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

Ecandrewsite-geikielite (Zn_1/2Mg_1/2TiO₃), ecandrewsite-pyrophanite (Zn_1/2Mn_1/2TiO₃), pyrophanite-geikielite (Mg_1/2Mn_1/2TiO₃), and ecandrewsite-pyrophanite-geikielite (Zn_1/3Mn_1/3Mg_1/3TiO₃) 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 A ²⁺ cation. All structures consist of distorted AO ₆ and TiO₆ octahedra. In common with pyrophanite and ilmenite, the distortion of the AO ₆ octahedra is less than that of the TiO₆ octahedra. Data are given for the volumes and distortion indexes of all coordination polyhedra. Published in Russian in Kristallografiya, 2006, Vol. 51, No. 3, pp. 417–424. The text was submitted by the authors in English.