Formation of Nd2Fe14B hydride by milling of anhydride particles in toluene in a closed reactor

Ram, S and Banerjee, H D and Halder, S and Ramachandrarao, P (1997) Formation of Nd2Fe14B hydride by milling of anhydride particles in toluene in a closed reactor. Bulletin of Materials Science, 20 (8). pp. 1049-1058.

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When milling micrometer thin Nd2Fe14B platelets, of an average 1–2 mm diameter, in toluene in a closed reactor, part of the toluene decomposes at the surface of the platelets and yields nascent hydrogen and carbon/low hydrocarbons. The hydrogen diffuses into the Nd2Fe14B platelets and the carbon forms a thin surface passivation layer of the platelets, forming the stable Nd2Fe14BH x ,x ≤ 5, hydride at room temperature. On heating in a calorimeter, the hydrogen desorbs off the sample with a well-defined endotherm between 370 and 425 K. An N2 gas atmosphere, if used during the heating, facilitates the H-desorption process with the modified kinetic parameters. For example, the enthalpy of the H-desorption ΔH and the related activation energyE a have the measured values ΔH = 153 J/g andE a = 58·2 kJ/mol in argon and ΔH = 256 J/g andE a = 41·6 kJ/mol in N2. It is argued that N2 gas has a fast reaction with the H atoms desorbing off the thin sample platelets and forms NH3 gas with an instantaneous decrease of the total external gas pressure at the sample. This supports the fast desorption of H atoms in the sample with the modified desorption kinetics in N2 gas.

Item Type:Article
Official URL/DOI:
Uncontrolled Keywords:Nd2Fe14BH x ,x ≤ 5 - hydrides - hydrogen intercalation - hydrogen desorption - stable metal hydride - thermal desorption - mechanical attrition
Divisions:Material Science and Technology
ID Code:763
Deposited By:Sahu A K
Deposited On:01 Jun 2010 13:52
Last Modified:08 Feb 2012 12:24
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