CRYSTAL-STRUCTURE OF BARIUM TITANYL OXALATE BATIO(C2O4)2.4.5H2O

The hydrated phase of barium titanyl oxalate, BaTiO(C2O4)2 · 4.5H2O, is monoclinic with a = 13.382(2), b = 13.812(2), c = 14.044(2) Å, β = 91.48(1)°, space group P21/n, Z = 8. The structure has been determined from Patterson and Fourier syntheses. The refinement was done by the method of least-squares. The final R values were R = 0.056 and Rw = 0.079 for 3261 unique reflections. The structure is characterized by a body-centered arrangement of finite groups consisting of four vertex-sharing TiO6 distorted octahedra. These groups are connected by barium polyhedra and oxalate groups. The study shows that the water molecule number is 4.5 by formula rather than 4 reported previously. This conclusion is supported by TG measurements. © 1991 Academic Press, Inc.