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A<sup>25</sup>Mg,<sup>89</sup>Y and<sup>115</sup>In solid state MAS NMR study of YT<sub>2</sub>X and Y(T<sub>0.5</sub>T′<sub>0.5</sub>)<sub>2</sub>X (T/T′ = Pd, Ag, Au; X = Mg, In) Heusler phases

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11

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24

References

2016

Year

Christopher Benndorf, Sebastian Stein, Lukas Heletta, Marcel Kersting, Hellmut Eckert, Rainer Pöttgen
Dalton Transactions

Abstract

Yttrium-transition metal-magnesium (indium) Heusler phases YPd<sub>2</sub>Mg, YPd<sub>2</sub>In, YAg<sub>2</sub>Mg, YAg<sub>2</sub>In, YAu<sub>2</sub>Mg, and YAu<sub>2</sub>In and their quaternary compounds (solid solutions) Y(Pd<sub>0.5</sub>Ag<sub>0.5</sub>)<sub>2</sub>Mg, Y(Pd<sub>0.5</sub>Ag<sub>0.5</sub>)<sub>2</sub>In, Y(Pd<sub>0.5</sub>Au<sub>0.5</sub>)<sub>2</sub>Mg, Y(Pd<sub>0.5</sub>Au<sub>0.5</sub>)<sub>2</sub>In, Y(Ag<sub>0.5</sub>Au<sub>0.5</sub>)<sub>2</sub>Mg and Y(Ag<sub>0.5</sub>Au<sub>0.5</sub>)<sub>2</sub>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 MnCu<sub>2</sub>Al type structure (Heusler phase), space group Fm3[combining macron]m. The structure of Y(Ag<sub>0.39</sub>Au<sub>0.61</sub>)<sub>2</sub>Mg was refined from single crystal X-ray diffractometer data: a = 689.97(5) pm, wR<sub>2</sub> = 0.0619, 52 F<sup>2</sup> values, 6 parameters. Magnetic susceptibility measurements show Pauli paramagnetic behavior for all samples. The compounds were investigated by <sup>25</sup>Mg, <sup>89</sup>Y and <sup>115</sup>In 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 <sup>89</sup>Y shifts show a correlation with the electronegativity of the main group atoms (Mg, Cd, In, Sn). The solid solutions Y(Ag<sub>1-x</sub>T<sub>x</sub>)<sub>2</sub>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.

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