Synthesis and decomposition mechanisms of ternary Mg2CoH 5 studied using in situ synchrotron X-ray diffraction
Małgorzata Norek , Thomas Kollin Nielsen , Marek Polanski , Izabela Kunce , Tomasz Płociński , Leszek R. Jaroszewicz , Y. Cerenius , Torben René Jensen , Jerzy Bystrzycki
AbstractA ternary Mg2CoH5 hydride was synthesized using a novel method that relies on a relatively short mechanical milling time (1 h) of a 2:1 MgH2-Co powder mixture followed by sintering at a sufficiently high hydrogen pressure (>85 bar) and heating from RT to 500 °C. The ternary hydride forms in less than 2.5 h (including the milling time) with a yield of ∼90% at ∼300 °C. The mechanisms of formation and decomposition of ternary Mg2CoH5 were studied in detail using an in situ synchrotron radiation powder X-ray diffraction (SR-PXD). The obtained experimental results are supported by morphological and microstructural investigations performed using SEM and high-resolution STEM. Additionally, thermal effects occurring during the desorption reaction were studied using DSC. The morphology of as-prepared ternary Mg2CoH5 is characterized by the presence of porous particles with various shapes and sizes, which, in fact, are a type of nanocomposite consisting mainly of nanocrystallites with a size of ∼5 nm. Mg2CoH5 decomposes at approximately 300 °C to elemental Mg and Co. Additionally, at approximately 400 °C, MgCo is formed as precipitates inserted into the Mg-Co matrix. During the rehydrogenation of the decomposed residues, prior to the formation of Mg2CoH5, MgH2 appears, which confirms its key role in the synthesis of the ternary Mg2CoH 5. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
|Journal series||International Journal of Hydrogen Energy, ISSN 0360-3199, (A 35 pkt)|
|Pages||10760 - 10770|
|Publication size in sheets||0.5|
|Keywords in English||In situ SR-PXD; Magnesium-cobalt hydride; Mechanical milling; Microstructure; Synthesis|
|ASJC Classification||; ; ;|
|Publication indicators||= 20; = 22; : 2011 = 1.829; : 2011 = 4.054 (2) - 2011=4.402 (5)|
|Citation count*||25 (2020-01-31)|
* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.