Crystalline phase transformation of electrospinning TiO2 nanofibres carried out by high temperature annealing

Secundino-Sánchez, O.; Dı́az-Reyes, J.; Aguila-López, J.; Ramírez, José Saúl Padilla

doi:10.1016/j.molstruc.2019.05.092

Cited by 23 publications

(16 citation statements)

References 37 publications

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“…21–1276) phases. The mixed TiO 2 phases resulted from the incomplete transition from anatase completely to rutile in high temperature [ 20 ]. There was no EMW absorption performance discrepancy between the two types of TiO 2 [ 21 ].…”

Section: Resultsmentioning

confidence: 99%

Non-Magnetic Bimetallic MOF-Derived Porous Carbon-Wrapped TiO2/ZrTiO4 Composites for Efficient Electromagnetic Wave Absorption

et al. 2021

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Highlights Non-magnetic bimetallic MOF-derived porous carbon-wrapped TiO2/ZrTiO4 composites are firstly used for efficient electromagnetic wave absorption. The electromagnetic wave absorption mechanisms including enhanced interfacial polarization and essential conductivity are intensively discussed. Abstract Modern communication technologies put forward higher requirements for electromagnetic wave (EMW) absorption materials. Metal–organic framework (MOF) derivatives have been widely concerned with its diverse advantages. To break the mindset of magnetic-derivative design, and make up the shortage of monometallic non-magnetic derivatives, we first try non-magnetic bimetallic MOFs derivatives to achieve efficient EMW absorption. The porous carbon-wrapped TiO2/ZrTiO4 composites derived from PCN-415 (TiZr-MOFs) are qualified with a minimum reflection loss of − 67.8 dB (2.16 mm, 13.0 GHz), and a maximum effective absorption bandwidth of 5.9 GHz (2.70 mm). Through in-depth discussions, the synergy of enhanced interfacial polarization and other attenuation mechanisms in the composites is revealed. Therefore, this work confirms the huge potentials of non-magnetic bimetallic MOFs derivatives in EMW absorption applications.

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Section: Resultsmentioning

confidence: 99%

Non-Magnetic Bimetallic MOF-Derived Porous Carbon-Wrapped TiO2/ZrTiO4 Composites for Efficient Electromagnetic Wave Absorption

et al. 2021

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“…In order to determine the crystalline phase and structural quality of TiO2, Raman scattering and X-ray diffraction (XRD) analysis of the samples were performed. As is shown by Raman spectroscopy, measured in the 80-800 cm -1 range, the as-synthesised TiO2-NF's are amorphous and become crystalline after annealing at a determined high temperature in an air atmosphere, which causes the annealed TiO2-NF's to transform the crystalline structure from amorphous  anatase  anatase-rutile mixed  rutile [27] (see Fig. 3A).…”

Section: Characterization By Raman Spectroscopymentioning

confidence: 84%

“…3B illustrates four typical Raman spectra of the samples (M5, M6, M8 and M9) that allow to clearly observe the vibrational bands associated to the different CP's, also the structural quality of the annealed samples. Additionally, it can be observed that there is a critical annealing temperature at which the CP transformation occurs, normally ~560 °C [27]. The M5 sample (AT = 500 °C) Raman spectrum (a) in Fig.…”

Section: Characterization By Raman Spectroscopymentioning

confidence: 99%

Systematic Structural and Optical Characterization of TiO2 Nanofibres Synthesised by Electrospinning

Secundino-Sánchez

Ramírez

Dı́az-Reyes

2021

Wseas Transactions on Electronics

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TiO2 nanofibres 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 nanofibres 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 nanofibres 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 nanofibres 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 microscopy. The average grain size, inside the nanofibres, 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, which is ranged in 3.75  Eg  2.42 eV, caused by the anatase → rutile crystalline phase transformation. The photoluminescence shows that radiative bands present a gradual red-shift as the annealing temperature increases due to the continuous change of Eg.

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“…However, this precursor produced bers that collapsed and fused easily, unlike in the case of either capillary needle or free-surface DC-electrospinning. [24][25][26][27][28][29][30][31][32][33]36,37 The fusion of AFES Ti(OBu) 4 /PVP bers can be attributed to the high density of brous ow and increased amount of residual solvent in collected bers. It has been determined that the PVP/HPC polymer blend with 1 : 1 mass ratio resulted in both good precursor spinnability and improved quality of collected brous material.…”

Section: Resultsmentioning

confidence: 99%

“…TiO 2 nanobers are mainly prepared by thermal processing of precursor bers fabricated by direct current (DC) electrospinning. [24][25][26][27][28][29][30] This simple method utilizes a static electric eld to generate the propagating liquid precursor jets that form bers upon drying. Usually, the precursor solution containing titanium alkoxide, polymer, and solvent in different molar ratios, is delivered through a capillary needle, which serves as the jet-generating electrode, and then solidied precursor bers are collected on an oppositely charged electrode.…”

Section: Introductionmentioning

confidence: 99%

Nanofibrous TiO₂produced using alternating field electrospinning of titanium alkoxide precursors: crystallization and phase development

et al. 2020

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Crystalline phase transformation of electrospinning TiO2 nanofibres carried out by high temperature annealing

Cited by 23 publications

References 37 publications

Non-Magnetic Bimetallic MOF-Derived Porous Carbon-Wrapped TiO2/ZrTiO4 Composites for Efficient Electromagnetic Wave Absorption

Non-Magnetic Bimetallic MOF-Derived Porous Carbon-Wrapped TiO2/ZrTiO4 Composites for Efficient Electromagnetic Wave Absorption

Systematic Structural and Optical Characterization of TiO2 Nanofibres Synthesised by Electrospinning

Nanofibrous TiO₂produced using alternating field electrospinning of titanium alkoxide precursors: crystallization and phase development

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Crystalline phase transformation of electrospinning TiO2 nanofibres carried out by high temperature annealing

Cited by 23 publications

References 37 publications

Non-Magnetic Bimetallic MOF-Derived Porous Carbon-Wrapped TiO2/ZrTiO4 Composites for Efficient Electromagnetic Wave Absorption

Non-Magnetic Bimetallic MOF-Derived Porous Carbon-Wrapped TiO2/ZrTiO4 Composites for Efficient Electromagnetic Wave Absorption

Systematic Structural and Optical Characterization of TiO2 Nanofibres Synthesised by Electrospinning

Nanofibrous TiO2produced using alternating field electrospinning of titanium alkoxide precursors: crystallization and phase development

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Nanofibrous TiO₂produced using alternating field electrospinning of titanium alkoxide precursors: crystallization and phase development