Crystallographic superstructure of Ti-doped hexagonal YMnO3

We synthesized hexagonal YMnO3 doped with Ti ions and investigated the crystal structure by means of transmission electron microscopy. Superlattice reflection spots with a modulation wave vector q=1/3c(*) appeared for the Ti-doped YMnO3. We found that Ti-doped YMnO3 intrinsically consists of the hexagonal phase and the rhombohedral phase derived from formation of a superstructure with the 3d(001) period along the c axis. The hexagonal-to-rhombohedral phase transition results from a change of the stacking manner in Mn(Ti) trimers in Mn(Ti)O layers.