Research ArticleMATERIALS SCIENCE

Resolving hydrogen atoms at metal-metal hydride interfaces

See allHide authors and affiliations

Science Advances  31 Jan 2020:
Vol. 6, no. 5, eaay4312
DOI: 10.1126/sciadv.aay4312
  • Fig. 1 Schematic of a STEM system and the γ-TiH crystal and its three possible interfaces with α-Ti.

    (A) iDPC images are captured with the quadrant detector (inner) and can be used simultaneously with the HAADF detector (outer). (B) Crystal structure model of the face-centered tetragonal (FCT) γ-TiH unit cell containing four hydrogen atoms that occupy tetrahedral sites. (C) Two columns in between the titanium columns are occupied by hydrogen atoms and two columns are empty. (D) Three potential models can describe the interface between γ-TiH and α-Ti.

  • Fig. 2 Comparison of images of the interface between γ-TiH and α-Ti using different techniques.

    (A) HAADF. (B) Contrast-inverted ABF. (C) iDPC. (D) Contrast-inverted dDPC. (E) DPC magnitude. (F) DPC vector field using color wheel representation. Insets: Simulated images of a 30-nm-thick specimen of interface model I shown in Fig. 1D. Field of view is 3.5 × 3.5 nm.

  • Fig. 3 Comparison of the experimental and simulated intensity profiles of the γ-TiH at the metal-metal hydride interface and the experimental SNR of the hydrogen column signal.

    (A) HAADF. (B) ABF. (C) dDPC. (D) iDPC. The pink and yellow bands represent the experimental intensity profiles of the Ti-empty-Ti-empty-Ti and Ti-H-Ti-H-Ti columns, respectively. The width of the bands is twice the SD, centered around the average value. Solid dark lines are the simulated profiles for a 32.2-nm-thick γ-TiH crystal. The SNR of the hydrogen signal is extracted from the experimental profiles and plotted below. a.u., arbitrary units.

  • Fig. 4 Comparison of high-quality images of γ-TiH far away from the interface.

    (A) HAADF. (B) Contrast-inverted ABF. (C) iDPC. Field of view is 3.13 × 3.13 nm.

  • Fig. 5 Comparison of the experimental and simulated intensity profiles of the γ-TiH under optimal imaging conditions and the SNR of the hydrogen column signal.

    (A) HAADF. (B) ABF. (C) iDPC. Here, the ABF is formed by summing the quadrants of the iDPC detector, such that the ABF and iDPC images use the exact identical raw data. The pink and yellow bands represent the experimental intensity profiles of the Ti-empty-Ti-empty-Ti and Ti-H-Ti-H-Ti columns, respectively. The width of the bands is twice the SD, centered around the average value. Solid dark lines are the simulated profiles for a 52-nm-thick γ-TiH crystal. The SNR of the hydrogen signal is extracted from the experimental profiles and plotted below.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/6/5/eaay4312/DC1

    Section S1. Specimen preparation and characteristics

    Section S2. Identification of the γ-TiH phase with electron energy loss spectroscopy (EELS)

    Section S3. Scanning transmission electron microscopy

    Section S4. Filtering procedure of the experimental images

    Section S5. Reciprocal space analysis of the hydrogen signal in γ-TiH

    Section S6. Multislice STEM simulations

    Section S7. Multislice simulations of the γ-TiH unit cell with and without hydrogen atoms

    Section S8. Multislice simulations of the tilted γ-TiH unit cell with and without hydrogen atoms

    Fig. S1. Electron backscatter diffraction map of the Ti sample.

    Fig. S2. Amorphous γ-TiH in thin parts of the specimen.

    Fig. S3. Crystal bending along the interface.

    Fig. S4. Plasmon mapping of Ti and γ-TiH.

    Fig. S5. Inspection of contamination with core loss EELS.

    Fig. S6. Effect of the applied spatial filter on images of γ-TiH.

    Fig. S7. Reciprocal space analysis of the hydrogen signal.

    Fig. S8. Image simulations of the γ-TiH unit cell with and without hydrogen atoms.

    Fig. S9. Simulated relative intensity of the hydrogen and titanium atoms in the ABF image.

    Fig. S10. Simulated relative intensity of the hydrogen and titanium atoms in the DPC sum (ABF-like) image.

    Fig. S11. Simulated relative intensity of the hydrogen and titanium atoms in the iDPC image.

    Fig. S12. Image simulations of the tilted γ-TiH unit cell with and without hydrogen atoms.

    Fig. S13. Comparison between experimental and simulated intensity profiles of the iDPC image of γ-TiH at the interface with Ti.

    Table S1. List of the electron detectors and their corresponding collection angles that are used in the experiment and simulation.

    References (4251)

  • Supplementary Materials

    This PDF file includes:

    • Section S1. Specimen preparation and characteristics
    • Section S2. Identification of the γ-TiH phase with electron energy loss spectroscopy (EELS)
    • Section S3. Scanning transmission electron microscopy
    • Section S4. Filtering procedure of the experimental images
    • Section S5. Reciprocal space analysis of the hydrogen signal in γ-TiH
    • Section S6. Multislice STEM simulations
    • Section S7. Multislice simulations of the γ-TiH unit cell with and without hydrogen atoms
    • Section S8. Multislice simulations of the tilted γ-TiH unit cell with and without hydrogen atoms
    • Fig. S1. Electron backscatter diffraction map of the Ti sample.
    • Fig. S2. Amorphous γ-TiH in thin parts of the specimen.
    • Fig. S3. Crystal bending along the interface.
    • Fig. S4. Plasmon mapping of Ti and γ-TiH.
    • Fig. S5. Inspection of contamination with core loss EELS.
    • Fig. S6. Effect of the applied spatial filter on images of γ-TiH.
    • Fig. S7. Reciprocal space analysis of the hydrogen signal.
    • Fig. S8. Image simulations of the γ-TiH unit cell with and without hydrogen atoms.
    • Fig. S9. Simulated relative intensity of the hydrogen and titanium atoms in the ABF image.
    • Fig. S10. Simulated relative intensity of the hydrogen and titanium atoms in the DPC sum (ABF-like) image.
    • Fig. S11. Simulated relative intensity of the hydrogen and titanium atoms in the iDPC image.
    • Fig. S12. Image simulations of the tilted γ-TiH unit cell with and without hydrogen atoms.
    • Fig. S13. Comparison between experimental and simulated intensity profiles of the iDPC image of γ-TiH at the interface with Ti.
    • Table S1. List of the electron detectors and their corresponding collection angles that are used in the experiment and simulation.
    • References (4251)

    Download PDF

    Files in this Data Supplement:

Stay Connected to Science Advances

Navigate This Article