Structural analysis of a potassium hollandite K1.35Ti8O16
1989; Elsevier BV; Volume: 83; Issue: 1 Linguagem: Inglês
10.1016/0022-4596(89)90054-6
ISSN1095-726X
AutoresThomas Vogt, Eberhard Schweda, Claus Wüstefeld, Joachim Strähle, Anthony K. Cheetham,
Tópico(s)Advanced Condensed Matter Physics
ResumoCrystals of K1.35Ti8O16 have been investigated by single-crystal X-ray analysis, X-ray powder patterns, electron diffraction, and high-resolution electron microscopy. K1.35Ti8O16 is obtained in the form of dark blue tetragonal crystals of the space group I4m having the hollandite structure with a = 1018.8(2) pm and c = 296.61(7) pm. The refinement converges to a reliability factor of 0.025. The occupation of the T(2,2) tunnel sites in potassium is not statistical. Incommensurate one-dimensional superstructures were found by powder diffraction patterns as well as by electron diffraction. The multiplicity calculated from powder X-ray diffraction is m = 5.79 and that found by electron diffraction is m = 8.1; this is explained in terms of beam damage and loss of potassium within the T(2,2) sites. The final step in the decomposition is the formation of rutile from K1.35Ti8O16 when all the potassium atoms are lost in the tunnels.
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