Synthesis, crystal structure and magnetism of the mixed metal hydrides Eu1−xSrxMg2H6 (0 ≤ x ≤ 0.6)

The hydrogenation products of the solid-solution series Eu1−xSrxMg2 (0 ≤ x ≤ 1; MgZn2-type structure) have been investigated. At x ≤ 0.6 red-orange coloured hydrides of composition Eu1−xSrxMg2H6 are formed that crystallize with a disordered EuMg2D6-type structure. For x > 0.8, yellow-grey hydrides of composition (Eu1−xSrx)2Mg3H10 and Ba2Ni3F10-type structure are formed. The deuterium distribution was ascertained for Eu0.6Sr0.4Mg2D6 by neutron powder diffraction (space group P4/mmm, a = 377.27(5) pm, c = 799.3(2), Z = 1), thus confirming a slightly elongated but still extremely short MgD bond of 179 pm. The hydrides are paramagnetic with magnetic moments close to the free ion value of Eu2+ and order ferromagnetically below TC = 21 and 15 K for x = 0.2 and 0.4, respectively.