FERROELASTIC DOMAIN BOUNDARY OF LANBO4

Ferroelastic material LaNbO4 is mentioned with Sapriel's procedure [Ph ys. Rev. B 12, 5128 (1975)] and experimental data from the neutron and X-ray diffraction analysis. According to Sapriel, ferroelastic materi al LaNbO4 should have incommensurate twin boundaries. On the other han d, the experiments of neutron and X-rag diffractions for LaNbP4 with c alculating the transformation matrix shows the Miller indices with the commensurate twin boundary. If the incommensurate twin boundaries are supposed to exist, its lattice relation can only exist within a restr icted area near to the domain boundary. It requires a domain wall with thickness and distortion.