Synthesis and decomposition mechanisms of ternary Mg2CoH5 studied using in situ synchrotron X-ray diffraction

Controlled mechanochemical synthesis and hydrogen desorption mechanisms of nanostructured Mg2CoH5

“…4(a), through the in-situ XRD analysis it is clear that the b-Mg 2 CoH 5 to g-Mg 2 CoH 5 phase transition occurs between 185 and 205 C. The decomposition of the g-Mg 2 CoH 5 structure starts at temperatures above 325 C. At 385 C, practically all of the g-Mg 2 CoH 5 had decomposed into Mg and Co. The MgeCo intermetallic compounds starts to appear at temperatures close to 400 C. In spite of the different heating rate employed, the results are in good agreement with the exothermic peaks observed in the DSC curves, and are similar to those reported by Norek et al a few years ago [20]. In this paper, the authors state that at temperatures close to 350 C, the g-Mg 2 CoH 5 decomposes directly into Mg and Co, similar to what is seen in Fig.…”

“…Although the phase transition be clearly seen through the in-situ XRD analyses, no endothermic peaks related to this transformation is observed in the DSC curve of the 12 h milled sample presented in Fig. 4, as reported before, see for example [20].…”

“…This result suggests that Co improves the hydrogen desorption kinetics of MgH 2 , as already well-established for other transition metal additions to MgH 2 [18]. The onset temperatures of desorption of the 6 h, 12 h and 24 h samples were also relatively low, ranging from 220 to 238 C. The 12 h and 24 h samples that were rich in Mg 2 CoH 5 also exhibited exothermic peaks at higher temperatures, i.e., above 400 C. As already reported, these peaks may be related to the formation of MgeCo intermetallics, such as MgCo and MgCo 2 , after hydride decomposition [19,20]. The second interesting observation is the absence of the endothermic peak close to 200 C related to the allotropic phase transition of the Mg 2 CoH 5 .…”

Mg-based compounds for hydrogen and energy storage

“…Hydrogen desorption from Mg 2 CoH 5 is a multistep process, which at 500°C leads to the formation of MgCo and Mg [43]. This process is, however, reversible and allows the synthesis of Mg 2 CoH 5 when the mixture MgCo ?…”

MgH2–CoO: a conversion-type composite electrode for LiBH4-based all-solid-state lithium ion batteries

“…Ball milling of MgH 2 and metallic Co is reported to result in formation of Mg 2 CoH 5 . 34,35 We nd that ball-milling MgH 2 /CoO using Spex for 3 h is enough to form signicant amounts of this phase. In this case, the analyzed patterns ( Fig.…”