SYNTHESIS OF ORTHORHOMBIC LiMnO2 BY HYDROTHERMAL PROCESS

Abstract

This work synthesised layered structural orthorhombic LiMnO2 powder via a hydrothermal process. The influences of hydrothermal temperature (t_r°), reaction time (t_ht), molar concentration of LiOH.H₂O in aqueous solutions (C_LH), and the ratio of Mn₂O₃ powder (x_r/t) were investigated. A high-purity LiMnO₂ powder was successfully synthesised using hydrothermal synthesis at C_LH = 4M, t_ht = 8 h, t_r° = 180 °C, and x_r/t = 0.9. The synthesis LiMnO₂ powders have layer structure, and the planar density calculations indicated that the (021) planes had a lower average planar density than those of (100) and (010) planes, which led to a faster crystal growth on (021) planes. Moreover, single crystals of LiMnO₂ were pseudo-hexagonal also due to the lower average planar density of (221) planes compared to that of (021) planes, which made the crystal grow faster on (221) planes.