“…NaFe 1/2 Mn 1/2 O 2 and Na 2/3 Fe 1/2 Mn 1/2 O 2 ,were synthesized using a solid-state process, 23,27 using Na 2 CO 3 (Sigma Aldrich, 99%), Fe 2 O 3 (Sigma Aldrich, 99%), and Mn 2 O 3 (Sigma Aldrich, 99%) as precursors with the molar ratios of 1 : 1/2 : 1/2 and 2/3 : 1/2 : 1/2, respectively. The precursors were mixed and e thoroughly ground using a mortar and pestle, and then pressed into pellets.…”