Modulated structure of the pseudohexagonal InFe1-x-4 delta,Tix+3 delta O3+x/2 (x=0.61) composite crystal

The structure of pseudohexagonal-type InFe1-x-4 deltaTix+3 deltaO3+x/2 (x = 0.61, delta = 0.04), indium iron titanium oxide, was refined on the basis of a four-dimensional superspace group. The crystal has a compositely modul ated structure consisting of two orthorhombic subsystems mutually incommens urate in b. The first subsystem InFe1-x-4 deltaTix+3 deltaO2 has a delafoss ite structure with lattice parameters a = 5.835 (3), b(1) = 3.349 (1) and c 12.082 (7) Angstrom. The second subsystem with b(2) = 2.568 (6) Angstrom c onsists of O atoms. The superspace group of the overall structure is Ccmm(1 , 1.305, 0)s00, which can be converted to Amam(0, 0, 0.305)0s0 (No. 63.8). Refinement on 1105 unique reflections converged to R = 0.0303 and wR = 0.03 25 with 63 structural parameters. The structure of the first subsystem is t he alternate stacking of an edge-shared InO6 octahedral layer and an Fe/Ti triangle-lattice plane along c. A sheet of O atoms in the second subsystem is also extending on the Fe/Ti plane, where displacive modulation of atoms is prominent.