AN ORIGINAL OXIDE OF ANTIMONY AND TUNGSTEN RELATED TO AURIVILLIUS PHASES

Aurivillius's phases exhibit original [Bi2O2]n layers ; up to now such phases exist only with bismuth. The aim of this paper is to report new related phase, containing only antimony, which is promissing because its ferroelastic properties. Synthesis, crystal growth and structure determination of the original double oxide Sb2WO6 has been performed. It crystallizes in the triclinic system, space group P1, with a=5.554(1), b=4.941(2), c=9.209(3)angstrom, alpha=90.05(3), beta=96.98(2), gamma =90.20(2)degrees, V=250.8(7)angstrom3. TEM and optical microscopy investigations allow to evidence a ferroelastic behaviour at room temperature with a phase transition in the range 300-400-degrees-C. The crystal structure of Sb2WO6 is built up by [WO4]n layers of WO6 octahedra sharing comers sandwiched by two [Sb2O2]n layers; it can be described as [WO2Sb2O4]n thick layers held together by weak Sb ... O interactions. The antimony atoms exhibit typical 3+1 one sided coordination. Via structural relationships with Sb2O3, VOSb2O4 and Bi2WO6, Sb2WO6 is related with the Aurivillius phases announcing how [Bi2O2]n layers with the shape encountered in red PbO can be formed or distorted.