A²⁵Mg,⁸⁹Y and¹¹⁵In solid state MAS NMR study of YT₂X and Y(T_0.5T′_0.5)₂X (T/T′ = Pd, Ag, Au; X = Mg, In) Heusler phases

Abstract

Yttrium-transition metal-magnesium (indium) Heusler phases YPdMg, YPdIn, YAgMg, YAgIn, YAuMg, and YAuIn and their quaternary compounds (solid solutions) Y(PdAg)Mg, Y(PdAg)In, Y(PdAu)Mg, Y(PdAu)In, Y(AgAu)Mg and Y(AgAu)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 MnCuAl type structure (Heusler phase), space group Fm3[combining macron]m. The structure of Y(AgAu)Mg was refined from single crystal X-ray diffractometer data: a = 689.97(5) pm, wR = 0.0619, 52 F values, 6 parameters. Magnetic susceptibility measurements show Pauli paramagnetic behavior for all samples. The compounds were investigated by Mg,Y and 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 theY shifts show a correlation with the electronegativity of the main group atoms (Mg, Cd, In, Sn). The solid solutions Y(AgT)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.

Crystal Structure, Magnetism, 89Y Solid State NMR, and 121Sb Mössbauer Spectroscopic Investigations of YIrSb

“…In comparison the isotypic compound YIrSn shows a higher Knight shift value of 2107 ppm . As previously discussed for the isotypic Heusler compounds YPd 2 X with X = Mg, Cd, In, Sn, the effect can be attributed to the electronegativity of the main group element (EN = 2.05 and 1.96 for Sb and Sn, respectively). The increased electron withdrawing character of Sb leads to a reduced spin‐density of s ‐electrons near the Fermi edge at the atomic yttrium site resulting in a lower Knight shift contribution to the 89 Y resonance shift.…”

Recent progress in solid‐state nuclear magnetic resonance of half‐integer spin low‐γ quadrupolar nuclei applied to inorganic materials

“…25 Mg NMR has been reported for the cubic Heusler phases Y (Pd,Ag,Au) 2 Mg, where a single resonance was observed with significant shifts of 499 to 924 ppm due to Knight shift effects. [151] Although lithium-based technology dominates rechargeable batteries, there is significant interest in looking at magnesium-ion alternatives. Given the role of magnesium ions will be central to the properties of these materials, there are still relatively few reports.…”