Thermal decomposition, phase evolution, sintering and characterization of lithium titanate synthesized by sol-gel process

Lithium titanate powder was prepared by evaporation of an aqueous suspension obtained in reaction between lithium nitrate (LiNO 3 ) and titanium hydroxide, formed by the hydrolysis of titanium tetrabutoxide Ti(C 4 H 9 O) 4 . Thermal decomposition and phase evolution behaviour of the dried powder were studied using TG-DTA and XRD, while powder characteristics (crystallite size, agglomerate size and morphology) were studied using X-ray diffraction, laser light scattering and SEM techniques. The synthesized powder exhibited loss in weight accompanied by corresponding heat effects in stages up to 550°C, transformed into an amorphous lithium titanate (Li 2 TiO 3 ) compound and finally underwent crystallization at temperatures ranging from 550 to 650°C (accompanied by an exotherm at the DTA pattern). The powder formed at 650°C was found to be nanocrystalline (crystallite size ~10 nm), while the crystallites grew to 50 nm with increasing temperature to 1000°C. Both SEM and particle size data confirmed that the calcined powder consists of agglomerates with the mean size of ~3 µm. Study of the powder sintering behaviour showed that densification and grain growth were very inten sive during heat treatment up to 1050°C. Sintering at 1200°C led to loss of lithium and formation of Li 0.14 TiO 2 phase. Thus, fine grained Li 2 TiO 3 bodies with density higher than 85% TD, required for tritium breeding in ITER (International thermonuclear experimental reactor) application, can be formed by sintering of the prepared powder at temperature of 1050°C.