Microcosmic analysis of stabilization of aluminum titanate ceramics by Mg migration into the Al2TiO5 lattice

The mechanism of Mg 2+ introduction on the thermal expansion properties of Al 2 TiO 5 ceramics was elucidated through experimental characterization and theoretical calculation for Mg x Al 2(1-x) Ti 1+x O 5 (x = 0, 0.25, 0.50, 0.75). Results showed that as x increased from 0 to 0.75, the calculated thermal expansion coefficient (single-crystal) exhibited minimal variation, while the apparent thermal expansion coefficient (polycrystalline) increased from 0.09 × 10 -6 K -1 to 3.85 × 10 -6 K -1 (1000 °C). The low apparent thermal expansion of Al 2 TiO 5 (x = 0) was attributed to microcrack healing and pore compensation effects. For x = 0.75, the enhanced apparent thermal expansion was correlated with reduced microcrack formation and improved densification. The incorporation of Mg 2+ reduced octahedral distortion and lattice stiffness, thereby suppressing transverse vibrations of bridging oxygen atoms and contraction along the c-axis. This reduced thermal expansion anisotropy and minimized microcrack formation. Additionally, as Mg 2+ content increased from x = 0 to x = 0.75, the porosity reduced from (11.23 ± 0.13) % to (3.96 ± 0.24) %, thereby weakening the pore compensation effect. These findings provide valuable insights for designing Al 2 TiO 5 -based ceramics with low thermal expansion.