Crystal structures of Na1/2Ln1/2TiO3 (Ln: La, Eu, Tb)

Neutron powder diffraction studies of Na1/2La1/2TiO3 and Na1/2Tb1/2TiO3, and a synchrotron X-ray powder diffraction study of Na1/2Eu1/2TiO3 have been carried out. Rietveld refinement of the structures confirmed that Na1/2Eu1/2TiO3 and Na1/2Tb1/2TiO3 crystallizes in GdFeO3 type of structure (space group Pbnm). The ambiguity in the literature regarding the crystal structure of Na1/2La1/2TiO3 has been resolved and the correct space group is found to be R3¯c. A detailed list of refined structural parameters of these compounds is presented for the first time.