Synthesis of MgTiO3 and Mg4Nb2O9 using stoichiometrically excess MgO

Synthesis of MgTiO3 and Mg4Nb2O9 phases having an ordered corundum type structure by reacting MgO and TiO2 or Nb2O4 together with the addition of excess MgO has been investigated. When MgO and TiO2 or Nb2O5 are reacted with 1:1 and 4:1 stoichiometry, MgTiO3 and Mg4Nb2O9 phases having an ordered corundum type structure are formed, Moreover, a minor amount of MgTi2O5 and MgNb2O6 phases are frequently observed along with the ordered corundum type phases. It has been shown that the formation of these additional phases can be suppressed by the addition of stoichiometrically excess of MgO, which can subsequently be removed after the reaction by treating with dilute mineral acid, thus fort-ning pure MgTiO3 and Mg4Nb2O9. (C) 2002 Elsevier Science B.V. All rights reserved.