التفاصيل البيبلوغرافية
| العنوان: |
Growth, optical, and wettability properties of iron modified titania and ferropseudobrookite thin films. |
| المؤلفون: |
Ferrara, Maria Cristina, Mazzarelli, Saverio, Schioppa, Monica, Pilloni, Luciano, Tapfer, Leander |
| المصدر: |
Journal of Applied Physics; 10/14/2021, Vol. 130 Issue 14, p1-14, 14p |
| مصطلحات موضوعية: |
TITANIUM dioxide films, THIN films, IRON chlorides, WETTING, CONTACT angle, DENDRITIC crystals, X-ray diffraction measurement |
| مستخلص: |
Iron (Fe)-modified titanium dioxide, Fe–TiO2, thin films with molar ratios Fe:Ti = 1:360, 1:60, and 1:30 and Fe-pseudobrookite, FeTi2O5 (molar ratio Fe:Ti = 1:2), were grown by the sol-gel process using acid-catalyzed solutions prepared with titanium isopropoxide and iron(III) chloride hexahydrate as Ti and Fe precursors, respectively. The layers were deposited by dip-coating onto soda–lime glasses and (100)-Si substrate wafers, and their chemical composition, crystal structure, and surface morphology were investigated in detail. For the low Fe-doped samples, the experimental results clearly indicate the formation of Fe–O–Ti heterolinkages. The films have an amorphous structure and high flatness surfaces if grown onto glass substrates. On the contrary, if grown onto (100)-Si substrates, they exhibit a granular structure (domain size ∼12 nm) made of a solid solution of Fe3+ ions within the anatase TiO2 lattice. For coatings with the molar ratio Fe:Ti = 1:2 (high Fe content), morphological investigations show the formation of wrinkled surfaces characterized by dendritic structures. X-ray diffraction measurements confirm the formation of nanocrystallites (domain size ∼15 nm) of pure, single-phase orthorhombic FeTi2O5. Wettability measurements conducted on amorphous low Fe-doped TiO2 samples revealed superhydrophilic properties with a surface–water contact angle <1°, whereas optical absorption and reflectance measurements yield bandgap widening and narrowing. A bandgap narrowing occurs with the formation of oxygen vacancies and of Ti3+ levels, but if the concentration of oxygen vacancies and Ti3+ levels increases, more electron donors are generated, which shift the Fermi level to the conduction band. This widening of the bandgap (blue shift) can be explained by the Burstein–Moss effect. The correlation of the large optical bandgap (3.61 < Eg < 3.74 eV) and the wettability results are interpreted and discussed with the presence of oxygen vacancies and Ti3+ and Fe3+ sites in the TiO2 matrix. [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: |
Complementary Index |
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