Solid solutions formed within the Al2O3-TiO2-Fe2O3 (Fe2xAl2(1-x)TiO5) system upon heat treatment were investigated by adjusting the substituting Fe3+ content in the range of x=0.0 to 1.0. X-ray diffraction phase analyses and lattice parameter determinations confirmed that substitution of Fe3+ ions within the aluminium titanate lattice was complete. For this complete solid solution, however, the trends observed for changes in d-spacing values indicated that there were certain discrete compositions to identify with Fe3+ substitution. Within these, Fe0.4Al1.6TiO5 and Fe1.6Al0.4TiO5 crystalline phases were investigated in detail and their X-ray diffraction cards were constructed. Self-healing effect occurring in repeated heating-cooling cycles in Fe3+ doped AT ceramics were proved; it was demonstrated that Fe3+ doped AT ceramics do not decompose even if exposed to repeated thermal shock.