Re-Examination of the Structure of Sr2(MgTe)O6 Double Perovskite
Sr(2)MgTeO(6) 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 (14/m) and the pseudotetragonal monoclinic P2(1)/n structure of Ca(2)MgTeO(6), both of which have previously been reported. Rather than undergoing an antiphase-to-in-phase tilt transition along the long axis, a more probable untilted-to-in-phase tilt transition was found, lowering the symmetry of Sr(2)MgTeO(6) to monoclinic, I2/m. Additionally, slight breaks in the fourfold symmetry expected in the < 001 > (tetragonal) orientations observed in electron diffraction patterns support the lowering of symmetry.
Ubic, Rick; Letourneau, Steven; Thomas, S.; Subodh, G.; and Sebastian, M. T.. (2011). "Re-Examination of the Structure of Sr2(MgTe)O6 Double Perovskite". Journal of the Australian Ceramic Society, 47(2), 49-56.