Crystal structures of Na(1/2)Ln(1/2)TiO(3) (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 havebeen carried out. Rietveld refinement of the structures confirmed thatNa1/2Eu1/2TiO3 and Na1/2Tb1/2TiO3 crystallizes in GdFeO3 type ofstructure (space group Pbnm). The ambiguity in the literature regardingthe crystal structure of Na-1/2 La1/2TiO3 has been resolved and thecorrect space group is found to be R3c. A detailed list of refinedstructural parameters of these compounds is presented for the firsttime.