In situ X-ray diffraction (XRD) shows that LaMg12 and La2Mg17 are thermally stable under argon upon heating to 330°C, while under hydrogen they decompose to LaH3 and MgH2 at about 290 and 270°C, respectively. The decomposition is believed to result from the large difference in enthalpy between the parent compounds and the resultants. Prior to the decomposition, the lattice parameters of LaMg12 and La2Mg17 do not change, indicating that hydrogen does not dissolve into them to form solid solution of LaMg12Hx and La2Mg17Hx. The enhanced mobility of La and/or Mg was observed in the presence of hydrogen, which might be related to the formation of the copious vacancy.
All Science Journal Classification (ASJC) codes
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry