MODULATED STRUCTURE OF ZIRCONIUM TITANATE

Zr0.992Hf0.008TiO4, M(r) = 203.81, orthorhombic, P111BARPbc2(1), a = 4.821 (2), b = 5.341 (7), c = 5.022 (3) angstrom, k = 0.43a*, V = 129.31 (1) angstrom 3, Z = 2, D(x) = 5.2346 g cm-3, lambda(Mo K-alpha) = 0.71073 angstrom, mu = 72.4 cm-1, F(000) = 188.51, T = 298 K, R = 0.093 for all, 0.067 for 565 main and 0.113 for 1082 first order satellite reflections. The structure can be regarded as an antiphase domain structure in which the cation sequences of Zr-Zr-Ti-Ti and Ti-Ti-Zr-Zr appear alternately with an average interval of (1-2\k\)-1 congruent-to 7.14a. Near the domain center, the Zr ion is coordinated by eight O atoms, while the Ti ion is coordinated by six. The domain boundary region takes a disordered structure.