Abstract
In the Ti-Al-O-N system a phase isostructural to aluminium titanate but with expanded unit cell dimensions was observed. It was stable between 1400 and 1700 °C and has unit cell dimensions of a=0.3719 nm, b=0.9703 nm and c=0.9869 nm with a composition of Ti 4+1.00 Al 3+0.54 Ti 3+1.46 N 3−0.28 O 2−4.58 □0.14 Several samples were prepared by reaction sintering mixtures of TiN, Al2O3 and AlN powders at 1400 to 1470 °C for 4 h in a nitrogen atmosphere to maximize this phase. One specific advantage of the nitrogen-containing aluminium titanate over aluminium titanate is that the former is unchanged at 1150 °C in a nitrogen atmosphere whereas the latter decomposes. In the Al2O3-TiO2 oxide system Al2TiO5 solid solution extends to approximately Al0.75Ti2.25O5 at 1470 °C under the mildly reducing conditions of a graphite furnace. The unit cell volume increases linearly with the increasing replacement of Al3+ by Ti3+.
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