T Siegrist, Terrell A. Vanderah, C Svensson, Robert S. Roth
Single-crystal X-ray diffraction studies indicate that the compound Ba27Fe16Ti33O117- crystallizes in the rhombohedral space group R-3m, with a hexagonal unit cell a=5.7400(8) , c=127.11(3) ; Z=1.5. The arrangement may be described as a 54-layer (54L) close-packed structure (stacking sequence (cch)18) built from oxygen and Ba,O} layers, with Ti4+ occupying octahedra and Fe3+ occupying both octahedral and tetrahedral interstices.The 54L structure contains hexagonal 6L BaTiO3-type (cch)2 units via a 9-fold repeat of the 6L stacking sequence, with iron preferentially occupying layers centered around z=1/6. Ba27Fe16Ti33O117 melts incongruently at 1270 C and is difficult to purify in polycrystalline form, although crystals are easily obtained from partial melts. The new compound is a member of a family of ternary Ba-Fe-Ti-O phases that may be considered as dielectric-magnetic hybrids of barium-polytitanate and barium-hexaferrite crystal chemistries.
Solid State Sciences
Ba<sub>27</sub>Fe<sub>16</sub>Ti<sub>d</sub>O<sub>117</sub>, barium iron titanates, barium iron titantium oxide