Structure determination of n = 1 Ruddlesden–Popper compound HLaTiO4 by powder neutron diffraction

A protonated n = 1 Ruddlesden–Popper compound, HLaTiO4 (DLaTiO4), has been prepared by an ion-exchange reaction of Na+ ions in NaLaTiO4 with H+ (D+) ions, and its structure has been analyzed in order to clarify the location of protons in the interlayer space, using powder neutron diffraction data. The crystal structure of DLaTiO4 belongs to the same space group, P4/nmm, as that of parent NaLaTiO4, and the D atoms were found to statistically occupy eight equivalent sites around an apical O atom of a TiO6 octahedron in the interlayer, which are different from the Na atom sites in NaLaTiO4. A comparison between DLaTiO4 and NaLaTiO4 indicated that the protonation brought the shrinkage of the interlayer space and the distortion of the TiO6 octahedron.