In
search of an experimental route to produce linear arrays of spins without the use of nanotechnological tools, we have doped
Nb28O70 with small amounts of transition metal
oxides(TM; in
this case Fe2O3) or rare-earth oxides3, and
investigated the location of the alien metal (Fe in this case) in the
structure. Previous AC magnetic susceptibility measurements at low temperatures
have been consistent with the formation of arrays of TM magnetic moments along the widely spaced columns parallel to the
crystallographic b-axis in the Nb28O70 structure. To obtain further details about the TM
distribution, the previous investigation has been extended now to include a
room-temperature Mössbauer spectroscopic analysis of the Fe-doped material. The
data are consistent with the presence of low-spin Fe3+ ions in both
octahedral and tetrahedral coordinations of oxygens, and confirm(as suggested in the
previous work) that Fe also interchanges positions with Nb ions located at
tetrahedrally coordinated sites in the columns of the structure.
References
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