The aim of our study was to modify the basis compound ß-TaON, which crystallizes in the monoclinic baddeleyite-type, by incorporation of appropriate dopant ions, in order to obtain anion-deficient cubic fluorite-type phases, which are of interest as solids with mobile nitrogen ions. For this purpose, scandium-doped tantalum oxide nitrides were prepared by ammonolysis of amorphous oxide precursors. An unexpected variety of phases with different structural features was observed: bixbyite-type phases of general composition Sc x Ta 1− x (O,N) y with 0.33≤ x≤1 and 1.7≤ y≤1.9, yellow colored metastable anatase-type phases such as Sc 0.1Ta 0.9O 1.2N 0.8 or Sc 0.15Ta 0.85O 1.3N 0.7 and, additionally, anosovite-type phases Sc x Ta 3− x O 2 x N 5−2 x with 0≤ x≤1.05. Selected phases were investigated by UV/vis spectroscopy. Anatase- and anosovite-type compounds show brilliant colors. In the anatase-type phase, a possible anion ordering was examined by theoretical methods. Additionally, energy calculations on phase stability were performed for Sc x Ta 1− x O 1+2 x N 1−2 x in the baddeleyite, rutile, and anatase structure types with varying amounts of dopants. New anatase- and bixbyite-type phases obtained as single-phase samples in the system Sc–Ta–O–N. Display omitted