Preparation and properties of Bi6Ti5WO22: a new phase in the Bi2O3–TiO2–WO3 system

In a recent report, the evaluation of the phase relations in the Bi2O3–TiO2–WO3 ternary system has shown the existence of a new phase with nominal composition close to Bi6Ti5WO22. In the present contribution we attempt to prepare this single phase by using a solid state route. Although XRD analyses also show traces of two minority Aurivillius-type phases in the synthesized materials, the crystal structure of the Bi6Ti5WO22 phase has been determined by Rietveld analyses revealing a complex structure similar to that of Bi3(AlSb2)O11 and PbHoAl3O8 related compounds. The electrical response of this new phase was characterized as well. Three peaks are observed in its dielectric response: two of them positioned around 0 °C and can be assigned to this Bi6Ti5WO22 structure. The third one rises up to 665 °C and confirms the presence of the Aurivillius-type phases.