A new oxygen deficient manganese oxide, Bi2Sr2Nb2MnO12-delta with the Auriv
illius type phase was successfully synthesized. It adopts an orthorhombic s
tructure that has Fmmm space group symmetry, and lattice parameters of a 5.
5243(4) Angstrom, b = 5.5246(3) Angstrom, and c = 32.9996(9) Angstrom. The
structure contains an oxygen deficient [MnO2-delta] layer that is interleav
ed between double [NbO2] layers. Virtually no disordered distribution of Mn
and Nb between two possible sites is observed. The temperature dependent d
ata of magnetic susceptibility and resistivity reveal that the compound is
paramagnetic and exhibits a semiconducting behaviour with the activation en
ergy E-a of 0.216 eV. (C) 1999 Published by Elsevier Science Ltd. Ail right
s reserved.