Effect of calcination temperatures on structures of TiO2 powders prepared by hydrothermal method using Thai leucoxene mineral

Abstract

TiO2 powders were synthesized by hydrothermal method with 10M NaOH solution at 115 ºC for 24 h using natural Thai leucoxene mineral as the starting materials. The effects of calcination temperatures on structures of the prepared materials were investigated. The structures of the prepared samples were characterized by X-ray diffraction (XRD) technique and scanning electron microscopy (SEM). The as-synthesized sample showed the nanotubes-nanofibers structures with ∼10-

20 nm in diameter of nanotubes and ∼20-50 nm in diameter of nanofibers. The XRD results showed that the as-prepared sample before being calcined were mixed phase of titanate and rutile. The titanate phase could transformed to anatase phase

at the calcination temperature higher than 300 ºC. As the calcination temperature increased, crystallization of the anatase phase enhanced. With further increase in the calcination temperature from 700 to 900 ºC, the intensity of rutile phase

increased. When the calcinations temperature reached 1000 ºC, only rutile phase was found in the XRD pattern.