Material Technology

Characterization of Al–Ti phases in cycled TiF3-enhanced Na2LiAlH6

Nakamura, Y. , Fossdal, A. , Brinks, H.W. , Hauback, B.C.
Journal of alloys and compounds, Vol. 416, no. 1/2 (8 June 2006), 274-278
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TiF3-enhanced Na2LiAlH6 was investigated after dehydrogenation–hydrogenation cycles by synchrotron X-ray diffraction. There was no sign of Ti after ball-milling with TiF3, but two types of Al–Ti phases were observed in the cycled samples. In a sample after measuring five pressure–composition isotherms in the temperature range from 170 to 250 °C, a fcc phase with a = 3.987 Å was observed. This phase is considered to be Al3Ti with the L12 structure. Samples after one or four cycles at selected temperatures between 170 and 250 °C showed diffraction from another fcc phase with a ≈ 4.03 Å. This indicates formation of an Al1−yTiy solid-solution phase with y ≈ 0.15 similar to previously reported for cycled NaAlH4 with Ti additives.
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