chemia - Studia

MONICA BAIA, MONICA SCARISOREANU, ION MORJAN, IULIANA P. MORJAN, LUCIAN BAIA ET ALL
located around 2θ=25 0 are given in Table 2. For comparison purpose the
commercial product Degussa P-25 was also investigated.
As can be observed from Table 2, different amounts of crystalline
phases are developed inside the samples. Thus, in the case of the SC 1-4
sample the rutile phase is preponderantly formed, while in the SC 6 sample
the anatase phase is the main developed crystalline phase. Previous
studies reported [9, 13] about the effect of carbon coating in stabilization of
the anatase phase. By taking into account the data summarized in Table 1
related to the carbon content, one can assume that the formation of the
anatase phase in the sample SC 6 as the main phase could be associated
with the existence of a higher amount of carbon.
Table 2. Structural parameters of the TiO 2 nano-powders as estimated
from XRD analysis
Samples
code
TiO 2 crystalline
phase content (%)
Crystallites
dimension (nm)
Specific surface
area (m 2 /g)
A R A R
SC 1-4 42 58 20 16 81
SC 6 75.5 24.5 17 14 86
Degussa P-25 80 20 ~ 20 ~ 30 50
(a)
(b)
8
Figure 2. TEM micrographs of the TiO 2 nanopowders and the corresponding
particle size distributions:(a) SC 1-4 and (b) SC 6.