The reaction kinetics for the formation of Ni-doped (10 mol%) Mg titanates (MgTi2O5 pseudobrookite – karrooite, MgTiO3 ilmenite –geikielite, and Mg2TiO4 spinel –qandilite) prepared by the conventional solid-state route (with MgCO3 as Mg precursor) and fast-fired up to 1000 and 1200 ◦C was found to decrease progressively in the series MgTi2O5 >MgTiO3>Mg2TiO4.Within the employed synthesis conditions, still higher firing temperatures
(at least 1400 ◦C) or higher Ni loadings are needed to obtain single phase solid solutions of Ni-geikielite (or Ni-qandilite).