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

Published

February 23, 1999

Author(s)

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

Abstract

Experimental X-ray powder diffraction patterns and refined unit cell parameters for two barium hollandite-type compounds. Ba_xFe_2xTi_8-2xO₁₆, 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 (Ba_1.333Fe_2.666Ti_5.334O₁₆: 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; Ba_143Fed2.286^Ti_5.714O₁₆: 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}.

Citation

Journal Powder Diffraction

Volume

14

Issue

1

Pub Type

Journals

Keywords

BaO:Fe₂O₃:TiO₂, barium iron titanium oxides, hollandite, incommensurate modulation, X-ray powder diffraction data

Citation

Loezos, J. , Vanderah, T. and Drews, A. (1999), Barium Hollandite-Type Compounds Ba_xFe_2xTi_8-2xO₁₆ with x= 1.143 and 1.333, Journal Powder Diffraction (Accessed October 14, 2025)