Microstructure and hydrogen storage capacity of magnesium hydride with zirconium and niobium fluoride additives after cyclic loading
I. Malka , J. Bystrzycki , Tomasz Płociński , T. Czujko
AbstractIn this work, new results on the microstructure and hydrogen storage capacity of MgH2 with ZrF4 and NbF5 after cyclic loading are presented. Commercial MgH2 powder was mixed with 7 wt.% metal halide powder and subsequently ball milled in an inert atmosphere. The microstructure of the powders was investigated with high-resolution SEM using BSE/STEM/EDS detectors. The thin samples were prepared by FIB. The materials exhibited good reversibility and hydrogen sorption stability. However, the hydrogen storage capacity decreased in both materials after prolonged cycling at 325 °C. Better sorption stability was observed for MgH 2 with ZrF4 than for MgH2/NbF5. Its microstructure consisted of an MgH2 matrix and stable nano-sized ZrF4 particles embedded in the "core" structure of the particles. The outer layer of the particles was identified as MgH 2.The gradual decrease in the hydrogen storage capacity while cyclic loading for this particular material is due to some stabilization of the fraction of MgH2/Mg with continues increase of grain size in the MgH2/Mg regions, from about 10 nm after ball milling to hundreds of nanometers after cycling. The stabilization process makes a fraction of MgH 2/Mg inactive in the process of hydrogen desorption/absorption. In contrast, the MgH2/NbF5 sample after cyclic loading exhibited an MgH2/Mg matrix with some amount of MgF2 phase and nano-sized Nb-rich precipitates. The formation of the MgF2 phase is mainly responsible for the lost of hydrogen storage capacity of the MgH 2/NbF5 sample while cyclic loading. © 2010 Elsevier B.V. All rights reserved.
|Journal series||Journal of Alloys and Compounds, ISSN 0925-8388, (A 35 pkt)|
|Pages||S616 - S620|
|Publication size in sheets||0.5|
|Keywords in English||Cyclic hydriding/dehydriding; Hydrogen storage capacity; Magnesium hydride; Metal halides; Microstructure|
|ASJC Classification||; ; ;|
|Publication indicators||= 21; : 2014 = 1.66; : 2011 = 2.289 (2) - 2011=2.104 (5)|
|Citation count*||26 (2019-12-28)|
* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.