Precise structural information on the (formula presented) superconductors in the vicinity of (formula presented) is derived from high-resolution synchrotron x-ray powder diffraction measurements. We find that a hexagonal superstructure, accompanied by doubling of the c axis, ordering of Mg and Al in alternating layers, and a shift of the B layers towards Al by (formula presented) is formed. The unusually large width of the (formula presented) superlattice peak implies the presence of microstrain broadening, arising from anisotropic stacking of Al and Mg layers and/or structural modulations within the (formula presented) plane. The ordered phase survives only over a limited range of compositions away from the optimum (formula presented) doping level.
|Number of pages||5|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2002|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics