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

Abstract

Lithium titanate powder was prepared by evaporation of an aqueous suspension obtained in reaction between lithium nitrate (LiNO3) and titanium hydroxide, formed by the hydrolysis of titanium tetrabutoxide Ti(C4H9O)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 (Li2TiO3) 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 intensive during heat treatment up to 1050°C. Sintering at 1200°C led to loss of lithium and formation of Li0.14TiO2 phase. Thus, fine grained Li2TiO3 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.

Keywords

• Lithium titanate
• Breeder materials
• Sol-gel
• ITER. SEM