TY - JOUR
T1 - Systematic structural and optical characterization of tio2 nanofibers synthesised by electrospinning
AU - Secundino-Sánchez, Oscar
AU - Sánchez-Ramírez, José F.
AU - Diaz-Reyes, Joel
N1 - Publisher Copyright:
© 2021, North Atlantic University Union NAUN. All rights reserved.
PY - 2021
Y1 - 2021
N2 - TiO2 nanofibers were synthesised by means of the electrospinning technique, which were annealed at high temperatures to achieve the crystalline phase transformation. The chemical stoichiometry of electrospun TiO2 nanofibers was estimated by EDS, finding that at low annealing temperatures excess of oxygen was detected and at high temperatures excess of titanium that originates oxygen vacancies. TEM images show clearly the formation of TiO2 nanofibers (NF’s) that exhibit a homogeneous and continuous aspect without the presence of crystalline defects, whose surface morphology depends strongly on the annealing temperature. The crystalline phase transformation was studied by Raman spectroscopy, which revealed that annealed TiO2 NF’s showed a crystalline phase transformation from pure anatase to, first a mix of anatase-rutile, then pure rutile as the annealing temperature increased, which was corroborated by X-ray diffraction and high-resolution TEM diffraction. The average grain size, inside the NF´s, increased with the crystalline phase transformation from 10 to 24 nm for anatase-TiO2 and from 30 to 47 nm for rutile-TiO2, estimated by using the Scherrer-Debye equation. The band gap energy (Eg), obtained from optical absorption spectra, decreases monotonically, where a local minimum is observed at 700 °C ranged in 3.75 £ Eg £ 2.42 eV, caused by the anatase → rutile crystalline phase transformation. The photoluminescence shows that radiative bands show a gradual red-shift as the temperature increases due to the continuous change of Eg.
AB - TiO2 nanofibers were synthesised by means of the electrospinning technique, which were annealed at high temperatures to achieve the crystalline phase transformation. The chemical stoichiometry of electrospun TiO2 nanofibers was estimated by EDS, finding that at low annealing temperatures excess of oxygen was detected and at high temperatures excess of titanium that originates oxygen vacancies. TEM images show clearly the formation of TiO2 nanofibers (NF’s) that exhibit a homogeneous and continuous aspect without the presence of crystalline defects, whose surface morphology depends strongly on the annealing temperature. The crystalline phase transformation was studied by Raman spectroscopy, which revealed that annealed TiO2 NF’s showed a crystalline phase transformation from pure anatase to, first a mix of anatase-rutile, then pure rutile as the annealing temperature increased, which was corroborated by X-ray diffraction and high-resolution TEM diffraction. The average grain size, inside the NF´s, increased with the crystalline phase transformation from 10 to 24 nm for anatase-TiO2 and from 30 to 47 nm for rutile-TiO2, estimated by using the Scherrer-Debye equation. The band gap energy (Eg), obtained from optical absorption spectra, decreases monotonically, where a local minimum is observed at 700 °C ranged in 3.75 £ Eg £ 2.42 eV, caused by the anatase → rutile crystalline phase transformation. The photoluminescence shows that radiative bands show a gradual red-shift as the temperature increases due to the continuous change of Eg.
KW - Crystalline phase transformation
KW - Electrospinning technique
KW - Optical properties
KW - Semiconductor nanofibres
KW - Thermal treatment
KW - Titanium dioxide
UR - http://www.scopus.com/inward/record.url?scp=85117591547&partnerID=8YFLogxK
U2 - 10.46300/9106.2021.15.162
DO - 10.46300/9106.2021.15.162
M3 - Artículo
AN - SCOPUS:85117591547
SN - 1998-4464
VL - 15
SP - 1497
EP - 1505
JO - International Journal of Circuits, Systems and Signal Processing
JF - International Journal of Circuits, Systems and Signal Processing
ER -