Abstract: anocrystalline titania powder was prepared by the hydrolysis of titanium butoxide. The grain sizes of the powder calcined at 500～800℃ were measured by XRD. It was
found that the thermal stability of nanosized titania powder was improved by adding 0.4wt% rutile. Meanwhile, the powder compacts (green density was 68.3%) were
sintered at 750℃ and 800℃ under 30MPa, 57MPa and 200MPa, respectively. The microstructural development was studied by Poresizer, Pycnometer and SEM. Because
of the high pressure which increases intrinsic driving force for the diffusional transport of the pores, the densification process of hot-pressed samples commences at 750℃.
After the samples were sintered at 200MPa/800℃, the relative density was about 97.2%. Furthermore, the interagglomerational pores with size of 3～15nm could be
found in the samples, even if high pressure was used. Probably it is the main reason that the nanosized titania could not be densified thoroughly at low temperature.

Key words: nano-titania, crystalline seed, thermal stability, hot-pressure sintering