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Training at Stockholm University (2007 09 12 - 10 02)

Training at Stockholm University (2007 09 12 - 10 02). Martynas Lelis. Contents. Background Objectives and tasks of the visit Measurements at SU Equipment Results Discussions. Background.

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Training at Stockholm University (2007 09 12 - 10 02)

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  1. Training at Stockholm University (2007 09 12 - 10 02) Martynas Lelis

  2. Contents • Background • Objectives and tasks of the visit • Measurements at SU • Equipment • Results • Discussions

  3. Background • In latter years in LEI there were experiments of formation of Mg2Ni alloys and their hydrogenation to Mg2NiH4 • There are three phases of Mg2NiH4 – LT1, LT2 (with microtwining) and HT • At ~235° C LT transforms to HT

  4. Background • Initial investigation of Mg2NiH4 samples prepared at LEI seems to be pseudo cubic HT phase (even at room temperatures) • Moreover, it exhibits unusual stability

  5. Objectives and tasks • Objective • To acquire new skills and better understanding in analyzing and characterization of hydrogen storage materials

  6. Objectives and tasks • Tasks • to learn the working principles of Differential scanning colorimeter (DSC) and spectrophotometer • to prepare and to measure samples from LEI • to analyze the results and to make conclusions

  7. Measurements at SU - equipment • Differential scanning calorimetry or DSC is a thermoanalytical technique in which the difference in the amount of heat required to increase the temperature of a sample and reference are measured as a function of temperature.

  8. Measurements at SU - equipment • The basic principle underlying this technique is that, when the sample undergoes a physical transformation such as phase transitions, more (or less) heat will need to flow to it than the reference to maintain both at the same temperature.

  9. Measurements at SU - equipment Perkin Elmer Pyris 1 • It can be used to find Heat Flow, Melting Temperature, Phase Transition Temperature etc. • Typical sample weights are 5-10mg

  10. Measurements at SU - results

  11. Measurements at SU - results

  12. Discussions

  13. Discussions - XRD

  14. Discussions - XRD • Thin film: • a=6.440 Å • Scratched powders: • a=6.507998 Å • Powder material: • 6.5295 Å

  15. Discussions - TEM D. Noréus, L. Kihlborg, J. Less-Comm. Met. 123 (1986) 233

  16. Discussions - TEM

  17. Discussions – DSC - powder

  18. Discussions – DSC – thin film

  19. Discussion – Band gap

  20. Discussion – Band gap

  21. Discussion - model Mg2Ni zones MgO Powder Mg zones Thin film

  22. Conclusions • During the visit to Stockholm university new analytical techniques were successfully learned and employed for sample characterization • Measurement of thin film samples has given some proving evidence (not complete) for the existence of pseudo cubic HT phase of Mg2NiH4

  23. Your suggestion and comments

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