High-pressure synthesis of L10 MnAl with near-stoichiometric composition

L10 MnAl, which is a nonequilibrium ferromagnetic phase, is fabricated successfully with various compositions via high-pressure synthesis. The L10 phase is observed at pressures higher than 5 GPa, indicating that the volume effect is crucial for the stabilization of this phase. The employed synthesis route does not require a Mn-rich ε-phase, which has conventionally been used as the precursor compound. This allows for the synthesis of the L10 phase with a near-stoichiometric composition. In addition to variations in the composition in terms of the Mn/Al ratio, the axial ratio (c/a) as well as the ordering parameter (S) are modified systematically, with the maximum c/a and S values corresponding to the stoichiometric composition. With this structural change, the highest coercive force is also observed at the stoichiometric composition.

Decoupling grain growth from densification during sintering of oxide nanoparticles

Unique shrinkage mode of oxide nanoparticles enables densification without grain growth.