X-RAY, ELECTRON-DIFFRACTION AND HREM STUDIES OF KHTI4O9, XH(2)O THERMOLYSIS - CHARACTERIZATION OF K4TI16O34

The structure of the new phase K4Ti16O34 was determined from electron diffraction and high resolution electron microscopy data supported by X-ray and thermogravimetric analysis. K2Ti8O17 obtained from the tetra titanate K2Ti4O9 by a soft chemistry reaction transforms at 750 degree s C into a high temperature form K4Ti16O34. The ''cut and projection'' method is used to analyze the electron diffraction patterns and to de termine the stacking sequences from geometrical feature of the diffrac tion patterns. The structure deduced from election diffraction pattern s and direct imaging can be described as resulting from a regular inte rgrowth of two tunnel titanates: the hexatitanate and an hypothetical decatitanate. As the homologous series of tunnels alkali titanates A(2 )Ti(m)O(2m+1) with m greater than or equal to 6, the structure is deri ved from the lepidocrocite archetype. The formation mechanism of the r egular block sequence is discussed.