Structural models for intergrowth structures in the phase system Al2O3–TiO2

The phase system Al2O3–TiO2 was investigated in the compositional range from 48:52 to 62:38 mol% Al2O3:TiO2. The samples were prepared by melting the binary oxides in an arc-imaging furnace and the obtained samples were examined by powder X-ray diffraction. The recorded powder patterns could be interpreted in terms of intergrowth structures consisting of two basic building blocks, which were deduced from the known crystal structures of β-Al2TiO5 and Al6Ti2O13. The structure of a new ordered compound with the formula Al16Ti5O34 is proposed. The thermal stability was estimated from DTA and tempering experiments and showed that all prepared samples decompose at temperatures around 800 °C into the binary oxides corundum and titania.

The crystal structures of (a) Al6Ti2O13 and (b) β-Al2TiO5 were compared and basic building blocks identified as indicated by solid lines. These units were used to assemble new crystal structures and to calculate the corresponding X-ray powder diffraction patterns which were compared with experimental data in the range from 48:52 to 62:38 mol% Al2O3:TiO2.Figure optionsDownload as PowerPoint slide