=) 23.612(2) (\AA), and (a=5.3186(8), b=5.3892(8), c=23.765(3) \AA), respectively. Superlattice modulation peaks ( (h \neq 4 n) ) are evident in the diffractogram of the first phase. XAFS spectra at the (K) edge of manganese were recorded for the two compounds and for metallic (\mathrm{Mn}, \mathrm{MnO}), and (\mathrm{Mn}{2} \mathrm{O}{3}). An energy shift of about (1.5 \mathrm{eV}) is observed between the profiles of the two phases. By comparison of spectral features with those of the simple oxides, the oxidation state of (\mathrm{Mn}) is inferred to be (+2.6(1)) and (+2.9(1)) in (\mathrm{Bi}{2} \mathrm{Sr}{2} \mathrm{MnO}{6+x}) and (\mathrm{BiPbSr}{2} \mathrm{MnO}{6}), respectively. 1994 Academic Press, Inc.