Mn, Mg, and Zn ilmenite group titanates: A reconnaissance rietveld study

Ecandrewsite-geikielite (Zn1/2Mg1/2TiO3), ecandrewsite-pyrophanite (Zn1/2Mn1/2TiO3), pyrophanite-geikielite (Mg1/2Mn1/2TiO3), and ecandrewsite-pyrophanite-geikielite (Zn1/3Mn1/3Mg1/3TiO3) titanates were synthesized at 900–1000°C at ambient pressure. All of the compounds adopt R— ilmenite-type structures. These structures were refined by the Rietveld method from X-ray powder diffraction data. Unit cell parameters and unit cell volumes decrease with decreasing average radii of the A2+ cation. All structures consist of distorted AO6 and TiO6 octahedra. In common with pyrophanite and ilmenite, the distortion of the AO6 octahedra is less than that of the TiO6 octahedra. Data are given for the volumes and distortion indexes of all coordination polyhedra.