Commensurate Nb₂Zr₅O₁₅: Accessible Within the Field Nb₂Zr O₂ After All

Doped niobium zirconium oxides are applied in field-effect transistors and as special-purpose coatings. Whereas their material properties are sufficiently known, their crystal structures remain widely uncharacterized. Herein, we report on the comparably mild sol-gel synthesis of Nb₂Zr₅O₁₅ and the elucidation of its commensurately modulated structure via neutron diffraction. We describe the structure using the most appropriate superspace as well as the convenient supercell approach. It is part of an α-PbO₂-homeotypic field with the formula Nb₂Zr O₂, which has previously been reported only for x≥5.1, and is closely related to the structure of Hf₃Ta₂O₁₁. The results, supported by X-ray diffraction and additional synthesis experiments, are contextualized within the existing literature. Via the sol-gel route, metastable Nb-Zr-O compounds and their heavier congeners are accessible that shed light on possible structures of these commercially utilized materials.