The crystal structure and stability of K 2NaAlH 6

The mixed alanate K 2NaAlH 6 has been synthesised by ball-milling a mixture of KH and NaAlH 4 and subsequent annealing at 150 °C under a stabilizing hydrogen pressure. It takes a cubic ordered perovskite-type structure (space group F m 3 ¯ m , a = 8.118(1) Å) where the ideal octahedral AlH 6 3− unit...

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Bibliographic Details
Published inJournal of alloys and compounds Vol. 415; no. 1; pp. 284 - 287
Main Authors Sørby, M.H., Brinks, H.W., Fossdal, A., Thorshaug, K., Hauback, B.C.
Format Journal Article
LanguageEnglish
Published Elsevier B.V 2006
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Summary:The mixed alanate K 2NaAlH 6 has been synthesised by ball-milling a mixture of KH and NaAlH 4 and subsequent annealing at 150 °C under a stabilizing hydrogen pressure. It takes a cubic ordered perovskite-type structure (space group F m 3 ¯ m , a = 8.118(1) Å) where the ideal octahedral AlH 6 3− units form a cubic close-packed structure with K + in all tetrahedral sites and Na + in all octahedral sites. K 2NaAlH 6 with 1 mol% TiF 3 decompose quickly and reversibly with a flat plateau. Pressure-composition isotherms have been measured at five temperatures in the range 280–325 °C. The decomposition enthalpy and entropy were determined to 98(2) kJ/mol H 2 and 150(4) J/(K mol H 2) from the van’t Hoff equation.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2005.08.010