Synthesis of lithium manganese oxide in different lithium-containing fluxes

By using a needle-like raw material gamma-MnOOH as a Mn-source, single crystals of lithium manganese oxides were synthesized in a variety of lithium-containing fluxes including LiNO3, Li2CO3, LiOH, LiCl and Li2SO4. Needle-like Li1.33Mn1.67O4 and Li2MnO3 crystals and plate-like polyhedral Li2MnO3 crystals were obtained in an LiNO3 flux heated within different temperature ranges (300-400, 500-750 and 900-1000 degrees C, respectively). Not only polyhedral and film Li2MnO3 but also octahedral LiMn2O4 single crystals were obtained in an LiCl flux by use of different shaped containers to control the exposure to the atmosphere. Orthorhombic LiMnO2 crystals with tube- and rod-like shapes could be obtained at the bottom of the LiCl melt at 1000 degrees C. The lithiation reaction (at low temperature) and dissolution-precipitation controlled growth (at high temperature) of Li2MnO3 were also observed in Li2CO3 and LiOH fluxes. According to the reaction mechanism, the Li-containing fluxes investigated can be classified into four types: (1) LiNO3, oxidizing flux; (2) LiCl, non-oxide flux; (3) LiOH and Li2CO3, oxidic, but non-oxidizing fluxes; and (4) Li2SO4, no reaction.