Synthesis, sintering and expansion of Al0.8Mg0.6Ti1.6O5: a low-thermal-expansion material resistant to thermal decomposition

A low-thermal-expansion ceramic with the composition Al0.8Mg0.6Ti1.6O5 that is isostructural to aluminium titanate Al2TiO5, was prepared by solid-state reaction of a mixture of alpha-Al2O3, MgO and TiO2-rutile. The synthesized material does not decompose after annealing for 250 h in the temperature range of 900-1175 °C. The ceramic sintered at 1350 °C has a 97% relative density, a grain size of 5 micron and an average thermal expansion coefficient between 80 and 1000 °C of+2x10^-6 K-1. Materials with the same composition, but obtained by reaction sintering, have a higher thermal expansion coefficient (4x10^-6 K-1) and showed the presence of secondary phases.