Electronic properties and bonding in ZrHx thin films investigated by valence-band x-ray photoelectron spectroscopy

Article

关键词: METAL-HYDRIDES;    ZIRCONIUM HYDRIDE;    1ST-PRINCIPLES;    PHOTOEMISSION;    STATE;    NB;    SC;    TI;   

DOI  :  10.1103/PhysRevB.96.195103

来源: SCIE

【 摘 要 】

The electronic structure and chemical bonding in reactively magnetron sputtered ZrHx (x = 0.15, 0.30, 1.16) thin films with oxygen content as low as 0.2 at.% are investigated by 4d valence band, shallow 4p core-level, and 3d core-level x-ray photoelectron spectroscopy. With increasing hydrogen content, we observe significant reduction of the 4d valence states close to the Fermi level as a result of redistribution of intensity toward the H 1s-Zr 4d hybridization region at similar to 6 eV below the Fermi level. For low hydrogen content (x = 0.15, 0.30), the films consist of a superposition of hexagonal closest-packed metal (alpha phase) and understoichiometric delta-ZrHx (CaF2-type structure) phases, while for x = 1.16, the films form single-phase ZrHx that largely resembles that of stoichiometric delta-ZrH2 phase. We show that the cubic delta-ZrHx phase is metastable as thin film up to x = 1.16, while for higher H contents the structure is predicted to be tetragonally distorted. For the investigated ZrH1.16 film, we find chemical shifts of 0.68 and 0.51 eV toward higher binding energies for the Zr 4p(3/2) and 3d(5/2) peak positions, respectively. Compared to the Zr metal binding energies of 27.26 and 178.87 eV, this signifies a charge transfer from Zr to H atoms. The change in the electronic structure, spectral line shapes, and chemical shifts as a function of hydrogen content is discussed in relation to the charge transfer from Zr to H that affects the conductivity by charge redistribution in the valence band.

【 授权许可】

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