Abstract
In this experimental study, aerosol methods for producing
titanium dioxide powders and increasing our knowledge of
particle and crystal formation have been developed.
Powders and ultrafine particles of titanium oxide were
produced by an aerosol droplet decomposition route in
tubular laminar flow reactors in air and nitrogen
atmospheres. Reactor temperatures up to 1500°C were used
with residence times in the range of 1-50 s. Novel
methods were introduced for the production of micron
sized powders, investigation of crystallization of
anatase in the particles, and for studying the formation
of crystal phase and morphology on ultrafine particles at
different temperatures. High-resolution transmission
electron microscopy, scanning electron microscopy,
aerosol measurements by differential mobility analyzer
and inertial impactor as well as materials
characterization by diffraction and spectroscopic methods
were performed. In addition, the production conditions in
aerosol reactors were evaluated using computational fluid
dynamics calculations. The results showed that titanium
dioxide powders can be produced from ultrafine up to
micron sized particles via droplet decomposition and
in-droplet hydrolysis methods starting from a titanium
alkoxide precursor. Crystal phase and crystallite size
can be controlled by reactor conditions and by thermal
post-annealing. Anatase formation in amorphous particles
was observed near surfaces. Investigation of ultrafine
particles revealed morphology development of rutile and
anatase single crystals. The 60 and 120 nm diameter
rutile crystal morphologies development was observed in
mobility particle size measurements. The 20 nm diameter
anatase particle morphology showed the development of
crystallographic {011} and {001} surfaces.
Original language | English |
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Qualification | Doctor Degree |
Awarding Institution |
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Supervisors/Advisors |
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Award date | 14 Sept 2001 |
Place of Publication | Espoo |
Publisher | |
Print ISBNs | 951-38-5857-X |
Electronic ISBNs | 951-38-5858-8 |
Publication status | Published - 2001 |
MoE publication type | G5 Doctoral dissertation (article) |
Keywords
- aerosols
- particles
- synthesis
- pyrolysis
- hydrolysis
- alkoxides
- titanium dioxide
- anatase
- rutile
- crystal morphology