Hydrogen in-situ refining method for preparing high purity gadolinium

• Hydrogen can shuttle gadolinium freely at high temperature.
• The concentration of O and N dropped to 30 ppm and 19 ppm, respectively.
• The hydrogen content could finally decrease to 17 ppm.
• Hydrogen, water and ammonia signals can be detected successfully.
• This method is environment friendly and no other recontaminations.

The removal of non-metallic impurities, especially oxygen and nitrogen, from the rare-earth metal gadolinium (Gd) is challenging, due to their strong affinity to Gd metal. Herein we present an effective approach to prepare high purity Gd via a novel hydrogen in-situ refining method. The final concentrations of oxygen and nitrogen could be reduced to 30 and 19 mass ppm, respectively. The changes of lattice parameters were derived from XRD; enthalpy values and gaseous speciation associated with the gas–solid physiochemical reactions were determined through a combination of DSC/MS measurements and thermodynamic calculations. The results show that oxygen and nitrogen can be efficiently removed by degassing Gd with dissolved hydrogen. The underlying mechanism for the refinement is discussed systematically in this paper.