PHASE FORMATION AND ELECTRONIC TRANSPORT-PROPERTIES IN THE CORUNDUM (TI2O3)-ILMENITE (MGTIO3) SYSTEM

At high temperatures the Ti2O3-MgTiO3 system shows extensive solid solution formation with an order/disorder transition between ilmenite- and corundum-type structures. At lower temperatures (<1000°C), there exists a large immiscibility dome, extending from Mg0.9Ti1.1O3 to Mg0.4Ti1.6O3. Although X-ray peak intensities indicate a gradual change from order to disorder with composition, there is a discontinuity at the ilmenite/corundum boundary. The relationship between unit cell parameters and composition generally obeys Vegard's Law, apart from a deviation close to the Ti2O3 end member. Above 180 K thermally activated conductivity is observed, with a discontinuity at the corundum/ilmenite boundary. At lower temperatures, a change in conductivity behavior occurs, with a linear relationship between log resistivity and temperature being found up to 30 K in samples with low Ti oxidation state. © 1993 Academic Press, Inc.