Irmantas Barnackas, prof. L. Pranevičius Lithuanian Energy Institute Destabilization of Mg-based hydrogen storage materials: experimental results

To synthesize destabilized MgH 2 hydride and to investigate the hydride properties The main goal of the work

Experimental technique: to produce nanocrystalline Mg, Mg-Ti thin film materials using magnetron sputtering; to hydrogenate Mg, Mg-Ti thin films in high hydrogen pressure and temperature (p,T); to study Mg, Mg-Ti thin films de-hydrogenation kinetics using GDOES techniques; to analyze Mg, Mg-Ti thin films properties of as- deposited, after hydrogenation and de- hydrogenation using XRD, SEM and GDOES methods.

Quartz substrate Mg film Ti layer Quartz substrate Ti layer Mg film Quartz substrate Mg + Ti film U Ti = 490 V, I Ti = 0.5 A, t = 5 sec. U Mg = 420 V, I Mg = 1 A, t = 5 min. U Ti = 480 V, I Ti = 0.5 A, t = 5 sec. U Mg = 405 V, I Mg = 1 A, t = 5 min. U Mg = 410 V, I Mg = 1 A U Ti = 440 V, I Ti = 0.5 A t = 5 min. Parameters of as-deposited Mg and MgTi films : Quartz substrate Mg film U Mg = 420 V, I Mg = 1 A, t = 5 min. Pressure (Ar) – 0.4 Pa U BIAS = -100 V, I BIAS = mA Pressure (Ar) – 0.4 Pa U BIAS = -100 V, I BIAS = mA

Parameters of hydrogenation/dehydrogenation of Mg, MgTi thin films in high hydrogen pressure and temperature (p,T) Parameters of hydrogenation: Pressure (H 2 ) – 8-11 bar Temperature – RT – C Hydrogenation duration – 6 hour Parameters of dehydrogenation: Temperature – RT – C Dehydrogenation duration – 60 min.

As-deposited Mg film: - XRD and SEM analysis XRD diffractogram of as-deposited Mg film on quartz substrate SEM micrograph of as-deposited Mg film on quartz substrate

Hydrogenation/dehydrogenation kinetics of Mg film: Hydrogenation/dehydrogenation kinetics of Mg film: - XRD and SEM analysis SEM micrograph of Mg film: (a) after hydrogenation; (b) after dehydrogenation XRD analysis of XRD analysis of Mg film after hydrogenation/dehydrogenation processes b a

Studies of de-hydrogenation kinetics of Mg thin films

As-deposited Mg-Ti film: - XRD and SEM analysis XRD diffractogram of as-deposited MgTi film on quartz substrate SEM micrograph of as-deposited MgTi film on quartz substrate

Hydrogenation/dehydrogenation kinetics of Mg-Ti film: Hydrogenation/dehydrogenation kinetics of Mg-Ti film: - XRD and SEM analysis XRD analysis of XRD analysis of Mg-Ti film after hydrogenation process SEM micrograph of MgTi film after hydrogenation

As-deposited Mg-Ti film: - XRD and SEM analysis XRD diffractogram of as-deposited MgTi film on quartz substrate SEM micrograph of as-deposited MgTi film on quartz substrate

Hydrogenation/dehydrogenation kinetics of Mg-Ti film: Hydrogenation/dehydrogenation kinetics of Mg-Ti film: - XRD and SEM analysis a b XRD analysis of XRD analysis of MgTi film after hydrogenation/dehydrogenation processes SEM micrograph of MgTi film: (a) after hydrogenation; (b) after dehydrogenation

Studies of de-hydrogenation kinetics of Mg-Ti thin films

As-deposited Mg-Ti film: - XRD and SEM analysis XRD diffractogram of as-deposited MgTi film on quartz substrate SEM micrograph of MgTi film after hydrogenation

Hydrogenation/dehydrogenation kinetics of Mg-Ti film: Hydrogenation/dehydrogenation kinetics of Mg-Ti film: - XRD and SEM analysis XRD analysis of XRD analysis of MgTi film after hydrogenation/dehydrogenation processes a b SEM micrograph of MgTi film: (a) after hydrogenation; (b) after dehydrogenation

Studies of de-hydrogenation kinetics of Mg-Ti thin films

XRD diffractogram of as-deposited MgTi film on quartz substrate As-deposited Mg-Ti film: - XRD and SEM analysis SEM micrograph of MgTi film after hydrogenation

Hydrogenation/dehydrogenation kinetics of Mg-Ti film: Hydrogenation/dehydrogenation kinetics of Mg-Ti film: - XRD and SEM analysis XRD analysis of XRD analysis of MgTi film after hydrogenation/dehydrogenation processes a b SEM micrograph of MgTi film: (a) after hydrogenation; (b) after dehydrogenation

Studies of de-hydrogenation kinetics of Mg-Ti thin films

Conclusions 1.2 µm Mg and Mg x Ti y thin films were successfully deposited on the quartz substrates using magnetron sputtering. 2.After the hydrogenation of pure Mg thin films in hydrogen atmosphere, in high pressure and high temperature, MgH 2 thin films were successfully formed. 3.The MgTi thin film deposited without bias voltage and hydrided in high pressure and high temperature (p,T) at C for 6 hour transforms to MgH 2.