NEW LAYERED BISMUTHATE (Sr,K)3Bi2O7: SYNTHESIS AND CRYSTAL STRUCTURE

摘要

A new layered Bi-based mixed oxide with appropriate composition Sr1.5K1.5Bi2O7 was synthesized at 300-450 C and p(O2)=40 bar. This phase is the second member of the Ruddlesden-Popper series (Sr,K)n+1BinO3n+1. From powder XRD, the structure was refined in the tetragonal space group I4/mmm with lattice constants a=4.1549(1) angstroms and c=21.8273(6) angstroms (Z=2, RI=0.08, RP=0.066). However, electron diffraction patterns revealed the existence of additional weak reflections requiring a square root of 2ap times square root of 2ap times c unit cell to be indexed. No superconducting signal was detected to 1.5 K. 12 refs.