Preparation of phase pure and well-crystallized Li 4Ti 5O 12 nanoparticles by precision control of starting mixture and calcining at lowest possible temperatures

Abstract

In an attempt to obtain spinel Li 4Ti 5O 12 with smallest possible grain size and highest possible phase purity via a solid state route, we tried to elevate reactivity of the reactant mixture by mechanical activation and appropriate choice of the starting materials. From the stoichiometric mixture comprising Li 2CO 3 and 150 nm anatase, we needed to heat at 950 °C for 1 h to obtain 81–88% phase purity ( PhP) of Li 4Ti 5O 12 with its average grain size ca 600 nm. After mechanical activation with a multi-ring mill for 30 min, 850 °C was enough to obtain 85–87% pure 500 nm spinel. From a combination of LiNO 3 and 50 nm anatase, 90–91% phase pure product with its grain size 240 nm was obtained at 750 °C due to fusion of the nitrate and shorter diffusion path. By using CH 3COOLi.2H 2O and 50 nm anatase we obtained 130 nm Li 4Ti 5O 12 with its PhP ca 90% by milling the mixture preliminarily calcined at 500 °C for 1 h and heating subsequently at 700 for 1 h.