Structural and vibrational investigations of Nb-doped TiO{sub 2} thin films

Journal Article · Mon Dec 15 04:00:00 EST 2014 · Materials Research Bulletin

DOI:https://doi.org/10.1016/J.MATERRESBULL.2014.08.035· OSTI ID:22420669

Gibaud, A.; Daniel, P. ^[1]; Sangaa, D.; Sevjidsuren, G.; Altantsog, P. ^[2]; Beuvier, T. ^[1]; Lee, Chih Hao ^[3]; Balagurov, A. M. ^[4]

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1. LUNAM Université, Université du Maine, CNRS UMR 6283, Institut des molécules et matériaux et du Mans–IMMM, Avenue Olivier Messiaen, Le Mans 72085 Cedex 9 (France)
2. Institute of Physics and Technology, Mongolian Academy of Sciences, Enkhtaivan Avenue 54B, Ulaanbaatar 13330 (Mongolia)
3. Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan (China)
4. Frank Laboratory of Neutron Physics, JINR, Dubna 141980 (Russian Federation)

Highlights: • We studied the evolutions of structure for TiO{sub 2} thin film as changes with Nb doping and temperatures. • Up to 800 °C, the grain size of Nb{sub 0.1}Ti{sub 0.9}O{sub 2} is smaller than for pure TiO{sub 2} because doped Nb hinders the growth of the TiO{sub 2} grains. • There was no formation of the rutile phase at high temperature. • Nb doped TiO{sub 2} films have high electron densities at 400–700 °C. • Nb dope extends the absorbance spectra of TiO{sub 2} which leads to the band gap reduce. - Abstract: Acid-catalyzed sol–gel and spin-coating methods were used to prepare Nb-doped TiO{sub 2} thin film. In this work, we studied the effect of niobium doping on the structure, surface, and absorption properties of TiO{sub 2} by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray reflectometry (XRR), X-ray photoelectron spectroscopy (XPS), Raman, and UV–vis absorption spectroscopy at various annealing temperatures. EDX spectra show that the Nb:Ti atomic ratios of the niobium-doped titania films are in good agreement with the nominal values (5 and 10%). XPS results suggest that charge compensation is achieved by the formation of Ti vacancies. Specific niobium phases are not observed, thus confirming that niobium is well incorporated into the titania crystal lattice. Thin films are amorphous at room temperature and the formation of anatase phase appeared at an annealing temperature close to 400 °C. The rutile phase was not observed even at 900 °C (XRD and Raman spectroscopy). Grain sizes and electron densities increased when the temperature was raised. Nb-doped films have higher electron densities and lower grain sizes due to niobium doping. Grain size inhibition can be explained by lattice stress induced by the incorporation of larger Nb{sup 5+} ions into the lattice. The band gap energy of indirect transition of the TiO{sub 2} thin films was calculated to be about 3.03 eV. After niobium doping, it decreased to 2.40 eV.

• OSTI ID: 22420669
• Journal Information: Materials Research Bulletin, Journal Name: Materials Research Bulletin Vol. 60; ISSN MRBUAC; ISSN 0025-5408
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ABSORPTION SPECTROSCOPY
ANNEALING
CRYSTAL LATTICES
DOPED MATERIALS
ELECTRON DENSITY
EV RANGE
GRAIN SIZE
NIOBIUM IONS
RAMAN SPECTROSCOPY
SOL-GEL PROCESS
STRESSES
TEMPERATURE DEPENDENCE
THIN FILMS
TITANIUM OXIDES
VACANCIES
X-RAY DIFFRACTION
X-RAY PHOTOELECTRON SPECTROSCOPY
X-RAY SPECTROSCOPY