Structures of ordered tungsten- or molybdenum-containing quaternary perovskite oxides

► Reports the structures of six double perovskites containing either Mo6+ or W6+. ► Compounds with similar tolerance factors (t) exhibited different symmetries. ► This effect was observed in Sr2ZnMO6 and Ba2CaMO6 (M=Mo or W). ► Contains a structural survey of 93 double perovskites. ► Octahedral tilting distortions are controlled by t and the nature of the A-cation.