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

Li1+deltaMn2-deltaO4 were synthesized by citric acid gel process using lithium acetate and manganese acetate as the sources of lithium and manganese. Spinel Li1+deltaMn2-deltaO4 had been synthesized at various temperatures from 200 to 500 degreesC and the synthesis mechanism was examined by thermal and structural analysis. Li1+deltaMn2-deltaO4 can be synthesized as low as 200 degreesC 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 Angstrom at 200 degreesC to 8.211 Angstrom at 500 degreesC. The specific surface area of sample calcined at 200 degreesC was 160 m(2)/g and deceased with calcination temperature increasing. From the SEM studies, the powder prepared at 200 degreesC 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 degreesC 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. (C) 2001 Elsevier Science Ltd. All rights reserved.