Preparation and Thermal Expansion Characteristics of Sintered Bodies of Al<sub>2</sub>TiO<sub>5</sub>-MgTi<sub>2</sub>O<sub>5</sub> Solid Solution with Preferred Orientation

Abstract

Rod-like particles of Al2TiO5-MgTi2O5 solid solutions were synthesized by heating mixed powders of MgO, Al2O3 and TiO2 above 1050°C in the presence of 10atom% mixed fluoride of MgF2 and AlF3. The rod diameter decreased with decreasing synthesis temperatures while the aspect ratio increased. At a certain temperature the rod diameter increased with increasing MgTi2O5 contents while the aspect ratio decreased. A sinterable powder composed of rod-like particles, in which rod diameter and aspect ratio were about 2μm and about 4, respectively, was obtained by heating the raw materials containing 50% MgTi2O5 at 1200°C. Using the rod-like particles, a sintered body of a highly oriented solid solution with the Lotgering's index f//a of 0.76, was obtained. Thermal expansion anisotropy was observed, and the hysteresis of the expansion-shrinkage behavior was smaller than that of the sintered body without preferred orientation.