Synthesis, structure and properties of the oxychalcogenide series A4O4TiSe4 (A=Sm, Gd, Tb, Dy, Ho, Er and Y)

Illustration of the A4O4TiSe4 crystal structure (C2/m symmetry), A4O and A3TiO edge sharing tetrahedral ribbons in red, chains of edge-sharing TiSe4O2 in blue. Rare earth=green, titanium=blue, selenium=yellow, and oxygen=red.