Synthesis and structure refinement of a new type of layered intergrowth phase: Sb_3+xNb_3−xTiO₁₄ and Sb_3+xTa_3−xTiO₁₄

Attempts to synthesize Sb-based analogues of the known Bi-based Aurivillius phase, Bi₃TiNbO₉, have led to the discovery of an isomorphous pair of a new type of layered intergrowth phase of general stoichiometry Sb_3+xNb_3−xTiO₁₄ and Sb_3+xTa_3−xTiO₁₄. Electron diffraction proved essential for the initial recognition and structural characterization of these phases. The structures of Sb_3+xNb_3−xTiO₁₄, x = 0.89, and Sb_3+xTa_3−xTiO₁₄, x = 1.26, are reported. The structures are described as ordered intergrowths of β-Sb₂O₄-type and Sb₂O₅-type structures, with Nb^V/Ta^V substituting for Sb^V in the former and Nb^V/Ta^V/Ti^IV substituting for Sb^V in the latter.

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