Mechanochemical synthesis of CeB₆ nanopowder

Mechanochemical synthesis of CeB₆ nanopowder was performed using a mixture of CeCl₃, CeO₂, B₂O₃ and either Mg or MgH₂. The reaction for the CeO₂-3B₂O₃-11MgH₂ mixture to form CeB₆ and MgO gradually proceeds during ball milling, while the mechanically induced self-propagating reaction (MSR) behavior is observed during ball milling of the CeO₂-3B₂O₃-11 Mg mixture. X-ray diffraction patterns of the CeO₂-3B₂O₃-11MgH₂ mixture indicate that CeH_2+x exists as an intermediate phase during the reaction. Scanning electron microscopy indicates that the particle size of CeB₆ powder from the CeO₂-3B₂O₃-11MgH₂ mixture is much smaller than that from the CeO₂-3B₂O₃-11 Mg mixture. Transmission electron microscopy revealed that CeB₆ particles 10–30 nm in size from the CeO₂-3B₂O₃-11MgH₂ mixture are highly agglomerated with surface oxide layers. The mechanochemical reaction of the 2CeCl₃-6B₂O₃-21MgH₂ mixture produces CeB₆ instead of Ce(BH₄)₃.