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

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Presentation on theme: "Training at Stockholm University (2007 09 12 - 10 02) Martynas Lelis."— Presentation transcript:

1 Training at Stockholm University ( ) 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 Mg 2 Ni alloys and their hydrogenation to Mg 2 NiH 4  There are three phases of Mg 2 NiH 4 – LT1, LT2 (with microtwining) and HT  At ~235° C LT transforms to HT

4 Background  Initial investigation of Mg 2 NiH 4 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

12 Discussions

13 Discussions - XRD

14 Thin film: a=6.440 Å Scratched powders: a= Å Powder material: 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

21 Discussion - model MgO Thin film Powder Mg 2 Ni zones Mg zones

22 Conclusions 1. During the visit to Stockholm university new analytical techniques were successfully learned and employed for sample characterization 2. Measurement of thin film samples has given some proving evidence (not complete) for the existence of pseudo cubic HT phase of Mg 2 NiH 4

23 Your suggestion and comments


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