Symmetry determination of the room-temperature form of LnNbO₄ (Ln = La,Nd) by convergent-beam electron diffraction

Three different space groups, C2/c, C2 and Cc, have been reported for the room-temperature form of the rare-earth orthoniobates, LnNbO₄ (Ln = La, Nd). They belong to different point groups: 2/m, 2 and m, respectively. By means of convergent-beam electron diffraction, the point group has been determined to be 2/m in the present study. Therefore the true space group must be C2/c.