Yi-Ming Hon

Synthesis and characterization of Li1+δMn2−δO4 powders prepared by citric acid gel process

Abstract Li1+δMn2−δO4 were synthesized by citric acid gel process using lithium acetate and manganese acetate as the sources of lithium and manganese. Spinel Li1+δMn2−δO4 had been synthesized at various temperatures from 200 to 500°C and the synthesis mechanism was examined by thermal and structural analysis. Li1+δMn2−δO4 can be synthesized as low as 200°C is attributed to the short distance between lithium and manganese formed in precursor prepared by citric acid gel process . Thus, lithium and manganese could react each other and form the desired compound at low temperatures. The lattice parameter of powders increased with increasing temperature from 8.136 A at 200°C to 8.211 A at 500°C. The specific surface area of sample calcined at 200°C was 160 m2/g and deceased with calcination temperature increasing. From the SEM studies, the powder prepared at 200°C showed porous structure due to the liberation of CO2 and H2O from the decomposition of organic material. The particle size of powder calcined at 300°C for 24 h in the range of 60 to 85 nm. The powder synthesized by citric acid gel process showed circular shape and did coarsen significantly with the calcination temperature increased.