“…2 shows the (1 1 1) reflection of crystalline fcc Al 1−x TM x (x < 0.25) solid solutions formed for TM = Sc, Ti, V, Cr, Mn, Zr and Pd in twice H cycled PM NaAlH 4 + 0.1TMCl n , with their associated unit cell dimension. We observe crystalline fcc solid solutions that typically contain significantly more TM atoms than the maximum TM solubility according to the equilibrium phase diagram, such as Al 87.6 Sc 12.4 (see analysis below), with equilibrium solubility of 0.08 at.% Sc [21], Al 85 Ti 15 [10] (equilibrium solubility of 2 at.% [22]), Al 90 V 10 [20] (equilibrium solubility of 0.2 at.% [23]), Al 97.73 Cr 2.27 [24] (equilibrium solubility of 0.04 at.% [25]), Al 95.67 Mn 4.33 [26] (equilibrium solubility of 0.65 at.% [27]), Al 94.5 Zr 5.5 [28] (equilibrium solubility of 0.08 at.% [28]), and Al 90 Pd 10 [29] (equilibrium solubility of 0.2 at.% [30]). For fcc Al 1−x TM x solid solutions with extended solubility, knowledge of the concentration dependent (0 < x < 25 at.%) lattice parameters is crucial to determine the correct Al:TM composition, as discussed extensively for the Ti case in [10], and for the concentration dependent lattice parameters provided for Cr, Mn and Zr in [24,26,28] respectively.…”