화학공학소재연구정보센터
Thermochimica Acta, Vol.346, No.1-2, 73-82, 2000
Thermal transformations of titania hydrolysates prepared from tetraisopropoxytitanium(iv)
Titania hydrolysates prepared from the hydrolysis of both unmodified and modified tetraisopropoxytitanium(iv) are shown by both FT-Raman spectroscopy and X-ray diffraction to be amorphous with no long range ordering. The Raman hydrolysate spectra show three broad bands, consisting of multiple components, at Raman shifts of similar to 210, 440 and 570 cm(-1). These bands do not correspond with any known phase of titania. Thermal analysis shows broad endothermic peaks centred at 106-136 degrees C and extending to greater than or equal to 200 degrees C for each of the hydrolysates acid is attributed to dehydration and loss of water. Strong broad exothermic peaks are observed in the modified hydrolysate curves, in the 310-340 degrees C temperature range and are attributed to the combustion of the residual surface adsorbed organics. Weight loss occurred during these exotherms. Crystallisation of the disordered hydrolysates into anatase occurs in the 500-600 degrees C temperature range. The anatase --> rutile phase transition was found between 665 degrees C and 691 degrees C.