Figure 1
(a) The effect of tilting of the octahedra about the axis perpendicular to the octahedra plane. (b) The pattern of the X anion shifts with respect to the A cations after tilting. X anions are in red, A cations are in blue. The B cation (black) is located within the octahedra. The pseudocubic unit cell is marked in each case by continuous black lines and the doubled supercell by dashed lines. |