A Mg-25, Y-89 and In-115 solid state MAS NMR study of YT2X and Y(T0.5T %26apos; (0.5))(2)X (T/T %26apos; = Pd, Ag, Au; X = Mg, In) Heusler phases

作者：Be***orf Christopher; Stein Sebastian; Heletta Lukas; Kersting Marcel; Eckert Hellmut; Poettgen Rainer

来源：Dalton Transactions, 2017, 46(1): 250-259.

DOI：10.1039/c6dt04097g

Yttrium-transition metal-magnesium (indium) Heusler phases YPd2Mg, YPd2In, YAg2Mg, YAg2In, YAu2Mg, and YAu2In and their quaternary compounds (solid solutions) Y(Pd0.5Ag0.5)(2)Mg, Y(Pd0.5Ag0.5)(2)In, Y(Pd0.5Au0.5)(2)Mg, Y(Pd0.5Au0.5)(2)In, Y(Ag0.5Au0.5)(2)Mg and Y(Ag0.5Au0.5)(2)In were synthesized from the elements in sealed niobium ampoules in a high-frequency furnace or by arc-melting, respectively. All compounds crystallize with the cubic MnCu2Al type structure (Heusler phase), space group Fm (3) over barm. The structure of Y(Ag0.39Au0.61)(2)Mg was refined from single crystal X-ray diffractometer data: a = 689.97(5) pm, wR(2) = 0.0619, 52 F-2 values, 6 parameters. Magnetic susceptibility measurements show Pauli paramagnetic behavior for all samples. The compounds were investigated by Mg-25, Y-89 and In-115 solid state MAS NMR spectroscopy. Large positive resonance shifts are observed for all nuclei. A review of the present data in the context of literature data on isotypic Heusler phases with Cd and Sn indicates that the 89Y shifts show a correlation with the electronegativity of the main group atoms (Mg, Cd, In, Sn). The solid solutions Y(Ag1-xTx)(2)Mg (x = 0.1, 0.25, 0.33, 0.5; T = Pd, Au) clearly show Vegard-like behavior concerning their lattice parameters, and their main group element resonance shifts arising from spin and orbital contributions are close to the interpolated values of the corresponding end-member compounds.

• 出版日期2017-1-7