Electronic structures and impurity cluster features in Mg-Zn-Y alloys with a synchronized long-period stacking ordered phase

Photoemission and inverse-photoemission spectroscopy (PES and IPES) measurements were carried out on polycrystalline Mg₉₇Zn₁Y₂, Mg₈₅Zn₆Y₉, and Mg₇₅Zn₁₀Y₁₅ alloys with a synchronized long-period stacking ordered phase together with non-doped Mg to investigate the valence- and conduction-band electronic structures, respectively. It was found from the valence-band PES spectra that the non-doped Mg includes at most 25% of an intrinsic oxidation portion. With increasing impurity concentration, the valence-band density of states (DOS) very slightly changes, while the conduction-band DOS drastically varies. The contributions of the impurity elements are clarified using a density functional theory calculation for the Mg₈₅Zn₆Y₉ alloy. The core-level PES measurements were also performed at the Mg 2s, 2p, Zn 3p, 3d, and Y 3d levels to study the chemical natures of the corresponding elements. The Y 3d core spectrum exhibits mostly three doublets in Mg₉₇Zn₁Y₂, while mostly only one in the heavily doped alloys, reflecting a coexistence of three different sites of the Y atoms; ones in the Zn₆Y₈ L1₂ clusters, ones in their fragments, and isolated ones in Mg₉₇Zn₁Y₂.