Papers by Author: T. Kubo

Abstract: In this study, the synthesis of nanotubular titanate was attempted though heat-treatment in an oil bath (non-hydrothermal treatment), heat-treatment with stirring in an oil bath (non-hydrothermal treatment), or hydrothermal treatment for metal Ti in NaOH aqueous solution systems. Obtained products were characterized by various methods, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XRD results suggested that products obtained by both hydrothermal treatment and heat-treatment in an oil bath with and without stirring could be identified as H2Ti4O9
H2O. From TEM observations, however, various morphologies for products obtained by these treatments were confirmed. Therefore, it was considered that morphologies of these products strongly depended on synthesis conditions.

Abstract: By the usage of the hydrolysis of Ti alkoxide, various types of TiO2 were obtained through the addition of catalyst (HCl, NH4OH, and CH3COONH4) and some additives into Ti alkoxide solution at room temperature. In special, the effect of two additives, diethylene glycol (DEG) and hexamethylphospheric triamide (HMPA), on hydrolysis behaviors and microstructure with various catalyst for hydrolysis of Ti-tetraisopropoxide was in detail investigated. In case of TiO2 powder with HMPA as an additive, the crystallinity of TiO2 except with NH4OH as a catalyst decreased in XRD patterns, compared to those of products with no additive and with DEG as an additive. The addition of HMPA prohibited the growth of TiO2 and led to fine TiO2 with the average particle size of approximately 10nm.