Solid-State Synthesis of 70 nm Li4Ti5O12 Particles by Mechanically Activating Intermediates with Amino Acids
A novel synthetic method of fine particles of highly pure Li4Ti5O12 with the smallest possible particle size was proposed. A stoichiometric mixture of CH3COOLi·2H2O and anatase fine particles of ca. 50 nm was calcined at 773 K to obtain an intermediate, comprising Li2TiO3 and unreacted titania. The intermediate was then intensively milled by a planetary ball mill for 1 h. After adding an amino acid, glycine, alanine (ALA), orl-phenylalanine (PHE), the mixture was further milled under a milder condition for another 3 h and subjected to a second calcination at 973 K for 1 h to obtain Li4Ti5O12 with a phase purity above 97%. When we used ALA or PHE as an additive, the microscopically determined average particle size of Li4Ti5O12 was 70±10 nm. The mechanisms and significance of the present two-step calcination with mechanical activation and addition of an amino acid to the intermediate were discussed in terms of the topotactic nature of transformation between the two layer-structured species: Li2TiO3 and Li4Ti5O12.
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Document Type: Research Article
Faculty of Science and Technology, Keio University, Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
Institut de Recherche d'Hydro-Québec (IREQ), Lionel-Boulet, Varennes, QC, Canada, J3X 1S1
May 1, 2008