Sr2MgTeO6 powders and pellets were prepared by a solid-state ceramic route. The structure and microstructure were investigated using x-ray diffraction, transmission electron microscopy and scanning electron microscopy methods. A structural inconsistency was discovered between the pseudocubic tetragonal structure and the pseudotetragonal monoclinic structure of Ca2MgTeO6, both of which have previously been repoted. Rather than undergoing an antiphase-to-in-phase tilt transition along the long axis, a more probably untitled-to-in-phase tilt transition was found, lowering the symmetry of Sr2MgTeO6 to monoclinic, I2/m. Additionally, slight breaks in the fourfold symmetry expected in the (tetragonal) orientations observed in electron diffraction patterns support the lowering of symmetry.
