Synthesis and properties of Bi5Nb3O15 thin films prepared by dual co-sputtering
Por:
Depablos-Rivera, Osmary, Medina, Juan C., Bizarro, Monserrat, Martinez, Ana, Zeinert, Andreas, Rodil, Sandra E.
Publicada:
25 feb 2017
Resumen:
Bismuth-based oxides have gained attention because of their particular
electronic configuration that enhances the mobility of photogenerated
carriers. In this work, we focused on the synthesis, and the evaluation
of the physical and photocatalytic properties of Bi5Nb3O15 films.
Bismuth niobate films were deposited by dual magnetron co-sputtering,
starting from Bi2O3 and Nb independently driven targets. Although the
substrates were heated at 150 degrees C during the deposition, the films
were amorphous; therefore, they were annealed at 600 degrees C in air
for 2 h to obtain the nanocrystalline Bi5Nb3O15 orthorhombic phase. The
Bi5Nb3O15 compound is an interesting material for applications in
microelectronics due to its high-k dielectric value at the
radiofrequency range; another possible and reported application is as
photocatalyst for degradation of organic pollutants and water splitting
processes. The films structure was confirmed by X-ray diffraction
(theta-2 theta and in-plane modes). The Raman and infrared spectra were
measured and compared with calculated vibrational modes since they have
not been reported in the past. The optical properties (refractive index,
extinction and absorption coefficients) of the Bi5Nb3O15 films were
estimated using UV-VIS reflectance and transmittance spectroscopy. The
optical band gap was estimated assuming an indirect fundamental
inter-band transition at 3.25 eV. The prospective to use the Bi5Nb3O15
films as a photocatalyst was evaluated through the measurement of the
photo-discoloration of indigo carmine (IC) dye solutions (5 ppm) under
UV light irradiation at three pHs: 3.5, 7 and 11. The results showed a
decrease in the absorbance spectrum of the IC solution as a function of
irradiation time only at acidic pH where almost 100% of degradation was
achieved at 270 min; this behavior is probably due to the increment of
the adsorption of IC molecules on the positively charged surface. A
similar response was observed after 5 cycles without any structural
change of the films. (C) 2016 Elsevier B.V. All rights reserved.
Filiaciones:
Depablos-Rivera, Osmary:
Univ Nacl Autonoma Mexico, Inst Invest Mat, Circuito Exterior S-N CU, Mexico City 04510, DF, Mexico
Univ Nacl Autonoma Mexico, Posgrad Ciencia & Ingn Mat, Unidad Posgrad, Edificio C,Piso 1, Mexico City 04510, DF, Mexico
Medina, Juan C.:
Univ Nacl Autonoma Mexico, Inst Invest Mat, Circuito Exterior S-N CU, Mexico City 04510, DF, Mexico
Univ Nacl Autonoma Mexico, Posgrad Ciencia & Ingn Mat, Unidad Posgrad, Edificio C,Piso 1, Mexico City 04510, DF, Mexico
Bizarro, Monserrat:
Univ Nacl Autonoma Mexico, Inst Invest Mat, Circuito Exterior S-N CU, Mexico City 04510, DF, Mexico
Martinez, Ana:
Univ Nacl Autonoma Mexico, Inst Invest Mat, Circuito Exterior S-N CU, Mexico City 04510, DF, Mexico
Zeinert, Andreas:
Univ Picardie Jules Verne, Lab Phys Matiere Condensee, 33 Rue St Leu, F-80039 Amiens 1, France
Rodil, Sandra E.:
Univ Nacl Autonoma Mexico, Inst Invest Mat, Circuito Exterior S-N CU, Mexico City 04510, DF, Mexico
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