Crystal structures and hydrogenation behavior of (Ca0.9Sr0.1)8(Al1-xZnx)3 alloys

The crystal structures and hydrogenation behavior of the (Ca0.9Sr0.1)8(Al1-xZnx)3 (x = 0, 0.1, 0.2, 0.3 and 0.4) alloys were investigated. The new phase (Ca,Sr)2(Al,Zn) was found when x ≥ 0.1. (Ca,Sr)2(Al,Zn) crystallizes in space group I4/mmm (A-139). The lattice parameters were calculated to be a = b = 1.1616(2) nm, c = 1.6422(4) nm. Zn atoms occupy the 8h and 16n sites together with Al atoms. The (Ca0.9Sr0.1)8Al3 alloy only contains a single Ca8Al3 phase. The (Ca0.9Sr0.1)8(Al1-xZnx)3 alloys consist of Ca8Al3, Ca5Zn3, Ca and (Ca,Sr)2(Al,Zn) phases when x is from 0.1 to 0.3. As x increasing to 0.4, the alloy consists of (Ca,Sr)2(Al,Zn), Ca5Zn3 and Ca. The hydrogenated (Ca0.9Sr0.1)8Al3 and (Ca0.9Sr0.1)8(Al0.9Zn0.1)3 samples consist of CaH2 and Al. The (Ca0.9Sr0.1)8(Al1-xZnx)3 (x = 0.2, 0.3 and 0.4) samples can be hydrogenated into CaH2, Al and CaZn13 under a hydrogen pressure of 5 MPa at 473 K.