@conference{
author = "Milojković, Natalija and Simović, Bojana and Žunić, Milan and Dapčević, Aleksandra",
year = "2023",
abstract = "Titanium dioxide exists in three different crystalline forms: anatase, rutile, and brookite.
It is well known that on heating, anatase and brookite can be easily transformed to rutile
which is considered as the most stable phase [1]. The aim of this study was to investigate
the influence of different dopants on anatase-rutile phase transition. Doped TiO2 samples
(TiO2-M, M = V, Mn, and Cu) containing 5 at% of the dopant were prepared by mixing
anatase and appropriate oxide (V2O5, MnO2, and CuO) in agate mortar for 30 min. In
order to determine the heat treatment conditions, TG/DTA analysis of the samples was
performed. Finally, mixed powders as well as the pure anatase phase (TiO2) were heat
treated at 700 °C for 3 h. XRD analysis was performed to estimate the phase composition,
unit cell parameters, and crystallite sizes. Rutile was formed in all samples: 2.8 wt% in
TiO2, 25.5 wt% in TiO2-Mn, 75.8 wt% in TiO2-V, and 95.2 wt% in TiO2-Cu. In TiO2-
Mn, TiO2-V, and TiO2, anatase was present beside rutile, while in the case of TiO2-Cu
4.8 wt% of the unreacted CuO was found. Obtained results revealed that all the dopants
accelerated anatase-rutile phase transition in the following order: Cu2+ > V5+ > Mn4+. It
is well known that defects are the driving force for the anatase-rutile phase transition and
since Ti4+ and Mn4+ are isovalent, no new defects were formed by incorporating Mn4+
ions into TiO2 lattice. This resulted in the least amount of rutile in TiO2-Mn comparing
to TiO2-V and TiO2-Cu where new defects were probably formed. As no initial oxides
were found in TiO2-Mn and TiO2-V, it can be concluded that Mn4+ and V5+ ions were
incorporated into the anatase lattice. On the other hand, in the case of TiO2-Cu, even 4.8
wt% of initial CuO was found. The detected residue of CuO can be explained by the fact
that the ionic radius of Cu2+ for an octahedral environment (0.870 Å) is much larger than
that of Ti4+ (0.745 Å), unlike those for Mn4+ (0.670 Å) and V5+ (0.680 Å). Although
almost all introduced quantity of CuO, i.e. 96 %, was found in TiO2-Cu, a small amount
was surely necessary to cause the anatase-rutile phase transition. According to calculated
crystallite sizes which were in the range of 55 – 90 nm, nanocrystalline samples were
prepared.
1. P. I. Gouma, M. J. Mills J. Am. Ceram. Soc. 2001, 84 (3) 619–622.",
publisher = "Serbian Chemical Society and Serbian Young Chemists’ Club, Belgrade, Serbia",
journal = "9th Conference of Young Chemists of Serbia, Novi Sad, Serbia",
title = "The influence of dopants on anatase-rutile phase transition",
pages = "164",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2196"
}
