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Structural Aspects of the False 2212 in a (Bi,Pb):2223 Superconductor

Domenii publicaţii > Fizica + Tipuri publicaţii > Articol în revistã ştiinţificã

Autori: D. Ciurchea

Editorial: World Scientific Publishers, International Journal of Modern Physics B, 16(4), p.583-592, 2002.


The full pattern decomposition method by Le Bail was applied to the X-ray diffraction pattern of a (Bi1.8Pb0.46)Sr1.88Ca.2.06.(Cu0.97Fe0.01Ca0.02)3Oy superconductor presenting the same characteristics as the false 2212 reported by Masqood et al (ICDD file 42-514). By using the Cmmm space group, AB5 coordination in the BiO planes was evidenced, yielding an explanation for the apparent cell colapse. Orthorombic-pseudohexagonal settings for the a and b lattice constants may be derived from the group-supergroup relationships, i.e. instead of a»b»5.38 Å= 3.8´√2 Å one may take a=2´3.8 Å and b=3.8´√3/2 Å. Indexing with these values avoids the assumption for the strange (0011) peak, and yields the refined values of a= 7.664 Å, b= 3.356 Å and c= 16.172 Å, space group Pmmm.

Cuvinte cheie: O structura supraconductoare noua pentru stiinta // A new superconducting structure in (Bi,Pb):2223