Nanocomposites and nanomaterials 

Composites of magnesium hydride with catalytic nanoadditives
Berezovets V.V.1, Zavaliy I.Yu.1, Pavlovska O.B.2, Vasylechko L.O.2, Kosarchyn Yu.V.1
1 Physico-Mechanical Institute of the NAS of Ukraine. 5, Naukova str., 79060, Lviv, Ukraine. E-mail: berezovets@gmail.com
2 Semiconductor Electronics Department, Lviv Polytechnic National University, 12, Stepan Bandera str., 79013, Lviv, Ukraine

New hydride composites based on magnesium and Dy1-xRxFeO3 nanopowders with perovskite structure have been synthesized. Magnesium powder with a particle size of 0.1-0.3 mm and Dy1-xRxFeO3 nanopowders obtained by sol-gel method [1] were used as initial components. Synthesis of hydride composites was carried out by reactive ball milling in hydrogen gas. During milling, the composite 95 wt.% Mg + 5% wt.% Dy0.5Nd0.5FeO3 absorbed 6.8 wt.% of hydrogen. The size of the magnesium hydride crystallites obtained from the X-ray powder diffraction analysis was in the range of 6-10 nm. Thermal desorption of hydrogen by nanocomposites proceeded in one-stage with a peak at 315 °C.
After desorption of hydrogen from the hydride composites, they were re-hydrogenated at H2 pressure of 1-2 MPa and temperature of 150 °C. After re-hydrogenation of the composites, the splitting of hydrogen desorption peak was observed. This phenomenon is possibly due to the interaction of magnesium and perovskite and the formation of additional phases on the surface of magnesium hydride particles [2]. For the 95 wt.% Mg + 5 wt.% Dy0.5Nd0.5FeO3 hydride composite the activation energy of hydrogen desorption of 147 kJ/mol H2 have been evaluated from a series of thermal desorption spectra measured at different heating rates. The properties of the studied composite Mg+Dy0.5R0.5FeO3 hydride will be compared with other MgH2-based materials with catalytic nanoadditives.

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