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Materials (Basel). 2019 May 7;12(9). pii: E1472. doi: 10.3390/ma12091472.

Titanium Oxide Microspheres with Tunable Size and Phase Composition.

Author information

1
Faculty of Materials Science, Lomonosov Moscow State University, Leninskiye Hills 1, Moscow 119234, Russia. anpolvk@gmail.com.
2
Baikov Institute of Metallurgy and Material Science RAS, Leninsky Avenue 49, Moscow 119334, Russia. vitaliy.chelpanov@gmail.com.
3
Faculty of Chemistry, Lomonosov Moscow State University, Leninskiye Hills 1, Moscow 119234, Russia. vasya_lebedev@mail.ru.
4
Faculty of Materials Science, Lomonosov Moscow State University, Leninskiye Hills 1, Moscow 119234, Russia. danilkozlove@gmail.com.
5
Institute of General Inorganic Chemistry RAS, Leninsky Avenue 31, Moscow 119071, Russia. danilkozlove@gmail.com.
6
Faculty of Materials Science, Lomonosov Moscow State University, Leninskiye Hills 1, Moscow 119234, Russia. khazovakm@gmail.com.
7
Faculty of Chemistry, Lomonosov Moscow State University, Leninskiye Hills 1, Moscow 119234, Russia. dmsvolkov@gmail.com.
8
Faculty of Materials Science, Lomonosov Moscow State University, Leninskiye Hills 1, Moscow 119234, Russia. kolesnik.iv@gmail.com.
9
Faculty of Chemistry, Lomonosov Moscow State University, Leninskiye Hills 1, Moscow 119234, Russia. kolesnik.iv@gmail.com.
10
Institute of General Inorganic Chemistry RAS, Leninsky Avenue 31, Moscow 119071, Russia. kolesnik.iv@gmail.com.
11
Faculty of Materials Science, Lomonosov Moscow State University, Leninskiye Hills 1, Moscow 119234, Russia. garshev@inorg.chem.msu.ru.
12
Faculty of Chemistry, Lomonosov Moscow State University, Leninskiye Hills 1, Moscow 119234, Russia. garshev@inorg.chem.msu.ru.

Abstract

Due to their unique physical and chemical properties, monodisperse titanium oxide microspheres can be used in dye-sensitized solar cells, as cosmetic pigments, and for other applications. However, the synthesis of microspheres with narrow size distribution, desired phase composition, and porosity is still a challenge. In this work, spherical titania particles with controllable size, crystallinity, and pore size were obtained by Ti(OnBu)4 hydrolysis in ethanol. The influence of NaOH addition on the particles' size and morphology was investigated for the first time. Particle diameter can be tailored from 300 nm to 1.5 μm by changing water and NaOH concentrations. Particle size was analyzed by the statistical processing of scanning electron microscopy (SEM) images and differential centrifugal sedimentation (DCS) measurements. Optical properties of the microspheres were studied by diffuse reflectance UV-Vis spectroscopy. Thermal and hydrothermal treatment allowed transforming amorphous phase in as-prepared particles into nanocrystalline anatase and/or rutile. Transmission electron microscopy (TEM) study of the lamellae, cut out from spherical particles using focused ion beam (FIB), revealed that as-synthesized microspheres are non-hollow, homogeneous, and crystallize throughout the whole volume of the particle. The spherical particles possess photoprotective properties; the highest sun protection factor (SPF) was observed for amorphous microspheres.

KEYWORDS:

SPF; alkoxide hydrolysis; amorphous titania; optical absorption edge; size control; sol-gel synthesis; titania microspheres

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