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Barium Hollandite-Type Compounds BaxFe2xTi8-2xO16 with x= 1.143 and 1.333



J. M. Loezos, Terrell A. Vanderah, A R. Drews


Experimental X-ray powder diffraction patterns and refined unit cell parameters for two barium hollandite-type compounds. BaxFe2xTi8-2xO16, with x = 1.143 and 1.333, are reported here. Compared to the tetragonal parent structure, both compounds exhibit monoclinic distortions that increase with Ba content (Ba1.333Fe2.666Ti5.334O16: a=102328(8) , b=2.9777(4) , c=9.899(1) , =91.04(1) , V=201.58(5) 3, Z=1, Pcalc =4.64 g/cm3; Ba143Fed2.286^Ti5.714O16: a=10.1066(6), b=2.9690(3), c=10.064(2) , =90.077(6) , V=301.98(4) 3, Z=1, Pcalc=4.48g/cm3. The X-ray powder patterns for both phases contain a number of broad, weak superlattice peaks attributed to ordering of the Ba2+ ions within the tunnels of the hollandite framework structure. According to the criteria developed by Cheary and Squadrito [Acta Crystallogr. B45, 205 (1989], the observed positions of the (Ok1)/(1kO) superlattice peaks are consistent with the nominal x-values of both compounds, and the k values calculated from the corresponding d-spacings suggest that the Ba ordering within the tunnels is commensurate for x=1.333 and incommensurate for x=1.143. High-temperature X-ray diffraction data indicate that the x=1.333 compound undergoes a mono-clinic>tetragonal phase transition at approximately 400 Celsius}.
Journal Powder Diffraction


BaO:Fe<sub>2</sub>O<sub>3</sub>:TiO<sub>2</sub>, barium iron titanium oxides, hollandite, incommensurate modulation, X-ray powder diffraction data


Loezos, J. , Vanderah, T. and Drews, A. (1999), Barium Hollandite-Type Compounds Ba<sub>x</sub>Fe<sub>2x</sub>Ti<sub>8-2x</sub>O<sub>16</sub> with x= 1.143 and 1.333, Journal Powder Diffraction (Accessed February 28, 2024)
Created February 22, 1999, Updated October 12, 2021